ref: af36a8b50ad95196fdc21deac251919cd7bbd18a
dir: /sys/src/games/midi/midifile.c/
#include <u.h>
#include <libc.h>
#include <bio.h>
#include "midifile.h"
Track *tracks;
Chan chan[Nchan];
Inst *inst;
int mfmt, ntrk, div = 1, tempo = 500000;
int samprate = Rate;
int trace, stream, writeback;
vlong tic;
Biobuf *inbf, *outbf;
int rate = Rate;
void *
emalloc(ulong n)
{
void *p;
p = mallocz(n, 1);
if(p == nil)
sysfatal("mallocz: %r");
setmalloctag(p, getcallerpc(&n));
return p;
}
void *
erealloc(void *p, usize n, usize oldn)
{
if((p = realloc(p, n)) == nil)
sysfatal("realloc: %r");
setrealloctag(p, getcallerpc(&p));
if(n > oldn)
memset((uchar *)p + oldn, 0, n - oldn);
return p;
}
void
dprint(char *fmt, ...)
{
char s[256];
va_list arg;
if(!trace)
return;
va_start(arg, fmt);
vseprint(s, s+sizeof s, fmt, arg);
va_end(arg);
fprint(2, "%s", s);
}
Biobuf *
efdopen(int fd, int mode)
{
Biobuf *bf;
if((bf = Bfdopen(fd, mode)) == nil)
sysfatal("efdopen: %r");
Blethal(bf, nil);
return bf;
}
Biobuf *
eopen(char *file, int mode)
{
int fd;
if((fd = open(file, mode)) < 0)
sysfatal("eopen: %r");
return efdopen(fd, mode);
}
u8int
get8(Track *t)
{
u8int v;
if(t == nil || t->cur == nil || t->buf == nil)
Bread(inbf, &v, 1);
else{
if(t->cur >= t->buf + t->bufsz || t->ended)
sysfatal("track overflow");
v = *t->cur++;
}
return v;
}
u16int
get16(Track *t)
{
u16int v;
v = get8(t) << 8;
return v | get8(t);
}
u32int
get32(Track *t)
{
u32int v;
v = get16(t) << 16;
return v | get16(t);
}
static void
growmid(Track *t, int n)
{
usize cur, run;
/* one extra byte for delay prefetch */
if(t->cur + n + 1 < t->buf + t->bufsz)
return;
cur = t->cur - t->buf;
run = t->run - t->buf;
if(n < 8192)
n = 8192;
t->buf = erealloc(t->buf, t->bufsz + n + 1, t->bufsz);
t->bufsz += n + 1;
t->cur = t->buf + cur;
t->run = t->buf + run;
}
static void
put8(Track *t, u8int v)
{
if(t != nil){
growmid(t, 1);
*t->cur++ = v;
}else
Bwrite(outbf, &v, 1);
}
static void
put16(Track *t, u16int v)
{
put8(t, v >> 8);
put8(t, v);
}
static void
put32(Track *t, u32int v)
{
put16(t, v >> 16);
put16(t, v);
}
static void
putvar(Track *t)
{
int w;
uchar u[4], *p;
p = u + nelem(u) - 1;
w = t->Δ;
if(w & 1<<31)
sysfatal("invalid variable-length number %08ux", w);
*p-- = w;
while(w >= 0x80){
w >>= 8;
*p-- = w;
}
Bwrite(outbf, p, u + sizeof(u) - 1 - p);
}
static int
getvar(Track *t)
{
int n, v, w;
w = get8(t);
v = w & 0x7f;
for(n=0; w&0x80; n++){
if(n == 3)
sysfatal("invalid variable-length number");
v <<= 7;
w = get8(t);
v |= w & 0x7f;
}
return v;
}
u32int
peekvar(Track *t)
{
uchar *cur;
uint v;
cur = t->cur;
v = getvar(t);
t->cur = cur;
return v;
}
static void
skip(Track *t, int n)
{
while(n-- > 0)
get8(t);
}
double
delay(double n)
{
return (n * tempo * samprate / div) / 1e6;
}
vlong
ns2tic(double n)
{
return n * div * 1e3 / tempo;
}
int
nextev(Track *t)
{
int e;
if(writeback)
putvar(t);
t->run = t->cur;
e = get8(t);
if((e & 0x80) == 0){
if(t->cur != nil){
t->cur--;
t->run--;
}
e = t->latch;
if((e & 0x80) == 0)
sysfatal("invalid event %#ux", e);
}else
t->latch = e;
return e;
}
static void
newmsg(Msg *m, int c, int type, int arg1, int arg2, usize size)
{
m->chan = chan + c;
m->type = type;
m->arg1 = arg1;
m->arg2 = arg2;
m->size = size;
}
void
translate(Track *t, int e, Msg *msg)
{
int c, n, m, type;
uchar *p;
c = e & 0xf;
dprint("Δ %.2f ch%02d ", t->Δ, c);
n = get8(t);
m = -1;
type = Cunknown;
switch(e >> 4){
case 0x8:
m = get8(t);
dprint("note off\t%02ux\taftertouch\t%02ux", n, m);
type = Cnoteoff;
break;
case 0x9:
m = get8(t);
dprint("note on\t%02ux\tvelocity\t%02ux", n, m);
type = Cnoteon;
break;
case 0xb:
m = get8(t);
dprint("control change: ");
switch(n){
case 0x00:
dprint("bank select msb\t%02ux", m);
type = Cbankmsb;
break;
case 0x07:
dprint("channel volume\t%02ux", m);
chan[c].vol = m;
type = Cchanvol;
break;
case 0x0a:
dprint("pan\t%02ux", m);
chan[c].pan = m < 32 ? 1<<4 : m > 96 ? 1<<5 : 3<<4;
type = Cpan;
break;
default:
dprint("unknown controller %.4ux", n);
break;
}
break;
case 0xc:
dprint("program change\t%02ux", n);
type = Cprogram;
break;
case 0xe:
n = (get8(t) << 7 | n) - 0x4000 / 2;
chan[c].bend = n;
dprint("pitch bend\t%02x", n);
type = Cpitchbend;
break;
case 0xf:
dprint("sysex:\t");
if((e & 0xf) == 0){
m = 0;
while(get8(t) != 0xf7)
m++;
fprint(2, "sysex n %d m %d\n", n, m);
type = Csysex;
break;
}
m = get8(t);
switch(n){
case 0x2f:
dprint("... so long!");
t->ended = 1;
type = Ceot;
break;
case 0x51:
tempo = get16(t) << 8;
tempo |= get8(t);
dprint("tempo change\t%d", tempo);
type = Ctempo;
break;
default:
dprint("skipping unhandled event %02ux", n);
skip(t, m);
break;
}
break;
case 0xa:
m = get8(t);
dprint("polyphonic key pressure/aftertouch\t%02ux\t%02ux", n, m);
type = Ckeyafter;
break;
case 0xd:
m = get8(t);
dprint("channel pressure/aftertouch\t%02ux\t%02ux", n, m);
type = Cchanafter;
break;
default: sysfatal("invalid event %#ux", e >> 4);
}
newmsg(msg, c, type, n, m, t->cur - t->run);
dprint("\t[");
for(p=t->run; p<t->cur; p++)
dprint("%02ux", *p);
dprint("]\n");
}
void
writemid(char *file)
{
u32int n;
Track *t;
outbf = file == nil ? efdopen(1, OWRITE) : eopen(file, OWRITE);
put32(nil, 0x4d546864); /* MThd */
put32(nil, 6);
put16(nil, mfmt);
put16(nil, ntrk);
put16(nil, div);
for(t=tracks; t<tracks+ntrk; t++){
put32(nil, 0x4d54726b); /* MTrack */
n = t->cur - t->buf;
put32(nil, n);
Bwrite(outbf, t->buf, n);
}
Bterm(outbf);
outbf = nil;
}
int
readmid(char *file)
{
u32int n, z;
Track *t;
inbf = file == nil ? efdopen(0, OREAD) : eopen(file, OREAD);
if(stream){
mfmt = 0;
ntrk = 1;
tracks = emalloc(ntrk * sizeof *tracks);
return 0;
}
if(get32(nil) != 0x4d546864 || get32(nil) != 6){
werrstr("invalid header");
return -1;
}
mfmt = get16(nil);
ntrk = get16(nil);
if(ntrk == 1)
mfmt = 0;
if(mfmt < 0 || mfmt > 1){
werrstr("unsupported format %d", mfmt);
return -1;
}
div = get16(nil);
tracks = emalloc(ntrk * sizeof *tracks);
for(t=tracks, z=-1UL; t<tracks+ntrk; t++){
if(get32(nil) != 0x4d54726b){
werrstr("invalid track");
return -1;
}
n = get32(nil);
growmid(t, n);
Bread(inbf, t->buf, n);
t->Δ = getvar(t); /* prearm */
if(t->Δ < z)
z = t->Δ;
}
for(t=tracks; t<tracks+ntrk; t++)
t->Δ -= z;
Bterm(inbf);
inbf = nil;
return 0;
}
void
evloop(void)
{
int end;
Track *t;
if(stream){
for(t=tracks;;){
t->Δ = getvar(t);
event(t);
if(t->ended)
return;
samp(1);
tic++;
}
}
for(;;){
end = 1;
for(t=tracks; t<tracks+ntrk; t++){
if(t->ended)
continue;
end = 0;
t->Δ--;
t->t += delay(1);
while(t->Δ <= 0){
event(t);
if(t->ended)
break;
t->Δ = getvar(t);
}
}
if(end)
break;
samp(1);
tic++;
}
}
void
initmid(void)
{
Chan *c;
for(c=chan; c<chan+nelem(chan); c++){
c->vol = 0x5a;
c->bend = 0;
c->pan = 3<<4;
}
}