ref: 0fbc9c2d198923bf95eaa5daa32a7ecf61dcae6e
dir: /midump.c/
#include <u.h>
#include <libc.h>
#include <bio.h>
enum{
Rate = 44100,
Ninst = 128 + 81-35+1,
};
typedef struct Trk Trk;
struct Trk{
u8int *s;
u8int *p;
u8int *e;
double Δ;
double t;
int ev;
int ended;
};
Trk *tr;
int desc, quiet;
int mfmt, ntrk, div = 1, tempo;
vlong tic;
Biobuf *ib;
void *
emalloc(ulong n)
{
void *p;
p = mallocz(n, 1);
if(p == nil)
sysfatal("mallocz: %r");
setmalloctag(p, getcallerpc(&n));
return p;
}
void
dprint(char *fmt, ...)
{
char s[256];
va_list arg;
if(!desc)
return;
va_start(arg, fmt);
vseprint(s, s+sizeof s, fmt, arg);
va_end(arg);
fprint(2, "%s", s);
}
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");
}
u8int
get8(Trk *x)
{
u8int v;
if(x == nil || x->p == nil || x->e == nil)
Bread(ib, &v, 1);
else{
if(x->p >= x->e || x->ended)
sysfatal("track overflow");
v = *x->p++;
}
if(!quiet)
print("%02hhux", 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 * Rate / div) / 1e6;
}
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;
}
int
ev(Trk *x)
{
int e, n, m;
dprint("%08lld ", tic);
print("[%02zd] ", x-tr);
quiet = 1;
e = get8(x);
quiet = 0;
if((e & 0x80) == 0){
x->p--;
e = x->ev;
print("%02ux*", e);
if((e & 0x80) == 0)
sysfatal("invalid event");
}else{
print("%02ux", e);
x->ev = e;
}
dprint("C%02d: %1ux ", e & 15, e >> 4);
n = get8(x);
switch(e >> 4){
case 0x8:
m = get8(x);
dprint("C%02d note off %02ux, aftertouch %02ux", e&0xf, n, m);
break;
case 0x9:
m = get8(x);
dprint("C%02d note on %02ux, velocity %02ux", e&0xf, n, m);
break;
case 0xb:
m = get8(x);
dprint("control change: ");
switch(n){
case 0x00: dprint("C%02d bank select msb %02ux", e&0xf, m); break;
case 0x07: dprint("C%02d channel volume %02ux", e&0xf, m); break;
case 0x0a: dprint("C%02d pan %02ux", e&0xf, m); break;
default: dprint("C%02d unknown controller %.4ux = %02ux", e&0xf, n, m);
}
break;
case 0xc: dprint("program change %02ux", e&0xf, n); break;
case 0xe:
n = get8(x) << 7 | n;
dprint("pitch bend change %02x", n - 0x4000 / 2);
break;
case 0xf:
dprint("sysex: ");
if((e & 0xf) == 0){
while(get8(x) != 0xf7)
;
break;
}
m = get8(x);
dprint("[%d] ", m);
switch(n){
case 0x2f: print(" -- so long!\n"); return -1;
case 0x51:
tempo = get16(x) << 8;
tempo |= get8(x);
dprint("tempo change %d", tempo);
break;
default: skip(x, m);
}
break;
case 0xa:
m = get8(x);
dprint("polyphonic key pressure/aftertouch %02ux", m);
break;
case 0xd:
m = get8(x);
dprint("channel pressure/aftertouch %02ux", m);
break;
default: sysfatal("invalid event %#ux", e >> 4);
}
print("\n");
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;
switch(mfmt){
case 0: dprint("format 0: single multi-channel track\n"); break;
case 1: dprint("format 1: multiple concurrent tracks\n"); break;
case 2: dprint("format 2: multiple independent tracks\n"); break;
}
dprint("%d tracks\n", ntrk);
if(mfmt < 0 || mfmt > 1)
sysfatal("unsupported format %d", mfmt);
div = get16(nil);
if(1) /* FIXME: properly introduce new members, etc. */
dprint("div: %d ticks per quarter note\n", div);
else
dprint("div: %d smpte format, %d ticks per frame\n", (s16int)div>>8, div & 0xff);
tr = emalloc(ntrk * sizeof *tr);
print("\n");
for(x=tr, z=-1UL; x<tr+ntrk; x++){
if(get32(nil) != 0x4d54726b)
sysfatal("invalid track");
n = get32(nil);
dprint("track %zd, %d bytes\n", x-tr, n);
s = emalloc(n);
bread(s, n);
x->s = s;
x->p = s;
x->e = s + n;
x->Δ = getvar(x); /* prearm */
if(x->Δ < z)
z = x->Δ;
print("\n");
}
for(x=tr; x<tr+ntrk; x++)
x->Δ -= z;
tic = z;
Bterm(ib);
}
void
usage(void)
{
fprint(2, "usage: %s [mid]\n", argv0);
exits("usage");
}
void
main(int argc, char **argv)
{
int end, stream;
Trk *x, ☺;
desc = 1;
stream = 0;
ARGBEGIN{
case 'b': desc = 0; break;
case 's': stream = 1; break;
default: usage();
}ARGEND
tempo = 500000;
if(stream){
ib = *argv != nil ? bopen(*argv, OREAD) : bfdopen(0, OREAD);
tr = &☺;
ntrk = 1;
memset(tr, 0, sizeof *tr);
for(;;){
getvar(&☺);
if(ev(&☺) < 0)
exits(nil);
}
}
readmid(*argv);
for(end=0; !end;){
end = 1;
for(x=tr; x<tr+ntrk; x++){
if(x->ended)
continue;
end = 0;
x->Δ--;
x->t += tc(1);
while(x->Δ <= 0){
if(x->ended = ev(x)){
x->p = x->e;
break;
}
x->Δ = getvar(x);
print(" ");
}
}
tic++;
}
exits(nil);
}