ref: ee93b99842546dc501a383e06fd0ba4af904e150
dir: /sys/src/games/gb/apu.c/
#include <u.h> #include <libc.h> #include <thread.h> #include "../eui.h" #include "dat.h" #include "fns.h" double TAU = 25000; Event evsamp; extern Event evenv; s16int sbuf[2*4000], *sbufp; enum { Freq = 44100, SRATEDIV = FREQ / Freq }; static int fd; u16int envmod; u8int sweepen, sweepcalc, sweepctr; u16int sweepfreq; typedef struct chan chan; struct chan { u8int *env, *freq; int per; u16int len; u8int n, ectr; u8int vol, ctr, samp; }; u8int wpos; u16int lfsr; u8int apustatus; ulong waveclock; u8int wavebuf; double samp[2]; chan sndch[4] = { { .n = 0, .env = reg + NR12, .freq = reg + NR14, .per = 8 * 2048, }, { .n = 1, .env = reg + NR22, .freq = reg + NR24, .per = 8 * 2048, }, { .n = 2, }, { .n = 3, .env = reg + NR42, .freq = reg + NR44, .per = 32 } }; Event chev[4] = { {.aux = &sndch[0]}, {.aux = &sndch[1]}, {.aux = &sndch[2]}, {.aux = &sndch[3]} }; Var apuvars[] = { VAR(apustatus), VAR(envmod), VAR(sweepen), VAR(sweepcalc), VAR(sweepctr), VAR(sweepfreq), VAR(wpos), VAR(lfsr), VAR(waveclock), VAR(wavebuf), VAR(sndch[0].ectr), VAR(sndch[0].len), VAR(sndch[0].per), VAR(sndch[0].ctr), VAR(sndch[0].vol), VAR(sndch[0].samp), VAR(sndch[1].ectr), VAR(sndch[1].len), VAR(sndch[1].per), VAR(sndch[1].ctr), VAR(sndch[1].vol), VAR(sndch[1].samp), VAR(sndch[2].ectr), VAR(sndch[2].len), VAR(sndch[2].per), VAR(sndch[2].vol), VAR(sndch[2].samp), VAR(sndch[3].ectr), VAR(sndch[3].len), VAR(sndch[3].per), VAR(sndch[3].vol), VAR(sndch[3].samp), {nil, 0, 0}, }; static void rate(chan *c, u16int v) { switch(c->n){ case 0: case 1: c->per = 8 * (2048 - (v & 0x7ff)); break; case 2: c->per = 4 * (2048 - (v & 0x7ff)); break; case 3: c->per = 32; if((v & 7) != 0) c->per *= v & 7; else c->per >>= 1; c->per <<= (v >> 4 & 15); } } static void filter(int t) { static int ov0, ov1; static u32int oclock; double e; u8int cntl, cnth; int i, v; e = exp((clock + t - oclock) * -(TAU / FREQ)); samp[0] = e * samp[0] + (1 - e) * ov0; samp[1] = e * samp[1] + (1 - e) * ov1; oclock = clock + t; cntl = reg[NR50]; cnth = reg[NR51]; ov0 = 0; ov1 = 0; for(i = 0; i < 4; i++){ if(i == 2 ? ((reg[NR30] & 0x80) == 0) : ((*sndch[i].env & 0xf8) == 0)) continue; v = sndch[i].samp * 2 - 15; if((cnth & 1<<4<<i) != 0) ov0 += v; if((cnth & 1<<i) != 0) ov1 += v; } ov0 *= 1 + (cntl >> 4 & 7); ov1 *= 1 + (cntl & 7); } static void chansamp(chan *c, int t) { u8int ov; ov = c->samp; switch(c->n){ case 0: case 1: c->samp = c->vol; switch(reg[NR21] >> 6){ case 0: if(c->ctr < 7) c->samp = 0; break; case 1: if(c->ctr < 6) c->samp = 0; break; case 2: if(c->ctr < 4) c->samp = 0; break; case 3: if(c->ctr >= 6) c->samp = 0; break; } break; case 2: if((apustatus & 1<<4) == 0){ c->samp = 0; break; } c->samp = wavebuf; if((wpos & 1) == 0) c->samp >>= 4; else c->samp &= 0xf; if((reg[NR32] & 3<<5) == 0) c->samp = 0; else c->samp = c->samp >> (reg[NR32] >> 5 & 3) - 1; break; case 3: c->samp = (lfsr & 1) != 0 ? 0 : c->vol; } if(ov != c->samp) filter(t); } void chantick(void *vc) { chan *c; u16int l; c = vc; switch(c->n){ case 0: case 1: c->ctr = c->ctr - 1 & 7; break; case 2: wpos = wpos + 1 & 31; wavebuf = reg[WAVE + (wpos >> 1)]; waveclock = clock; break; case 3: l = lfsr; lfsr >>= 1; if(((l ^ lfsr) & 1) != 0) if((reg[NR43] & 1<<3) != 0) lfsr |= 0x40; else lfsr |= 0x4000; break; } chansamp(c, chev[c->n].time); addevent(&chev[c->n], c->per); } static void env(chan *c, int t) { if((envmod & 1) == 0 && c->len > 0 && (*c->freq & 1<<6) != 0) if(--c->len == 0){ apustatus &= ~(1<<c->n); c->vol = 0; chansamp(c, t); return; } if((apustatus & 1<<c->n) == 0 || (envmod & 7) != 7 || c->ectr == 0 || --c->ectr != 0) return; c->ectr = *c->env & 7; if((*c->env & 1<<3) != 0){ if(c->vol < 15){ c->vol++; chansamp(c, t); } }else if(c->vol > 0){ c->vol--; chansamp(c, t); } } static void sweep(int wb, int t) { u16int fr; int d; u16int cnt; cnt = reg[NR10]; d = sweepfreq >> (cnt & 7); if((cnt & 1<<3) != 0) d = -d; fr = sweepfreq + d; sweepcalc |= cnt; if(fr > 2047){ sndch[0].len = 0; sndch[0].vol = 0; chansamp(&sndch[0], t); apustatus &= ~1; sweepen = 0; }else if(wb && (cnt & 7) != 0){ sweepfreq = fr; reg[NR13] = fr; reg[NR14] = reg[NR14] & 0xf8 | fr >> 8; rate(&sndch[0], fr); sweep(0, t); } } void sndstart(chan *c, u8int v) { u8int cnt; filter(0); c->vol = *c->env >> 4; c->ectr = *c->env & 7; if(c->len == 0) c->len = 64; apustatus |= 1<<c->n; if(c == sndch){ cnt = reg[NR10]; sweepen = (cnt & 0x07) != 0 || (cnt & 0x70) != 0; sweepctr = cnt >> 4 & 7; sweepctr += sweepctr - 1 & 8; sweepfreq = v << 8 & 0x700 | reg[NR13]; sweepcalc = 0; if((cnt & 0x07) != 0) sweep(0, 0); } if((*c->freq & 0x40) == 0 && (v & 0x40) != 0 && (envmod & 1) != 0 && --c->len == 0 || (*c->env & 0xf8) == 0){ apustatus &= ~(1<<c->n); c->vol = 0; } chansamp(c, 0); } void envtick(void *) { env(&sndch[0], evenv.time); env(&sndch[1], evenv.time); if((envmod & 1) == 0 && sndch[2].len > 0 && (reg[NR34] & 0x40) != 0) if(--sndch[2].len == 0){ apustatus &= ~4; delevent(&chev[2]); } env(&sndch[3], evenv.time); if((envmod & 3) == 2 && sweepen && --sweepctr == 0){ sweepctr = reg[NR10] >> 4 & 7; sweepctr += sweepctr - 1 & 8; if((reg[NR10] & 0x70) != 0) sweep(1, evenv.time); } envmod++; addevent(&evenv, FREQ / 512); } void sampletick(void *) { filter(evsamp.time); if(sbufp < sbuf + nelem(sbuf)){ sbufp[0] = samp[0] * 30; sbufp[1] = samp[1] * 30; sbufp += 2; } addevent(&evsamp, SRATEDIV); } void sndwrite(u8int a, u8int v) { static u16int thr[4] = {0x2000, 0x4000, 0x8000, 0xC000}; static u8int clrreg[] = { 0x80, 0x3f, 0x00, 0xff, 0xbf, 0xff, 0x3f, 0x00, 0xff, 0xbf, 0x7f, 0xff, 0x9f, 0xff, 0xbf, 0xff, 0xff, 0x00, 0x00, 0xbf, 0x00, 0x00 }; if((reg[NR52] & 0x80) == 0 && a != NR52 && ((mode & CGB) != 0 || a != NR11 && a != NR21 && a != NR31 && a != NR41)) return; switch(a){ case NR10: if((sweepcalc & 0x08) != 0 && (reg[NR10] & ~v & 0x08) != 0){ sndch[0].vol = 0; apustatus &= ~1; sweepcalc = 0; } break; case NR11: sndch[0].len = 64 - (v & 63); break; case NR12: if((v & 0xf8) == 0){ sndch[0].vol = 0; apustatus &= ~1; } break; case NR13: rate(&sndch[0], reg[NR14] << 8 & 0x700 | v); break; case NR14: rate(&sndch[0], v << 8 & 0x700 | reg[NR13]); if((v & 1<<7) != 0) sndstart(&sndch[0], v); break; case NR21: sndch[1].len = 64 - (v & 63); break; case NR22: if((v & 0xf8) == 0){ sndch[1].vol = 0; apustatus &= ~2; } break; case NR23: rate(&sndch[1], reg[NR24] << 8 & 0x700 | v); break; case NR24: rate(&sndch[1], v << 8 & 0x700 | reg[NR23]); if((v & 1<<7) != 0) sndstart(&sndch[1], v); break; case NR30: if((v & 0x80) == 0){ apustatus &= ~4; delevent(&chev[2]); } break; case NR31: sndch[2].len = 256 - (v & 0xff); break; case NR33: rate(&sndch[2], reg[NR34] << 8 & 0x700 | v); break; case NR34: rate(&sndch[2], v << 8 & 0x700 | reg[NR33]); if((v & 0x80) != 0){ if(sndch[2].len == 0) sndch[2].len = 256; wpos = 0; if((reg[NR30] & 0x80) != 0){ apustatus |= 4; delevent(&chev[2]); addevent(&chev[2], sndch[2].per); } } break; case NR41: sndch[3].len = 64 - (v & 63); break; case NR42: if((v & 0xf8) == 0){ sndch[3].vol = 0; apustatus &= ~8; } break; case NR43: rate(&sndch[3], v); break; case NR44: if((v & 1<<7) != 0){ if((reg[NR43] & 1<<3) != 0) lfsr = 0x7f; else lfsr = 0x7fff; sndstart(&sndch[3], v); } break; case NR50: case NR51: filter(0); break; case NR52: apustatus = v & 0xf0 | apustatus & 0x0f; if((v & 0x80) == 0){ memcpy(reg + NR10, clrreg, NR52 - NR10); if((mode & CGB) != 0){ sndch[0].len = 0; sndch[1].len = 0; sndch[2].len = 0; sndch[3].len = 0; apustatus = 0; delevent(&chev[2]); } }else if((reg[NR52] & 0x80) == 0){ envmod = 0; delevent(&evenv); addevent(&evenv, FREQ / 512); sndch[0].ctr = 0; sndch[1].ctr = 0; } } reg[a] = v; } u8int waveread(u8int a) { if((apustatus & 4) != 0) if((mode & CGB) != 0 || clock - waveclock == 0) return wavebuf; else return 0xff; return reg[WAVE + a]; } void wavewrite(u8int a, u8int v) { reg[WAVE + a] = v; } void audioinit(void) { fd = open("/dev/audio", OWRITE); if(fd < 0) sysfatal("open: %r"); sbufp = sbuf; evsamp.f = sampletick; addevent(&evsamp, SRATEDIV); addevent(&chev[0], 8 * 2048); addevent(&chev[1], 8 * 2048); addevent(&chev[3], 8 * 2048); } int audioout(void) { int rc; static int cl; if(sbufp == nil) return -1; if(sbufp == sbuf) return 0; cl = clock; rc = warp10 ? (sbufp - sbuf) * 2 : write(fd, sbuf, (sbufp - sbuf) * 2); if(rc > 0) sbufp -= (rc+1)/2; if(sbufp < sbuf) sbufp = sbuf; return 0; }