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cosmopolitan/third_party/zlib/trees.c

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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:4;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=4 sts=4 sw=4 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 1995-2017 Jean-loup Gailly │
│ Use of this source code is governed by the BSD-style licenses that can │
│ be found in the third_party/zlib/LICENSE file. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/stdio/stdio.h"
#include "libc/str/str.h"
#include "third_party/zlib/deflate.h"
#include "third_party/zlib/internal.h"
asm(".ident\t\"\\n\\n\
zlib (zlib License)\\n\
Copyright 1995-2017 Jean-loup Gailly and Mark Adler\"");
asm(".include \"libc/disclaimer.inc\"");
/**
* @fileoverview output deflated data using Huffman coding
*
* ALGORITHM
*
* The "deflation" process uses several Huffman trees. The more
* common source values are represented by shorter bit sequences.
*
* Each code tree is stored in a compressed form which is itself a
* Huffman encoding of the lengths of all the code strings (in
* ascending order by source values). The actual code strings are
* reconstructed from the lengths in the inflate process, as
* described in the deflate specification.
*
* REFERENCES
*
* Deutsch, L.P.,"'Deflate' Compressed Data Format Specification".
* Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc
*
* Storer, James A.
* Data Compression: Methods and Theory, pp. 49-50.
* Computer Science Press, 1988. ISBN 0-7167-8156-5.
*
* Sedgewick, R.
* Algorithms, p290.
* Addison-Wesley, 1983. ISBN 0-201-06672-6.
*/
/* Bit length codes must not exceed MAX_BL_BITS bits */
#define MAX_BL_BITS 7
/* end of block literal code */
#define END_BLOCK 256
/* repeat previous bit length 3-6 times (2 bits of repeat count) */
#define REP_3_6 16
/* repeat a zero length 3-10 times (3 bits of repeat count) */
#define REPZ_3_10 17
/* repeat a zero length 11-138 times (7 bits of repeat count) */
#define REPZ_11_138 18
static const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
= {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};
static const int extra_dbits[D_CODES] /* extra bits for each distance code */
= {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 const int
extra_blbits[BL_CODES] /* extra bits for each bit length code */
= {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 3, 7};
static const uint8_t bl_order[BL_CODES] = {16, 17, 18, 0, 8, 7, 9, 6, 10, 5,
11, 4, 12, 3, 13, 2, 14, 1, 15};
/* The lengths of the bit length codes are sent in order of decreasing
* probability, to avoid transmitting the lengths for unused bit length codes.
*/
/**
* Local data. These are initialized only once.
*/
struct static_tree_desc_s {
const ct_data *static_tree; /* static tree or NULL */
const intf *extra_bits; /* extra bits for each code or NULL */
int extra_base; /* base index for extra_bits */
int elems; /* max number of elements in the tree */
int max_length; /* max bit length for the codes */
};
static const static_tree_desc static_l_desc = {kZlibStaticLtree, extra_lbits,
LITERALS + 1, L_CODES, MAX_BITS};
static const static_tree_desc static_d_desc = {kZlibStaticDtree, extra_dbits, 0,
D_CODES, MAX_BITS};
static const static_tree_desc static_bl_desc = {
(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS};
/**
* Local (static) routines in this file.
*/
static void tr_static_init(void);
static void init_block(struct DeflateState *s);
static void pqdownheap(struct DeflateState *s, ct_data *tree, int k);
static void gen_bitlen(struct DeflateState *s, tree_desc *desc);
static void gen_codes(ct_data *tree, int max_code, uint16_t *bl_count);
static void build_tree(struct DeflateState *s, tree_desc *desc);
static void scan_tree(struct DeflateState *s, ct_data *tree, int max_code);
static void send_tree(struct DeflateState *s, ct_data *tree, int max_code);
static int build_bl_tree(struct DeflateState *s);
static void send_all_trees(struct DeflateState *s, int lcodes, int dcodes,
int blcodes);
static void compress_block(struct DeflateState *s, const ct_data *ltree,
const ct_data *dtree);
static int detect_data_type(struct DeflateState *s);
static unsigned bi_reverse(unsigned value, int length);
static void bi_windup(struct DeflateState *s);
static void bi_flush(struct DeflateState *s);
#ifdef GEN_TREES_H
static void gen_trees_header(void);
#endif
#ifndef ZLIB_DEBUG
#define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
/* Send a code of the given tree. c and tree must not have side effects */
#else /* !ZLIB_DEBUG */
#define send_code(s, c, tree) \
{ \
if (z_verbose > 2) fprintf(stderr, "\ncd %3d ", (c)); \
send_bits(s, tree[c].Code, tree[c].Len); \
}
#endif
/**
* Output a short LSB first on the stream.
* IN assertion: there is enough room in pendingBuf.
*/
#define put_short(s, w) \
{ \
put_byte(s, (uint8_t)((w)&0xff)); \
put_byte(s, (uint8_t)((uint16_t)(w) >> 8)); \
}
/**
* Send a value on a given number of bits.
* IN assertion: length <= 16 and value fits in length bits.
*/
#ifdef ZLIB_DEBUG
static void send_bits(struct DeflateState *s, int value, int length) {
Tracevv((stderr, " l %2d v %4x ", length, value));
Assert(length > 0 && length <= 15, "invalid length");
s->bits_sent += (uint64_t)length;
/* If not enough room in bi_buf, use (valid) bits from bi_buf and
* (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
* unused bits in value.
*/
if (s->bi_valid > (int)Buf_size - length) {
s->bi_buf |= (uint16_t)value << s->bi_valid;
put_short(s, s->bi_buf);
s->bi_buf = (uint16_t)value >> (Buf_size - s->bi_valid);
s->bi_valid += length - Buf_size;
} else {
s->bi_buf |= (uint16_t)value << s->bi_valid;
s->bi_valid += length;
}
}
#else /* !ZLIB_DEBUG */
#define send_bits(s, value, length) \
{ \
int len = length; \
if (s->bi_valid > (int)Buf_size - len) { \
int val = (int)value; \
s->bi_buf |= (uint16_t)val << s->bi_valid; \
put_short(s, s->bi_buf); \
s->bi_buf = (uint16_t)val >> (Buf_size - s->bi_valid); \
s->bi_valid += len - Buf_size; \
} else { \
s->bi_buf |= (uint16_t)(value) << s->bi_valid; \
s->bi_valid += len; \
} \
}
#endif /* ZLIB_DEBUG */
/* the arguments must not have side effects */
/**
* Initialize the various 'constant' tables.
*/
static void tr_static_init(void) {
#if defined(GEN_TREES_H) || !defined(STDC)
static int static_init_done = 0;
int n; /* iterates over tree elements */
int bits; /* bit counter */
int length; /* length value */
int code; /* code value */
int dist; /* distance index */
uint16_t bl_count[MAX_BITS + 1];
/* number of codes at each bit length for an optimal tree */
if (static_init_done) return;
/* For some embedded targets, global variables are not initialized: */
#ifdef NO_INIT_GLOBAL_POINTERS
static_l_desc.static_tree = kZlibStaticLtree;
static_l_desc.extra_bits = extra_lbits;
static_d_desc.static_tree = kZlibStaticDtree;
static_d_desc.extra_bits = extra_dbits;
static_bl_desc.extra_bits = extra_blbits;
#endif
/* Initialize the mapping length (0..255) -> length code (0..28) */
length = 0;
for (code = 0; code < LENGTH_CODES - 1; code++) {
kZlibBaseLength[code] = length;
for (n = 0; n < (1u << extra_lbits[code]); n++) {
kZlibLengthCode[length++] = (uint8_t)code;
}
}
Assert(length == 256, "tr_static_init: length != 256");
/* Note that the length 255 (match length 258) can be represented
* in two different ways: code 284 + 5 bits or code 285, so we
* overwrite length_code[255] to use the best encoding:
*/
kZlibLengthCode[length - 1] = (uint8_t)code;
/* Initialize the mapping dist (0..32K) -> dist code (0..29) */
dist = 0;
for (code = 0; code < 16; code++) {
kZlibBaseDist[code] = dist;
for (n = 0; n < (1u << extra_dbits[code]); n++) {
kZlibDistCode[dist++] = (uint8_t)code;
}
}
Assert(dist == 256, "tr_static_init: dist != 256");
dist >>= 7; /* from now on, all distances are divided by 128 */
for (; code < D_CODES; code++) {
kZlibBaseDist[code] = dist << 7;
for (n = 0; n < (1 << (extra_dbits[code] - 7)); n++) {
kZlibDistCode[256 + dist++] = (uint8_t)code;
}
}
Assert(dist == 256, "tr_static_init: 256+dist != 512");
/* Construct the codes of the static literal tree */
for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
n = 0;
while (n <= 143) kZlibStaticLtree[n++].Len = 8, bl_count[8]++;
while (n <= 255) kZlibStaticLtree[n++].Len = 9, bl_count[9]++;
while (n <= 279) kZlibStaticLtree[n++].Len = 7, bl_count[7]++;
while (n <= 287) kZlibStaticLtree[n++].Len = 8, bl_count[8]++;
/* Codes 286 and 287 do not exist, but we must include them in the
* tree construction to get a canonical Huffman tree (longest code
* all ones)
*/
gen_codes((ct_data *)kZlibStaticLtree, L_CODES + 1, bl_count);
/* The static distance tree is trivial: */
for (n = 0; n < D_CODES; n++) {
kZlibStaticDtree[n].Len = 5;
kZlibStaticDtree[n].Code = bi_reverse((unsigned)n, 5);
}
static_init_done = 1;
#ifdef GEN_TREES_H
gen_trees_header();
#endif
#endif /* defined(GEN_TREES_H) || !defined(STDC) */
}
/**
* Genererate the file trees.h describing the static trees.
*/
#ifdef GEN_TREES_H
#define SEPARATOR(i, last, width) \
((i) == (last) ? "\n};\n\n" : ((i) % (width) == (width)-1 ? ",\n" : ", "))
void gen_trees_header(void) {
FILE *header = fopen("trees.h", "w");
int i;
Assert(header != NULL, "Can't open trees.h");
fprintf(header, "/* header created automatically with -DGEN_TREES_H */\n\n");
fprintf(header, "local const ct_data kZlibStaticLtree[L_CODES+2] = {\n");
for (i = 0; i < L_CODES + 2; i++) {
fprintf(header, "{{%3u},{%3u}}%s", kZlibStaticLtree[i].Code,
kZlibStaticLtree[i].Len, SEPARATOR(i, L_CODES + 1, 5));
}
fprintf(header, "local const ct_data kZlibStaticDtree[D_CODES] = {\n");
for (i = 0; i < D_CODES; i++) {
fprintf(header, "{{%2u},{%2u}}%s", kZlibStaticDtree[i].Code,
kZlibStaticDtree[i].Len, SEPARATOR(i, D_CODES - 1, 5));
}
fprintf(header, "const uint8_t kZlibDistCode[DIST_CODE_LEN] = {\n");
for (i = 0; i < DIST_CODE_LEN; i++) {
fprintf(header, "%2u%s", kZlibDistCode[i],
SEPARATOR(i, DIST_CODE_LEN - 1, 20));
}
fprintf(header, "const uint8_t kZlibLengthCode[MAX_MATCH-MIN_MATCH+1]= {\n");
for (i = 0; i < MAX_MATCH - MIN_MATCH + 1; i++) {
fprintf(header, "%2u%s", kZlibLengthCode[i],
SEPARATOR(i, MAX_MATCH - MIN_MATCH, 20));
}
fprintf(header, "local const int kZlibBaseLength[LENGTH_CODES] = {\n");
for (i = 0; i < LENGTH_CODES; i++) {
fprintf(header, "%1u%s", kZlibBaseLength[i],
SEPARATOR(i, LENGTH_CODES - 1, 20));
}
fprintf(header, "local const int kZlibBaseDist[D_CODES] = {\n");
for (i = 0; i < D_CODES; i++) {
fprintf(header, "%5u%s", kZlibBaseDist[i], SEPARATOR(i, D_CODES - 1, 10));
}
fclose(header);
}
#endif /* GEN_TREES_H */
/**
* Initialize the tree data structures for a new zlib stream.
*/
void _tr_init(struct DeflateState *s) {
tr_static_init();
s->l_desc.dyn_tree = s->dyn_ltree;
s->l_desc.stat_desc = &static_l_desc;
s->d_desc.dyn_tree = s->dyn_dtree;
s->d_desc.stat_desc = &static_d_desc;
s->bl_desc.dyn_tree = s->bl_tree;
s->bl_desc.stat_desc = &static_bl_desc;
s->bi_buf = 0;
s->bi_valid = 0;
#ifdef ZLIB_DEBUG
s->compressed_len = 0L;
s->bits_sent = 0L;
#endif
/* Initialize the first block of the first file: */
init_block(s);
}
/**
* Initialize a new block.
*/
static void init_block(struct DeflateState *s) {
int n; /* iterates over tree elements */
/* Initialize the trees. */
for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0;
for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0;
for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
s->dyn_ltree[END_BLOCK].Freq = 1;
s->opt_len = s->static_len = 0L;
s->sym_next = s->matches = 0;
}
#define SMALLEST 1
/* Index within the heap array of least frequent node in the Huffman tree */
/**
* Remove the smallest element from the heap and recreate the heap with
* one less element. Updates heap and heap_len.
*/
#define pqremove(s, tree, top) \
{ \
top = s->heap[SMALLEST]; \
s->heap[SMALLEST] = s->heap[s->heap_len--]; \
pqdownheap(s, tree, SMALLEST); \
}
/**
* Compares to subtrees, using the tree depth as tie breaker when
* the subtrees have equal frequency. This minimizes the worst case length.
*/
#define smaller(tree, n, m, depth) \
(tree[n].Freq < tree[m].Freq || \
(tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
/**
* Restore the heap property by moving down the tree starting at node k,
* exchanging a node with the smallest of its two sons if necessary, stopping
* when the heap property is re-established (each father smaller than its
* two sons).
* @param tree is tree to restore
* @param k is node to move down
*/
static void pqdownheap(struct DeflateState *s, ct_data *tree, int k) {
int v = s->heap[k];
int j = k << 1; /* left son of k */
while (j <= s->heap_len) {
/* Set j to the smallest of the two sons: */
if (j < s->heap_len &&
smaller(tree, s->heap[j + 1], s->heap[j], s->depth)) {
j++;
}
/* Exit if v is smaller than both sons */
if (smaller(tree, v, s->heap[j], s->depth)) break;
/* Exchange v with the smallest son */
s->heap[k] = s->heap[j];
k = j;
/* And continue down the tree, setting j to the left son of k */
j <<= 1;
}
s->heap[k] = v;
}
/**
* Compute the optimal bit lengths for a tree and update the total bit length
* for the current block.
* IN assertion: the fields freq and dad are set, heap[heap_max] and
* above are the tree nodes sorted by increasing frequency.
* OUT assertions: the field len is set to the optimal bit length, the
* array bl_count contains the frequencies for each bit length.
* The length opt_len is updated; static_len is also updated if stree is
* not null.
*/
static void gen_bitlen(struct DeflateState *s, tree_desc *desc) {
ct_data *tree = desc->dyn_tree;
int max_code = desc->max_code;
const ct_data *stree = desc->stat_desc->static_tree;
const intf *extra = desc->stat_desc->extra_bits;
int base = desc->stat_desc->extra_base;
int max_length = desc->stat_desc->max_length;
int h; /* heap index */
int n, m; /* iterate over the tree elements */
int bits; /* bit length */
int xbits; /* extra bits */
uint16_t f; /* frequency */
int overflow = 0; /* number of elements with bit length too large */
for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
/* In a first pass, compute the optimal bit lengths (which may
* overflow in the case of the bit length tree).
*/
tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
for (h = s->heap_max + 1; h < HEAP_SIZE; h++) {
n = s->heap[h];
bits = tree[tree[n].Dad].Len + 1;
if (bits > max_length) bits = max_length, overflow++;
tree[n].Len = (uint16_t)bits;
/* We overwrite tree[n].Dad which is no longer needed */
if (n > max_code) continue; /* not a leaf node */
s->bl_count[bits]++;
xbits = 0;
if (n >= base) xbits = extra[n - base];
f = tree[n].Freq;
s->opt_len += (uint64_t)f * (unsigned)(bits + xbits);
if (stree) s->static_len += (uint64_t)f * (unsigned)(stree[n].Len + xbits);
}
if (overflow == 0) return;
Tracev((stderr, "\nbit length overflow\n"));
/* This happens for example on obj2 and pic of the Calgary corpus */
/* Find the first bit length which could increase: */
do {
bits = max_length - 1;
while (s->bl_count[bits] == 0) bits--;
s->bl_count[bits]--; /* move one leaf down the tree */
s->bl_count[bits + 1] += 2; /* move one overflow item as its brother */
s->bl_count[max_length]--;
/* The brother of the overflow item also moves one step up,
* but this does not affect bl_count[max_length]
*/
overflow -= 2;
} while (overflow > 0);
/* Now recompute all bit lengths, scanning in increasing frequency.
* h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
* lengths instead of fixing only the wrong ones. This idea is taken
* from 'ar' written by Haruhiko Okumura.)
*/
for (bits = max_length; bits != 0; bits--) {
n = s->bl_count[bits];
while (n != 0) {
m = s->heap[--h];
if (m > max_code) continue;
if ((unsigned)tree[m].Len != (unsigned)bits) {
Tracev((stderr, "code %d bits %d->%d\n", m, tree[m].Len, bits));
s->opt_len += ((uint64_t)bits - tree[m].Len) * tree[m].Freq;
tree[m].Len = (uint16_t)bits;
}
n--;
}
}
}
/**
* Generates codes for given tree and bit counts (need not be optimal).
*
* IN assertion: the array bl_count contains the bit length statistics for
* the given tree and the field len is set for all tree elements.
* OUT assertion: the field code is set for all tree elements of non
* zero code length.
*
* @param max_code is largest code with non zero frequency
* @param bl_count is number of codes at each bit length
*/
static void gen_codes(ct_data *tree, int max_code, uint16_t *bl_count) {
uint16_t next_code[MAX_BITS + 1]; /* next code value for each bit length */
unsigned code = 0; /* running code value */
int bits; /* bit index */
int n; /* code index */
/* The distribution counts are first used to generate the code values
* without bit reversal.
*/
for (bits = 1; bits <= MAX_BITS; bits++) {
code = (code + bl_count[bits - 1]) << 1;
next_code[bits] = (uint16_t)code;
}
/* Check that the bit counts in bl_count are consistent. The last code
* must be all ones.
*/
Assert(code + bl_count[MAX_BITS] - 1 == (1 << MAX_BITS) - 1,
"inconsistent bit counts");
Tracev((stderr, "\ngen_codes: max_code %d ", max_code));
for (n = 0; n <= max_code; n++) {
int len = tree[n].Len;
if (len == 0) continue;
/* Now reverse the bits */
tree[n].Code = (uint16_t)bi_reverse(next_code[len]++, len);
Tracecv(tree != kZlibStaticLtree,
(stderr, "\nn %3d %c l %2d c %4x (%x) ", n, (isgraph(n) ? n : ' '),
len, tree[n].Code, next_code[len] - 1));
}
}
/**
* Construct one Huffman tree and assigns the code bit strings and lengths.
* Update the total bit length for the current block.
* IN assertion: the field freq is set for all tree elements.
* OUT assertions: the fields len and code are set to the optimal bit length
* and corresponding code. The length opt_len is updated; static_len is
* also updated if stree is not null. The field max_code is set.
*/
static void build_tree(struct DeflateState *s, tree_desc *desc) {
ct_data *tree = desc->dyn_tree;
const ct_data *stree = desc->stat_desc->static_tree;
int elems = desc->stat_desc->elems;
int n, m; /* iterate over heap elements */
int max_code = -1; /* largest code with non zero frequency */
int node; /* new node being created */
/* Construct the initial heap, with least frequent element in
* heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
* heap[0] is not used.
*/
s->heap_len = 0, s->heap_max = HEAP_SIZE;
for (n = 0; n < elems; n++) {
if (tree[n].Freq != 0) {
s->heap[++(s->heap_len)] = max_code = n;
s->depth[n] = 0;
} else {
tree[n].Len = 0;
}
}
/* The pkzip format requires that at least one distance code exists,
* and that at least one bit should be sent even if there is only one
* possible code. So to avoid special checks later on we force at least
* two codes of non zero frequency.
*/
while (s->heap_len < 2) {
node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
tree[node].Freq = 1;
s->depth[node] = 0;
s->opt_len--;
if (stree) s->static_len -= stree[node].Len;
/* node is 0 or 1 so it does not have extra bits */
}
desc->max_code = max_code;
/* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
* establish sub-heaps of increasing lengths:
*/
for (n = s->heap_len / 2; n >= 1; n--) pqdownheap(s, tree, n);
/* Construct the Huffman tree by repeatedly combining the least two
* frequent nodes.
*/
node = elems; /* next internal node of the tree */
do {
pqremove(s, tree, n); /* n = node of least frequency */
m = s->heap[SMALLEST]; /* m = node of next least frequency */
s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
s->heap[--(s->heap_max)] = m;
/* Create a new node father of n and m */
tree[node].Freq = tree[n].Freq + tree[m].Freq;
s->depth[node] =
(uint8_t)((s->depth[n] >= s->depth[m] ? s->depth[n] : s->depth[m]) + 1);
tree[n].Dad = tree[m].Dad = (uint16_t)node;
#ifdef DUMP_BL_TREE
if (tree == s->bl_tree) {
fprintf(stderr, "\nnode %d(%d), sons %d(%d) %d(%d)", node,
tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
}
#endif
/* and insert the new node in the heap */
s->heap[SMALLEST] = node++;
pqdownheap(s, tree, SMALLEST);
} while (s->heap_len >= 2);
s->heap[--(s->heap_max)] = s->heap[SMALLEST];
/* At this point, the fields freq and dad are set. We can now
* generate the bit lengths.
*/
gen_bitlen(s, (tree_desc *)desc);
/* The field len is now set, we can generate the bit codes */
gen_codes((ct_data *)tree, max_code, s->bl_count);
}
/**
* Scan a literal or distance tree to determine the frequencies of the
* codes in the bit length tree.
*
* @param tree is tree to be scanned
* @param max_code is its largest code of non zero frequency
*/
static void scan_tree(struct DeflateState *s, ct_data *tree, int max_code) {
int n; /* iterates over all tree elements */
int prevlen = -1; /* last emitted length */
int curlen; /* length of current code */
int nextlen = tree[0].Len; /* length of next code */
int count = 0; /* repeat count of the current code */
int max_count = 7; /* max repeat count */
int min_count = 4; /* min repeat count */
if (nextlen == 0) max_count = 138, min_count = 3;
tree[max_code + 1].Len = (uint16_t)0xffff; /* guard */
for (n = 0; n <= max_code; n++) {
curlen = nextlen;
nextlen = tree[n + 1].Len;
if (++count < max_count && curlen == nextlen) {
continue;
} else if (count < min_count) {
s->bl_tree[curlen].Freq += count;
} else if (curlen != 0) {
if (curlen != prevlen) s->bl_tree[curlen].Freq++;
s->bl_tree[REP_3_6].Freq++;
} else if (count <= 10) {
s->bl_tree[REPZ_3_10].Freq++;
} else {
s->bl_tree[REPZ_11_138].Freq++;
}
count = 0;
prevlen = curlen;
if (nextlen == 0) {
max_count = 138, min_count = 3;
} else if (curlen == nextlen) {
max_count = 6, min_count = 3;
} else {
max_count = 7, min_count = 4;
}
}
}
/**
* Send a literal or distance tree in compressed form, using the codes in
* bl_tree.
*
* @param tree is tree to be scanned
* @param max_code is its largest code of non zero frequency
*/
static void send_tree(struct DeflateState *s, ct_data *tree, int max_code) {
int n; /* iterates over all tree elements */
int prevlen = -1; /* last emitted length */
int curlen; /* length of current code */
int nextlen = tree[0].Len; /* length of next code */
int count = 0; /* repeat count of the current code */
int max_count = 7; /* max repeat count */
int min_count = 4; /* min repeat count */
/* tree[max_code+1].Len = -1; */ /* guard already set */
if (nextlen == 0) max_count = 138, min_count = 3;
for (n = 0; n <= max_code; n++) {
curlen = nextlen;
nextlen = tree[n + 1].Len;
if (++count < max_count && curlen == nextlen) {
continue;
} else if (count < min_count) {
do {
send_code(s, curlen, s->bl_tree);
} while (--count != 0);
} else if (curlen != 0) {
if (curlen != prevlen) {
send_code(s, curlen, s->bl_tree);
count--;
}
Assert(count >= 3 && count <= 6, " 3_6?");
send_code(s, REP_3_6, s->bl_tree);
send_bits(s, count - 3, 2);
} else if (count <= 10) {
send_code(s, REPZ_3_10, s->bl_tree);
send_bits(s, count - 3, 3);
} else {
send_code(s, REPZ_11_138, s->bl_tree);
send_bits(s, count - 11, 7);
}
count = 0;
prevlen = curlen;
if (nextlen == 0) {
max_count = 138, min_count = 3;
} else if (curlen == nextlen) {
max_count = 6, min_count = 3;
} else {
max_count = 7, min_count = 4;
}
}
}
/**
* Construct the Huffman tree for the bit lengths and return the index in
* bl_order of the last bit length code to send.
*/
static int build_bl_tree(struct DeflateState *s) {
int max_blindex; /* index of last bit length code of non zero freq */
/* Determine the bit length frequencies for literal and distance trees */
scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
/* Build the bit length tree: */
build_tree(s, (tree_desc *)(&(s->bl_desc)));
/* opt_len now includes the length of the tree representations, except
* the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
*/
/* Determine the number of bit length codes to send. The pkzip format
* requires that at least 4 bit length codes be sent. (appnote.txt says
* 3 but the actual value used is 4.)
*/
for (max_blindex = BL_CODES - 1; max_blindex >= 3; max_blindex--) {
if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
}
/* Update opt_len to include the bit length tree and counts */
s->opt_len += 3 * ((uint64_t)max_blindex + 1) + 5 + 5 + 4;
Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", s->opt_len, s->static_len));
return max_blindex;
}
/**
* Send the header for a block using dynamic Huffman trees: the counts, the
* lengths of the bit length codes, the literal tree and the distance tree.
* IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
*/
static void send_all_trees(struct DeflateState *s, int lcodes, int dcodes,
int blcodes) {
int rank; /* index in bl_order */
Assert(lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
Assert(lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
"too many codes");
Tracev((stderr, "\nbl counts: "));
send_bits(s, lcodes - 257, 5); /* not +255 as stated in appnote.txt */
send_bits(s, dcodes - 1, 5);
send_bits(s, blcodes - 4, 4); /* not -3 as stated in appnote.txt */
for (rank = 0; rank < blcodes; rank++) {
Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
}
Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
send_tree(s, (ct_data *)s->dyn_ltree, lcodes - 1); /* literal tree */
Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
send_tree(s, (ct_data *)s->dyn_dtree, dcodes - 1); /* distance tree */
Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
}
/**
* Sends stored block.
* @param last is one if this is the last block of file
*/
void _tr_stored_block(struct DeflateState *s, charf *buf, uint64_t stored_len,
int last) {
send_bits(s, (STORED_BLOCK << 1) + last, 3); /* send block type */
bi_windup(s); /* align on byte boundary */
put_short(s, (uint16_t)stored_len);
put_short(s, (uint16_t)~stored_len);
memcpy(s->pending_buf + s->pending, (Bytef *)buf, stored_len);
s->pending += stored_len;
#ifdef ZLIB_DEBUG
s->compressed_len = (s->compressed_len + 3 + 7) & (uint64_t)~7L;
s->compressed_len += (stored_len + 4) << 3;
s->bits_sent += 2 * 16;
s->bits_sent += stored_len << 3;
#endif
}
/**
* Flushes bits in bit buffer to pending output (leaves at most 7 bits)
*/
void _tr_flush_bits(struct DeflateState *s) { bi_flush(s); }
/**
* Sends one empty static block to give enough lookahead for inflate.
* This takes 10 bits, of which 7 may remain in the bit buffer.
*/
void _tr_align(struct DeflateState *s) {
send_bits(s, STATIC_TREES << 1, 3);
send_code(s, END_BLOCK, kZlibStaticLtree);
#ifdef ZLIB_DEBUG
s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
#endif
bi_flush(s);
}
/**
* Determine the best encoding for the current block: dynamic trees,
* static trees or store, and write out the encoded block.
*
* @param last is one if this is the last block of file
*/
void _tr_flush_block(struct DeflateState *s, charf *buf, uint64_t stored_len,
int last) {
uint64_t opt_lenb, static_lenb; /* opt_len and static_len in bytes */
int max_blindex = 0; /* index of last bit length code of non zero freq */
/* Build the Huffman trees unless a stored block is forced */
if (s->level > 0) {
/* Check if the file is binary or text */
if (s->strm->data_type == Z_UNKNOWN)
s->strm->data_type = detect_data_type(s);
/* Construct the literal and distance trees */
build_tree(s, (tree_desc *)(&(s->l_desc)));
Tracev(
(stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len, s->static_len));
build_tree(s, (tree_desc *)(&(s->d_desc)));
Tracev(
(stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len, s->static_len));
/* At this point, opt_len and static_len are the total bit lengths of
* the compressed block data, excluding the tree representations.
*/
/* Build the bit length tree for the above two trees, and get the index
* in bl_order of the last bit length code to send.
*/
max_blindex = build_bl_tree(s);
/* Determine the best encoding. Compute the block lengths in bytes. */
opt_lenb = (s->opt_len + 3 + 7) >> 3;
static_lenb = (s->static_len + 3 + 7) >> 3;
Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ", opt_lenb,
s->opt_len, static_lenb, s->static_len, stored_len,
s->sym_next / 3));
if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
} else {
Assert(buf != (char *)0, "lost buf");
opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
}
#ifdef FORCE_STORED
if (buf != (char *)0) { /* force stored block */
#else
if (stored_len + 4 <= opt_lenb && buf != (char *)0) {
/* 4: two words for the lengths */
#endif
/* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
* Otherwise we can't have processed more than WSIZE input bytes since
* the last block flush, because compression would have been
* successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
* transform a block into a stored block.
*/
_tr_stored_block(s, buf, stored_len, last);
#ifdef FORCE_STATIC
} else if (static_lenb >= 0) { /* force static trees */
#else
} else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
#endif
send_bits(s, (STATIC_TREES << 1) + last, 3);
compress_block(s, (const ct_data *)kZlibStaticLtree,
(const ct_data *)kZlibStaticDtree);
#ifdef ZLIB_DEBUG
s->compressed_len += 3 + s->static_len;
#endif
} else {
send_bits(s, (DYN_TREES << 1) + last, 3);
send_all_trees(s, s->l_desc.max_code + 1, s->d_desc.max_code + 1,
max_blindex + 1);
compress_block(s, (const ct_data *)s->dyn_ltree,
(const ct_data *)s->dyn_dtree);
#ifdef ZLIB_DEBUG
s->compressed_len += 3 + s->opt_len;
#endif
}
Assert(s->compressed_len == s->bits_sent, "bad compressed size");
/* The above check is made mod 2^32, for files larger than 512 MB
* and uLong implemented on 32 bits.
*/
init_block(s);
if (last) {
bi_windup(s);
#ifdef ZLIB_DEBUG
s->compressed_len += 7; /* align on byte boundary */
#endif
}
Tracev((stderr, "\ncomprlen %lu(%lu) ", s->compressed_len >> 3,
s->compressed_len - 7 * last));
}
/**
* Save the match info and tally the frequency counts. Return true if
* the current block must be flushed.
*
* @param dist is distance of matched string
* @param lc is match length-MIN_MATCH or unmatched char (if dist==0)
*/
int _tr_tally(struct DeflateState *s, unsigned dist, unsigned lc) {
s->sym_buf[s->sym_next++] = dist;
s->sym_buf[s->sym_next++] = dist >> 8;
s->sym_buf[s->sym_next++] = lc;
if (dist == 0) {
/* lc is the unmatched char */
s->dyn_ltree[lc].Freq++;
} else {
s->matches++;
/* Here, lc is the match length - MIN_MATCH */
dist--; /* dist = match distance - 1 */
Assert((uint16_t)dist < (uint16_t)MAX_DIST(s) &&
(uint16_t)lc <= (uint16_t)(MAX_MATCH - MIN_MATCH) &&
(uint16_t)d_code(dist) < (uint16_t)D_CODES,
"_tr_tally: bad match");
s->dyn_ltree[kZlibLengthCode[lc] + LITERALS + 1].Freq++;
s->dyn_dtree[d_code(dist)].Freq++;
}
return (s->sym_next == s->sym_end);
}
/**
* Send the block data compressed using the given Huffman trees
*/
static void compress_block(struct DeflateState *s, const ct_data *ltree,
const ct_data *dtree) {
unsigned dist; /* distance of matched string */
int lc; /* match length or unmatched char (if dist == 0) */
unsigned sx = 0; /* running index in sym_buf */
unsigned code; /* the code to send */
int extra; /* number of extra bits to send */
if (s->sym_next != 0) do {
dist = s->sym_buf[sx++] & 0xff;
dist += (unsigned)(s->sym_buf[sx++] & 0xff) << 8;
lc = s->sym_buf[sx++];
if (dist == 0) {
send_code(s, lc, ltree); /* send a literal byte */
Tracecv(isgraph(lc), (stderr, " '%c' ", lc));
} else {
/* Here, lc is the match length - MIN_MATCH */
code = kZlibLengthCode[lc];
send_code(s, code + LITERALS + 1, ltree); /* send the length code */
extra = extra_lbits[code];
if (extra != 0) {
lc -= kZlibBaseLength[code];
send_bits(s, lc, extra); /* send the extra length bits */
}
dist--; /* dist is now the match distance - 1 */
code = d_code(dist);
Assert(code < D_CODES, "bad d_code");
send_code(s, code, dtree); /* send the distance code */
extra = extra_dbits[code];
if (extra != 0) {
dist -= (unsigned)kZlibBaseDist[code];
send_bits(s, dist, extra); /* send the extra distance bits */
}
} /* literal or match pair ? */
/* Check that the overlay between pending_buf and sym_buf is ok: */
Assert(s->pending < s->lit_bufsize + sx, "pendingBuf overflow");
} while (sx < s->sym_next);
send_code(s, END_BLOCK, ltree);
}
/**
* Checks if data type is TEXT or BINARY.
*
* This uses the following algorithm:
*
* - TEXT if the two conditions below are satisfied:
* a) There are no non-portable control characters belonging to the
* "black list" (0..6, 14..25, 28..31).
* b) There is at least one printable character belonging to the
* "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
* - BINARY otherwise.
* - The following partially-portable control characters form a
* "gray list" that is ignored in this detection algorithm:
* (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).
*
* IN assertion: the fields Freq of dyn_ltree are set.
*/
static int detect_data_type(struct DeflateState *s) {
/* black_mask is the bit mask of black-listed bytes
* set bits 0..6, 14..25, and 28..31
* 0xf3ffc07f = binary 11110011111111111100000001111111
*/
unsigned long black_mask = 0xf3ffc07fUL;
int n;
/* Check for non-textual ("black-listed") bytes. */
for (n = 0; n <= 31; n++, black_mask >>= 1)
if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0)) return Z_BINARY;
/* Check for textual ("white-listed") bytes. */
if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0 ||
s->dyn_ltree[13].Freq != 0)
return Z_TEXT;
for (n = 32; n < LITERALS; n++)
if (s->dyn_ltree[n].Freq != 0) return Z_TEXT;
/* There are no "black-listed" or "white-listed" bytes:
* this stream either is empty or has tolerated ("gray-listed") bytes only.
*/
return Z_BINARY;
}
/**
* Reverse the first len bits of a code, using straightforward code (a
* faster method would use a table).
*
* IN assertion: 1 <= len <= 15
*
* @param code is value to invert
* @param len is in bits
*/
static unsigned bi_reverse(unsigned code, int len) {
register unsigned res = 0;
do {
res |= code & 1;
code >>= 1, res <<= 1;
} while (--len > 0);
return res >> 1;
}
/**
* Flushes bit buffer, keeping at most 7 bits in it.
*/
static void bi_flush(struct DeflateState *s) {
if (s->bi_valid == 16) {
put_short(s, s->bi_buf);
s->bi_buf = 0;
s->bi_valid = 0;
} else if (s->bi_valid >= 8) {
put_byte(s, (Byte)s->bi_buf);
s->bi_buf >>= 8;
s->bi_valid -= 8;
}
}
/**
* Flushes bit buffer and align the output on a byte boundary
*/
static void bi_windup(struct DeflateState *s) {
if (s->bi_valid > 8) {
put_short(s, s->bi_buf);
} else if (s->bi_valid > 0) {
put_byte(s, (Byte)s->bi_buf);
}
s->bi_buf = 0;
s->bi_valid = 0;
#ifdef ZLIB_DEBUG
s->bits_sent = (s->bits_sent + 7) & ~7;
#endif
}
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