ref: fe93e698589d6b23a02ec8e6d104f83e533661f3
dir: /sys/src/games/midi.c/
#include <u.h> #include <libc.h> enum { SAMPLE = 44100 }; struct Tracker { uchar *data; char ended; vlong t; vlong Δ; uchar notes[16][128]; int cmd; } *tr; typedef struct Tracker Tracker; int debug; int fd, ofd, div, tempo = 500000, ntrack; int freq[128]; uchar out[8192], *outp = out; void * emallocz(int size) { void *v; v = malloc(size); if(v == nil) sysfatal("malloc: %r"); memset(v, 0, size); return v; } void dprint(char *fmt, ...) { char s[256]; va_list arg; if(!debug) return; va_start(arg, fmt); vseprint(s, s+sizeof s, fmt, arg); va_end(arg); fprint(2, "%s", s); } int get8(Tracker *src) { uchar c; if(src == nil){ if(read(fd, &c, 1) == 0) sysfatal("unexpected eof"); return c; } dprint("%#p:%02ux", src, *src->data); return *src->data++; } int get16(Tracker *src) { int x; x = get8(src) << 8; return x | get8(src); } int get32(Tracker *src) { int x; x = get16(src) << 16; return x | get16(src); } int getvar(Tracker *src) { int k, x; x = get8(src); k = x & 0x7F; while(x & 0x80){ k <<= 7; x = get8(src); k |= x & 0x7F; } return k; } int peekvar(Tracker *src) { uchar *p; int v; p = src->data; v = getvar(src); src->data = p; return v; } void skip(Tracker *src, int x) { if(x) do get8(src); while(--x); } double tconv(int n) { double v; v = n; v *= tempo; v *= SAMPLE; v /= div; v /= 1000000; return v; } void run(double n) { int j, k, no[128]; int t, f; short u; uvlong samp; double Δ; Tracker *x; static double T, ε; static uvlong τ; Δ = tconv(n) + ε; samp = Δ; ε = Δ - samp; if(samp <= 0) return; memset(no, 0, sizeof no); for(x = tr; x < tr + ntrack; x++){ if(x->ended) continue; for(j = 0; j < 16; j++) for(k = 0; k < 128; k++) no[k] += x->notes[j][k]; } while(samp--){ t = 0; for(k = 0; k < 128; k++){ f = (τ % freq[k]) >= freq[k]/2 ? 1 : 0; t += f * no[k]; } u = t*10; outp[0] = outp[2] = u; outp[1] = outp[3] = u >> 8; outp += 4; if(outp == out + sizeof out){ write(ofd, out, sizeof out); outp = out; } τ++; } } void readevent(Tracker *src) { int n,t; dprint(" [%zd] ", src - tr); t = get8(src); if((t & 0x80) == 0){ src->data--; t = src->cmd; if((t & 0x80) == 0) sysfatal("invalid midi"); }else src->cmd = t; dprint("(%02ux) ", t >> 4); switch(t >> 4){ case 0x8: n = get8(src); get8(src); src->notes[t & 15][n] = 0; break; case 0x9: n = get8(src); src->notes[t & 15][n] = get8(src); break; case 0xA: case 0xD: case 0xC: get8(src); break; case 0xB: case 0xE: get16(src); break; case 0xF: if((t & 0xF) == 0){ while(get8(src) != 0xF7) ; return; } t = get8(src); n = get8(src); switch(t){ case 0x2F: src->ended = 1; break; case 0x51: tempo = get16(src) << 8; tempo |= get8(src); break; case 5: write(2, src->data, n); skip(src, n); break; default: dprint("unknown meta event type %.2x\n", t); case 3: case 1: case 2: case 0x58: case 0x59: case 0x21: skip(src, n); } break; default: sysfatal("unknown event type %x", t>>4); } dprint("\n"); } void main(int argc, char **argv) { int i, size, end; uvlong z; Tracker *x; ARGBEGIN{ case 'D': debug = 1; break; case 'c': ofd = 1; break; }ARGEND; if(*argv != nil) fd = open(*argv, OREAD); if(ofd == 0) ofd = open("/dev/audio", OWRITE); if(fd < 0 || ofd < 0) sysfatal("open: %r"); if(get32(nil) != 0x4D546864 || get32(nil) != 6) sysfatal("invalid file header"); get16(nil); ntrack = get16(nil); div = get16(nil); tr = emallocz(ntrack * sizeof(*tr)); for(x=tr, z=-1UL; x<tr+ntrack; x++){ if(get32(nil) != 0x4D54726B) sysfatal("invalid track header"); size = get32(nil); x->data = emallocz(size); readn(fd, x->data, size); x->Δ = getvar(x); /* prearm */ if(x->Δ < z) z = x->Δ; } for(x=tr; x<tr+ntrack; x++) x->Δ -= z; for(i = 0; i < 128; i++) freq[i] = SAMPLE / (440 * pow(1.05946, i - 69)); for(end=0; !end;){ end = 1; for(x=tr; x<tr+ntrack; x++){ if(x->ended) continue; end = 0; x->Δ--; x->t += tconv(1); while(x->Δ <= 0){ readevent(x); if(x->ended) break; x->Δ = getvar(x); } } run(1); } exits(nil); }