ref: 765c104f7a15d8a2d82288e581a9872310b1045c
dir: /mid2s.c/
#include <u.h>
#include <libc.h>
#include <bio.h>
enum{
Rate = 44100,
Nchan = 16,
Maxch = 16, // FIXME: could have more
Percch = 9,
};
typedef struct Trk Trk;
struct Trk{
u8int *s;
u8int *p;
u8int *q;
u8int *e;
double Δ;
double t;
int ev;
int ended;
};
Trk *tr;
int m2ich[Maxch], i2mch[Maxch], age[Maxch];
int nch = Nchan, percch = Percch;
int trace;
int mfmt, ntrk, div = 1, tempo;
Biobuf *ib;
void *
emalloc(ulong n)
{
void *p;
p = mallocz(n, 1);
if(p == nil)
sysfatal("mallocz: %r");
setmalloctag(p, getcallerpc(&n));
return p;
}
Biobuf *
bfdopen(int fd, int mode)
{
Biobuf *bf;
bf = Bfdopen(fd, mode);
if(bf == nil)
sysfatal("bfdopen: %r");
Blethal(bf, nil);
return bf;
}
Biobuf *
bopen(char *file, int mode)
{
int fd;
fd = open(file, mode);
if(fd < 0)
sysfatal("bopen: %r");
return bfdopen(fd, mode);
}
void
bread(void *u, int n)
{
if(Bread(ib, u, n) != n)
sysfatal("bread: short read");
}
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);
}
u8int
get8(Trk *x)
{
u8int v;
if(x == nil)
Bread(ib, &v, 1);
else{
if(x->p >= x->e || x->ended)
sysfatal("track overflow");
v = *x->p++;
}
dprint("%02ux", v);
return v;
}
u16int
get16(Trk *x)
{
u16int v;
v = get8(x) << 8;
return v | get8(x);
}
u32int
get32(Trk *x)
{
u32int v;
v = get16(x) << 16;
return v | get16(x);
}
double
tc(double n)
{
return (n * tempo / div);
}
void
skip(Trk *x, int n)
{
while(n-- > 0)
get8(x);
}
int
getvar(Trk *x)
{
int v, w;
w = get8(x);
v = w & 0x7f;
while(w & 0x80){
if(v & 0xff000000)
sysfatal("invalid variable-length number");
v <<= 7;
w = get8(x);
v |= w & 0x7f;
}
return v;
}
// FIXME: common midi.c shit (midilib.c? midifile?)
void
samp(double n)
{
double Δt;
long s;
static double t0, t1;
if(t0 == 0.0)
t0 = nsec();
t1 = t0 + n * 1000 * tempo / div;
t0 = t1;
Δt = t1 - nsec();
s = floor(Δt / 1000000);
if(s > 0)
sleep(s);
}
int
mapinst(Trk *, int c, int e)
{
int i, m, a;
i = m2ich[c];
if(c == 9)
i = percch;
else if(e >> 4 != 0x9){
if(e >> 4 == 0x8 && i >= 0){
i2mch[i] = -1;
m2ich[c] = -1;
}
return e;
}else if(i < 0){
for(i=0; i<nch; i++){
if(i == percch)
continue;
if(i2mch[i] < 0)
break;
}
if(i == nch){
for(m=i=a=0; i<nch; i++){
if(i == percch)
continue;
if(age[i] > age[m]){
m = i;
a = age[i];
}
}
if(a < 100){
fprint(2, "could not remap %d\n", c);
return e;
}
i = m;
fprint(2, "remapped %d → %d\n", c, i);
}
}
age[i] = 0;
m2ich[c] = i;
i2mch[i] = c;
return e & ~(Nchan-1) | i;
}
int
ev(Trk *x, vlong)
{
int e, n, m;
x->q = x->p - 1;
dprint(" [%zd] ", x - tr);
e = get8(x);
if((e & 0x80) == 0){
x->p--;
e = x->ev;
x->q--;
x->q[1] = e;
if((e & 0x80) == 0)
sysfatal("invalid event");
}else
x->ev = e;
dprint("(%02ux) ", e);
e = mapinst(x, e & 15, e);
n = get8(x);
if((e & 15) == percch){
if(n < 36)
n += 36 - n;
}
switch(e >> 4){
case 0x8: get8(x); break;
case 0x9: get8(x); break;
case 0xb: get8(x); break;
case 0xc: break;
case 0xe: get8(x); break;
case 0xf:
if((e & 0xf) == 0){
while(get8(x) != 0xf7)
;
break;
}
m = get8(x);
switch(n){
case 0x2f: dprint(" -- so long!\n"); return -1;
case 0x51: tempo = get16(x) << 8; tempo |= get8(x); break;
default: skip(x, m);
}
break;
case 0xa: get8(x); break;
case 0xd: get8(x); break;
default: sysfatal("invalid event %#ux\n", e >> 4);
}
dprint("\n");
if(x->p > x->q){
x->q[1] = e;
x->q[0] = x->q[1] >> 4 | (x->q[1] & 0xff) << 4;
write(1, x->q, x->p - x->q);
x->q = x->p;
}
return 0;
}
void
readmid(char *file)
{
u32int n, z;
uchar *s;
Trk *x;
ib = file != nil ? bopen(file, OREAD) : bfdopen(0, OREAD);
if(get32(nil) != 0x4d546864 || get32(nil) != 6)
sysfatal("invalid header");
mfmt = get16(nil);
ntrk = get16(nil);
if(ntrk == 1)
mfmt = 0;
if(mfmt < 0 || mfmt > 1)
sysfatal("unsupported format %d", mfmt);
div = get16(nil);
tr = emalloc(ntrk * sizeof *tr);
for(x=tr, z=-1UL; x<tr+ntrk; x++){
if(get32(nil) != 0x4d54726b)
sysfatal("invalid track");
n = get32(nil);
s = emalloc(n);
bread(s, n);
x->s = s;
x->p = s;
x->q = x->p;
x->e = s + n;
x->Δ = getvar(x); /* prearm */
if(x->Δ < z)
z = x->Δ;
}
for(x=tr; x<tr+ntrk; x++)
x->Δ -= z;
Bterm(ib);
}
void
usage(void)
{
fprint(2, "usage: %s [-D] [-c nch] [-p percch] [mid]\n", argv0);
exits("usage");
}
void
main(int argc, char **argv)
{
int i, c, end, debug;
Trk *x;
debug = 0;
ARGBEGIN{
case 'D': debug = 1; break;
case 'c':
nch = atoi(EARGF(usage()));
break;
case 'p':
percch = atoi(EARGF(usage()));
break;
default: usage();
}ARGEND
if(nch <= 0 || nch > Maxch)
usage();
if(percch <= 0 || percch > nch)
usage();
readmid(*argv);
tempo = 500000;
trace = debug;
for(i=0; i<nelem(m2ich); i++){
m2ich[i] = i2mch[i] = -1;
age[i] = -1UL;
}
for(;;){
end = 1;
for(x=tr; x<tr+ntrk; x++){
if(x->ended)
continue;
end = 0;
x->Δ--;
while(x->Δ <= 0){
if(x->ended = ev(x, 0)){
c = x - tr;
i = m2ich[c];
if(i >= 0){
i2mch[i] = -1;
m2ich[c] = -1;
}
break;
}
x->Δ = getvar(x);
}
}
if(end){
write(1, tr[0].q, tr[0].p - tr[0].q);
break;
}
samp(1);
for(i=0; i<nch; i++){
if(i2mch[i] < 0)
continue;
age[i]++;
if(age[i] > 10000){
fprint(2, "reset %d\n", i2mch[i]);
m2ich[i2mch[i]] = -1;
i2mch[i] = -1;
}
}
}
exits(nil);
}