Improve emulator color math
Video game emulators seem to convert colors for modern displays poorly. Check out https://youtu.be/Eds63YbGhDQ?t=481 where we notice in the CRT displays Super Mario Bros with a blue sky, whereas the PC shows purple. It's likely b/c NTSC used Illuminant C whereas sRGB uses Illuminant D65. See the improvement: https://justine.storage.googleapis.com/nesemu3.png Now you can play video games in the terminal as they looked in the 80's. This change also reduces CPU usage to a third.main
Justine Tunney
parent
72b654cb6c
commit
467504308a
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@ -3,6 +3,8 @@
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/* PORTED TO TELETYPEWRITERS IN YEAR 2020 BY JUSTINE ALEXANDRA ROBERTS TUNNEY */
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/* TRADEMARKS ARE OWNED BY THEIR RESPECTIVE OWNERS LAWYERCATS LUV TAUTOLOGIES */
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/* https://bisqwit.iki.fi/jutut/kuvat/programming_examples/nesemu1/nesemu1.cc */
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#include "dsp/core/core.h"
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#include "dsp/core/illumination.h"
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#include "dsp/scale/scale.h"
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#include "dsp/tty/itoa8.h"
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#include "dsp/tty/quant.h"
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@ -35,12 +37,14 @@
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#include "libc/sysv/consts/sig.h"
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#include "libc/time/time.h"
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#include "libc/x/x.h"
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#include "tool/viz/lib/knobs.h"
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#define DYN 240
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#define DXN 256
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#define FPS 60.0988
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#define HZ 1789773
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#define KEYHZ 20
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#define GAMMA 2.2
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#define CTRL(C) ((C) ^ 0100)
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#define ALT(C) ((033 << 010) | (C))
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@ -52,8 +56,10 @@ typedef uint16_t u16;
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typedef uint8_t u8;
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typedef int8_t s8;
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static const struct itimerval kNesFps = {{0, 1. / FPS * 1e6},
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{0, 1. / FPS * 1e6}};
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static const struct itimerval kNesFps = {
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{0, 1. / FPS * 1e6},
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{0, 1. / FPS * 1e6},
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};
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struct Frame {
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char *p, *w, *mem;
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@ -78,11 +84,12 @@ static bool exited_;
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static bool timeout_;
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static bool resized_;
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static size_t vtsize_;
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static bool artifacts_;
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static long tyn_, txn_;
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static const char* ffplay_;
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static struct Audio audio_;
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static struct TtyRgb* ttyrgb_;
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static struct Frame frames_[2];
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static struct Frame vf_[2];
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static unsigned char *R, *G, *B;
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static struct Action arrow_, button_;
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static struct SamplingSolution* asx_;
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@ -94,8 +101,61 @@ static int joy_current_[2] = {0, 0};
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static int joy_next_[2] = {0, 0};
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static int joypos_[2] = {0, 0};
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static int Clamp(int v) { return v > 255 ? 255 : v; }
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static float FixGamma(float f) { return f > 0 ? powf(f, 2.2f / 1.8f) : 0; }
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static int Clamp(int v) { return MAX(0, MIN(255, v)); }
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static double FixGamma(double x) { return tv2pcgamma(x, GAMMA); }
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void InitPalette(void) {
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// The input value is a NES color index (with de-emphasis bits).
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// See http://wiki.nesdev.com/w/index.php/NTSC_video for magic numbers
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// We need RGB values. To produce a RGB value, we emulate the NTSC circuitry.
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double A[3] = {-1.109, -.275, .947};
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double B[3] = {1.709, -.636, .624};
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double rgbc[3], lightbulb[3][3], rgbd65[3];
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int o, u, r, c, b, p, y, i, l, q, e, p0, p1, pixel;
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signed char volt[] = "\372\273\32\305\35\311I\330D\357\175\13D!}N";
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GetChromaticAdaptationMatrix(lightbulb, kIlluminantC, kIlluminantD65);
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for (o = 0; o < 3; ++o) {
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for (p0 = 0; p0 < 512; ++p0) {
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for (p1 = 0; p1 < 64; ++p1) {
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for (u = 0; u < 3; ++u) {
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// Calculate the luma and chroma by emulating the relevant circuits:
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y = 0;
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i = 0;
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q = 0;
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// 12 samples of NTSC signal constitute a color.
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for (p = 0; p < 12; ++p) {
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// Sample either the previous or the current pixel.
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r = (p + o * 4) % 12;
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// Decode the color index.
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if (artifacts_) {
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pixel = r < 8 - u * 2 ? p0 : p1;
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} else {
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pixel = p0;
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}
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c = pixel % 16;
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l = c < 0xE ? pixel / 4 & 12 : 4;
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e = p0 / 64;
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// NES NTSC modulator
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// square wave between up to four voltage levels
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b = 40 + volt[(c > 12 * ((c + 8 + p) % 12 < 6)) +
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2 * !(0451326 >> p / 2 * 3 & e) + l];
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// Ideal TV NTSC demodulator?
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y += b;
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i += b * round(cos(M_PI * p / 6) * 5909);
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q += b * round(sin(M_PI * p / 6) * 5909);
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}
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// Converts YIQ to RGB
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// Store color at subpixel precision
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rgbc[u] = FixGamma(y / 1980. + i * A[u] / 9e6 + q * B[u] / 9e6);
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}
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matvmul3(rgbd65, lightbulb, rgbc);
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for (u = 0; u < 3; ++u) {
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palette_[o][p1][p0][u] = Clamp(rgbd65[u] * 255);
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}
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}
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}
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}
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}
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static void WriteStringNow(const char* s) {
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ttywrite(STDOUT_FILENO, s, strlen(s));
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@ -133,8 +193,8 @@ void GetTermSize(void) {
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vtsize_ = ((tyn_ * txn_ * strlen("\e[48;2;255;48;2;255m▄")) +
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(tyn_ * strlen("\e[0m\r\n")) + 128);
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frame_ = 0;
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InitFrame(&frames_[0]);
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InitFrame(&frames_[1]);
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InitFrame(&vf_[0]);
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InitFrame(&vf_[1]);
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WriteStringNow("\e[0m\e[H\e[J");
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}
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@ -203,6 +263,10 @@ void ReadKeyboard(void) {
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}
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}
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switch (ch) {
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case '1':
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artifacts_ = !artifacts_;
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InitPalette();
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break;
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case ' ':
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button_.code = 0b00100000; // A
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button_.wait = KEYHZ;
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@ -261,22 +325,24 @@ void ReadKeyboard(void) {
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}
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}
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bool HasVideo(struct Frame* f) { return f->w < f->p; }
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bool HasPendingVideo(void) { return HasVideo(&vf_[0]) || HasVideo(&vf_[1]); }
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bool HasPendingAudio(void) { return playpid_ && audio_.i; }
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struct Frame* FlipFrameBuffer(void) {
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frame_ = !frame_;
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return &frames_[frame_];
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return &vf_[frame_];
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}
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void TransmitVideo(void) {
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ssize_t rc;
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struct Frame* f;
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f = &frames_[frame_];
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if (f->w >= f->p) f = FlipFrameBuffer();
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if (f->w < f->p) {
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if ((rc = write(STDOUT_FILENO, f->w, f->p - f->w)) != -1) {
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f->w += rc;
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} else {
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SystemFailure();
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}
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f = &vf_[frame_];
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if (!HasVideo(f)) f = FlipFrameBuffer();
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if ((rc = write(STDOUT_FILENO, f->w, f->p - f->w)) != -1) {
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f->w += rc;
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} else {
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SystemFailure();
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}
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}
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@ -316,15 +382,21 @@ void KeyCountdown(struct Action* a) {
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}
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}
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void DrainAndExit(void) {
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while (HasPendingVideo()) TransmitVideo();
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WriteStringNow("\r\n\e[0m\e[J");
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exit(0);
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}
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void PollAndSynchronize(void) {
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struct pollfd fds[3];
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fds[0].fd = STDIN_FILENO;
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fds[0].events = POLLIN;
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fds[1].fd = STDOUT_FILENO;
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fds[1].events = POLLOUT;
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fds[2].fd = playpid_ ? playfd_ : -1;
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fds[2].events = POLLOUT;
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do {
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fds[0].fd = STDIN_FILENO;
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fds[0].events = POLLIN;
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fds[1].fd = HasPendingVideo() ? STDOUT_FILENO : -1;
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fds[1].events = POLLOUT;
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fds[2].fd = HasPendingAudio() ? playfd_ : -1;
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fds[2].events = POLLOUT;
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if (poll(fds, ARRAYLEN(fds), 1. / FPS * 1e3) != -1) {
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if (fds[0].revents & (POLLIN | POLLERR)) ReadKeyboard();
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if (fds[1].revents & (POLLOUT | POLLERR)) TransmitVideo();
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@ -333,8 +405,7 @@ void PollAndSynchronize(void) {
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SystemFailure();
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}
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if (exited_) {
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WriteStringNow("\r\n\e[0m\e[J");
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exit(0);
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DrainAndExit();
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}
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if (resized_) {
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resized_ = false;
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@ -354,7 +425,7 @@ void Raster(void) {
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struct TtyRgb bg = {0x12, 0x34, 0x56, 0};
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struct TtyRgb fg = {0x12, 0x34, 0x56, 0};
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ScaleVideoFrameToTeletypewriter();
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f = &frames_[!frame_];
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f = &vf_[!frame_];
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f->p = f->w = f->mem;
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f->p = stpcpy(f->p, "\e[0m\e[H");
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f->p = ttyraster(f->p, ttyrgb_, tyn_, txn_, bg, fg);
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@ -371,52 +442,6 @@ void FlushScanline(unsigned py) {
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}
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}
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void InitPalette(void) {
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// The input value is a NES color index (with de-emphasis bits).
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// We need RGB values. To produce a RGB value, we emulate the NTSC circuitry.
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// For most part, this process is described at:
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// http://wiki.nesdev.com/w/index.php/NTSC_video
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// Incidentally, this code is shorter than a table of 64*8 RGB values.
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signed char sa[] = "\372\273\32\305\35\311I\330D\357\175\13D!}N";
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int o, u, r, c, b, p, y, i, l, q, e, p0, p1, pixel;
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for (o = 0; o < 3; ++o) {
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for (u = 0; u < 3; ++u) {
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for (p0 = 0; p0 < 512; ++p0) {
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for (p1 = 0; p1 < 64; ++p1) {
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// Calculate the luma and chroma by emulating the relevant circuits:
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y = 0;
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i = 0;
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q = 0;
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// 12 samples of NTSC signal constitute a color.
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for (p = 0; p < 12; ++p) {
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// Sample either the previous or the current pixel.
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r = (p + o * 4) % 12;
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// Use pixel=p0 to disable artifacts.
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// Decode the color index.
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pixel = r < 8 - u * 2 ? p0 : p1;
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c = pixel % 16;
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l = c < 0xE ? pixel / 4 & 12 : 4;
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e = p0 / 64;
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// NES NTSC modulator
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// square wave between up to four voltage levels
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b = 40 + sa[(c > 12 * ((c + 8 + p) % 12 < 6)) +
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2 * !(0451326 >> p / 2 * 3 & e) + l];
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// Ideal TV NTSC demodulator?
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y += b;
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i += b * round(cos(M_PI * p / 6) * 5909);
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q += b * round(sin(M_PI * p / 6) * 5909);
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}
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// Converts YIQ to RGB
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// Store color at subpixel precision
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float A[3] = {-1.109, -.275, .947}, B[3] = {1.709, -.636, .624};
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palette_[o][p1][p0][u] = Clamp(
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255 * FixGamma(y / 1980.f + i * A[u] / 9e6f + q * B[u] / 9e6f));
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}
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}
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}
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}
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}
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static void PutPixel(unsigned px, unsigned py, unsigned pixel, int offset) {
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static bool once;
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static unsigned prev;
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