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cosmopolitan/third_party/stb/stb_image.c

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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program is distributed in the hope that it will be useful, but │
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/bits/bits.h"
#include "libc/calls/calls.h"
#include "libc/fmt/conv.h"
#include "libc/limits.h"
#include "libc/log/gdb.h"
#include "libc/log/log.h"
#include "libc/macros.h"
#include "libc/math.h"
#include "libc/mem/mem.h"
#include "libc/nexgen32e/x86feature.h"
#include "libc/runtime/runtime.h"
#include "libc/stdio/stdio.h"
#include "libc/str/str.h"
#include "libc/x/x.h"
#include "third_party/stb/internal.h"
#include "third_party/stb/stb_image.h"
#define ROL(w, k) ((w) << (k) | CheckUnsigned(w) >> (sizeof(w) * 8 - (k)))
asm(".ident\t\"\\n\\n\
stb_image (Public Domain)\\n\
Credit: Sean Barrett, et al.\\n\
http://nothings.org/stb\"");
#ifndef STBI_REALLOC_SIZED
#define STBI_REALLOC_SIZED(p, oldsz, newsz) realloc(p, newsz)
#endif
// stbi__context structure is our basic context used by all images, so it
// contains all the IO context, plus some basic image information
typedef struct {
uint32_t img_x, img_y;
int img_n, img_out_n;
stbi_io_callbacks io;
void *io_user_data;
int read_from_callbacks;
int buflen;
unsigned char buffer_start[128];
unsigned char *img_buffer, *img_buffer_end;
unsigned char *img_buffer_original, *img_buffer_original_end;
} stbi__context;
static const unsigned char kPngSig[8] = {137, 80, 78, 71, 13, 10, 26, 10};
static void stbi__refill_buffer(stbi__context *s);
// initialize a memory-decode context
static void stbi__start_mem(stbi__context *s, unsigned char const *buffer,
int len) {
s->io.read = NULL;
s->read_from_callbacks = 0;
s->img_buffer = s->img_buffer_original = (unsigned char *)buffer;
s->img_buffer_end = s->img_buffer_original_end =
(unsigned char *)buffer + len;
}
// initialize a callback-based context
static void stbi__start_callbacks(stbi__context *s, stbi_io_callbacks *c,
void *user) {
s->io = *c;
s->io_user_data = user;
s->buflen = sizeof(s->buffer_start);
s->read_from_callbacks = 1;
s->img_buffer_original = s->buffer_start;
stbi__refill_buffer(s);
s->img_buffer_original_end = s->img_buffer_end;
}
static int stbi__stdio_read(void *user, char *data, int size) {
return fread(data, 1, size, user);
}
static void stbi__stdio_skip(void *user, int n) {
fseek(user, n, SEEK_CUR);
}
static int stbi__stdio_eof(void *user) {
return feof(user);
}
static stbi_io_callbacks stbi__stdio_callbacks = {
stbi__stdio_read,
stbi__stdio_skip,
stbi__stdio_eof,
};
static void stbi__start_file(stbi__context *s, FILE *f) {
stbi__start_callbacks(s, &stbi__stdio_callbacks, (void *)f);
}
static void stbi__rewind(stbi__context *s) {
// conceptually rewind SHOULD rewind to the beginning of the stream,
// but we just rewind to the beginning of the initial buffer, because
// we only use it after doing 'test', which only ever looks at at most 92
// bytes
s->img_buffer = s->img_buffer_original;
s->img_buffer_end = s->img_buffer_original_end;
}
enum { STBI_ORDER_RGB, STBI_ORDER_BGR };
typedef struct {
int bits_per_channel;
int num_channels;
} stbi__result_info;
static int stbi__jpeg_test(stbi__context *);
static void *stbi__jpeg_load(stbi__context *, int *, int *, int *, int,
stbi__result_info *);
static int stbi__jpeg_info(stbi__context *, int *, int *, int *);
static int stbi__png_test(stbi__context *);
static void *stbi__png_load(stbi__context *, int *, int *, int *, int,
stbi__result_info *);
static int stbi__png_info(stbi__context *, int *, int *, int *);
static int stbi__png_is16(stbi__context *);
static int stbi__gif_test(stbi__context *);
static void *stbi__gif_load(stbi__context *, int *, int *, int *, int,
stbi__result_info *);
static void *stbi__load_gif_main(stbi__context *, int **, int *, int *, int *,
int *, int);
static int stbi__gif_info(stbi__context *, int *, int *, int *);
static int stbi__pnm_test(stbi__context *);
static void *stbi__pnm_load(stbi__context *, int *, int *, int *, int,
stbi__result_info *);
static int stbi__pnm_info(stbi__context *, int *, int *, int *);
static const char *stbi__g_failure_reason;
static int stbi__vertically_flip_on_load = 0;
const char *stbi_failure_reason(void) {
return stbi__g_failure_reason;
}
static int stbi__err(const char *specific_details,
const char *general_details) {
/* DebugBreak(); */
/* WARNF("%s: %s", general_details, specific_details); */
stbi__g_failure_reason = general_details;
return 0;
}
// stb_image uses ints pervasively, including for offset calculations.
// therefore the largest decoded image size we can support with the
// current code, even on 64-bit targets, is INT_MAX. this is not a
// significant limitation for the intended use case.
//
// we do, however, need to make sure our size calculations don't
// overflow. hence a few helper functions for size calculations that
// multiply integers together, making sure that they're non-negative
// and no overflow occurs.
// return 1 if the sum is valid, 0 on overflow.
// negative terms are considered invalid.
static int stbi__addsizes_valid(int a, int b) {
if (b < 0) return 0;
// now 0 <= b <= INT_MAX, hence also
// 0 <= INT_MAX - b <= INTMAX.
// And "a + b <= INT_MAX" (which might overflow) is the
// same as a <= INT_MAX - b (no overflow)
return a <= INT_MAX - b;
}
// returns 1 if the product is valid, 0 on overflow.
// negative factors are considered invalid.
static int stbi__mul2sizes_valid(int a, int b) {
if (a < 0 || b < 0) return 0;
if (b == 0) return 1; // mul-by-0 is always safe
// portable way to check for no overflows in a*b
return a <= INT_MAX / b;
}
// returns 1 if "a*b + add" has no negative terms/factors and doesn't overflow
static int stbi__mad2sizes_valid(int a, int b, int add) {
return stbi__mul2sizes_valid(a, b) && stbi__addsizes_valid(a * b, add);
}
// returns 1 if "a*b*c + add" has no negative terms/factors and doesn't overflow
static int stbi__mad3sizes_valid(int a, int b, int c, int add) {
return stbi__mul2sizes_valid(a, b) && stbi__mul2sizes_valid(a * b, c) &&
stbi__addsizes_valid(a * b * c, add);
}
// mallocs with size overflow checking
static void *stbi__malloc_mad2(int a, int b, int add) {
if (!stbi__mad2sizes_valid(a, b, add)) return NULL;
return xmalloc(a * b + add);
}
static void *stbi__malloc_mad3(int a, int b, int c, int add) {
if (!stbi__mad3sizes_valid(a, b, c, add)) return NULL;
return xmalloc(a * b * c + add);
}
#define stbi__errpf(x, y) \
({ \
stbi__err(x, y); \
NULL; \
})
#define stbi__errpuc(x, y) \
({ \
stbi__err(x, y); \
NULL; \
})
void stbi_image_free(void *retval_from_stbi_load) {
free(retval_from_stbi_load);
}
void stbi_set_flip_vertically_on_load(int flag_true_if_should_flip) {
stbi__vertically_flip_on_load = flag_true_if_should_flip;
}
static void *stbi__load_main(stbi__context *s, int *x, int *y, int *comp,
int req_comp, stbi__result_info *ri, int bpc) {
memset(ri, 0, sizeof(*ri));
ri->bits_per_channel = 8;
ri->num_channels = 0;
#ifndef STBI_NO_JPEG
if (stbi__jpeg_test(s)) return stbi__jpeg_load(s, x, y, comp, req_comp, ri);
#endif
#ifndef STBI_NO_PNG
if (stbi__png_test(s)) return stbi__png_load(s, x, y, comp, req_comp, ri);
#endif
#ifndef STBI_NO_GIF
if (stbi__gif_test(s)) return stbi__gif_load(s, x, y, comp, req_comp, ri);
#endif
#ifndef STBI_NO_PNM
if (stbi__pnm_test(s)) return stbi__pnm_load(s, x, y, comp, req_comp, ri);
#endif
return stbi__errpuc("unknown image type",
"Image not of any known type, or corrupt");
}
unsigned char *stbi__convert_16_to_8(uint16_t *orig, int w, int h,
int channels) {
int i;
int img_len = w * h * channels;
unsigned char *reduced = xmalloc(img_len);
for (i = 0; i < img_len; ++i) {
// top half of each byte is sufficient
// approx of 16->8 bit scaling
reduced[i] = (orig[i] >> 8) & 0xff;
}
free(orig);
return reduced;
}
uint16_t *stbi__convert_8_to_16(unsigned char *orig, int w, int h,
int channels) {
int i;
int img_len = w * h * channels;
uint16_t *enlarged = xmalloc(img_len * 2);
for (i = 0; i < img_len; ++i) {
// replicate to high and low byte, maps 0->0, 255->0xffff
enlarged[i] = (uint16_t)((orig[i] << 8) + orig[i]);
}
free(orig);
return enlarged;
}
static void stbi__vertical_flip(void *image, int w, int h,
int bytes_per_pixel) {
int row;
size_t bytes_per_row, bytes_left, bytes_copy;
unsigned char *row0, *row1, *bytes, temp[2048];
bytes = image;
bytes_per_row = bytes_per_pixel * w;
for (row = 0; row < (h >> 1); row++) {
row0 = bytes + row * bytes_per_row;
row1 = bytes + (h - row - 1) * bytes_per_row;
// swap row0 with row1
bytes_left = bytes_per_row;
while (bytes_left) {
bytes_copy = bytes_left < sizeof(temp) ? bytes_left : sizeof(temp);
memcpy(temp, row0, bytes_copy);
memcpy(row0, row1, bytes_copy);
memcpy(row1, temp, bytes_copy);
row0 += bytes_copy;
row1 += bytes_copy;
bytes_left -= bytes_copy;
}
}
}
static void stbi__vertical_flip_slices(void *image, int w, int h, int z,
int bytes_per_pixel) {
unsigned char *bytes;
int slice, slice_size;
bytes = image;
slice_size = w * h * bytes_per_pixel;
for (slice = 0; slice < z; ++slice) {
stbi__vertical_flip(bytes, w, h, bytes_per_pixel);
bytes += slice_size;
}
}
static unsigned char *stbi__load_and_postprocess_8bit(stbi__context *s, int *x,
int *y, int *comp,
int req_comp) {
void *result;
stbi__result_info ri;
result = stbi__load_main(s, x, y, comp, req_comp, &ri, 8);
if (result == NULL) return NULL;
if (ri.bits_per_channel != 8) {
assert(ri.bits_per_channel == 16);
result =
stbi__convert_16_to_8(result, *x, *y, req_comp == 0 ? *comp : req_comp);
ri.bits_per_channel = 8;
}
// @TODO: move stbi__convert_format to here
if (stbi__vertically_flip_on_load) {
int channels = req_comp ? req_comp : *comp;
stbi__vertical_flip(result, *x, *y, channels * sizeof(unsigned char));
}
return (unsigned char *)result;
}
static uint16_t *stbi__load_and_postprocess_16bit(stbi__context *s, int *x,
int *y, int *comp,
int req_comp) {
stbi__result_info ri;
void *result = stbi__load_main(s, x, y, comp, req_comp, &ri, 16);
if (result == NULL) return NULL;
if (ri.bits_per_channel != 16) {
assert(ri.bits_per_channel == 8);
result = stbi__convert_8_to_16((unsigned char *)result, *x, *y,
req_comp == 0 ? *comp : req_comp);
ri.bits_per_channel = 16;
}
// @TODO: move stbi__convert_format16 to here
// @TODO: special case RGB-to-Y (and RGBA-to-YA) for 8-bit-to-16-bit case to
// keep more precision
if (stbi__vertically_flip_on_load) {
int channels = req_comp ? req_comp : *comp;
stbi__vertical_flip(result, *x, *y, channels * sizeof(uint16_t));
}
return (uint16_t *)result;
}
static FILE *stbi__fopen(char const *filename, char const *mode) {
return fopen(filename, mode);
}
unsigned char *stbi_load(char const *filename, int *x, int *y, int *comp,
int req_comp) {
FILE *f = stbi__fopen(filename, "rb");
unsigned char *result;
if (!f) return stbi__errpuc("can't fopen", "Unable to open file");
result = stbi_load_from_file(f, x, y, comp, req_comp);
fclose(f);
return result;
}
unsigned char *stbi_load_from_file(FILE *f, int *x, int *y, int *comp,
int req_comp) {
unsigned char *result;
stbi__context s;
stbi__start_file(&s, f);
result = stbi__load_and_postprocess_8bit(&s, x, y, comp, req_comp);
if (result) {
// need to 'unget' all the characters in the IO buffer
fseek(f, -(int)(s.img_buffer_end - s.img_buffer), SEEK_CUR);
}
return result;
}
uint16_t *stbi_load_from_file_16(FILE *f, int *x, int *y, int *comp,
int req_comp) {
uint16_t *result;
stbi__context s;
stbi__start_file(&s, f);
result = stbi__load_and_postprocess_16bit(&s, x, y, comp, req_comp);
if (result) {
// need to 'unget' all the characters in the IO buffer
fseek(f, -(int)(s.img_buffer_end - s.img_buffer), SEEK_CUR);
}
return result;
}
unsigned short *stbi_load_16(char const *filename, int *x, int *y, int *comp,
int req_comp) {
FILE *f = stbi__fopen(filename, "rb");
uint16_t *result;
if (!f) return stbi__errpuc("can't fopen", "Unable to open file");
result = stbi_load_from_file_16(f, x, y, comp, req_comp);
fclose(f);
return result;
}
unsigned short *stbi_load_16_from_memory(unsigned char const *buffer, int len,
int *x, int *y, int *channels_in_file,
int desired_channels) {
stbi__context s;
stbi__start_mem(&s, buffer, len);
return stbi__load_and_postprocess_16bit(&s, x, y, channels_in_file,
desired_channels);
}
unsigned short *stbi_load_16_from_callbacks(stbi_io_callbacks const *clbk,
void *user, int *x, int *y,
int *channels_in_file,
int desired_channels) {
stbi__context s;
stbi__start_callbacks(&s, (stbi_io_callbacks *)clbk, user);
return stbi__load_and_postprocess_16bit(&s, x, y, channels_in_file,
desired_channels);
}
unsigned char *stbi_load_from_memory(unsigned char const *buffer, int len,
int *x, int *y, int *comp, int req_comp) {
stbi__context s;
stbi__start_mem(&s, buffer, len);
return stbi__load_and_postprocess_8bit(&s, x, y, comp, req_comp);
}
unsigned char *stbi_load_from_callbacks(stbi_io_callbacks const *clbk,
void *user, int *x, int *y, int *comp,
int req_comp) {
stbi__context s;
stbi__start_callbacks(&s, (stbi_io_callbacks *)clbk, user);
return stbi__load_and_postprocess_8bit(&s, x, y, comp, req_comp);
}
unsigned char *stbi_load_gif_from_memory(unsigned char const *buffer, int len,
int **delays, int *x, int *y, int *z,
int *comp, int req_comp) {
unsigned char *result;
stbi__context s;
stbi__start_mem(&s, buffer, len);
result =
(unsigned char *)stbi__load_gif_main(&s, delays, x, y, z, comp, req_comp);
if (stbi__vertically_flip_on_load) {
stbi__vertical_flip_slices(result, *x, *y, *z, *comp);
}
return result;
}
enum { STBI__SCAN_load = 0, STBI__SCAN_type, STBI__SCAN_header };
static void stbi__refill_buffer(stbi__context *s) {
int n = (s->io.read)(s->io_user_data, (char *)s->buffer_start, s->buflen);
if (n == 0) {
// at end of file, treat same as if from memory, but need to handle case
// where s->img_buffer isn't pointing to safe memory, e.g. 0-byte file
s->read_from_callbacks = 0;
s->img_buffer = s->buffer_start;
s->img_buffer_end = s->buffer_start + 1;
*s->img_buffer = 0;
} else {
s->img_buffer = s->buffer_start;
s->img_buffer_end = s->buffer_start + n;
}
}
forceinline unsigned char stbi__get8(stbi__context *s) {
if (s->img_buffer < s->img_buffer_end) return *s->img_buffer++;
if (s->read_from_callbacks) {
stbi__refill_buffer(s);
return *s->img_buffer++;
}
return 0;
}
forceinline int stbi__at_eof(stbi__context *s) {
if (s->io.read) {
if (!(s->io.eof)(s->io_user_data)) return 0;
// if feof() is true, check if buffer = end
// special case: we've only got the special 0 character at the end
if (s->read_from_callbacks == 0) return 1;
}
return s->img_buffer >= s->img_buffer_end;
}
static void stbi__skip(stbi__context *s, int n) {
if (n < 0) {
s->img_buffer = s->img_buffer_end;
return;
}
if (s->io.read) {
int blen = (int)(s->img_buffer_end - s->img_buffer);
if (blen < n) {
s->img_buffer = s->img_buffer_end;
(s->io.skip)(s->io_user_data, n - blen);
return;
}
}
s->img_buffer += n;
}
static int stbi__getn(stbi__context *s, unsigned char *buffer, int n) {
if (s->io.read) {
int blen = (int)(s->img_buffer_end - s->img_buffer);
if (blen < n) {
int res, count;
memcpy(buffer, s->img_buffer, blen);
count = (s->io.read)(s->io_user_data, (char *)buffer + blen, n - blen);
res = (count == (n - blen));
s->img_buffer = s->img_buffer_end;
return res;
}
}
if (s->img_buffer + n <= s->img_buffer_end) {
memcpy(buffer, s->img_buffer, n);
s->img_buffer += n;
return 1;
} else {
return 0;
}
}
static int stbi__get16le(stbi__context *s) {
int z = stbi__get8(s);
return z + (stbi__get8(s) << 8);
}
static int stbi__get16be(stbi__context *s) {
int z = stbi__get8(s);
return (z << 8) + stbi__get8(s);
}
static uint32_t stbi__get32be(stbi__context *s) {
uint32_t z = stbi__get16be(s);
return (z << 16) + stbi__get16be(s);
}
#define STBI__BYTECAST(x) \
((unsigned char)((x)&255)) // truncate int to byte without warnings
//////////////////////////////////////////////////////////////////////////////
//
// generic converter from built-in img_n to req_comp
// individual types do this automatically as much as possible (e.g. jpeg
// does all cases internally since it needs to colorspace convert anyway,
// and it never has alpha, so very few cases ). png can automatically
// interleave an alpha=255 channel, but falls back to this for other cases
//
// assume data buffer is malloced, so malloc a new one and free that one
// only failure mode is malloc failing
static unsigned char stbi__compute_y(int r, int g, int b) {
return (unsigned char)(((r * 77) + (g * 150) + (29 * b)) >> 8);
}
static unsigned char *stbi__convert_format(unsigned char *data, int img_n,
int req_comp, unsigned int x,
unsigned int y) {
int i, j;
unsigned char *good, *src, *dest;
if (req_comp == img_n) return data;
assert(req_comp >= 1 && req_comp <= 4);
good = stbi__malloc_mad3(req_comp, x, y, 0);
for (j = 0; j < (int)y; ++j) {
src = data + j * x * img_n;
dest = good + j * x * req_comp;
#define STBI__COMBO(a, b) ((a)*8 + (b))
#define STBI__CASE(a, b) \
case STBI__COMBO(a, b): \
for (i = x - 1; i >= 0; --i, src += a, dest += b)
// convert source image with img_n components to one with req_comp
// components; avoid switch per pixel, so use switch per scanline and
// massive macros
switch (STBI__COMBO(img_n, req_comp)) {
STBI__CASE(1, 2) {
dest[0] = src[0];
dest[1] = 255;
}
break;
STBI__CASE(1, 3) {
dest[0] = dest[1] = dest[2] = src[0];
}
break;
STBI__CASE(1, 4) {
dest[0] = dest[1] = dest[2] = src[0];
dest[3] = 255;
}
break;
STBI__CASE(2, 1) {
dest[0] = src[0];
}
break;
STBI__CASE(2, 3) {
dest[0] = dest[1] = dest[2] = src[0];
}
break;
STBI__CASE(2, 4) {
dest[0] = dest[1] = dest[2] = src[0];
dest[3] = src[1];
}
break;
STBI__CASE(3, 4) {
dest[0] = src[0];
dest[1] = src[1];
dest[2] = src[2];
dest[3] = 255;
}
break;
STBI__CASE(3, 1) {
dest[0] = stbi__compute_y(src[0], src[1], src[2]);
}
break;
STBI__CASE(3, 2) {
dest[0] = stbi__compute_y(src[0], src[1], src[2]);
dest[1] = 255;
}
break;
STBI__CASE(4, 1) {
dest[0] = stbi__compute_y(src[0], src[1], src[2]);
}
break;
STBI__CASE(4, 2) {
dest[0] = stbi__compute_y(src[0], src[1], src[2]);
dest[1] = src[3];
}
break;
STBI__CASE(4, 3) {
dest[0] = src[0];
dest[1] = src[1];
dest[2] = src[2];
}
break;
default:
assert(0);
}
#undef STBI__CASE
}
free(data);
return good;
}
static uint16_t stbi__compute_y_16(int r, int g, int b) {
return (uint16_t)(((r * 77) + (g * 150) + (29 * b)) >> 8);
}
static uint16_t *stbi__convert_format16(uint16_t *data, int img_n, int req_comp,
unsigned int x, unsigned int y) {
int i, j;
uint16_t *good;
if (req_comp == img_n) return data;
assert(req_comp >= 1 && req_comp <= 4);
good = xmalloc(req_comp * x * y * 2);
for (j = 0; j < (int)y; ++j) {
uint16_t *src = data + j * x * img_n;
uint16_t *dest = good + j * x * req_comp;
#define STBI__COMBO(a, b) ((a)*8 + (b))
#define STBI__CASE(a, b) \
case STBI__COMBO(a, b): \
for (i = x - 1; i >= 0; --i, src += a, dest += b)
// convert source image with img_n components to one with req_comp
// components; avoid switch per pixel, so use switch per scanline and
// massive macros
switch (STBI__COMBO(img_n, req_comp)) {
STBI__CASE(1, 2) {
dest[0] = src[0];
dest[1] = 0xffff;
}
break;
STBI__CASE(1, 3) {
dest[0] = dest[1] = dest[2] = src[0];
}
break;
STBI__CASE(1, 4) {
dest[0] = dest[1] = dest[2] = src[0];
dest[3] = 0xffff;
}
break;
STBI__CASE(2, 1) {
dest[0] = src[0];
}
break;
STBI__CASE(2, 3) {
dest[0] = dest[1] = dest[2] = src[0];
}
break;
STBI__CASE(2, 4) {
dest[0] = dest[1] = dest[2] = src[0];
dest[3] = src[1];
}
break;
STBI__CASE(3, 4) {
dest[0] = src[0];
dest[1] = src[1];
dest[2] = src[2];
dest[3] = 0xffff;
}
break;
STBI__CASE(3, 1) {
dest[0] = stbi__compute_y_16(src[0], src[1], src[2]);
}
break;
STBI__CASE(3, 2) {
dest[0] = stbi__compute_y_16(src[0], src[1], src[2]);
dest[1] = 0xffff;
}
break;
STBI__CASE(4, 1) {
dest[0] = stbi__compute_y_16(src[0], src[1], src[2]);
}
break;
STBI__CASE(4, 2) {
dest[0] = stbi__compute_y_16(src[0], src[1], src[2]);
dest[1] = src[3];
}
break;
STBI__CASE(4, 3) {
dest[0] = src[0];
dest[1] = src[1];
dest[2] = src[2];
}
break;
default:
assert(0);
}
#undef STBI__CASE
}
free(data);
return good;
}
//////////////////////////////////////////////////////////////////////////////
//
// "baseline" JPEG/JFIF decoder
//
// simple implementation
// - doesn't support delayed output of y-dimension
// - simple interface (only one output format: 8-bit interleaved RGB)
// - doesn't try to recover corrupt jpegs
// - doesn't allow partial loading, loading multiple at once
// - still fast on x86 (copying globals into locals doesn't help x86)
// - allocates lots of intermediate memory (full size of all components)
// - non-interleaved case requires this anyway
// - allows good upsampling (see next)
// high-quality
// - upsampled channels are bilinearly interpolated, even across blocks
// - quality integer IDCT derived from IJG's 'slow'
// performance
// - fast huffman; reasonable integer IDCT
// - some SIMD kernels for common paths on targets with SSE2/NEON
// - uses a lot of intermediate memory, could cache poorly
// huffman decoding acceleration
#define FAST_BITS 9 // larger handles more cases; smaller stomps less cache
typedef struct {
unsigned char fast[1 << FAST_BITS];
// weirdly, repacking this into AoS is a 10% speed loss, instead of a win
uint16_t code[256];
unsigned char values[256];
unsigned char size[257];
unsigned int maxcode[18];
int delta[17]; // old 'firstsymbol' - old 'firstcode'
} stbi__huffman;
typedef struct {
stbi__context *s;
stbi__huffman huff_dc[4];
stbi__huffman huff_ac[4];
uint16_t dequant[4][64];
int16_t fast_ac[4][1 << FAST_BITS];
// sizes for components, interleaved MCUs
int img_h_max, img_v_max;
int img_mcu_x, img_mcu_y;
int img_mcu_w, img_mcu_h;
// definition of jpeg image component
struct {
int id;
int h, v;
int tq;
int hd, ha;
int dc_pred;
int x, y, w2, h2;
unsigned char *data;
unsigned char *linebuf;
short *coeff; // progressive only
int coeff_w, coeff_h; // number of 8x8 coefficient blocks
} img_comp[4];
uint32_t code_buffer; // jpeg entropy-coded buffer
int code_bits; // number of valid bits
unsigned char marker; // marker seen while filling entropy buffer
int nomore; // flag if we saw a marker so must stop
int progressive;
int spec_start;
int spec_end;
int succ_high;
int succ_low;
int eob_run;
int jfif;
int app14_color_transform; // Adobe APP14 tag
int rgb;
int scan_n, order[4];
int restart_interval, todo;
// kernels
unsigned char *(*resample_row_hv_2_kernel)(unsigned char *out,
unsigned char *in_near,
unsigned char *in_far, int w,
int hs);
} stbi__jpeg;
static int stbi__build_huffman(stbi__huffman *h, int *count) {
int i, j, k = 0;
unsigned int code;
// build size list for each symbol (from JPEG spec)
for (i = 0; i < 16; ++i)
for (j = 0; j < count[i]; ++j) h->size[k++] = (unsigned char)(i + 1);
h->size[k] = 0;
// compute actual symbols (from jpeg spec)
code = 0;
k = 0;
for (j = 1; j <= 16; ++j) {
// compute delta to add to code to compute symbol id
h->delta[j] = k - code;
if (h->size[k] == j) {
while (h->size[k] == j) h->code[k++] = (uint16_t)(code++);
if (code - 1 >= (1u << j)) {
return stbi__err("bad code lengths", "Corrupt JPEG");
}
}
// compute largest code + 1 for this size, preshifted as needed later
h->maxcode[j] = code << (16 - j);
code <<= 1;
}
h->maxcode[j] = 0xffffffff;
// build non-spec acceleration table; 255 is flag for not-accelerated
memset(h->fast, 255, 1 << FAST_BITS);
for (i = 0; i < k; ++i) {
int s = h->size[i];
if (s <= FAST_BITS) {
int c = h->code[i] << (FAST_BITS - s);
int m = 1 << (FAST_BITS - s);
for (j = 0; j < m; ++j) {
h->fast[c + j] = (unsigned char)i;
}
}
}
return 1;
}
// build a table that decodes both magnitude and value of small ACs in
// one go.
static void stbi__build_fast_ac(int16_t *fast_ac, stbi__huffman *h) {
int i;
for (i = 0; i < (1 << FAST_BITS); ++i) {
unsigned char fast = h->fast[i];
fast_ac[i] = 0;
if (fast < 255) {
int rs = h->values[fast];
int run = (rs >> 4) & 15;
int magbits = rs & 15;
int len = h->size[fast];
if (magbits && len + magbits <= FAST_BITS) {
// magnitude code followed by receive_extend code
int k = ((i << len) & ((1 << FAST_BITS) - 1)) >> (FAST_BITS - magbits);
int m = 1 << (magbits - 1);
if (k < m) k += (~0U << magbits) + 1;
// if the result is small enough, we can fit it in fast_ac table
if (k >= -128 && k <= 127)
fast_ac[i] = (int16_t)((k * 256) + (run * 16) + (len + magbits));
}
}
}
}
static void stbi__grow_buffer_unsafe(stbi__jpeg *j) {
do {
unsigned b = j->nomore ? 0 : stbi__get8(j->s);
if (b == 0xff) {
int c = stbi__get8(j->s);
while (c == 0xff) c = stbi__get8(j->s); // consume fill bytes
if (c != 0) {
j->marker = (unsigned char)c;
j->nomore = 1;
return;
}
}
j->code_buffer |= b << (24 - j->code_bits);
j->code_bits += 8;
} while (j->code_bits <= 24);
}
// (1 << n) - 1
static const uint32_t stbi__bmask[17] = {0, 1, 3, 7, 15, 31,
63, 127, 255, 511, 1023, 2047,
4095, 8191, 16383, 32767, 65535};
// decode a jpeg huffman value from the bitstream
forceinline int stbi__jpeg_huff_decode(stbi__jpeg *j, stbi__huffman *h) {
unsigned int temp;
int c, k;
if (j->code_bits < 16) stbi__grow_buffer_unsafe(j);
// look at the top FAST_BITS and determine what symbol ID it is,
// if the code is <= FAST_BITS
c = (j->code_buffer >> (32 - FAST_BITS)) & ((1 << FAST_BITS) - 1);
k = h->fast[c];
if (k < 255) {
int s = h->size[k];
if (s > j->code_bits) return -1;
j->code_buffer <<= s;
j->code_bits -= s;
return h->values[k];
}
// naive test is to shift the code_buffer down so k bits are
// valid, then test against maxcode. To speed this up, we've
// preshifted maxcode left so that it has (16-k) 0s at the
// end; in other words, regardless of the number of bits, it
// wants to be compared against something shifted to have 16;
// that way we don't need to shift inside the loop.
temp = j->code_buffer >> 16;
for (k = FAST_BITS + 1;; ++k)
if (temp < h->maxcode[k]) break;
if (k == 17) {
// error! code not found
j->code_bits -= 16;
return -1;
}
if (k > j->code_bits) return -1;
// convert the huffman code to the symbol id
c = ((j->code_buffer >> (32 - k)) & stbi__bmask[k]) + h->delta[k];
assert((((j->code_buffer) >> (32 - h->size[c])) & stbi__bmask[h->size[c]]) ==
h->code[c]);
// convert the id to a symbol
j->code_bits -= k;
j->code_buffer <<= k;
return h->values[c];
}
// bias[n] = (-1<<n) + 1
static const int stbi__jbias[16] = {0, -1, -3, -7, -15, -31,
-63, -127, -255, -511, -1023, -2047,
-4095, -8191, -16383, -32767};
// combined JPEG 'receive' and JPEG 'extend', since baseline
// always extends everything it receives.
forceinline int stbi__extend_receive(stbi__jpeg *j, int n) {
int sgn;
unsigned int k;
// TODO(jart): what is this
if (j->code_bits < n) stbi__grow_buffer_unsafe(j);
sgn = (int32_t)j->code_buffer >> 31; // sign bit is always in MSB
k = ROL(j->code_buffer, n);
assert(n >= 0 && n < (int)(sizeof(stbi__bmask) / sizeof(*stbi__bmask)));
j->code_buffer = k & ~stbi__bmask[n];
k &= stbi__bmask[n];
j->code_bits -= n;
return k + (stbi__jbias[n] & ~sgn);
}
// get some unsigned bits
forceinline int stbi__jpeg_get_bits(stbi__jpeg *j, int n) {
unsigned int k;
if (j->code_bits < n) stbi__grow_buffer_unsafe(j);
k = ROL(j->code_buffer, n);
j->code_buffer = k & ~stbi__bmask[n];
k &= stbi__bmask[n];
j->code_bits -= n;
return k;
}
forceinline int stbi__jpeg_get_bit(stbi__jpeg *j) {
unsigned int k;
if (j->code_bits < 1) stbi__grow_buffer_unsafe(j);
k = j->code_buffer;
j->code_buffer <<= 1;
--j->code_bits;
return k & 0x80000000;
}
// given a value that's at position X in the zigzag stream,
// where does it appear in the 8x8 matrix coded as row-major?
static const unsigned char stbi__jpeg_dezigzag[64 + 15] = {
0, 1, 8, 16, 9, 2, 3, 10, 17, 24, 32, 25, 18, 11, 4, 5, 12, 19, 26, 33, 40,
48, 41, 34, 27, 20, 13, 6, 7, 14, 21, 28, 35, 42, 49, 56, 57, 50, 43, 36,
29, 22, 15, 23, 30, 37, 44, 51, 58, 59, 52, 45, 38, 31, 39, 46, 53, 60, 61,
54, 47, 55, 62, 63,
// let corrupt input sample past end
63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63};
// decode one 64-entry block
static optimizespeed int stbi__jpeg_decode_block(stbi__jpeg *j, short data[64],
stbi__huffman *hdc,
stbi__huffman *hac,
int16_t *fac, int b,
uint16_t *dequant) {
unsigned int zig;
int diff, dc, k, t, c, r, s, rs;
if (j->code_bits < 16) stbi__grow_buffer_unsafe(j);
t = stbi__jpeg_huff_decode(j, hdc);
if (t < 0) return stbi__err("bad huffman code", "Corrupt JPEG");
// 0 all the ac values now so we can do it 32-bits at a time
memset(data, 0, 64 * sizeof(data[0]));
diff = t ? stbi__extend_receive(j, t) : 0;
dc = j->img_comp[b].dc_pred + diff;
j->img_comp[b].dc_pred = dc;
data[0] = (short)(dc * dequant[0]);
// decode AC components, see JPEG spec
k = 1;
do {
if (j->code_bits < 16) stbi__grow_buffer_unsafe(j);
c = (j->code_buffer >> (32 - FAST_BITS)) & ((1 << FAST_BITS) - 1);
r = fac[c];
if (r) { // fast-AC path
k += (r >> 4) & 15; // run
s = r & 15; // combined length
j->code_buffer <<= s;
j->code_bits -= s;
// decode into unzigzag'd location
zig = stbi__jpeg_dezigzag[k++];
data[zig] = (short)((r >> 8) * dequant[zig]);
} else {
rs = stbi__jpeg_huff_decode(j, hac);
if (rs < 0) return stbi__err("bad huffman code", "Corrupt JPEG");
s = rs & 15;
r = rs >> 4;
if (s == 0) {
if (rs != 0xf0) break; // end block
k += 16;
} else {
k += r;
// decode into unzigzag'd location
zig = stbi__jpeg_dezigzag[k++];
data[zig] = (short)(stbi__extend_receive(j, s) * dequant[zig]);
}
}
} while (k < 64);
return 1;
}
static int stbi__jpeg_decode_block_prog_dc(stbi__jpeg *j, short data[64],
stbi__huffman *hdc, int b) {
int t;
short s;
int diff, dc;
if (j->spec_end != 0) {
return stbi__err("can't merge dc and ac", "Corrupt JPEG");
}
if (j->code_bits < 16) stbi__grow_buffer_unsafe(j);
if (j->succ_high == 0) {
// first scan for DC coefficient, must be first
memset(data, 0, 64 * sizeof(data[0])); // 0 all the ac values now
t = stbi__jpeg_huff_decode(j, hdc);
diff = t ? stbi__extend_receive(j, t) : 0;
dc = j->img_comp[b].dc_pred + diff;
j->img_comp[b].dc_pred = dc;
s = dc;
s *= 1u << j->succ_low;
data[0] = s; /* (short)(dc << j->succ_low); */
} else {
// refinement scan for DC coefficient
if (stbi__jpeg_get_bit(j)) data[0] += (short)(1 << j->succ_low);
}
return 1;
}
// @OPTIMIZE: store non-zigzagged during the decode passes,
// and only de-zigzag when dequantizing
static int stbi__jpeg_decode_block_prog_ac(stbi__jpeg *j, short data[64],
stbi__huffman *hac, int16_t *fac) {
short bit;
unsigned zig;
int k, c, r, s, rs, shift;
if (j->spec_start == 0) {
return stbi__err("can't merge dc and ac", "Corrupt JPEG");
}
if (j->succ_high == 0) {
shift = j->succ_low;
if (j->eob_run) {
--j->eob_run;
return 1;
}
k = j->spec_start;
do {
if (j->code_bits < 16) stbi__grow_buffer_unsafe(j);
c = (j->code_buffer >> (32 - FAST_BITS)) & ((1 << FAST_BITS) - 1);
r = fac[c];
if (r) { // fast-AC path
k += (r >> 4) & 15; // run
s = r & 15; // combined length
j->code_buffer <<= s;
j->code_bits -= s;
zig = stbi__jpeg_dezigzag[k++];
data[zig] = (r / 256) * (1u << shift);
} else {
rs = stbi__jpeg_huff_decode(j, hac);
if (rs < 0) return stbi__err("bad huffman code", "Corrupt JPEG");
s = rs & 15;
r = rs >> 4;
if (s == 0) {
if (r < 15) {
j->eob_run = (1 << r);
if (r) j->eob_run += stbi__jpeg_get_bits(j, r);
--j->eob_run;
break;
}
k += 16;
} else {
k += r;
zig = stbi__jpeg_dezigzag[k++];
data[zig] = stbi__extend_receive(j, s) * (1u << shift);
}
}
} while (k <= j->spec_end);
} else {
// refinement scan for these AC coefficients
bit = (short)(1 << j->succ_low);
if (j->eob_run) {
--j->eob_run;
for (k = j->spec_start; k <= j->spec_end; ++k) {
short *p = &data[stbi__jpeg_dezigzag[k]];
if (*p != 0)
if (stbi__jpeg_get_bit(j))
if ((*p & bit) == 0) {
if (*p > 0)
*p += bit;
else
*p -= bit;
}
}
} else {
k = j->spec_start;
do {
rs = stbi__jpeg_huff_decode(j, hac);
if (rs < 0) return stbi__err("bad huffman code", "Corrupt JPEG");
s = rs & 15;
r = rs >> 4;
if (s == 0) {
if (r < 15) {
j->eob_run = (1 << r) - 1;
if (r) j->eob_run += stbi__jpeg_get_bits(j, r);
r = 64; // force end of block
} else {
// r=15 s=0 should write 16 0s, so we just do
// a run of 15 0s and then write s (which is 0),
// so we don't have to do anything special here
}
} else {
if (s != 1) return stbi__err("bad huffman code", "Corrupt JPEG");
// sign bit
if (stbi__jpeg_get_bit(j)) {
s = bit;
} else {
s = -bit;
}
}
// advance by r
while (k <= j->spec_end) {
short *p = &data[stbi__jpeg_dezigzag[k++]];
if (*p != 0) {
if (stbi__jpeg_get_bit(j))
if ((*p & bit) == 0) {
if (*p > 0)
*p += bit;
else
*p -= bit;
}
} else {
if (r == 0) {
*p = (short)s;
break;
}
--r;
}
}
} while (k <= j->spec_end);
}
}
return 1;
}
// take a -128..127 value and stbi__clamp it and convert to 0..255
forceinline unsigned char stbi__clamp(int x) {
// trick to use a single test to catch both cases
if ((unsigned int)x > 255) {
if (x < 0) return 0;
if (x > 255) return 255;
}
return (unsigned char)x;
}
#define STBI__MARKER_none 0xff
// if there's a pending marker from the entropy stream, return that
// otherwise, fetch from the stream and get a marker. if there's no
// marker, return 0xff, which is never a valid marker value
static unsigned char stbi__get_marker(stbi__jpeg *j) {
unsigned char x;
if (j->marker != STBI__MARKER_none) {
x = j->marker;
j->marker = STBI__MARKER_none;
return x;
}
x = stbi__get8(j->s);
if (x != 0xff) return STBI__MARKER_none;
while (x == 0xff) x = stbi__get8(j->s); // consume repeated 0xff fill bytes
return x;
}
// in each scan, we'll have scan_n components, and the order
// of the components is specified by order[]
#define STBI__RESTART(x) ((x) >= 0xd0 && (x) <= 0xd7)
// after a restart interval, stbi__jpeg_reset the entropy decoder and
// the dc prediction
static void stbi__jpeg_reset(stbi__jpeg *j) {
j->code_bits = 0;
j->code_buffer = 0;
j->nomore = 0;
j->img_comp[0].dc_pred = j->img_comp[1].dc_pred = j->img_comp[2].dc_pred =
j->img_comp[3].dc_pred = 0;
j->marker = STBI__MARKER_none;
j->todo = j->restart_interval ? j->restart_interval : 0x7fffffff;
j->eob_run = 0;
// no more than 1<<31 MCUs if no restart_interal? that's plenty safe,
// since we don't even allow 1<<30 pixels
}
static int stbi__parse_entropy_coded_data(stbi__jpeg *z) {
stbi__jpeg_reset(z);
if (!z->progressive) {
if (z->scan_n == 1) {
int i, j;
short data[64] forcealign(16);
int n = z->order[0];
// non-interleaved data, we just need to process one block at a time,
// in trivial scanline order
// number of blocks to do just depends on how many actual "pixels" this
// component has, independent of interleaved MCU blocking and such
int w = (z->img_comp[n].x + 7) >> 3;
int h = (z->img_comp[n].y + 7) >> 3;
for (j = 0; j < h; ++j) {
for (i = 0; i < w; ++i) {
int ha = z->img_comp[n].ha;
if (!stbi__jpeg_decode_block(z, data, z->huff_dc + z->img_comp[n].hd,
z->huff_ac + ha, z->fast_ac[ha], n,
z->dequant[z->img_comp[n].tq]))
return 0;
stbi__idct_simd$sse(
z->img_comp[n].data + z->img_comp[n].w2 * j * 8 + i * 8,
z->img_comp[n].w2, data);
// every data block is an MCU, so countdown the restart interval
if (--z->todo <= 0) {
if (z->code_bits < 24) stbi__grow_buffer_unsafe(z);
// if it's NOT a restart, then just bail, so we get corrupt data
// rather than no data
if (!STBI__RESTART(z->marker)) return 1;
stbi__jpeg_reset(z);
}
}
}
return 1;
} else { // interleaved
int i, j, k, x, y;
short data[64] forcealign(16);
for (j = 0; j < z->img_mcu_y; ++j) {
for (i = 0; i < z->img_mcu_x; ++i) {
// scan an interleaved mcu... process scan_n components in order
for (k = 0; k < z->scan_n; ++k) {
int n = z->order[k];
// scan out an mcu's worth of this component; that's just determined
// by the basic H and V specified for the component
for (y = 0; y < z->img_comp[n].v; ++y) {
for (x = 0; x < z->img_comp[n].h; ++x) {
int x2 = (i * z->img_comp[n].h + x) * 8;
int y2 = (j * z->img_comp[n].v + y) * 8;
int ha = z->img_comp[n].ha;
if (!stbi__jpeg_decode_block(z, data,
z->huff_dc + z->img_comp[n].hd,
z->huff_ac + ha, z->fast_ac[ha], n,
z->dequant[z->img_comp[n].tq]))
return 0;
stbi__idct_simd$sse(
z->img_comp[n].data + z->img_comp[n].w2 * y2 + x2,
z->img_comp[n].w2, data);
}
}
}
// after all interleaved components, that's an interleaved MCU,
// so now count down the restart interval
if (--z->todo <= 0) {
if (z->code_bits < 24) stbi__grow_buffer_unsafe(z);
if (!STBI__RESTART(z->marker)) return 1;
stbi__jpeg_reset(z);
}
}
}
return 1;
}
} else {
if (z->scan_n == 1) {
int i, j;
int n = z->order[0];
// non-interleaved data, we just need to process one block at a time,
// in trivial scanline order
// number of blocks to do just depends on how many actual "pixels" this
// component has, independent of interleaved MCU blocking and such
int w = (z->img_comp[n].x + 7) >> 3;
int h = (z->img_comp[n].y + 7) >> 3;
for (j = 0; j < h; ++j) {
for (i = 0; i < w; ++i) {
short *data =
z->img_comp[n].coeff + 64 * (i + j * z->img_comp[n].coeff_w);
if (z->spec_start == 0) {
if (!stbi__jpeg_decode_block_prog_dc(
z, data, &z->huff_dc[z->img_comp[n].hd], n))
return 0;
} else {
int ha = z->img_comp[n].ha;
if (!stbi__jpeg_decode_block_prog_ac(z, data, &z->huff_ac[ha],
z->fast_ac[ha]))
return 0;
}
// every data block is an MCU, so countdown the restart interval
if (--z->todo <= 0) {
if (z->code_bits < 24) stbi__grow_buffer_unsafe(z);
if (!STBI__RESTART(z->marker)) return 1;
stbi__jpeg_reset(z);
}
}
}
return 1;
} else { // interleaved
int i, j, k, x, y;
for (j = 0; j < z->img_mcu_y; ++j) {
for (i = 0; i < z->img_mcu_x; ++i) {
// scan an interleaved mcu... process scan_n components in order
for (k = 0; k < z->scan_n; ++k) {
int n = z->order[k];
// scan out an mcu's worth of this component; that's just determined
// by the basic H and V specified for the component
for (y = 0; y < z->img_comp[n].v; ++y) {
for (x = 0; x < z->img_comp[n].h; ++x) {
int x2 = (i * z->img_comp[n].h + x);
int y2 = (j * z->img_comp[n].v + y);
short *data = z->img_comp[n].coeff +
64 * (x2 + y2 * z->img_comp[n].coeff_w);
if (!stbi__jpeg_decode_block_prog_dc(
z, data, &z->huff_dc[z->img_comp[n].hd], n))
return 0;
}
}
}
// after all interleaved components, that's an interleaved MCU,
// so now count down the restart interval
if (--z->todo <= 0) {
if (z->code_bits < 24) stbi__grow_buffer_unsafe(z);
if (!STBI__RESTART(z->marker)) return 1;
stbi__jpeg_reset(z);
}
}
}
return 1;
}
}
}
static void stbi__jpeg_dequantize(short *data, uint16_t *dequant) {
int i;
for (i = 0; i < 64; ++i) data[i] *= dequant[i];
}
static void stbi__jpeg_finish(stbi__jpeg *z) {
if (z->progressive) {
// dequantize and idct the data
int i, j, n;
for (n = 0; n < z->s->img_n; ++n) {
int w = (z->img_comp[n].x + 7) >> 3;
int h = (z->img_comp[n].y + 7) >> 3;
for (j = 0; j < h; ++j) {
for (i = 0; i < w; ++i) {
short *data =
z->img_comp[n].coeff + 64 * (i + j * z->img_comp[n].coeff_w);
stbi__jpeg_dequantize(data, z->dequant[z->img_comp[n].tq]);
stbi__idct_simd$sse(
z->img_comp[n].data + z->img_comp[n].w2 * j * 8 + i * 8,
z->img_comp[n].w2, data);
}
}
}
}
}
static int stbi__process_marker(stbi__jpeg *z, int m) {
int L;
switch (m) {
case STBI__MARKER_none: // no marker found
return stbi__err("expected marker", "Corrupt JPEG");
case 0xDD: // DRI - specify restart interval
if (stbi__get16be(z->s) != 4)
return stbi__err("bad DRI len", "Corrupt JPEG");
z->restart_interval = stbi__get16be(z->s);
return 1;
case 0xDB: // DQT - define quantization table
L = stbi__get16be(z->s) - 2;
while (L > 0) {
int q = stbi__get8(z->s);
int p = q >> 4, sixteen = (p != 0);
int t = q & 15, i;
if (p != 0 && p != 1) return stbi__err("bad DQT type", "Corrupt JPEG");
if (t > 3) return stbi__err("bad DQT table", "Corrupt JPEG");
for (i = 0; i < 64; ++i)
z->dequant[t][stbi__jpeg_dezigzag[i]] =
(uint16_t)(sixteen ? stbi__get16be(z->s) : stbi__get8(z->s));
L -= (sixteen ? 129 : 65);
}
return L == 0;
case 0xC4: // DHT - define huffman table
L = stbi__get16be(z->s) - 2;
while (L > 0) {
unsigned char *v;
int sizes[16], i, n = 0;
int q = stbi__get8(z->s);
int tc = q >> 4;
int th = q & 15;
if (tc > 1 || th > 3)
return stbi__err("bad DHT header", "Corrupt JPEG");
for (i = 0; i < 16; ++i) {
sizes[i] = stbi__get8(z->s);
n += sizes[i];
}
L -= 17;
if (tc == 0) {
if (!stbi__build_huffman(z->huff_dc + th, sizes)) return 0;
v = z->huff_dc[th].values;
} else {
if (!stbi__build_huffman(z->huff_ac + th, sizes)) return 0;
v = z->huff_ac[th].values;
}
for (i = 0; i < n; ++i) v[i] = stbi__get8(z->s);
if (tc != 0) stbi__build_fast_ac(z->fast_ac[th], z->huff_ac + th);
L -= n;
}
return L == 0;
}
// check for comment block or APP blocks
if ((m >= 0xE0 && m <= 0xEF) || m == 0xFE) {
L = stbi__get16be(z->s);
if (L < 2) {
if (m == 0xFE)
return stbi__err("bad COM len", "Corrupt JPEG");
else
return stbi__err("bad APP len", "Corrupt JPEG");
}
L -= 2;
if (m == 0xE0 && L >= 5) { // JFIF APP0 segment
static const unsigned char tag[5] = {'J', 'F', 'I', 'F', '\0'};
int ok = 1;
int i;
for (i = 0; i < 5; ++i)
if (stbi__get8(z->s) != tag[i]) ok = 0;
L -= 5;
if (ok) z->jfif = 1;
} else if (m == 0xEE && L >= 12) { // Adobe APP14 segment
static const unsigned char tag[6] = {'A', 'd', 'o', 'b', 'e', '\0'};
int ok = 1;
int i;
for (i = 0; i < 6; ++i)
if (stbi__get8(z->s) != tag[i]) ok = 0;
L -= 6;
if (ok) {
stbi__get8(z->s); // version
stbi__get16be(z->s); // flags0
stbi__get16be(z->s); // flags1
z->app14_color_transform = stbi__get8(z->s); // color transform
L -= 6;
}
}
stbi__skip(z->s, L);
return 1;
}
return stbi__err("unknown marker", "Corrupt JPEG");
}
// after we see SOS
static int stbi__process_scan_header(stbi__jpeg *z) {
int i;
int Ls = stbi__get16be(z->s);
z->scan_n = stbi__get8(z->s);
if (z->scan_n < 1 || z->scan_n > 4 || z->scan_n > (int)z->s->img_n)
return stbi__err("bad SOS component count", "Corrupt JPEG");
if (Ls != 6 + 2 * z->scan_n) return stbi__err("bad SOS len", "Corrupt JPEG");
for (i = 0; i < z->scan_n; ++i) {
int id = stbi__get8(z->s), which;
int q = stbi__get8(z->s);
for (which = 0; which < z->s->img_n; ++which)
if (z->img_comp[which].id == id) break;
if (which == z->s->img_n) return 0; // no match
z->img_comp[which].hd = q >> 4;
if (z->img_comp[which].hd > 3)
return stbi__err("bad DC huff", "Corrupt JPEG");
z->img_comp[which].ha = q & 15;
if (z->img_comp[which].ha > 3)
return stbi__err("bad AC huff", "Corrupt JPEG");
z->order[i] = which;
}
{
int aa;
z->spec_start = stbi__get8(z->s);
z->spec_end = stbi__get8(z->s); // should be 63, but might be 0
aa = stbi__get8(z->s);
z->succ_high = (aa >> 4);
z->succ_low = (aa & 15);
if (z->progressive) {
if (z->spec_start > 63 || z->spec_end > 63 ||
z->spec_start > z->spec_end || z->succ_high > 13 || z->succ_low > 13)
return stbi__err("bad SOS", "Corrupt JPEG");
} else {
if (z->spec_start != 0) return stbi__err("bad SOS", "Corrupt JPEG");
if (z->succ_high != 0 || z->succ_low != 0)
return stbi__err("bad SOS", "Corrupt JPEG");
z->spec_end = 63;
}
}
return 1;
}
static int stbi__free_jpeg_components(stbi__jpeg *z, int ncomp, int why) {
int i;
for (i = 0; i < ncomp; ++i) {
if (z->img_comp[i].data) {
free(z->img_comp[i].data);
z->img_comp[i].data = NULL;
}
if (z->img_comp[i].coeff) {
free(z->img_comp[i].coeff);
z->img_comp[i].coeff = NULL;
}
if (z->img_comp[i].linebuf) {
free(z->img_comp[i].linebuf);
z->img_comp[i].linebuf = NULL;
}
}
return why;
}
static int stbi__process_frame_header(stbi__jpeg *z, int scan) {
stbi__context *s = z->s;
int Lf, p, i, q, h_max = 1, v_max = 1, c;
Lf = stbi__get16be(s);
if (Lf < 11) return stbi__err("bad SOF len", "Corrupt JPEG"); // JPEG
p = stbi__get8(s);
if (p != 8)
return stbi__err("only 8-bit",
"JPEG format not supported: 8-bit only"); // JPEG baseline
s->img_y = stbi__get16be(s);
if (s->img_y == 0)
return stbi__err(
"no header height",
"JPEG format not supported: delayed height"); // Legal, but we don't
// handle it--but neither
// does IJG
s->img_x = stbi__get16be(s);
if (s->img_x == 0)
return stbi__err("0 width", "Corrupt JPEG"); // JPEG requires
c = stbi__get8(s);
if (c != 3 && c != 1 && c != 4)
return stbi__err("bad component count", "Corrupt JPEG");
s->img_n = c;
for (i = 0; i < c; ++i) {
z->img_comp[i].data = NULL;
z->img_comp[i].linebuf = NULL;
}
if (Lf != 8 + 3 * s->img_n) return stbi__err("bad SOF len", "Corrupt JPEG");
z->rgb = 0;
for (i = 0; i < s->img_n; ++i) {
static const unsigned char rgb[3] = {'R', 'G', 'B'};
z->img_comp[i].id = stbi__get8(s);
if (s->img_n == 3 && z->img_comp[i].id == rgb[i]) ++z->rgb;
q = stbi__get8(s);
z->img_comp[i].h = (q >> 4);
if (!z->img_comp[i].h || z->img_comp[i].h > 4)
return stbi__err("bad H", "Corrupt JPEG");
z->img_comp[i].v = q & 15;
if (!z->img_comp[i].v || z->img_comp[i].v > 4)
return stbi__err("bad V", "Corrupt JPEG");
z->img_comp[i].tq = stbi__get8(s);
if (z->img_comp[i].tq > 3) return stbi__err("bad TQ", "Corrupt JPEG");
}
if (scan != STBI__SCAN_load) return 1;
if (!stbi__mad3sizes_valid(s->img_x, s->img_y, s->img_n, 0))
return stbi__err("too large", "Image too large to decode");
for (i = 0; i < s->img_n; ++i) {
if (z->img_comp[i].h > h_max) h_max = z->img_comp[i].h;
if (z->img_comp[i].v > v_max) v_max = z->img_comp[i].v;
}
// compute interleaved mcu info
z->img_h_max = h_max;
z->img_v_max = v_max;
z->img_mcu_w = h_max * 8;
z->img_mcu_h = v_max * 8;
// these sizes can't be more than 17 bits
z->img_mcu_x = (s->img_x + z->img_mcu_w - 1) / z->img_mcu_w;
z->img_mcu_y = (s->img_y + z->img_mcu_h - 1) / z->img_mcu_h;
for (i = 0; i < s->img_n; ++i) {
// number of effective pixels (e.g. for non-interleaved MCU)
z->img_comp[i].x = (s->img_x * z->img_comp[i].h + h_max - 1) / h_max;
z->img_comp[i].y = (s->img_y * z->img_comp[i].v + v_max - 1) / v_max;
// to simplify generation, we'll allocate enough memory to decode
// the bogus oversized data from using interleaved MCUs and their
// big blocks (e.g. a 16x16 iMCU on an image of width 33); we won't
// discard the extra data until colorspace conversion
//
// img_mcu_x, img_mcu_y: <=17 bits; comp[i].h and .v are <=4 (checked
// earlier) so these muls can't overflow with 32-bit ints (which we require)
z->img_comp[i].w2 = z->img_mcu_x * z->img_comp[i].h * 8;
z->img_comp[i].h2 = z->img_mcu_y * z->img_comp[i].v * 8;
z->img_comp[i].coeff = NULL;
z->img_comp[i].linebuf = NULL;
z->img_comp[i].data =
stbi__malloc_mad2(z->img_comp[i].w2, z->img_comp[i].h2, 15);
if (z->progressive) {
// w2, h2 are multiples of 8 (see above)
z->img_comp[i].coeff_w = z->img_comp[i].w2 / 8;
z->img_comp[i].coeff_h = z->img_comp[i].h2 / 8;
z->img_comp[i].coeff = stbi__malloc_mad3(
z->img_comp[i].w2, z->img_comp[i].h2, sizeof(short), 15);
}
}
return 1;
}
// use comparisons since in some cases we handle more than one case (e.g. SOF)
#define stbi__DNL(x) ((x) == 0xdc)
#define stbi__SOI(x) ((x) == 0xd8)
#define stbi__EOI(x) ((x) == 0xd9)
#define stbi__SOF(x) ((x) == 0xc0 || (x) == 0xc1 || (x) == 0xc2)
#define stbi__SOS(x) ((x) == 0xda)
#define stbi__SOF_progressive(x) ((x) == 0xc2)
static int stbi__decode_jpeg_header(stbi__jpeg *z, int scan) {
int m;
z->jfif = 0;
z->app14_color_transform = -1; // valid values are 0,1,2
z->marker = STBI__MARKER_none; // initialize cached marker to empty
m = stbi__get_marker(z);
if (!stbi__SOI(m)) return 0;
if (scan == STBI__SCAN_type) return 1;
m = stbi__get_marker(z);
while (!stbi__SOF(m)) {
if (!stbi__process_marker(z, m)) return 0;
m = stbi__get_marker(z);
while (m == STBI__MARKER_none) {
// some files have extra padding after their blocks, so ok, we'll scan
if (stbi__at_eof(z->s)) return stbi__err("no SOF", "Corrupt JPEG");
m = stbi__get_marker(z);
}
}
z->progressive = stbi__SOF_progressive(m);
if (!stbi__process_frame_header(z, scan)) return 0;
return 1;
}
// decode image to YCbCr format
static int stbi__decode_jpeg_image(stbi__jpeg *j) {
int m;
for (m = 0; m < 4; m++) {
j->img_comp[m].data = NULL;
j->img_comp[m].coeff = NULL;
}
j->restart_interval = 0;
if (!stbi__decode_jpeg_header(j, STBI__SCAN_load)) return 0;
m = stbi__get_marker(j);
while (!stbi__EOI(m)) {
if (stbi__SOS(m)) {
if (!stbi__process_scan_header(j)) return 0;
if (!stbi__parse_entropy_coded_data(j)) return 0;
if (j->marker == STBI__MARKER_none) {
// handle 0s at the end of image data from IP Kamera 9060
while (!stbi__at_eof(j->s)) {
int x = stbi__get8(j->s);
if (x == 255) {
j->marker = stbi__get8(j->s);
break;
}
}
// if we reach eof without hitting a marker, stbi__get_marker() below
// will fail and we'll eventually return 0
}
} else if (stbi__DNL(m)) {
int Ld = stbi__get16be(j->s);
uint32_t NL = stbi__get16be(j->s);
if (Ld != 4) return stbi__err("bad DNL len", "Corrupt JPEG");
if (NL != j->s->img_y) return stbi__err("bad DNL height", "Corrupt JPEG");
} else {
if (!stbi__process_marker(j, m)) return 0;
}
m = stbi__get_marker(j);
}
if (j->progressive) stbi__jpeg_finish(j);
return 1;
}
// static jfif-centered resampling (across block boundaries)
typedef unsigned char *(*resample_row_func)(unsigned char *out,
unsigned char *in0,
unsigned char *in1, int w, int hs);
#define stbi__div4(x) ((unsigned char)((x) >> 2))
static unsigned char *resample_row_1(unsigned char *out, unsigned char *in_near,
unsigned char *in_far, int w, int hs) {
return in_near;
}
static unsigned char *stbi__resample_row_v_2(unsigned char *out,
unsigned char *in_near,
unsigned char *in_far, int w,
int hs) {
// need to generate two samples vertically for every one in input
int i;
for (i = 0; i < w; ++i) out[i] = stbi__div4(3 * in_near[i] + in_far[i] + 2);
return out;
}
static unsigned char *stbi__resample_row_h_2(unsigned char *out,
unsigned char *in_near,
unsigned char *in_far, int w,
int hs) {
// need to generate two samples horizontally for every one in input
int i;
unsigned char *input = in_near;
if (w == 1) {
// if only one sample, can't do any interpolation
out[0] = out[1] = input[0];
return out;
}
out[0] = input[0];
out[1] = stbi__div4(input[0] * 3 + input[1] + 2);
for (i = 1; i < w - 1; ++i) {
int n = 3 * input[i] + 2;
out[i * 2 + 0] = stbi__div4(n + input[i - 1]);
out[i * 2 + 1] = stbi__div4(n + input[i + 1]);
}
out[i * 2 + 0] = stbi__div4(input[w - 2] * 3 + input[w - 1] + 2);
out[i * 2 + 1] = input[w - 1];
return out;
}
#define stbi__div16(x) ((unsigned char)((x) >> 4))
static unsigned char *stbi__resample_row_hv_2(unsigned char *out,
unsigned char *in_near,
unsigned char *in_far, int w,
int hs) {
// need to generate 2x2 samples for every one in input
int i, t0, t1;
if (w == 1) {
out[0] = out[1] = stbi__div4(3 * in_near[0] + in_far[0] + 2);
return out;
}
t1 = 3 * in_near[0] + in_far[0];
out[0] = stbi__div4(t1 + 2);
for (i = 1; i < w; ++i) {
t0 = t1;
t1 = 3 * in_near[i] + in_far[i];
out[i * 2 - 1] = stbi__div16(3 * t0 + t1 + 8);
out[i * 2] = stbi__div16(3 * t1 + t0 + 8);
}
out[w * 2 - 1] = stbi__div4(t1 + 2);
return out;
}
#if defined(STBI_SSE2)
static unsigned char *stbi__resample_row_hv_2_simd(unsigned char *out,
unsigned char *in_near,
unsigned char *in_far, int w,
int hs) {
// need to generate 2x2 samples for every one in input
int i = 0, t0, t1;
if (w == 1) {
out[0] = out[1] = stbi__div4(3 * in_near[0] + in_far[0] + 2);
return out;
}
t1 = 3 * in_near[0] + in_far[0];
// process groups of 8 pixels for as long as we can.
// note we can't handle the last pixel in a row in this loop
// because we need to handle the filter boundary conditions.
for (; i < ((w - 1) & ~7); i += 8) {
// load and perform the vertical filtering pass
// this uses 3*x + y = 4*x + (y - x)
__m128i zero = _mm_setzero_si128();
__m128i farb = _mm_loadl_epi64((__m128i *)(in_far + i));
__m128i nearb = _mm_loadl_epi64((__m128i *)(in_near + i));
__m128i farw = _mm_unpacklo_epi8(farb, zero);
__m128i nearw = _mm_unpacklo_epi8(nearb, zero);
__m128i diff = _mm_sub_epi16(farw, nearw);
__m128i nears = _mm_slli_epi16(nearw, 2);
__m128i curr = _mm_add_epi16(nears, diff); // current row
// horizontal filter works the same based on shifted vers of current
// row. "prev" is current row shifted right by 1 pixel; we need to
// insert the previous pixel value (from t1).
// "next" is current row shifted left by 1 pixel, with first pixel
// of next block of 8 pixels added in.
__m128i prv0 = _mm_slli_si128(curr, 2);
__m128i nxt0 = _mm_srli_si128(curr, 2);
__m128i prev = _mm_insert_epi16(prv0, t1, 0);
__m128i next =
_mm_insert_epi16(nxt0, 3 * in_near[i + 8] + in_far[i + 8], 7);
// horizontal filter, polyphase implementation since it's convenient:
// even pixels = 3*cur + prev = cur*4 + (prev - cur)
// odd pixels = 3*cur + next = cur*4 + (next - cur)
// note the shared term.
__m128i bias = _mm_set1_epi16(8);
__m128i curs = _mm_slli_epi16(curr, 2);
__m128i prvd = _mm_sub_epi16(prev, curr);
__m128i nxtd = _mm_sub_epi16(next, curr);
__m128i curb = _mm_add_epi16(curs, bias);
__m128i even = _mm_add_epi16(prvd, curb);
__m128i odd = _mm_add_epi16(nxtd, curb);
// interleave even and odd pixels, then undo scaling.
__m128i int0 = _mm_unpacklo_epi16(even, odd);
__m128i int1 = _mm_unpackhi_epi16(even, odd);
__m128i de0 = _mm_srli_epi16(int0, 4);
__m128i de1 = _mm_srli_epi16(int1, 4);
// pack and write output
__m128i outv = _mm_packus_epi16(de0, de1);
_mm_storeu_si128((__m128i *)(out + i * 2), outv);
// "previous" value for next iter
t1 = 3 * in_near[i + 7] + in_far[i + 7];
}
t0 = t1;
t1 = 3 * in_near[i] + in_far[i];
out[i * 2] = stbi__div16(3 * t1 + t0 + 8);
for (++i; i < w; ++i) {
t0 = t1;
t1 = 3 * in_near[i] + in_far[i];
out[i * 2 - 1] = stbi__div16(3 * t0 + t1 + 8);
out[i * 2] = stbi__div16(3 * t1 + t0 + 8);
}
out[w * 2 - 1] = stbi__div4(t1 + 2);
return out;
}
#endif
static unsigned char *stbi__resample_row_nearest(unsigned char *out,
unsigned char *in_near,
unsigned char *in_far, int w,
int hs) {
int i, j;
for (i = 0; i < w; ++i) {
for (j = 0; j < hs; ++j) {
out[i * hs + j] = in_near[i];
}
}
return out;
}
// set up the kernels
static void stbi__setup_jpeg(stbi__jpeg *j) {
j->resample_row_hv_2_kernel = stbi__resample_row_hv_2;
#if 0
if (stbi__sse2_available()) {
j->resample_row_hv_2_kernel = stbi__resample_row_hv_2_simd;
}
#endif
}
// clean up the temporary component buffers
static void stbi__cleanup_jpeg(stbi__jpeg *j) {
stbi__free_jpeg_components(j, j->s->img_n, 0);
}
typedef struct {
resample_row_func resample;
unsigned char *line0, *line1;
int hs, vs; // expansion factor in each axis
int w_lores; // horizontal pixels pre-expansion
int ystep; // how far through vertical expansion we are
int ypos; // which pre-expansion row we're on
} stbi__resample;
// fast 0..255 * 0..255 => 0..255 rounded multiplication
static unsigned char stbi__blinn_8x8(unsigned char x, unsigned char y) {
unsigned t;
t = x * y + 128;
return (t + (t >> 8)) >> 8;
}
static unsigned char *load_jpeg_image(stbi__jpeg *z, int *out_x, int *out_y,
int *comp, int req_comp) {
int n, decode_n, is_rgb;
z->s->img_n = 0; // make stbi__cleanup_jpeg safe
// validate req_comp
if (req_comp < 0 || req_comp > 4) {
return stbi__errpuc("bad req_comp", "Internal error");
}
// load a jpeg image from whichever source, but leave in YCbCr format
if (!stbi__decode_jpeg_image(z)) {
stbi__cleanup_jpeg(z);
return NULL;
}
// determine actual number of components to generate
n = req_comp ? req_comp : z->s->img_n >= 3 ? 3 : 1;
is_rgb = z->s->img_n == 3 &&
(z->rgb == 3 || (z->app14_color_transform == 0 && !z->jfif));
if (z->s->img_n == 3 && n < 3 && !is_rgb) {
decode_n = 1;
} else {
decode_n = z->s->img_n;
}
// resample and color-convert
{
int k;
unsigned int i, j;
unsigned char *output;
unsigned char *coutput[4];
stbi__resample res_comp[4];
memset(coutput, 0, sizeof(coutput));
for (k = 0; k < decode_n; ++k) {
stbi__resample *r = &res_comp[k];
// allocate line buffer big enough for upsampling off the edges
// with upsample factor of 4
z->img_comp[k].linebuf = xmalloc(z->s->img_x + 3);
r->hs = z->img_h_max / z->img_comp[k].h;
r->vs = z->img_v_max / z->img_comp[k].v;
r->ystep = r->vs >> 1;
r->w_lores = (z->s->img_x + r->hs - 1) / r->hs;
r->ypos = 0;
r->line0 = r->line1 = z->img_comp[k].data;
if (r->hs == 1 && r->vs == 1) {
r->resample = resample_row_1;
} else if (r->hs == 1 && r->vs == 2) {
r->resample = stbi__resample_row_v_2;
} else if (r->hs == 2 && r->vs == 1) {
r->resample = stbi__resample_row_h_2;
} else if (r->hs == 2 && r->vs == 2) {
r->resample = z->resample_row_hv_2_kernel;
} else {
r->resample = stbi__resample_row_nearest;
}
}
// can't error after this so, this is safe
output = stbi__malloc_mad3(n, z->s->img_x, z->s->img_y, 1);
// now go ahead and resample
for (j = 0; j < z->s->img_y; ++j) {
unsigned char *out = output + n * z->s->img_x * j;
for (k = 0; k < decode_n; ++k) {
stbi__resample *r = &res_comp[k];
int y_bot = r->ystep >= (r->vs >> 1);
coutput[k] =
r->resample(z->img_comp[k].linebuf, y_bot ? r->line1 : r->line0,
y_bot ? r->line0 : r->line1, r->w_lores, r->hs);
if (++r->ystep >= r->vs) {
r->ystep = 0;
r->line0 = r->line1;
if (++r->ypos < z->img_comp[k].y) r->line1 += z->img_comp[k].w2;
}
}
if (n >= 3) {
unsigned char *y = coutput[0];
if (z->s->img_n == 3) {
if (is_rgb) {
for (i = 0; i < z->s->img_x; ++i) {
out[0] = y[i];
out[1] = coutput[1][i];
out[2] = coutput[2][i];
out[3] = 255;
out += n;
}
} else {
stbi__YCbCr_to_RGB_row(out, y, coutput[1], coutput[2], z->s->img_x,
n);
}
} else if (z->s->img_n == 4) {
if (z->app14_color_transform == 0) { // CMYK
for (i = 0; i < z->s->img_x; ++i) {
unsigned char m = coutput[3][i];
out[0] = stbi__blinn_8x8(coutput[0][i], m);
out[1] = stbi__blinn_8x8(coutput[1][i], m);
out[2] = stbi__blinn_8x8(coutput[2][i], m);
out[3] = 255;
out += n;
}
} else if (z->app14_color_transform == 2) { // YCCK
stbi__YCbCr_to_RGB_row(out, y, coutput[1], coutput[2], z->s->img_x,
n);
for (i = 0; i < z->s->img_x; ++i) {
unsigned char m = coutput[3][i];
out[0] = stbi__blinn_8x8(255 - out[0], m);
out[1] = stbi__blinn_8x8(255 - out[1], m);
out[2] = stbi__blinn_8x8(255 - out[2], m);
out += n;
}
} else { // YCbCr + alpha? Ignore the fourth channel for now
stbi__YCbCr_to_RGB_row(out, y, coutput[1], coutput[2], z->s->img_x,
n);
}
} else
for (i = 0; i < z->s->img_x; ++i) {
out[0] = out[1] = out[2] = y[i];
out[3] = 255; // not used if n==3
out += n;
}
} else {
if (is_rgb) {
if (n == 1)
for (i = 0; i < z->s->img_x; ++i)
*out++ =
stbi__compute_y(coutput[0][i], coutput[1][i], coutput[2][i]);
else {
for (i = 0; i < z->s->img_x; ++i, out += 2) {
out[0] =
stbi__compute_y(coutput[0][i], coutput[1][i], coutput[2][i]);
out[1] = 255;
}
}
} else if (z->s->img_n == 4 && z->app14_color_transform == 0) {
for (i = 0; i < z->s->img_x; ++i) {
unsigned char m = coutput[3][i];
unsigned char r = stbi__blinn_8x8(coutput[0][i], m);
unsigned char g = stbi__blinn_8x8(coutput[1][i], m);
unsigned char b = stbi__blinn_8x8(coutput[2][i], m);
out[0] = stbi__compute_y(r, g, b);
out[1] = 255;
out += n;
}
} else if (z->s->img_n == 4 && z->app14_color_transform == 2) {
for (i = 0; i < z->s->img_x; ++i) {
out[0] = stbi__blinn_8x8(255 - coutput[0][i], coutput[3][i]);
out[1] = 255;
out += n;
}
} else {
unsigned char *y = coutput[0];
if (n == 1)
for (i = 0; i < z->s->img_x; ++i) out[i] = y[i];
else
for (i = 0; i < z->s->img_x; ++i) {
*out++ = y[i];
*out++ = 255;
}
}
}
}
stbi__cleanup_jpeg(z);
*out_x = z->s->img_x;
*out_y = z->s->img_y;
if (comp)
*comp =
z->s->img_n >= 3 ? 3 : 1; // report original components, not output
return output;
}
}
static noinline void *stbi__jpeg_load(stbi__context *s, int *x, int *y,
int *comp, int req_comp,
stbi__result_info *ri) {
unsigned char *result;
stbi__jpeg *j = (stbi__jpeg *)malloc(sizeof(stbi__jpeg));
j->s = s;
stbi__setup_jpeg(j);
result = load_jpeg_image(j, x, y, comp, req_comp);
free(j);
return result;
}
static int stbi__jpeg_test(stbi__context *s) {
int r;
stbi__jpeg *j;
j = malloc(sizeof(stbi__jpeg));
j->s = s;
stbi__setup_jpeg(j);
r = stbi__decode_jpeg_header(j, STBI__SCAN_type);
stbi__rewind(s);
free(j);
return r;
}
static int stbi__jpeg_info_raw(stbi__jpeg *j, int *x, int *y, int *comp) {
if (!stbi__decode_jpeg_header(j, STBI__SCAN_header)) {
stbi__rewind(j->s);
return 0;
}
if (x) *x = j->s->img_x;
if (y) *y = j->s->img_y;
if (comp) *comp = j->s->img_n >= 3 ? 3 : 1;
return 1;
}
static int stbi__jpeg_info(stbi__context *s, int *x, int *y, int *comp) {
int result;
stbi__jpeg *j = (stbi__jpeg *)(malloc(sizeof(stbi__jpeg)));
j->s = s;
result = stbi__jpeg_info_raw(j, x, y, comp);
free(j);
return result;
}
// public domain zlib decode v0.2 Sean Barrett 2006-11-18
// simple implementation
// - all input must be provided in an upfront buffer
// - all output is written to a single output buffer (can malloc/realloc)
// performance
// - fast huffman
// fast-way is faster to check than jpeg huffman, but slow way is slower
#define STBI__ZFAST_BITS 9 // accelerate all cases in default tables
#define STBI__ZFAST_MASK ((1 << STBI__ZFAST_BITS) - 1)
// zlib-style huffman encoding
// (jpegs packs from left, zlib from right, so can't share code)
typedef struct {
uint16_t fast[1 << STBI__ZFAST_BITS];
uint16_t firstcode[16];
int maxcode[17];
uint16_t firstsymbol[16];
unsigned char size[288];
uint16_t value[288];
} stbi__zhuffman;
forceinline int stbi__bitreverse16(int n) {
n = ((n & 0xAAAA) >> 1) | ((n & 0x5555) << 1);
n = ((n & 0xCCCC) >> 2) | ((n & 0x3333) << 2);
n = ((n & 0xF0F0) >> 4) | ((n & 0x0F0F) << 4);
n = ((n & 0xFF00) >> 8) | ((n & 0x00FF) << 8);
return n;
}
forceinline int stbi__bit_reverse(int v, int bits) {
assert(bits <= 16);
// to bit reverse n bits, reverse 16 and shift
// e.g. 11 bits, bit reverse and shift away 5
return stbi__bitreverse16(v) >> (16 - bits);
}
static int stbi__zbuild_huffman(stbi__zhuffman *z,
const unsigned char *sizelist, int num) {
int i, k = 0;
int code, next_code[16], sizes[17];
// DEFLATE spec for generating codes
memset(sizes, 0, sizeof(sizes));
memset(z->fast, 0, sizeof(z->fast));
for (i = 0; i < num; ++i) ++sizes[sizelist[i]];
sizes[0] = 0;
for (i = 1; i < 16; ++i)
if (sizes[i] > (1 << i)) return stbi__err("bad sizes", "Corrupt PNG");
code = 0;
for (i = 1; i < 16; ++i) {
next_code[i] = code;
z->firstcode[i] = (uint16_t)code;
z->firstsymbol[i] = (uint16_t)k;
code = (code + sizes[i]);
if (sizes[i])
if (code - 1 >= (1 << i))
return stbi__err("bad codelengths", "Corrupt PNG");
z->maxcode[i] = code << (16 - i); // preshift for inner loop
code <<= 1;
k += sizes[i];
}
z->maxcode[16] = 0x10000; // sentinel
for (i = 0; i < num; ++i) {
int s = sizelist[i];
if (s) {
int c = next_code[s] - z->firstcode[s] + z->firstsymbol[s];
uint16_t fastv = (uint16_t)((s << 9) | i);
z->size[c] = (unsigned char)s;
z->value[c] = (uint16_t)i;
if (s <= STBI__ZFAST_BITS) {
int j = stbi__bit_reverse(next_code[s], s);
while (j < (1 << STBI__ZFAST_BITS)) {
z->fast[j] = fastv;
j += (1 << s);
}
}
++next_code[s];
}
}
return 1;
}
// zlib-from-memory implementation for PNG reading
// because PNG allows splitting the zlib stream arbitrarily,
// and it's annoying structurally to have PNG call ZLIB call PNG,
// we require PNG read all the IDATs and combine them into a single
// memory buffer
typedef struct {
unsigned char *zbuffer, *zbuffer_end;
int num_bits;
uint32_t code_buffer;
char *zout;
char *zout_start;
char *zout_end;
int z_expandable;
stbi__zhuffman z_length, z_distance;
} stbi__zbuf;
forceinline unsigned char stbi__zget8(stbi__zbuf *z) {
if (z->zbuffer >= z->zbuffer_end) return 0;
return *z->zbuffer++;
}
static void stbi__fill_bits(stbi__zbuf *z) {
do {
assert(z->code_buffer < (1u << z->num_bits));
z->code_buffer |= (unsigned int)stbi__zget8(z) << z->num_bits;
z->num_bits += 8;
} while (z->num_bits <= 24);
}
forceinline unsigned int stbi__zreceive(stbi__zbuf *z, int n) {
unsigned int k;
if (z->num_bits < n) stbi__fill_bits(z);
k = z->code_buffer & ((1 << n) - 1);
z->code_buffer >>= n;
z->num_bits -= n;
return k;
}
static int stbi__zhuffman_decode_slowpath(stbi__zbuf *a, stbi__zhuffman *z) {
int b, s, k;
// not resolved by fast table, so compute it the slow way
// use jpeg approach, which requires MSbits at top
k = stbi__bit_reverse(a->code_buffer, 16);
for (s = STBI__ZFAST_BITS + 1;; ++s)
if (k < z->maxcode[s]) break;
if (s == 16) return -1; // invalid code!
// code size is s, so:
b = (k >> (16 - s)) - z->firstcode[s] + z->firstsymbol[s];
assert(z->size[b] == s);
a->code_buffer >>= s;
a->num_bits -= s;
return z->value[b];
}
forceinline int stbi__zhuffman_decode(stbi__zbuf *a, stbi__zhuffman *z) {
int b, s;
if (a->num_bits < 16) stbi__fill_bits(a);
b = z->fast[a->code_buffer & STBI__ZFAST_MASK];
if (b) {
s = b >> 9;
a->code_buffer >>= s;
a->num_bits -= s;
return b & 511;
}
return stbi__zhuffman_decode_slowpath(a, z);
}
static int stbi__zexpand(stbi__zbuf *z, char *zout, int n) {
char *q;
int cur, limit, old_limit;
z->zout = zout;
if (!z->z_expandable) return stbi__err("output buffer limit", "Corrupt PNG");
cur = (int)(z->zout - z->zout_start);
limit = old_limit = (int)(z->zout_end - z->zout_start);
while (cur + n > limit) limit *= 2;
q = (char *)STBI_REALLOC_SIZED(z->zout_start, old_limit, limit);
if (q == NULL) return stbi__err("outofmem", "Out of memory");
z->zout_start = q;
z->zout = q + cur;
z->zout_end = q + limit;
return 1;
}
static const int stbi__zlength_base[31] = {
3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0,
};
static const int stbi__zlength_extra[31] = {
0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, 0, 0,
};
static const int stbi__zdist_base[32] = {
1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33,
49, 65, 97, 129, 193, 257, 385, 513, 769, 1025, 1537,
2049, 3073, 4097, 6145, 8193, 12289, 16385, 24577, 0, 0,
};
static const int stbi__zdist_extra[32] = {
0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6,
6, 7, 7, 8, 8, 9, 9, 10, 10, 11, 11, 12, 12, 13, 13,
};
static int stbi__parse_huffman_block(stbi__zbuf *a) {
char *zout = a->zout;
for (;;) {
int z = stbi__zhuffman_decode(a, &a->z_length);
if (z < 256) {
if (z < 0) return stbi__err("bad huffman code", "Corrupt PNG");
if (zout >= a->zout_end) {
if (!stbi__zexpand(a, zout, 1)) return 0;
zout = a->zout;
}
*zout++ = (char)z;
} else {
unsigned char *p;
int len, dist;
if (z == 256) {
a->zout = zout;
return 1;
}
z -= 257;
len = stbi__zlength_base[z];
if (stbi__zlength_extra[z])
len += stbi__zreceive(a, stbi__zlength_extra[z]);
z = stbi__zhuffman_decode(a, &a->z_distance);
if (z < 0) return stbi__err("bad huffman code", "Corrupt PNG");
dist = stbi__zdist_base[z];
if (stbi__zdist_extra[z]) dist += stbi__zreceive(a, stbi__zdist_extra[z]);
if (zout - a->zout_start < dist)
return stbi__err("bad dist", "Corrupt PNG");
if (zout + len > a->zout_end) {
if (!stbi__zexpand(a, zout, len)) return 0;
zout = a->zout;
}
p = (unsigned char *)(zout - dist);
if (dist == 1) { // run of one byte; common in images.
unsigned char v = *p;
if (len) {
do
*zout++ = v;
while (--len);
}
} else {
if (len) {
do
*zout++ = *p++;
while (--len);
}
}
}
}
}
static int stbi__compute_huffman_codes(stbi__zbuf *a) {
static const unsigned char length_dezigzag[19] = {
16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
stbi__zhuffman z_codelength;
unsigned char lencodes[286 + 32 + 137]; // padding for maximum single op
unsigned char codelength_sizes[19];
int i, n;
int hlit = stbi__zreceive(a, 5) + 257;
int hdist = stbi__zreceive(a, 5) + 1;
int hclen = stbi__zreceive(a, 4) + 4;
int ntot = hlit + hdist;
memset(codelength_sizes, 0, sizeof(codelength_sizes));
for (i = 0; i < hclen; ++i) {
int s = stbi__zreceive(a, 3);
codelength_sizes[length_dezigzag[i]] = (unsigned char)s;
}
if (!stbi__zbuild_huffman(&z_codelength, codelength_sizes, 19)) return 0;
n = 0;
while (n < ntot) {
int c = stbi__zhuffman_decode(a, &z_codelength);
if (c < 0 || c >= 19) return stbi__err("bad codelengths", "Corrupt PNG");
if (c < 16)
lencodes[n++] = (unsigned char)c;
else {
unsigned char fill = 0;
if (c == 16) {
c = stbi__zreceive(a, 2) + 3;
if (n == 0) return stbi__err("bad codelengths", "Corrupt PNG");
fill = lencodes[n - 1];
} else if (c == 17)
c = stbi__zreceive(a, 3) + 3;
else {
assert(c == 18);
c = stbi__zreceive(a, 7) + 11;
}
if (ntot - n < c) return stbi__err("bad codelengths", "Corrupt PNG");
memset(lencodes + n, fill, c);
n += c;
}
}
if (n != ntot) return stbi__err("bad codelengths", "Corrupt PNG");
if (!stbi__zbuild_huffman(&a->z_length, lencodes, hlit)) return 0;
if (!stbi__zbuild_huffman(&a->z_distance, lencodes + hlit, hdist)) return 0;
return 1;
}
static int stbi__parse_uncompressed_block(stbi__zbuf *a) {
unsigned char header[4];
int len, nlen, k;
if (a->num_bits & 7) stbi__zreceive(a, a->num_bits & 7); // discard
// drain the bit-packed data into header
k = 0;
while (a->num_bits > 0) {
header[k++] =
(unsigned char)(a->code_buffer & 255); // suppress MSVC run-time check
a->code_buffer >>= 8;
a->num_bits -= 8;
}
assert(a->num_bits == 0);
// now fill header the normal way
while (k < 4) header[k++] = stbi__zget8(a);
len = header[1] * 256 + header[0];
nlen = header[3] * 256 + header[2];
if (nlen != (len ^ 0xffff)) return stbi__err("zlib corrupt", "Corrupt PNG");
if (a->zbuffer + len > a->zbuffer_end)
return stbi__err("read past buffer", "Corrupt PNG");
if (a->zout + len > a->zout_end)
if (!stbi__zexpand(a, a->zout, len)) return 0;
memcpy(a->zout, a->zbuffer, len);
a->zbuffer += len;
a->zout += len;
return 1;
}
static int stbi__parse_zlib_header(stbi__zbuf *a) {
int cmf = stbi__zget8(a);
int cm = cmf & 15;
/* int cinfo = cmf >> 4; */
int flg = stbi__zget8(a);
if ((cmf * 256 + flg) % 31 != 0)
return stbi__err("bad zlib header", "Corrupt PNG"); // zlib spec
if (flg & 32)
return stbi__err("no preset dict",
"Corrupt PNG"); // preset dictionary not allowed in png
if (cm != 8)
return stbi__err("bad compression",
"Corrupt PNG"); // DEFLATE required for png
// window = 1 << (8 + cinfo)... but who cares, we fully buffer output
return 1;
}
static const unsigned char stbi__zdefault_length[288] = {
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8};
static const unsigned char stbi__zdefault_distance[32] = {
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
};
/*
Init algorithm:{
int i; // use <= to match clearly with spec
for (i=0; i <= 143; ++i) stbi__zdefault_length[i] = 8;
for ( ; i <= 255; ++i) stbi__zdefault_length[i] = 9;
for ( ; i <= 279; ++i) stbi__zdefault_length[i] = 7;
for ( ; i <= 287; ++i) stbi__zdefault_length[i] = 8;
for (i=0; i <= 31; ++i) stbi__zdefault_distance[i] = 5;
}
*/
static int stbi__parse_zlib(stbi__zbuf *a, int parse_header) {
int final, type;
if (parse_header)
if (!stbi__parse_zlib_header(a)) return 0;
a->num_bits = 0;
a->code_buffer = 0;
do {
final = stbi__zreceive(a, 1);
type = stbi__zreceive(a, 2);
if (type == 0) {
if (!stbi__parse_uncompressed_block(a)) return 0;
} else if (type == 3) {
return 0;
} else {
if (type == 1) {
// use fixed code lengths
if (!stbi__zbuild_huffman(&a->z_length, stbi__zdefault_length, 288))
return 0;
if (!stbi__zbuild_huffman(&a->z_distance, stbi__zdefault_distance, 32))
return 0;
} else {
if (!stbi__compute_huffman_codes(a)) return 0;
}
if (!stbi__parse_huffman_block(a)) return 0;
}
} while (!final);
return 1;
}
static int stbi__do_zlib(stbi__zbuf *a, char *obuf, int olen, int exp,
int parse_header) {
a->zout_start = obuf;
a->zout = obuf;
a->zout_end = obuf + olen;
a->z_expandable = exp;
return stbi__parse_zlib(a, parse_header);
}
char *stbi_zlib_decode_malloc_guesssize(const char *buffer, int len,
int initial_size, int *outlen) {
char *res, *p;
stbi__zbuf *a;
a = NULL;
res = NULL;
if ((p = (char *)malloc(initial_size)) &&
(a = (stbi__zbuf *)malloc(sizeof(stbi__zbuf)))) {
a->zbuffer = (unsigned char *)buffer;
a->zbuffer_end = (unsigned char *)buffer + len;
if (stbi__do_zlib(a, p, initial_size, 1, 1)) {
if (outlen) *outlen = (int)(a->zout - a->zout_start);
res = a->zout_start;
a->zout_start = NULL;
}
}
free(a->zout_start);
free(a);
return res;
}
char *stbi_zlib_decode_malloc(char const *buffer, int len, int *outlen) {
return stbi_zlib_decode_malloc_guesssize(buffer, len, 16384, outlen);
}
char *stbi_zlib_decode_malloc_guesssize_headerflag(const char *buffer, int len,
int initial_size,
int *outlen,
int parse_header) {
char *res;
stbi__zbuf *a = malloc(sizeof(stbi__zbuf));
char *p = (char *)malloc(initial_size);
if (!p) return NULL;
a->zbuffer = (unsigned char *)buffer;
a->zbuffer_end = (unsigned char *)buffer + len;
if (stbi__do_zlib(a, p, initial_size, 1, parse_header)) {
if (outlen) *outlen = (int)(a->zout - a->zout_start);
res = a->zout_start;
} else {
free(a->zout_start);
res = NULL;
}
free(a);
return res;
}
int stbi_zlib_decode_buffer(char *obuffer, int olen, char const *ibuffer,
int ilen) {
stbi__zbuf a;
a.zbuffer = (unsigned char *)ibuffer;
a.zbuffer_end = (unsigned char *)ibuffer + ilen;
if (stbi__do_zlib(&a, obuffer, olen, 0, 1))
return (int)(a.zout - a.zout_start);
else
return -1;
}
char *stbi_zlib_decode_noheader_malloc(char const *buffer, int len,
int *outlen) {
stbi__zbuf a;
char *p = (char *)malloc(16384);
if (p == NULL) return NULL;
a.zbuffer = (unsigned char *)buffer;
a.zbuffer_end = (unsigned char *)buffer + len;
if (stbi__do_zlib(&a, p, 16384, 1, 0)) {
if (outlen) *outlen = (int)(a.zout - a.zout_start);
return a.zout_start;
} else {
free(a.zout_start);
return NULL;
}
}
int stbi_zlib_decode_noheader_buffer(char *obuffer, int olen,
const char *ibuffer, int ilen) {
stbi__zbuf a;
a.zbuffer = (unsigned char *)ibuffer;
a.zbuffer_end = (unsigned char *)ibuffer + ilen;
if (stbi__do_zlib(&a, obuffer, olen, 0, 0))
return (int)(a.zout - a.zout_start);
else
return -1;
}
// public domain "baseline" PNG decoder v0.10 Sean Barrett 2006-11-18
// simple implementation
// - only 8-bit samples
// - no CRC checking
// - allocates lots of intermediate memory
// - avoids problem of streaming data between subsystems
// - avoids explicit window management
// performance
// - uses stb_zlib, a PD zlib implementation with fast huffman decoding
typedef struct {
uint32_t length;
uint32_t type;
} stbi__pngchunk;
static stbi__pngchunk stbi__get_chunk_header(stbi__context *s) {
stbi__pngchunk c;
c.length = stbi__get32be(s);
c.type = stbi__get32be(s);
return c;
}
static int stbi__check_png_header(stbi__context *s) {
int i;
for (i = 0; i < 8; ++i) {
if (stbi__get8(s) != kPngSig[i]) {
return stbi__err("bad png sig", "Not a PNG");
}
}
return 1;
}
typedef struct {
stbi__context *s;
unsigned char *idata, *expanded, *out;
int depth;
} stbi__png;
enum {
STBI__F_none = 0,
STBI__F_sub = 1,
STBI__F_up = 2,
STBI__F_avg = 3,
STBI__F_paeth = 4,
// synthetic filters used for first scanline to avoid needing a dummy row of
// 0s
STBI__F_avg_first,
STBI__F_paeth_first
};
static int stbi__de_iphone_flag = 0;
static int stbi__unpremultiply_on_load = 0;
static unsigned char first_row_filter[5] = {STBI__F_none, STBI__F_sub,
STBI__F_none, STBI__F_avg_first,
STBI__F_paeth_first};
static int stbi__paeth(int a, int b, int c) {
int p = a + b - c;
int pa = abs(p - a);
int pb = abs(p - b);
int pc = abs(p - c);
if (pa <= pb && pa <= pc) return a;
if (pb <= pc) return b;
return c;
}
static const unsigned char stbi__depth_scale_table[9] = {
0, 0xff, 0x55, 0, 0x11, 0, 0, 0, 0x01};
// create the png data from post-deflated data
static int stbi__create_png_image_raw(stbi__png *a, unsigned char *raw,
uint32_t raw_len, int out_n, uint32_t x,
uint32_t y, int depth, int color) {
int bytes = (depth == 16 ? 2 : 1);
stbi__context *s = a->s;
uint32_t i, j, stride = x * out_n * bytes;
uint32_t img_len, img_width_bytes;
int k;
int img_n = s->img_n; // copy it into a local for later
int output_bytes = out_n * bytes;
int filter_bytes = img_n * bytes;
int width = x;
assert(out_n == s->img_n || out_n == s->img_n + 1);
a->out = stbi__malloc_mad3(x, y, output_bytes,
0); // extra bytes to write off the end into
if (!stbi__mad3sizes_valid(img_n, x, depth, 7))
return stbi__err("too large", "Corrupt PNG");
img_width_bytes = (((img_n * x * depth) + 7) >> 3);
img_len = (img_width_bytes + 1) * y;
// we used to check for exact match between raw_len and img_len on
// non-interlaced PNGs, but issue #276 reported a PNG in the wild that had
// extra data at the end (all zeros), so just check for raw_len < img_len
// always.
if (raw_len < img_len) return stbi__err("not enough pixels", "Corrupt PNG");
for (j = 0; j < y; ++j) {
unsigned char *cur = a->out + stride * j;
unsigned char *prior;
int filter = *raw++;
if (filter > 4) return stbi__err("invalid filter", "Corrupt PNG");
if (depth < 8) {
assert(img_width_bytes <= x);
cur +=
x * out_n - img_width_bytes; // store output to the rightmost img_len
// bytes, so we can decode in place
filter_bytes = 1;
width = img_width_bytes;
}
prior = cur - stride; // bugfix: need to compute this after 'cur +='
// computation above
// if first row, use special filter that doesn't sample previous row
if (j == 0) filter = first_row_filter[filter];
// handle first byte explicitly
for (k = 0; k < filter_bytes; ++k) {
switch (filter) {
case STBI__F_none:
cur[k] = raw[k];
break;
case STBI__F_sub:
cur[k] = raw[k];
break;
case STBI__F_up:
cur[k] = STBI__BYTECAST(raw[k] + prior[k]);
break;
case STBI__F_avg:
cur[k] = STBI__BYTECAST(raw[k] + (prior[k] >> 1));
break;
case STBI__F_paeth:
cur[k] = STBI__BYTECAST(raw[k] + stbi__paeth(0, prior[k], 0));
break;
case STBI__F_avg_first:
cur[k] = raw[k];
break;
case STBI__F_paeth_first:
cur[k] = raw[k];
break;
}
}
if (depth == 8) {
if (img_n != out_n) cur[img_n] = 255; // first pixel
raw += img_n;
cur += out_n;
prior += out_n;
} else if (depth == 16) {
if (img_n != out_n) {
cur[filter_bytes] = 255; // first pixel top byte
cur[filter_bytes + 1] = 255; // first pixel bottom byte
}
raw += filter_bytes;
cur += output_bytes;
prior += output_bytes;
} else {
raw += 1;
cur += 1;
prior += 1;
}
// this is a little gross, so that we don't switch per-pixel or
// per-component
if (depth < 8 || img_n == out_n) {
int nk = (width - 1) * filter_bytes;
#define STBI__CASE(f) \
case f: \
for (k = 0; k < nk; ++k)
switch (filter) {
// "none" filter turns into a memcpy here; make that explicit.
case STBI__F_none:
memcpy(cur, raw, nk);
break;
STBI__CASE(STBI__F_sub) {
cur[k] = STBI__BYTECAST(raw[k] + cur[k - filter_bytes]);
}
break;
STBI__CASE(STBI__F_up) {
cur[k] = STBI__BYTECAST(raw[k] + prior[k]);
}
break;
STBI__CASE(STBI__F_avg) {
cur[k] = STBI__BYTECAST(raw[k] +
((prior[k] + cur[k - filter_bytes]) >> 1));
}
break;
STBI__CASE(STBI__F_paeth) {
cur[k] = STBI__BYTECAST(raw[k] +
stbi__paeth(cur[k - filter_bytes], prior[k],
prior[k - filter_bytes]));
}
break;
STBI__CASE(STBI__F_avg_first) {
cur[k] = STBI__BYTECAST(raw[k] + (cur[k - filter_bytes] >> 1));
}
break;
STBI__CASE(STBI__F_paeth_first) {
cur[k] = STBI__BYTECAST(raw[k] +
stbi__paeth(cur[k - filter_bytes], 0, 0));
}
break;
}
#undef STBI__CASE
raw += nk;
} else {
assert(img_n + 1 == out_n);
#define STBI__CASE(f) \
case f: \
for (i = x - 1; i >= 1; --i, cur[filter_bytes] = 255, raw += filter_bytes, \
cur += output_bytes, prior += output_bytes) \
for (k = 0; k < filter_bytes; ++k)
switch (filter) {
STBI__CASE(STBI__F_none) {
cur[k] = raw[k];
}
break;
STBI__CASE(STBI__F_sub) {
cur[k] = STBI__BYTECAST(raw[k] + cur[k - output_bytes]);
}
break;
STBI__CASE(STBI__F_up) {
cur[k] = STBI__BYTECAST(raw[k] + prior[k]);
}
break;
STBI__CASE(STBI__F_avg) {
cur[k] = STBI__BYTECAST(raw[k] +
((prior[k] + cur[k - output_bytes]) >> 1));
}
break;
STBI__CASE(STBI__F_paeth) {
cur[k] = STBI__BYTECAST(raw[k] +
stbi__paeth(cur[k - output_bytes], prior[k],
prior[k - output_bytes]));
}
break;
STBI__CASE(STBI__F_avg_first) {
cur[k] = STBI__BYTECAST(raw[k] + (cur[k - output_bytes] >> 1));
}
break;
STBI__CASE(STBI__F_paeth_first) {
cur[k] =
STBI__BYTECAST(raw[k] + stbi__paeth(cur[k - output_bytes], 0, 0));
}
break;
}
#undef STBI__CASE
// the loop above sets the high byte of the pixels' alpha, but for
// 16 bit png files we also need the low byte set. we'll do that here.
if (depth == 16) {
cur = a->out + stride * j; // start at the beginning of the row again
for (i = 0; i < x; ++i, cur += output_bytes) {
cur[filter_bytes + 1] = 255;
}
}
}
}
// we make a separate pass to expand bits to pixels; for performance,
// this could run two scanlines behind the above code, so it won't
// intefere with filtering but will still be in the cache.
if (depth < 8) {
for (j = 0; j < y; ++j) {
unsigned char *cur = a->out + stride * j;
unsigned char *in = a->out + stride * j + x * out_n - img_width_bytes;
// unpack 1/2/4-bit into a 8-bit buffer. allows us to keep the common
// 8-bit path optimal at minimal cost for 1/2/4-bit png guarante byte
// alignment, if width is not multiple of 8/4/2 we'll decode dummy
// trailing data that will be skipped in the later loop
unsigned char scale = (color == 0)
? stbi__depth_scale_table[depth]
: 1; // scale grayscale values to 0..255 range
// note that the final byte might overshoot and write more data than
// desired. we can allocate enough data that this never writes out of
// memory, but it could also overwrite the next scanline. can it
// overwrite non-empty data on the next scanline? yes, consider
// 1-pixel-wide scanlines with 1-bit-per-pixel. so we need to explicitly
// clamp the final ones
if (depth == 4) {
for (k = x * img_n; k >= 2; k -= 2, ++in) {
*cur++ = scale * ((*in >> 4));
*cur++ = scale * ((*in) & 0x0f);
}
if (k > 0) *cur++ = scale * ((*in >> 4));
} else if (depth == 2) {
for (k = x * img_n; k >= 4; k -= 4, ++in) {
*cur++ = scale * ((*in >> 6));
*cur++ = scale * ((*in >> 4) & 0x03);
*cur++ = scale * ((*in >> 2) & 0x03);
*cur++ = scale * ((*in) & 0x03);
}
if (k > 0) *cur++ = scale * ((*in >> 6));
if (k > 1) *cur++ = scale * ((*in >> 4) & 0x03);
if (k > 2) *cur++ = scale * ((*in >> 2) & 0x03);
} else if (depth == 1) {
for (k = x * img_n; k >= 8; k -= 8, ++in) {
*cur++ = scale * ((*in >> 7));
*cur++ = scale * ((*in >> 6) & 0x01);
*cur++ = scale * ((*in >> 5) & 0x01);
*cur++ = scale * ((*in >> 4) & 0x01);
*cur++ = scale * ((*in >> 3) & 0x01);
*cur++ = scale * ((*in >> 2) & 0x01);
*cur++ = scale * ((*in >> 1) & 0x01);
*cur++ = scale * ((*in) & 0x01);
}
if (k > 0) *cur++ = scale * ((*in >> 7));
if (k > 1) *cur++ = scale * ((*in >> 6) & 0x01);
if (k > 2) *cur++ = scale * ((*in >> 5) & 0x01);
if (k > 3) *cur++ = scale * ((*in >> 4) & 0x01);
if (k > 4) *cur++ = scale * ((*in >> 3) & 0x01);
if (k > 5) *cur++ = scale * ((*in >> 2) & 0x01);
if (k > 6) *cur++ = scale * ((*in >> 1) & 0x01);
}
if (img_n != out_n) {
int q;
// insert alpha = 255
cur = a->out + stride * j;
if (img_n == 1) {
for (q = x - 1; q >= 0; --q) {
cur[q * 2 + 1] = 255;
cur[q * 2 + 0] = cur[q];
}
} else {
assert(img_n == 3);
for (q = x - 1; q >= 0; --q) {
cur[q * 4 + 3] = 255;
cur[q * 4 + 2] = cur[q * 3 + 2];
cur[q * 4 + 1] = cur[q * 3 + 1];
cur[q * 4 + 0] = cur[q * 3 + 0];
}
}
}
}
} else if (depth == 16) {
// force the image data from big-endian to platform-native.
// this is done in a separate pass due to the decoding relying
// on the data being untouched, but could probably be done
// per-line during decode if care is taken.
unsigned char *cur = a->out;
uint16_t *cur16 = (uint16_t *)cur;
for (i = 0; i < x * y * out_n; ++i, cur16++, cur += 2) {
*cur16 = (cur[0] << 8) | cur[1];
}
}
return 1;
}
static int stbi__create_png_image(stbi__png *a, unsigned char *image_data,
uint32_t image_data_len, int out_n, int depth,
int color, int interlaced) {
int bytes = (depth == 16 ? 2 : 1);
int out_bytes = out_n * bytes;
unsigned char *final;
int p;
if (!interlaced)
return stbi__create_png_image_raw(a, image_data, image_data_len, out_n,
a->s->img_x, a->s->img_y, depth, color);
// de-interlacing
final = stbi__malloc_mad3(a->s->img_x, a->s->img_y, out_bytes, 0);
for (p = 0; p < 7; ++p) {
int xorig[] = {0, 4, 0, 2, 0, 1, 0};
int yorig[] = {0, 0, 4, 0, 2, 0, 1};
int xspc[] = {8, 8, 4, 4, 2, 2, 1};
int yspc[] = {8, 8, 8, 4, 4, 2, 2};
int i, j, x, y;
// pass1_x[4] = 0, pass1_x[5] = 1, pass1_x[12] = 1
x = (a->s->img_x - xorig[p] + xspc[p] - 1) / xspc[p];
y = (a->s->img_y - yorig[p] + yspc[p] - 1) / yspc[p];
if (x && y) {
uint32_t img_len = ((((a->s->img_n * x * depth) + 7) >> 3) + 1) * y;
if (!stbi__create_png_image_raw(a, image_data, image_data_len, out_n, x,
y, depth, color)) {
free(final);
return 0;
}
for (j = 0; j < y; ++j) {
for (i = 0; i < x; ++i) {
int out_y = j * yspc[p] + yorig[p];
int out_x = i * xspc[p] + xorig[p];
memcpy(final + out_y * a->s->img_x * out_bytes + out_x * out_bytes,
a->out + (j * x + i) * out_bytes, out_bytes);
}
}
free(a->out);
image_data += img_len;
image_data_len -= img_len;
}
}
a->out = final;
return 1;
}
static int stbi__compute_transparency(stbi__png *z, unsigned char tc[3],
int out_n) {
stbi__context *s = z->s;
uint32_t i, pixel_count = s->img_x * s->img_y;
unsigned char *p = z->out;
// compute color-based transparency, assuming we've
// already got 255 as the alpha value in the output
assert(out_n == 2 || out_n == 4);
if (out_n == 2) {
for (i = 0; i < pixel_count; ++i) {
p[1] = (p[0] == tc[0] ? 0 : 255);
p += 2;
}
} else {
for (i = 0; i < pixel_count; ++i) {
if (p[0] == tc[0] && p[1] == tc[1] && p[2] == tc[2]) p[3] = 0;
p += 4;
}
}
return 1;
}
static int stbi__compute_transparency16(stbi__png *z, uint16_t tc[3],
int out_n) {
stbi__context *s = z->s;
uint32_t i, pixel_count = s->img_x * s->img_y;
uint16_t *p = (uint16_t *)z->out;
// compute color-based transparency, assuming we've
// already got 65535 as the alpha value in the output
assert(out_n == 2 || out_n == 4);
if (out_n == 2) {
for (i = 0; i < pixel_count; ++i) {
p[1] = (p[0] == tc[0] ? 0 : 65535);
p += 2;
}
} else {
for (i = 0; i < pixel_count; ++i) {
if (p[0] == tc[0] && p[1] == tc[1] && p[2] == tc[2]) p[3] = 0;
p += 4;
}
}
return 1;
}
static int stbi__expand_png_palette(stbi__png *a, unsigned char *palette,
int len, int pal_img_n) {
uint32_t i, pixel_count = a->s->img_x * a->s->img_y;
unsigned char *p, *temp_out, *orig = a->out;
p = stbi__malloc_mad2(pixel_count, pal_img_n, 0);
// between here and free(out) below, exitting would leak
temp_out = p;
if (pal_img_n == 3) {
for (i = 0; i < pixel_count; ++i) {
int n = orig[i] * 4;
p[0] = palette[n];
p[1] = palette[n + 1];
p[2] = palette[n + 2];
p += 3;
}
} else {
for (i = 0; i < pixel_count; ++i) {
int n = orig[i] * 4;
p[0] = palette[n];
p[1] = palette[n + 1];
p[2] = palette[n + 2];
p[3] = palette[n + 3];
p += 4;
}
}
free(a->out);
a->out = temp_out;
return 1;
}
void stbi_set_unpremultiply_on_load(int flag_true_if_should_unpremultiply) {
stbi__unpremultiply_on_load = flag_true_if_should_unpremultiply;
}
void stbi_convert_iphone_png_to_rgb(int flag_true_if_should_convert) {
stbi__de_iphone_flag = flag_true_if_should_convert;
}
static void stbi__de_iphone(stbi__png *z) {
stbi__context *s = z->s;
uint32_t i, pixel_count = s->img_x * s->img_y;
unsigned char *p = z->out;
if (s->img_out_n == 3) { // convert bgr to rgb
for (i = 0; i < pixel_count; ++i) {
unsigned char t = p[0];
p[0] = p[2];
p[2] = t;
p += 3;
}
} else {
assert(s->img_out_n == 4);
if (stbi__unpremultiply_on_load) {
// convert bgr to rgb and unpremultiply
for (i = 0; i < pixel_count; ++i) {
unsigned char a = p[3];
unsigned char t = p[0];
if (a) {
unsigned char half = a / 2;
p[0] = (p[2] * 255 + half) / a;
p[1] = (p[1] * 255 + half) / a;
p[2] = (t * 255 + half) / a;
} else {
p[0] = p[2];
p[2] = t;
}
p += 4;
}
} else {
// convert bgr to rgb
for (i = 0; i < pixel_count; ++i) {
unsigned char t = p[0];
p[0] = p[2];
p[2] = t;
p += 4;
}
}
}
}
#define STBI__PNG_TYPE(a, b, c, d) \
(((unsigned)(a) << 24) + ((unsigned)(b) << 16) + ((unsigned)(c) << 8) + \
(unsigned)(d))
static int stbi__parse_png_file(stbi__png *z, int scan, int req_comp) {
unsigned char palette[1024], pal_img_n = 0;
unsigned char has_trans = 0, tc[3] = {0};
uint16_t tc16[3];
uint32_t ioff = 0, idata_limit = 0, i, pal_len = 0;
int first = 1, k, interlace = 0, color = 0, is_iphone = 0;
stbi__context *s = z->s;
z->expanded = NULL;
z->idata = NULL;
z->out = NULL;
if (!stbi__check_png_header(s)) return 0;
if (scan == STBI__SCAN_type) return 1;
for (;;) {
stbi__pngchunk c = stbi__get_chunk_header(s);
switch (c.type) {
case STBI__PNG_TYPE('C', 'g', 'B', 'I'):
is_iphone = 1;
stbi__skip(s, c.length);
break;
case STBI__PNG_TYPE('I', 'H', 'D', 'R'): {
int comp, filter;
if (!first) return stbi__err("multiple IHDR", "Corrupt PNG");
first = 0;
if (c.length != 13) return stbi__err("bad IHDR len", "Corrupt PNG");
s->img_x = stbi__get32be(s);
if (s->img_x > (1 << 24))
return stbi__err("too large", "Very large image (corrupt?)");
s->img_y = stbi__get32be(s);
if (s->img_y > (1 << 24))
return stbi__err("too large", "Very large image (corrupt?)");
z->depth = stbi__get8(s);
if (z->depth != 1 && z->depth != 2 && z->depth != 4 && z->depth != 8 &&
z->depth != 16)
return stbi__err("1/2/4/8/16-bit only",
"PNG not supported: 1/2/4/8/16-bit only");
color = stbi__get8(s);
if (color > 6) return stbi__err("bad ctype", "Corrupt PNG");
if (color == 3 && z->depth == 16)
return stbi__err("bad ctype", "Corrupt PNG");
if (color == 3)
pal_img_n = 3;
else if (color & 1)
return stbi__err("bad ctype", "Corrupt PNG");
comp = stbi__get8(s);
if (comp) return stbi__err("bad comp method", "Corrupt PNG");
filter = stbi__get8(s);
if (filter) return stbi__err("bad filter method", "Corrupt PNG");
interlace = stbi__get8(s);
if (interlace > 1)
return stbi__err("bad interlace method", "Corrupt PNG");
if (!s->img_x || !s->img_y)
return stbi__err("0-pixel image", "Corrupt PNG");
if (!pal_img_n) {
s->img_n = (color & 2 ? 3 : 1) + (color & 4 ? 1 : 0);
if ((1 << 30) / s->img_x / s->img_n < s->img_y)
return stbi__err("too large", "Image too large to decode");
if (scan == STBI__SCAN_header) return 1;
} else {
// if paletted, then pal_n is our final components, and
// img_n is # components to decompress/filter.
s->img_n = 1;
if ((1 << 30) / s->img_x / 4 < s->img_y)
return stbi__err("too large", "Corrupt PNG");
// if SCAN_header, have to scan to see if we have a tRNS
}
break;
}
case STBI__PNG_TYPE('P', 'L', 'T', 'E'): {
if (first) return stbi__err("first not IHDR", "Corrupt PNG");
if (c.length > 256 * 3) return stbi__err("invalid PLTE", "Corrupt PNG");
pal_len = c.length / 3;
if (pal_len * 3 != c.length)
return stbi__err("invalid PLTE", "Corrupt PNG");
for (i = 0; i < pal_len; ++i) {
palette[i * 4 + 0] = stbi__get8(s);
palette[i * 4 + 1] = stbi__get8(s);
palette[i * 4 + 2] = stbi__get8(s);
palette[i * 4 + 3] = 255;
}
break;
}
case STBI__PNG_TYPE('t', 'R', 'N', 'S'): {
if (first) return stbi__err("first not IHDR", "Corrupt PNG");
if (z->idata) return stbi__err("tRNS after IDAT", "Corrupt PNG");
if (pal_img_n) {
if (scan == STBI__SCAN_header) {
s->img_n = 4;
return 1;
}
if (pal_len == 0) return stbi__err("tRNS before PLTE", "Corrupt PNG");
if (c.length > pal_len)
return stbi__err("bad tRNS len", "Corrupt PNG");
pal_img_n = 4;
for (i = 0; i < c.length; ++i) palette[i * 4 + 3] = stbi__get8(s);
} else {
if (!(s->img_n & 1))
return stbi__err("tRNS with alpha", "Corrupt PNG");
if (c.length != (uint32_t)s->img_n * 2)
return stbi__err("bad tRNS len", "Corrupt PNG");
has_trans = 1;
if (z->depth == 16) {
for (k = 0; k < s->img_n; ++k)
tc16[k] = (uint16_t)stbi__get16be(s); // copy the values as-is
} else {
for (k = 0; k < s->img_n; ++k)
tc[k] = (unsigned char)(stbi__get16be(s) & 255) *
stbi__depth_scale_table[z->depth]; // non 8-bit images
// will be larger
}
}
break;
}
case STBI__PNG_TYPE('I', 'D', 'A', 'T'): {
if (first) return stbi__err("first not IHDR", "Corrupt PNG");
if (pal_img_n && !pal_len) return stbi__err("no PLTE", "Corrupt PNG");
if (scan == STBI__SCAN_header) {
s->img_n = pal_img_n;
return 1;
}
if ((int)(ioff + c.length) < (int)ioff) return 0;
if (ioff + c.length > idata_limit) {
uint32_t idata_limit_old = idata_limit;
unsigned char *p;
if (idata_limit == 0) idata_limit = c.length > 4096 ? c.length : 4096;
while (ioff + c.length > idata_limit) idata_limit *= 2;
(void)idata_limit_old;
p = STBI_REALLOC_SIZED(z->idata, idata_limit_old, idata_limit);
if (p == NULL) return stbi__err("outofmem", "Out of memory");
z->idata = p;
}
if (!stbi__getn(s, z->idata + ioff, c.length))
return stbi__err("outofdata", "Corrupt PNG");
ioff += c.length;
break;
}
case STBI__PNG_TYPE('I', 'E', 'N', 'D'): {
uint32_t raw_len, bpl;
if (first) return stbi__err("first not IHDR", "Corrupt PNG");
if (scan != STBI__SCAN_load) return 1;
if (z->idata == NULL) return stbi__err("no IDAT", "Corrupt PNG");
// initial guess for decoded data size to avoid unnecessary reallocs
bpl = (s->img_x * z->depth + 7) / 8; // bytes per line, per component
raw_len = bpl * s->img_y * s->img_n /* pixels */ +
s->img_y /* filter mode per row */;
z->expanded =
(unsigned char *)stbi_zlib_decode_malloc_guesssize_headerflag(
(char *)z->idata, ioff, raw_len, (int *)&raw_len, !is_iphone);
if (z->expanded == NULL) return 0; // zlib should set error
free(z->idata);
z->idata = NULL;
if ((req_comp == s->img_n + 1 && req_comp != 3 && !pal_img_n) ||
has_trans) {
s->img_out_n = s->img_n + 1;
} else {
s->img_out_n = s->img_n;
}
if (!stbi__create_png_image(z, z->expanded, raw_len, s->img_out_n,
z->depth, color, interlace))
return 0;
if (has_trans) {
if (z->depth == 16) {
if (!stbi__compute_transparency16(z, tc16, s->img_out_n)) return 0;
} else {
if (!stbi__compute_transparency(z, tc, s->img_out_n)) return 0;
}
}
if (is_iphone && stbi__de_iphone_flag && s->img_out_n > 2)
stbi__de_iphone(z);
if (pal_img_n) {
// pal_img_n == 3 or 4
s->img_n = pal_img_n; // record the actual colors we had
s->img_out_n = pal_img_n;
if (req_comp >= 3) s->img_out_n = req_comp;
if (!stbi__expand_png_palette(z, palette, pal_len, s->img_out_n))
return 0;
} else if (has_trans) {
// non-paletted image with tRNS -> source image has (constant) alpha
++s->img_n;
}
free(z->expanded);
z->expanded = NULL;
stbi__get32be(s); /* nothings/stb#835 */
return 1;
}
default:
// if critical, fail
if (first) return stbi__err("first not IHDR", "Corrupt PNG");
if ((c.type & (1 << 29)) == 0) {
#ifndef STBI_NO_FAILURE_STRINGS
// not threadsafe
static char invalid_chunk[] = "XXXX PNG chunk not known";
invalid_chunk[0] = STBI__BYTECAST(c.type >> 24);
invalid_chunk[1] = STBI__BYTECAST(c.type >> 16);
invalid_chunk[2] = STBI__BYTECAST(c.type >> 8);
invalid_chunk[3] = STBI__BYTECAST(c.type >> 0);
#endif
return stbi__err(invalid_chunk,
"PNG not supported: unknown PNG chunk type");
}
stbi__skip(s, c.length);
break;
}
// end of PNG chunk, read and skip CRC
stbi__get32be(s);
}
}
static void *stbi__do_png(stbi__png *p, int *x, int *y, int *n, int req_comp,
stbi__result_info *ri) {
void *result = NULL;
if (req_comp < 0 || req_comp > 4)
return stbi__errpuc("bad req_comp", "Internal error");
if (stbi__parse_png_file(p, STBI__SCAN_load, req_comp)) {
if (p->depth < 8)
ri->bits_per_channel = 8;
else
ri->bits_per_channel = p->depth;
result = p->out;
p->out = NULL;
if (req_comp && req_comp != p->s->img_out_n) {
if (ri->bits_per_channel == 8)
result = stbi__convert_format((unsigned char *)result, p->s->img_out_n,
req_comp, p->s->img_x, p->s->img_y);
else
result = stbi__convert_format16((uint16_t *)result, p->s->img_out_n,
req_comp, p->s->img_x, p->s->img_y);
p->s->img_out_n = req_comp;
if (result == NULL) return result;
}
*x = p->s->img_x;
*y = p->s->img_y;
if (n) *n = p->s->img_n;
}
free(p->out);
p->out = NULL;
free(p->expanded);
p->expanded = NULL;
free(p->idata);
p->idata = NULL;
return result;
}
static noinline void *stbi__png_load(stbi__context *s, int *x, int *y,
int *comp, int req_comp,
stbi__result_info *ri) {
stbi__png p;
p.s = s;
return stbi__do_png(&p, x, y, comp, req_comp, ri);
}
static int stbi__png_test(stbi__context *s) {
int r;
r = stbi__check_png_header(s);
stbi__rewind(s);
return r;
}
static int stbi__png_info_raw(stbi__png *p, int *x, int *y, int *comp) {
if (!stbi__parse_png_file(p, STBI__SCAN_header, 0)) {
stbi__rewind(p->s);
return 0;
}
if (x) *x = p->s->img_x;
if (y) *y = p->s->img_y;
if (comp) *comp = p->s->img_n;
return 1;
}
static int stbi__png_info(stbi__context *s, int *x, int *y, int *comp) {
stbi__png p;
p.s = s;
return stbi__png_info_raw(&p, x, y, comp);
}
static int stbi__png_is16(stbi__context *s) {
stbi__png p;
p.s = s;
if (!stbi__png_info_raw(&p, NULL, NULL, NULL)) return 0;
if (p.depth != 16) {
stbi__rewind(p.s);
return 0;
}
return 1;
}
// *****************************************************************************
// GIF loader -- public domain by Jean-Marc Lienher -- simplified/shrunk by
// stb
typedef struct {
int16_t prefix;
unsigned char first;
unsigned char suffix;
} stbi__gif_lzw;
typedef struct {
int w, h;
unsigned char *out; // output buffer (always 4 components)
unsigned char
*background; // The current "background" as far as a gif is concerned
unsigned char *history;
int flags, bgindex, ratio, transparent, eflags;
unsigned char pal[256][4];
unsigned char lpal[256][4];
stbi__gif_lzw codes[8192];
unsigned char *color_table;
int parse, step;
int lflags;
int start_x, start_y;
int max_x, max_y;
int cur_x, cur_y;
int line_size;
int delay;
} stbi__gif;
static int stbi__gif_test_raw(stbi__context *s) {
int sz;
if (stbi__get8(s) != 'G' || stbi__get8(s) != 'I' || stbi__get8(s) != 'F' ||
stbi__get8(s) != '8')
return 0;
sz = stbi__get8(s);
if (sz != '9' && sz != '7') return 0;
if (stbi__get8(s) != 'a') return 0;
return 1;
}
static int stbi__gif_test(stbi__context *s) {
int r = stbi__gif_test_raw(s);
stbi__rewind(s);
return r;
}
static void stbi__gif_parse_colortable(stbi__context *s,
unsigned char pal[256][4],
int num_entries, int transp) {
int i;
for (i = 0; i < num_entries; ++i) {
pal[i][2] = stbi__get8(s);
pal[i][1] = stbi__get8(s);
pal[i][0] = stbi__get8(s);
pal[i][3] = transp == i ? 0 : 255;
}
}
static int stbi__gif_header(stbi__context *s, stbi__gif *g, int *comp,
int is_info) {
unsigned char version;
if (stbi__get8(s) != 'G' || stbi__get8(s) != 'I' || stbi__get8(s) != 'F' ||
stbi__get8(s) != '8')
return stbi__err("not GIF", "Corrupt GIF");
version = stbi__get8(s);
if (version != '7' && version != '9') {
return stbi__err("not GIF", "Corrupt GIF");
}
if (stbi__get8(s) != 'a') return stbi__err("not GIF", "Corrupt GIF");
stbi__g_failure_reason = "";
g->w = stbi__get16le(s);
g->h = stbi__get16le(s);
g->flags = stbi__get8(s);
g->bgindex = stbi__get8(s);
g->ratio = stbi__get8(s);
g->transparent = -1;
if (comp != 0) {
*comp = 4; // can't actually tell whether it's 3 or 4 until we parse the
// comments
}
if (is_info) return 1;
if (g->flags & 0x80) {
stbi__gif_parse_colortable(s, g->pal, 2 << (g->flags & 7), -1);
}
return 1;
}
static int stbi__gif_info_raw(stbi__context *s, int *x, int *y, int *comp) {
stbi__gif *g = (stbi__gif *)malloc(sizeof(stbi__gif));
if (!stbi__gif_header(s, g, comp, 1)) {
free(g);
stbi__rewind(s);
return 0;
}
if (x) *x = g->w;
if (y) *y = g->h;
free(g);
return 1;
}
static void stbi__out_gif_code(stbi__gif *g, uint16_t code) {
unsigned char *p, *c;
int idx;
// recurse to decode the prefixes, since the linked-list is backwards,
// and working backwards through an interleaved image would be nasty
if (g->codes[code].prefix >= 0) stbi__out_gif_code(g, g->codes[code].prefix);
if (g->cur_y >= g->max_y) return;
idx = g->cur_x + g->cur_y;
p = &g->out[idx];
g->history[idx / 4] = 1;
c = &g->color_table[g->codes[code].suffix * 4];
if (c[3] > 128) { // don't render transparent pixels;
p[0] = c[2];
p[1] = c[1];
p[2] = c[0];
p[3] = c[3];
}
g->cur_x += 4;
if (g->cur_x >= g->max_x) {
g->cur_x = g->start_x;
g->cur_y += g->step;
while (g->cur_y >= g->max_y && g->parse > 0) {
g->step = (1 << g->parse) * g->line_size;
g->cur_y = g->start_y + (g->step >> 1);
--g->parse;
}
}
}
static unsigned char *stbi__process_gif_raster(stbi__context *s, stbi__gif *g) {
unsigned char lzw_cs;
int32_t len, init_code;
uint32_t first;
int32_t codesize, codemask, avail, oldcode, bits, valid_bits, clear;
stbi__gif_lzw *p;
lzw_cs = stbi__get8(s);
if (lzw_cs > 12) return NULL;
clear = 1 << lzw_cs;
first = 1;
codesize = lzw_cs + 1;
codemask = (1 << codesize) - 1;
bits = 0;
valid_bits = 0;
for (init_code = 0; init_code < clear; init_code++) {
g->codes[init_code].prefix = -1;
g->codes[init_code].first = (unsigned char)init_code;
g->codes[init_code].suffix = (unsigned char)init_code;
}
// support no starting clear code
avail = clear + 2;
oldcode = -1;
len = 0;
for (;;) {
if (valid_bits < codesize) {
if (len == 0) {
len = stbi__get8(s); // start new block
if (len == 0) return g->out;
}
--len;
bits |= (int32_t)stbi__get8(s) << valid_bits;
valid_bits += 8;
} else {
int32_t code = bits & codemask;
bits >>= codesize;
valid_bits -= codesize;
// @OPTIMIZE: is there some way we can accelerate the non-clear path?
if (code == clear) { // clear code
codesize = lzw_cs + 1;
codemask = (1 << codesize) - 1;
avail = clear + 2;
oldcode = -1;
first = 0;
} else if (code == clear + 1) { // end of stream code
stbi__skip(s, len);
while ((len = stbi__get8(s)) > 0) stbi__skip(s, len);
return g->out;
} else if (code <= avail) {
if (first) {
return stbi__errpuc("no clear code", "Corrupt GIF");
}
if (oldcode >= 0) {
p = &g->codes[avail++];
if (avail > 8192) {
return stbi__errpuc("too many codes", "Corrupt GIF");
}
p->prefix = (int16_t)oldcode;
p->first = g->codes[oldcode].first;
p->suffix = (code == avail) ? p->first : g->codes[code].first;
} else if (code == avail)
return stbi__errpuc("illegal code in raster", "Corrupt GIF");
stbi__out_gif_code(g, (uint16_t)code);
if ((avail & codemask) == 0 && avail <= 0x0FFF) {
codesize++;
codemask = (1 << codesize) - 1;
}
oldcode = code;
} else {
return stbi__errpuc("illegal code in raster", "Corrupt GIF");
}
}
}
}
// this function is designed to support animated gifs, although stb_image
// doesn't support it two back is the image from two frames ago, used for a
// very specific disposal format
static unsigned char *stbi__gif_load_next(stbi__context *s, stbi__gif *g,
int *comp, int req_comp,
unsigned char *two_back) {
int dispose;
int first_frame;
int pi;
int pcount;
// on first frame, any non-written pixels get the background colour
// (non-transparent)
first_frame = 0;
if (g->out == 0) {
if (!stbi__gif_header(s, g, comp, 0))
return 0; // stbi__g_failure_reason set by stbi__gif_header
if (!stbi__mad3sizes_valid(4, g->w, g->h, 0))
return stbi__errpuc("too large", "GIF image is too large");
pcount = g->w * g->h;
g->out = malloc(4 * pcount);
g->background = malloc(4 * pcount);
g->history = malloc(pcount);
if (!g->out || !g->background || !g->history)
return stbi__errpuc("outofmem", "Out of memory");
// image is treated as "transparent" at the start - ie, nothing overwrites
// the current background; background colour is only used for pixels that
// are not rendered first frame, after that "background" color refers to
// the color that was there the previous frame.
memset(g->out, 0x00, 4 * pcount);
memset(g->background, 0x00,
4 * pcount); // state of the background (starts transparent)
memset(g->history, 0x00,
pcount); // pixels that were affected previous frame
first_frame = 1;
} else {
// second frame - how do we dispoase of the previous one?
dispose = (g->eflags & 0x1C) >> 2;
pcount = g->w * g->h;
if ((dispose == 3) && (two_back == 0)) {
dispose = 2; // if I don't have an image to revert back to, default to
// the old background
}
if (dispose == 3) { // use previous graphic
for (pi = 0; pi < pcount; ++pi) {
if (g->history[pi]) {
memcpy(&g->out[pi * 4], &two_back[pi * 4], 4);
}
}
} else if (dispose == 2) {
// restore what was changed last frame to background before that frame;
for (pi = 0; pi < pcount; ++pi) {
if (g->history[pi]) {
memcpy(&g->out[pi * 4], &g->background[pi * 4], 4);
}
}
} else {
// This is a non-disposal case eithe way, so just
// leave the pixels as is, and they will become the new background
// 1: do not dispose
// 0: not specified.
}
// background is what out is after the undoing of the previou frame;
memcpy(g->background, g->out, 4 * g->w * g->h);
}
// clear my history;
memset(g->history, 0x00,
g->w * g->h); // pixels that were affected previous frame
for (;;) {
int tag = stbi__get8(s);
switch (tag) {
case 0x2C: /* Image Descriptor */
{
int32_t x, y, w, h;
unsigned char *o;
x = stbi__get16le(s);
y = stbi__get16le(s);
w = stbi__get16le(s);
h = stbi__get16le(s);
if (((x + w) > (g->w)) || ((y + h) > (g->h)))
return stbi__errpuc("bad Image Descriptor", "Corrupt GIF");
g->line_size = g->w * 4;
g->start_x = x * 4;
g->start_y = y * g->line_size;
g->max_x = g->start_x + w * 4;
g->max_y = g->start_y + h * g->line_size;
g->cur_x = g->start_x;
g->cur_y = g->start_y;
// if the width of the specified rectangle is 0, that means
// we may not see *any* pixels or the image is malformed;
// to make sure this is caught, move the current y down to
// max_y (which is what out_gif_code checks).
if (w == 0) g->cur_y = g->max_y;
g->lflags = stbi__get8(s);
if (g->lflags & 0x40) {
g->step = 8 * g->line_size; // first interlaced spacing
g->parse = 3;
} else {
g->step = g->line_size;
g->parse = 0;
}
if (g->lflags & 0x80) {
stbi__gif_parse_colortable(s, g->lpal, 2 << (g->lflags & 7),
g->eflags & 0x01 ? g->transparent : -1);
g->color_table = (unsigned char *)g->lpal;
} else if (g->flags & 0x80) {
g->color_table = (unsigned char *)g->pal;
} else
return stbi__errpuc("missing color table", "Corrupt GIF");
o = stbi__process_gif_raster(s, g);
if (!o) return NULL;
// if this was the first frame,
pcount = g->w * g->h;
if (first_frame && (g->bgindex > 0)) {
// if first frame, any pixel not drawn to gets the background color
for (pi = 0; pi < pcount; ++pi) {
if (g->history[pi] == 0) {
g->pal[g->bgindex][3] =
255; // just in case it was made transparent, undo that; It
// will be reset next frame if need be;
memcpy(&g->out[pi * 4], &g->pal[g->bgindex], 4);
}
}
}
return o;
}
case 0x21: // Comment Extension.
{
int len;
int ext = stbi__get8(s);
if (ext == 0xF9) { // Graphic Control Extension.
len = stbi__get8(s);
if (len == 4) {
g->eflags = stbi__get8(s);
g->delay =
10 *
stbi__get16le(
s); // delay - 1/100th of a second, saving as 1/1000ths.
// unset old transparent
if (g->transparent >= 0) {
g->pal[g->transparent][3] = 255;
}
if (g->eflags & 0x01) {
g->transparent = stbi__get8(s);
if (g->transparent >= 0) {
g->pal[g->transparent][3] = 0;
}
} else {
// don't need transparent
stbi__skip(s, 1);
g->transparent = -1;
}
} else {
stbi__skip(s, len);
break;
}
}
while ((len = stbi__get8(s)) != 0) {
stbi__skip(s, len);
}
break;
}
case 0x3B: // gif stream termination code
return (
unsigned char *)s; // using '1' causes warning on some compilers
default:
return stbi__errpuc("unknown code", "Corrupt GIF");
}
}
}
static void *stbi__load_gif_main(stbi__context *s, int **delays, int *x, int *y,
int *z, int *comp, int req_comp) {
if (stbi__gif_test(s)) {
int layers = 0;
unsigned char *u = 0;
unsigned char *out = 0;
unsigned char *two_back = 0;
stbi__gif *g;
int stride;
g = calloc(1, sizeof(stbi__gif));
if (delays) {
*delays = 0;
}
do {
u = stbi__gif_load_next(s, g, comp, req_comp, two_back);
if (u == (unsigned char *)s) u = 0; // end of animated gif marker
if (u) {
*x = g->w;
*y = g->h;
++layers;
stride = g->w * g->h * 4;
if (out) {
out = (unsigned char *)realloc(out, layers * stride);
if (!out) abort();
if (delays) {
*delays = (int *)realloc(*delays, sizeof(int) * layers);
if (!*delays) abort();
}
} else {
out = malloc(layers * stride);
if (delays) {
*delays = malloc(layers * sizeof(int));
}
}
memcpy(out + ((layers - 1) * stride), u, stride);
if (layers >= 2) {
two_back = out - 2 * stride;
}
if (delays) {
(*delays)[layers - 1U] = g->delay;
}
}
} while (u != 0);
free(g->out);
free(g->history);
free(g->background);
// do the final conversion after loading everything;
if (req_comp && req_comp != 4)
out = stbi__convert_format(out, 4, req_comp, layers * g->w, g->h);
free(g);
*z = layers;
return out;
} else {
return stbi__errpuc("not GIF", "Image was not as a gif type.");
}
}
static noinline void *stbi__gif_load(stbi__context *s, int *x, int *y,
int *comp, int req_comp,
stbi__result_info *ri) {
unsigned char *u = 0;
stbi__gif *g;
g = calloc(1, sizeof(stbi__gif));
u = stbi__gif_load_next(s, g, comp, req_comp, 0);
if (u == (unsigned char *)s) u = 0; // end of animated gif marker
if (u) {
*x = g->w;
*y = g->h;
// moved conversion to after successful load so that the same
// can be done for multiple frames.
if (req_comp && req_comp != 4)
u = stbi__convert_format(u, 4, req_comp, g->w, g->h);
} else if (g->out) {
// if there was an error and we allocated an image buffer, free it!
free(g->out);
}
// free buffers needed for multiple frame loading;
free(g->history);
free(g->background);
free(g);
return u;
}
static int stbi__gif_info(stbi__context *s, int *x, int *y, int *comp) {
return stbi__gif_info_raw(s, x, y, comp);
}
// ********************************************************************
// Portable Gray Map and Portable Pixel Map loader
// by Ken Miller
//
// PGM: http://netpbm.sourceforge.net/doc/pgm.html
// PPM: http://netpbm.sourceforge.net/doc/ppm.html
//
// Known limitations:
// Does not support comments in the header section
// Does not support ASCII image data (formats P2 and P3)
// Does not support 16-bit-per-channel
static int stbi__pnm_test(stbi__context *s) {
char p, t;
p = (char)stbi__get8(s);
t = (char)stbi__get8(s);
if (p != 'P' || (t != '5' && t != '6')) {
stbi__rewind(s);
return 0;
}
return 1;
}
static noinline void *stbi__pnm_load(stbi__context *s, int *x, int *y,
int *comp, int req_comp,
stbi__result_info *ri) {
unsigned char *out;
if (!stbi__pnm_info(s, (int *)&s->img_x, (int *)&s->img_y,
(int *)&s->img_n)) {
return 0;
}
*x = s->img_x;
*y = s->img_y;
if (comp) *comp = s->img_n;
if (!stbi__mad3sizes_valid(s->img_n, s->img_x, s->img_y, 0)) {
return stbi__errpuc("too large", "PNM too large");
}
out = stbi__malloc_mad3(s->img_n, s->img_x, s->img_y, 0);
stbi__getn(s, out, s->img_n * s->img_x * s->img_y);
if (req_comp && req_comp != s->img_n) {
out = stbi__convert_format(out, s->img_n, req_comp, s->img_x, s->img_y);
if (out == NULL) return out; // stbi__convert_format frees input on failure
}
return out;
}
static int stbi__pnm_isspace(char c) {
return c == ' ' || c == '\t' || c == '\n' || c == '\v' || c == '\f' ||
c == '\r';
}
static void stbi__pnm_skip_whitespace(stbi__context *s, char *c) {
for (;;) {
while (!stbi__at_eof(s) && stbi__pnm_isspace(*c)) *c = (char)stbi__get8(s);
if (stbi__at_eof(s) || *c != '#') break;
while (!stbi__at_eof(s) && *c != '\n' && *c != '\r')
*c = (char)stbi__get8(s);
}
}
static int stbi__pnm_isdigit(char c) {
return c >= '0' && c <= '9';
}
static int stbi__pnm_getinteger(stbi__context *s, char *c) {
int value = 0;
while (!stbi__at_eof(s) && stbi__pnm_isdigit(*c)) {
value = value * 10 + (*c - '0');
*c = (char)stbi__get8(s);
}
return value;
}
static int stbi__pnm_info(stbi__context *s, int *x, int *y, int *comp) {
int maxv, dummy;
char c, p, t;
if (!x) x = &dummy;
if (!y) y = &dummy;
if (!comp) comp = &dummy;
stbi__rewind(s);
// Get identifier
p = (char)stbi__get8(s);
t = (char)stbi__get8(s);
if (p != 'P' || (t != '5' && t != '6')) {
stbi__rewind(s);
return 0;
}
*comp =
(t == '6') ? 3 : 1; // '5' is 1-component .pgm; '6' is 3-component .ppm
c = (char)stbi__get8(s);
stbi__pnm_skip_whitespace(s, &c);
*x = stbi__pnm_getinteger(s, &c); // read width
stbi__pnm_skip_whitespace(s, &c);
*y = stbi__pnm_getinteger(s, &c); // read height
stbi__pnm_skip_whitespace(s, &c);
maxv = stbi__pnm_getinteger(s, &c); // read max value
if (maxv > 255)
return stbi__err("max value > 255", "PPM image not 8-bit");
else {
return 1;
}
}
static int stbi__info_main(stbi__context *s, int *x, int *y, int *comp) {
#ifndef STBI_NO_JPEG
if (stbi__jpeg_info(s, x, y, comp)) return 1;
#endif
#ifndef STBI_NO_PNG
if (stbi__png_info(s, x, y, comp)) return 1;
#endif
#ifndef STBI_NO_GIF
if (stbi__gif_info(s, x, y, comp)) return 1;
#endif
#ifndef STBI_NO_PNM
if (stbi__pnm_info(s, x, y, comp)) return 1;
#endif
return stbi__err("unknown image type",
"Image not of any known type, or corrupt");
}
static int stbi__is_16_main(stbi__context *s) {
if (stbi__png_is16(s)) return 1;
return 0;
}
int stbi_info(char const *filename, int *x, int *y, int *comp) {
FILE *f = stbi__fopen(filename, "rb");
int result;
if (!f) return stbi__err("can't fopen", "Unable to open file");
result = stbi_info_from_file(f, x, y, comp);
fclose(f);
return result;
}
int stbi_info_from_file(FILE *f, int *x, int *y, int *comp) {
int r;
stbi__context s;
long pos = ftell(f);
stbi__start_file(&s, f);
r = stbi__info_main(&s, x, y, comp);
fseek(f, pos, SEEK_SET);
return r;
}
int stbi_is_16_bit(char const *filename) {
FILE *f = stbi__fopen(filename, "rb");
int result;
if (!f) return stbi__err("can't fopen", "Unable to open file");
result = stbi_is_16_bit_from_file(f);
fclose(f);
return result;
}
int stbi_is_16_bit_from_file(FILE *f) {
int r;
stbi__context s;
long pos = ftell(f);
stbi__start_file(&s, f);
r = stbi__is_16_main(&s);
fseek(f, pos, SEEK_SET);
return r;
}
int stbi_info_from_memory(unsigned char const *buffer, int len, int *x, int *y,
int *comp) {
stbi__context s;
stbi__start_mem(&s, buffer, len);
return stbi__info_main(&s, x, y, comp);
}
int stbi_info_from_callbacks(stbi_io_callbacks const *c, void *user, int *x,
int *y, int *comp) {
stbi__context s;
stbi__start_callbacks(&s, (stbi_io_callbacks *)c, user);
return stbi__info_main(&s, x, y, comp);
}
int stbi_is_16_bit_from_memory(unsigned char const *buffer, int len) {
stbi__context s;
stbi__start_mem(&s, buffer, len);
return stbi__is_16_main(&s);
}
int stbi_is_16_bit_from_callbacks(stbi_io_callbacks const *c, void *user) {
stbi__context s;
stbi__start_callbacks(&s, (stbi_io_callbacks *)c, user);
return stbi__is_16_main(&s);
}
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