103 lines
2.7 KiB
C
103 lines
2.7 KiB
C
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// markov.c
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/* TODO:
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* remove hardcoded FRAME_SAMPLES
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*/
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// !!!YOU WERE HERE!!!! //
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// write a proper markov chain, only run for 256 samples per chain
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// - make sure we DONT EVER fall into a zero len state
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// - test with sine wave, should work on any freq
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// s8 to u8 conversion macros ?
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// lo / hi nibble extracion macros
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void markov_gen(Markov_4 *m, s8 *audio) {
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const u8 cur_1st = (u8)(((s32) audio[0]) + 128);
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const u8 cur_2nd = (u8)(((s32) audio[1]) + 128);
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// 1st goes in low bits, 2nd in high
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m -> start = (cur_1st >> 4) | (cur_2nd & 0xf0);
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for int sam = 0; sam < 512; sam += 2 do {
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const u8 cur_1st = (u8)(((s32) audio[sam]) + 128);
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const u8 cur_2nd = (u8)(((s32) audio[sam + 1]) + 128);
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// 1st goes in low bits, 2nd in high
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const u8 cur = (cur_1st >> 4) | (cur_2nd & 0xf0);
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const int nex_sam = sam == 510 ?
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0 : // loop back to first sample
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sam + 2;
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const u8 nex_1st = (u8)(((s32) audio[nex_sam]) + 128);
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const u8 nex_2nd = (u8)(((s32) audio[nex_sam + 1]) + 128);
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// 1st goes in low bits, 2nd in high
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const u8 nex = (nex_1st >> 4) | (nex_2nd & 0xf0);
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m->chain[cur][nex] = MIN(m->chain[cur][nex] + 1, 255);
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}
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for int x = 0; x < 256; x++ do {
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static u8 x_copy[256];
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for int i = 0; i < 256; i++ do
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x_copy[i] = m->chain[x][i];
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u8 len = 0;
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for int y = 0; y < 256; y++ do
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for ; len < x_copy[y]; len++ do
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m -> chain[x][len] = y;
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m -> lens[x] = len;
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}
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}
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void markov_synth(Markov_4 *m, s8 *audio_out) {
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if SDL_GetKeyboardState(NULL)[SDL_SCANCODE_SPACE] do return;
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u8 x = m -> start;
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for int sam = 0; sam < FRAME_SAMPLES; sam += 2 do {
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if m->lens[x] == 0 do {
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puts("asdsdgsdgKLJASDUGEAKLJASKLJSDILKWJASDKLJ, WHY IS THERE A ZERO");
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break;
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}
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// split x into low + hi
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s8 lo = (x & 0xf), hi = ((x & 0xf0) >> 4);
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//audio_out[sam] = (lo - 8) << 4;
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//audio_out[sam + 1] = (hi - 8) << 4;
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if 1 do { // bit crush
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const int b = 4;
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audio_out[sam] = (audio_out[sam] >> b) << b;
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audio_out[sam + 1] = (audio_out[sam + 1] >> b) << b;
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}
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u8 rnd_y = rnd_u8() % m->lens[x];
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x = m->chain[x][rnd_y];
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}
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}
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void markov_draw(Markov_4 *mar, SDL_Renderer *r) {
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const int w = 256;
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for int x = 0; x < 256; x += 1 do
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//for int y = 0; y < mar->lens[x]; y += 1 do {
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for int y = 0; y < 256; y += 1 do {
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s32 m = mar->chain[x][y];
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SDL_SetRenderDrawColor(r,
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m >= 10 ? m : 0,
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MIN(255, m < 4 ? m * 100 : 0),
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MIN(255, m < 10 and m >= 4 ? m * 100 : 0), 255);
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//SDL_SetRenderDrawColor(r, m * 32, 0, 0, 255);
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if m != 0 do {
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const int y2 = 255 - y;
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SDL_RenderDrawPoint(r, x * 2, y2 * 2);
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SDL_RenderDrawPoint(r, x * 2 + 1, y2 * 2);
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SDL_RenderDrawPoint(r, x * 2, y2 * 2 + 1);
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SDL_RenderDrawPoint(r, x * 2 + 1, y2 * 2 + 1);
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}
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}
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}
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