ref: c6aa11d04e721aebe5cb2969166785fa37652cd7
dir: /sys/src/games/md/ym.c/
#include <u.h>
#include <libc.h>
#include <thread.h>
#include "dat.h"
#include "fns.h"
extern int debug;
u8int ym[512];
enum {
MODE = 0x27,
FDIV = 1048576 * 2 * 144,
};
#define min(a, b) ((a)<=(b)?(a):(b))
typedef struct oper oper;
typedef struct fm fm;
struct oper {
enum {OFF, ATTACK, DECAY, SUSTAIN, RELEASE} st;
u8int *r;
int env;
u8int ar, sr, dr, rs, rr, mult;
u16int tl, sl;
u8int keyon, keyoff, rate;
int det;
u8int kc;
u32int phi, amp, dp;
int val, val0;
};
struct fm {
oper op[4];
u8int st, alg, en, fbs;
float samp;
} fms[6];
u8int ymstat;
static u32int cyc;
static u16int tima;
static u8int timb;
static short sbuf[2 * 2000], *sbufp;
static int fd;
static int sint[256], expt[256];
static void
timers(void)
{
u8int m;
static u8int bdiv;
m = ym[0x27];
if((m & 1) != 0){
tima = (tima + 1) & 0x3ff;
if(tima == 0 && (m & 4) != 0){
ymstat |= 1;
tima = ym[0x24] | ym[0x25] << 8 & 0x300;
}
}
if(++bdiv == 8){
bdiv = 0;
if((m & 2) != 0){
timb++;
if(timb == 0 && (m & 8) != 0){
ymstat |= 2;
timb = ym[0x26];
}
}
}
}
static void
calcfreq(int n)
{
int i, fr;
fm *f;
oper *p;
uchar *r;
static u8int det[4][32] = {
{0},
{0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2,
2, 3, 3, 3, 4, 4, 4, 5, 5, 6, 6, 7, 8, 8, 8, 8},
{1, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 4, 4, 4, 5,
5, 6, 6, 7, 8, 8, 9,10,11,12,13,14,16,16,16,16},
{2, 2, 2, 2, 2, 3, 3, 3, 4, 4, 4, 5, 5, 6, 6, 7,
8, 8, 9,10,11,12,13,14,16,17,19,20,22,22,22,22}
};
r = ym;
f = &fms[n];
if(n >= 3){
n -= 3;
r += 0x100;
}
fr = r[0xa0 + n] | r[0xa4 + n] << 8 & 0x3f00;
for(i = 0; i < 3; i++){
p = &f->op[i];
if(n == 2 && (ym[MODE] & 0xc0) == 0x40 && i != 0)
fr = r[0xa7+i] | r[0xab+i] << 8 & 0x3f00;
p->kc = fr >> 9 & 0x1e;
if((fr & 0x780) >= 0x380 && (fr & 0x780) != 0x400)
p->kc |= 1;
p->dp = ((fr & 0x7ff) << (fr >> 11)) >> 1;
if((p->det & 4) != 0)
p->dp -= det[p->det & 3][p->kc];
else
p->dp += det[p->det][p->kc];
if(p->mult != 0)
p->dp = (p->dp & 0x1ffff) * p->mult;
else
p->dp = (u16int)(p->dp >> 1);
}
}
void
ymwrite(u8int a, u8int v, u8int c)
{
int ch, i;
oper *p;
fm *f;
ym[c ? a|0x100 : a] = v;
if(a >= 0x30 && a < 0xa0){
ch = a & 3;
if(ch == 3)
return;
ch += c;
f = &fms[ch];
i = a >> 3 & 1 | a >> 1 & 2;
p = &f->op[i];
switch(a & 0xf0){
case 0x30:
p->mult = v & 0x0f;
p->det = v >> 4 & 7;
calcfreq(ch);
break;
case 0x40:
p->tl = v << 3 & 0x3f8;
break;
case 0x50:
p->ar = v << 1 & 0x3e;
p->rs = 3 - (v >> 6);
break;
case 0x60:
p->dr = v << 1 & 0x3e;
break;
case 0x70:
p->sr = v << 1 & 0x3e;
break;
case 0x80:
p->sl = v << 2 & 0x3c0;
p->rr = v << 2 & 0x3c | 0x02;
break;
};
}else{
ch = c + (a & 3);
switch(a){
case MODE:
if((v & 0x10) != 0)
ymstat &= ~2;
if((v & 0x20) != 0)
ymstat &= ~1;
calcfreq(2);
calcfreq(5);
break;
case 0x28:
ch = v & 3;
if(ch == 3)
break;
if((v & 4) != 0)
ch += 3;
f = &fms[ch];
for(i = 0; i < 4; i++){
p = &f->op[i];
if((v & 1<<4+i) != 0){
if(p->st == OFF || p->st == RELEASE)
p->keyon++;
}else
if(p->st != OFF)
p->keyoff++;
}
break;
case 0xa0: case 0xa1: case 0xa2:
case 0xa4: case 0xa5: case 0xa6:
calcfreq(ch);
break;
case 0xa8: case 0xa9: case 0xaa:
case 0xac: case 0xad: case 0xae:
calcfreq((a & 0x100) != 0 ? 5 : 2);
break;
case 0xb0: case 0xb1: case 0xb2:
fms[ch].alg = v & 7;
fms[ch].fbs = 7 - (v >> 3 & 7);
break;
case 0xb4: case 0xb5: case 0xb6:
fms[ch].en = v;
break;
}
}
}
static void
tables(void)
{
int i;
double x;
for(i = 0; i < 256; i++){
x = sin(((i << 1) + 1) * PI / 1024);
x = -log(x)/log(2);
sint[i] = x * 256 + 0.5;
}
for(i = 0; i < 256; i++){
x = pow(2, -(i+1)/256.0);
expt[i] = x * 2048 + 0.5;
}
}
void
ymreset(void)
{
int i, j;
for(i = 0; i < 6; i++){
fms[i].en = 0xc0;
for(j = 0; j < 4; j++)
fms[i].op[j].rs = 3;
}
tables();
}
static u8int
rate(oper *p, u8int r)
{
if(r == 0)
return 0;
r += p->kc >> p->rs;
if(r > 63)
return 63;
return r;
}
static void
env(oper *p)
{
int v, sh, ai;
static u8int ait[64][8] = {
{0,0,0,0,0,0,0,0}, {0,0,0,0,0,0,0,0}, {0,1,0,1,0,1,0,1}, {0,1,0,1,0,1,0,1},
{0,1,0,1,0,1,0,1}, {0,1,0,1,0,1,0,1}, {0,1,1,1,0,1,1,1}, {0,1,1,1,0,1,1,1},
{0,1,0,1,0,1,0,1}, {0,1,0,1,1,1,0,1}, {0,1,1,1,0,1,1,1}, {0,1,1,1,1,1,1,1},
{0,1,0,1,0,1,0,1}, {0,1,0,1,1,1,0,1}, {0,1,1,1,0,1,1,1}, {0,1,1,1,1,1,1,1},
{0,1,0,1,0,1,0,1}, {0,1,0,1,1,1,0,1}, {0,1,1,1,0,1,1,1}, {0,1,1,1,1,1,1,1},
{0,1,0,1,0,1,0,1}, {0,1,0,1,1,1,0,1}, {0,1,1,1,0,1,1,1}, {0,1,1,1,1,1,1,1},
{0,1,0,1,0,1,0,1}, {0,1,0,1,1,1,0,1}, {0,1,1,1,0,1,1,1}, {0,1,1,1,1,1,1,1},
{0,1,0,1,0,1,0,1}, {0,1,0,1,1,1,0,1}, {0,1,1,1,0,1,1,1}, {0,1,1,1,1,1,1,1},
{0,1,0,1,0,1,0,1}, {0,1,0,1,1,1,0,1}, {0,1,1,1,0,1,1,1}, {0,1,1,1,1,1,1,1},
{0,1,0,1,0,1,0,1}, {0,1,0,1,1,1,0,1}, {0,1,1,1,0,1,1,1}, {0,1,1,1,1,1,1,1},
{0,1,0,1,0,1,0,1}, {0,1,0,1,1,1,0,1}, {0,1,1,1,0,1,1,1}, {0,1,1,1,1,1,1,1},
{0,1,0,1,0,1,0,1}, {0,1,0,1,1,1,0,1}, {0,1,1,1,0,1,1,1}, {0,1,1,1,1,1,1,1},
{1,1,1,1,1,1,1,1}, {1,1,1,2,1,1,1,2}, {1,2,1,2,1,2,1,2}, {1,2,2,2,1,2,2,2},
{2,2,2,2,2,2,2,2}, {2,2,2,4,2,2,2,4}, {2,4,2,4,2,4,2,4}, {2,4,4,4,2,4,4,4},
{4,4,4,4,4,4,4,4}, {4,4,4,8,4,4,4,8}, {4,8,4,8,4,8,4,8}, {4,8,8,8,4,8,8,8},
{8,8,8,8,8,8,8,8}, {8,8,8,8,8,8,8,8}, {8,8,8,8,8,8,8,8}, {8,8,8,8,8,8,8,8},
};
if(p->keyon > 0){
p->st = ATTACK;
p->rate = rate(p, p->ar);
p->env = 0;
p->keyon = 0;
}else if(p->keyoff > 0){
p->st = RELEASE;
p->rate = rate(p, p->rr);
p->keyoff = 0;
}
if(p->rate > 0){
sh = p->rate >> 2;
if(sh < 11)
sh = 11 - sh;
else
sh = 0;
if((cyc & (1 << sh) - 1) == 0){
ai = ait[p->rate][(cyc >> sh) & 7];
switch(p->st){
case ATTACK:
p->env += ai * ((1024 - p->env >> 4) + 1);
if(p->env >= 1024){
p->env = 0;
p->st = DECAY;
p->rate = rate(p, p->dr);
}
break;
case DECAY:
p->env += ai;
if(p->env >= 1024)
p->env = 1023;
if(p->env >= p->sl){
p->st = SUSTAIN;
p->rate = rate(p, p->sr);
}
break;
case SUSTAIN:
case RELEASE:
p->env += ai;
if(p->env >= 1024){
p->env = 1023;
p->st = OFF;
p->rate = 0;
}
break;
}
}
}
if(p->st == OFF){
p->amp = 1023;
return;
}
v = p->env;
if(p->st == ATTACK)
v ^= 1023;
v += p->tl;
if(v > 1023)
p->amp = 1023;
else
p->amp = v;
}
static void
opr(oper *p, int inp)
{
int v, x, r;
p->phi += p->dp;
v = (p->phi >> 10) + inp;
if((v & 0x100) != 0)
v ^= 0xff;
x = sint[v & 0xff] + (p->amp << 2);
r = expt[x & 0xff] << 2 >> (x >> 8);
p->val0 = p->val;
if((v & 0x200) != 0)
p->val = -r;
else
p->val = r;
}
void
ymstep(void)
{
static int ymch, ymop, ymcyc;
fm *f;
oper *p;
int x;
f = fms + ymch;
p = f->op + ymop;
x = 0;
if(ymop == 0){
if(f->fbs != 7)
x = p->val + p->val0 >> f->fbs + 2;
}else{
switch(f->alg << 4 | ymop){
default: x = p[-1].val; break;
case 0x11: break;
case 0x12: x = f->op[0].val + f->op[1].val; break;
case 0x21: break;
case 0x23: x = f->op[0].val + f->op[2].val; break;
case 0x32: break;
case 0x33: x = f->op[1].val + f->op[2].val; break;
case 0x42: break;
case 0x52: case 0x53: x = f->op[0].val; break;
case 0x62: case 0x63: break;
case 0x71: case 0x72: case 0x73: break;
}
x >>= 1;
}
if(ymcyc == 0)
env(p);
opr(p, x);
if(ymop == 3){
switch(f->alg){
default: x = p->val >> 5; break;
case 4: x = (f->op[1].val >> 5) + (p->val >> 5); break;
case 5: case 6: x = (f->op[1].val >> 5) + (f->op[2].val >> 5) + (p->val >> 5); break;
case 7: x = (f->op[0].val >> 5) + (f->op[1].val >> 5) + (f->op[2].val >> 5) + (p->val >> 5); break;
}
if(x > 256) x = 256;
if(x < -256) x = -256;
f->samp = x / 256.0;
if(++ymch == 6){
ymch = 0;
if(++ymcyc == 3){
cyc++;
ymcyc = 0;
timers();
}
}
ymop = 0;
}else
ymop++;
}
void
audiosample(void)
{
int i;
u8int x;
float v, vl, vr;
if(sbufp == nil)
return;
vl = vr = 0;
for(i = 0; i < 6; i++){
if(i == 5 && (ym[0x2b] & 0x80) != 0)
v = ym[0x2a] / 255.0;
else
v = fms[i].samp;
x = fms[i].en;
if((x & 0x80) != 0)
vl += v;
if((x & 0x40) != 0)
vr += v;
}
if(sbufp < sbuf + nelem(sbuf) - 1){
*sbufp++ = vl * 5000;
*sbufp++ = vr * 5000;
}
}
int
audioout(void)
{
int rc;
if(sbufp == nil)
return -1;
if(sbufp == sbuf)
return 0;
rc = write(fd, sbuf, (sbufp - sbuf) * 2);
if(rc > 0)
sbufp -= (rc+1)/2;
if(sbufp < sbuf)
sbufp = sbuf;
return 0;
}
void
initaudio(void)
{
fd = open("/dev/audio", OWRITE);
if(fd < 0)
return;
sbufp = sbuf;
}