ref: 81e6b7e9c958bd5da3c93e204fff59e6868bd0fc
dir: /sys/src/games/gb/apu.c/
#include <u.h>
#include <libc.h>
#include <thread.h>
#include "dat.h"
#include "fns.h"
Event evsamp;
extern Event evenv, evwave;
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 n, ectr;
u16int len;
u8int *env, *freq;
u16int fctr, fthr;
u32int finc;
u8int vol;
};
u8int wpos;
u16int lfsr;
u8int apustatus;
ulong waveclock;
u8int wavebuf;
chan sndch[4] = {
{
.n = 0,
.env = reg + NR12,
.freq = reg + NR14,
},
{
.n = 1,
.env = reg + NR22,
.freq = reg + NR24,
},
{
.n = 2,
},
{
.n = 3,
.env = reg + NR42,
.freq = reg + NR44,
}
};
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].fctr), VAR(sndch[0].fthr), VAR(sndch[0].finc), VAR(sndch[0].vol),
VAR(sndch[1].ectr), VAR(sndch[1].len), VAR(sndch[1].fctr), VAR(sndch[1].fthr), VAR(sndch[1].finc), VAR(sndch[1].vol),
VAR(sndch[2].ectr), VAR(sndch[2].len), VAR(sndch[2].fctr), VAR(sndch[2].fthr), VAR(sndch[2].finc), VAR(sndch[2].vol),
VAR(sndch[3].ectr), VAR(sndch[3].len), VAR(sndch[3].fctr), VAR(sndch[3].fthr), VAR(sndch[3].finc), VAR(sndch[3].vol),
{nil, 0, 0},
};
void
rate(int i, u16int v)
{
switch(i){
case 0: case 1:
sndch[i].finc = 131072ULL * 65536 / (Freq * (2048 - (v & 0x7ff)));
break;
case 2:
sndch[2].finc = 4 * (2048 - (v & 0x7ff));
break;
case 3:
sndch[3].finc = 524288ULL * 65536 / Freq;
if((v & 7) != 0)
sndch[3].finc /= v & 7;
else
sndch[3].finc <<= 1;
sndch[3].finc >>= (v >> 4 & 15) + 1;
}
}
void
env(chan *c)
{
if((envmod & 1) == 0 && c->len > 0 && (*c->freq & 1<<6) != 0)
if(--c->len == 0){
apustatus &= ~(1<<c->n);
c->vol = 0;
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++;
}else
if(c->vol > 0)
c->vol--;
}
void
wavetick(void *)
{
addevent(&evwave, sndch[2].finc);
wpos = wpos + 1 & 31;
wavebuf = reg[WAVE + (wpos >> 1)];
waveclock = clock;
}
s8int
wavesamp(void)
{
u8int x;
if((apustatus & 1<<4) == 0)
return 0;
x = wavebuf;
if((wpos & 1) == 0)
x >>= 4;
else
x &= 0xf;
if((reg[NR32] & 3<<5) == 0)
x = 0;
else
x = x >> (reg[NR32] >> 5 & 3) - 1;
return x;
}
s8int
lfsrsamp(void)
{
int v;
u16int l;
sndch[3].fctr = v = sndch[3].fctr + sndch[3].finc;
for(;;){
l = lfsr;
v -= 0x10000;
if(v < 0)
break;
lfsr >>= 1;
if(((l ^ lfsr) & 1) != 0)
if((reg[NR43] & 1<<3) != 0)
lfsr |= 0x40;
else
lfsr |= 0x4000;
}
if((l & 1) != 0)
return 0;
else
return sndch[3].vol;
}
void
sweep(int wb)
{
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;
apustatus &= ~1;
sweepen = 0;
}else if(wb && (cnt & 7) != 0){
sweepfreq = fr;
reg[NR13] = fr;
reg[NR14] = reg[NR14] & 0xf8 | fr >> 8;
rate(0, fr);
sweep(0);
}
}
void
sndstart(chan *c, u8int v)
{
u8int cnt;
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);
}
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;
}
}
void
envtick(void *)
{
addevent(&evenv, FREQ / 512);
env(&sndch[0]);
env(&sndch[1]);
if((envmod & 1) == 0 && sndch[2].len > 0 && (reg[NR34] & 0x40) != 0)
if(--sndch[2].len == 0){
apustatus &= ~4;
delevent(&evwave);
}
env(&sndch[3]);
if((envmod & 3) == 2 && sweepen && --sweepctr == 0){
sweepctr = reg[NR10] >> 4 & 7;
sweepctr += sweepctr - 1 & 8;
if((reg[NR10] & 0x70) != 0)
sweep(1);
}
envmod++;
}
void
sampletick(void *)
{
u8int cntl, cnth;
s16int ch[4];
s16int s[2];
int i;
addevent(&evsamp, SRATEDIV);
sndch[0].fctr += sndch[0].finc;
if(sndch[0].fctr >= sndch[0].fthr)
ch[0] = sndch[0].vol;
else
ch[0] = 0;
sndch[1].fctr += sndch[1].finc;
if(sndch[1].fctr >= sndch[1].fthr)
ch[1] = sndch[1].vol;
else
ch[1] = 0;
ch[2] = wavesamp();
ch[3] = lfsrsamp();
cntl = reg[NR50];
cnth = reg[NR51];
s[0] = 0;
s[1] = 0;
for(i = 0; i < 4; i++){
if(i == 2 ? ((reg[NR30] & 0x80) == 0) : ((*sndch[i].env & 0xf8) == 0))
continue;
ch[i] = ch[i] * 2 - 15;
if((cnth & 1<<i) != 0)
s[0] += ch[i];
if((cnth & 1<<4<<i) != 0)
s[1] += ch[i];
}
s[0] *= 1 + (cntl & 7);
s[1] *= 1 + (cntl >> 4 & 7);
if(sbufp < sbuf + nelem(sbuf)){
sbufp[0] = s[0] * 30;
sbufp[1] = s[1] * 30;
sbufp += 2;
}
}
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].fthr = thr[v >> 6 & 3];
sndch[0].len = 64 - (v & 63);
break;
case NR12:
if((v & 0xf8) == 0){
sndch[0].vol = 0;
apustatus &= ~1;
}
break;
case NR13:
rate(0, reg[NR14] << 8 & 0x700 | v);
break;
case NR14:
rate(0, v << 8 & 0x700 | reg[NR13]);
if((v & 1<<7) != 0)
sndstart(&sndch[0], v);
break;
case NR21:
sndch[1].fthr = thr[v >> 6 & 3];
sndch[1].len = 64 - (v & 63);
break;
case NR22:
if((v & 0xf8) == 0){
sndch[1].vol = 0;
apustatus &= ~2;
}
break;
case NR23:
rate(1, reg[NR24] << 8 & 0x700 | v);
break;
case NR24:
rate(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(&evwave);
}
break;
case NR31:
sndch[2].len = 256 - (v & 0xff);
break;
case NR33:
rate(2, reg[NR34] << 8 & 0x700 | v);
break;
case NR34:
rate(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(&evwave);
addevent(&evwave, sndch[2].finc);
}
}
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(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 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(&evwave);
}
}else if((reg[NR52] & 0x80) == 0){
envmod = 0;
delevent(&evenv);
addevent(&evenv, FREQ / 512);
sndch[0].fctr = 0;
sndch[1].fctr = 0;
sndch[3].fctr = 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);
}
int
audioout(void)
{
int rc;
static int cl;
if(sbufp == nil)
return -1;
if(sbufp == sbuf)
return 0;
cl = clock;
rc = write(fd, sbuf, (sbufp - sbuf) * 2);
if(rc > 0)
sbufp -= (rc+1)/2;
if(sbufp < sbuf)
sbufp = sbuf;
return 0;
}