ref: 17f7f6be4e1a316c0f5f26ff70e047aece4de2bc
dir: /sys/src/games/opl3/opl3m.c/
#include <u.h> #include <libc.h> #include <bio.h> void opl3out(uchar *, int); void opl3wr(int, int); void opl3init(int); enum{ OPLrate = 49716, /* 14318180Hz master clock / 288 */ Devrate = 44100, Srate = Devrate / 100, }; void usage(void) { fprint(2, "usage: %s [-s] [-r rate] [file]\n", argv0); exits("usage"); } void main(int argc, char **argv) { int rate, stream, n, r, v, fd, pfd[2]; uchar sb[64*1024], u[5]; double s, f, dt, T; Biobuf *bi; fd = 0; stream = 0; rate = OPLrate; ARGBEGIN{ case 'r': rate = atoi(EARGF(usage())); if(rate <= 0 || rate > OPLrate) usage(); break; case 's': stream = 1; break; default: usage(); }ARGEND; if(*argv != nil) if((fd = open(*argv, OREAD)) < 0) sysfatal("open: %r"); bi = Bfdopen(fd, OREAD); if(bi == nil) sysfatal("Bfdopen: %r"); opl3init(OPLrate); if(pipe(pfd) < 0) sysfatal("pipe: %r"); switch(rfork(RFPROC|RFFDG)){ case -1: sysfatal("rfork: %r"); case 0: close(0); close(pfd[1]); dup(pfd[0], 0); execl("/bin/audio/pcmconv", "pcmconv", "-i", "s16c2r49716", "-o", "s16c2r44100", nil); sysfatal("execl: %r"); default: close(1); close(pfd[0]); } f = (double)OPLrate / rate; dt = 0; T = nsec(); if(stream){ switch(rfork(RFPROC|RFMEM)){ case -1: sysfatal("rfork: %r"); case 0: for(;;){ n = Srate; s = 1e9 * n / OPLrate; T += s; dt = floor((T - nsec()) / 1e6); n *= 4; opl3out(sb, n); if(write(pfd[1], sb, n) != n) break; if(dt > 0) sleep(dt); } } } while((n = Bread(bi, u, sizeof u)) > 0){ r = u[1] << 8 | u[0]; v = u[2]; opl3wr(r, v); if(stream) continue; dt += (u[4] << 8 | u[3]) * f; while((n = dt) > 0){ if(n > sizeof sb / 4) n = sizeof sb / 4; dt -= n; T += n * 1e9 / OPLrate; n *= 4; opl3out(sb, n); write(pfd[1], sb, n); } } if(n < 0) sysfatal("read: %r"); close(pfd[1]); waitpid(); exits(nil); }