ref: b7105fe0662b57689f629ac768dd084f8a1589a4
dir: /sys/src/cmd/audio/mixfs/mixfs.c/
#include <u.h> #include <libc.h> #include <fcall.h> #include <thread.h> #include <9p.h> enum { NBUF = 8*1024, NDELAY = 2048, NCHAN = 2, FREQ = 44100, }; typedef struct Stream Stream; struct Stream { int used; int run; ulong wp; QLock; Rendez; }; ulong mixrp; int mixbuf[NBUF][NCHAN]; Lock mixlock; Stream streams[16]; int s16(uchar *p) { int v; v = p[0]<<(sizeof(int)-2)*8 | p[1]<<(sizeof(int)-1)*8; v >>= (sizeof(int)-2)*8; return v; } int clip16(int v) { if(v > 0x7fff) return 0x7fff; if(v < -0x8000) return -0x8000; return v; } void fsopen(Req *r) { Stream *s; if(strcmp(r->fid->file->name, "audio") != 0){ respond(r, nil); return; } for(s = streams; s < streams+nelem(streams); s++){ qlock(s); if(s->used == 0 && s->run == 0){ s->used = 1; qunlock(s); r->fid->aux = s; respond(r, nil); return; } qunlock(s); } respond(r, "all streams in use"); } void fsclunk(Fid *f) { Stream *s; if(f->file != nil && strcmp(f->file->name, "audio") == 0 && (s = f->aux) != nil){ f->aux = nil; s->used = 0; } } void audioproc(void *) { static uchar buf[NBUF*NCHAN*2]; int sweep, fd, i, j, n, m, v; Stream *s; uchar *p; threadsetname("audioproc"); fd = -1; sweep = 0; for(;;){ m = NBUF; for(s = streams; s < streams+nelem(streams); s++){ qlock(s); if(s->run){ n = (long)(s->wp - mixrp); if(n <= 0 && (s->used == 0 || sweep)) s->run = 0; else if(n < m) m = n; if(n < NDELAY) rwakeup(s); } qunlock(s); } m %= NBUF; if(m == 0){ int ms; ms = 100; if(fd >= 0){ if(sweep){ close(fd); fd = -1; } else { /* attempt to sleep just shortly before buffer underrun */ ms = seek(fd, 0, 2); if(ms > 0){ ms *= 800; ms /= FREQ*NCHAN*2; } else ms = 4; } sweep = 1; } sleep(ms); continue; } sweep = 0; if(fd < 0) if((fd = open("/dev/audio", OWRITE)) < 0){ fprint(2, "%s: open /dev/audio: %r\n", argv0); sleep(1000); continue; } p = buf; for(i=0; i<m; i++){ for(j=0; j<NCHAN; j++){ v = clip16(mixbuf[mixrp % NBUF][j]); mixbuf[mixrp % NBUF][j] = 0; *p++ = v & 0xFF; *p++ = v >> 8; } mixrp++; } write(fd, buf, p - buf); } } void fswrite(Req *r) { Srv *srv; int i, j, n, m; Stream *s; uchar *p; p = (uchar*)r->ifcall.data; n = r->ifcall.count; r->ofcall.count = n; n /= (NCHAN*2); srv = r->srv; srvrelease(srv); s = r->fid->aux; qlock(s); while(n > 0){ if(s->run == 0){ s->wp = mixrp; s->run = 1; } m = NBUF-1 - (long)(s->wp - mixrp); if(m <= 0){ s->run = 1; rsleep(s); continue; } if(m > n) m = n; lock(&mixlock); for(i=0; i<m; i++){ for(j=0; j<NCHAN; j++){ mixbuf[s->wp % NBUF][j] += s16(p); p += 2; } s->wp++; } unlock(&mixlock); n -= m; } if((long)(s->wp - mixrp) >= NDELAY){ s->run = 1; rsleep(s); } qunlock(s); respond(r, nil); srvacquire(srv); } void fsstat(Req *r) { Stream *s; if(r->fid->file == nil){ respond(r, "bug"); return; } if(strcmp(r->fid->file->name, "audio") == 0 && (s = r->fid->aux) != nil){ qlock(s); if(s->run){ r->d.length = (long)(s->wp - mixrp); r->d.length *= NCHAN*2; } else { r->d.length = 0; } qunlock(s); } respond(r, nil); } void fsstart(Srv *) { Stream *s; for(s=streams; s < streams+nelem(streams); s++){ s->used = s->run = 0; s->Rendez.l = &s->QLock; } proccreate(audioproc, nil, 16*1024); } void fsend(Srv *) { threadexitsall(nil); } Srv fs = { .open= fsopen, .write= fswrite, .stat= fsstat, .destroyfid= fsclunk, .start= fsstart, .end= fsend, }; void usage(void) { fprint(2, "usage: %s [-D] [-s srvname] [-m mtpt]\n", argv0); exits("usage"); } void threadmain(int argc, char **argv) { char *srv = nil; char *mtpt = "/mnt/mix"; ARGBEGIN{ case 'D': chatty9p++; break; case 's': srv = EARGF(usage()); break; case 'm': mtpt = EARGF(usage()); break; default: usage(); }ARGEND; if(argc) usage(); fs.tree = alloctree(nil, nil, DMDIR|0777, nil); createfile(fs.tree->root, "audio", nil, 0222, nil); threadpostmountsrv(&fs, srv, mtpt, MREPL); mtpt = smprint("%s/audio", mtpt); if(bind(mtpt, "/dev/audio", MREPL) < 0) sysfatal("bind: %r"); free(mtpt); threadexits(0); }