ref: c1d40df49550393f3afe53fb6e6d500dfa8eb7a8
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,
};
#define MIN(a,b) ((a)<(b)?(a):(b))
#define MAX(a,b) ((a)>(b)?(a):(b))
typedef struct Stream Stream;
struct Stream
{
int used;
int mode;
int flush;
int run;
ulong rp;
ulong wp;
QLock;
Rendez;
};
ulong mixrp;
Lock rplock;
int lbbuf[NBUF][NCHAN];
int mixbuf[NBUF][NCHAN];
Lock mixlock;
Stream streams[16];
int volfd;
int volume[2] = {100, 100};
int vol64k[2] = {65536, 65536};
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;
s->mode = r->ifcall.mode;
s->flush = 0;
qunlock(s);
r->fid->aux = s;
respond(r, nil);
return;
}
qunlock(s);
}
respond(r, "all streams in use");
}
void
fsflush(Req *r)
{
Fid *f = r->oldreq->fid;
Stream *s;
if(f->file != nil && strcmp(f->file->name, "audio") == 0 && (s = f->aux) != nil){
qlock(s);
if(s->used && s->run){
s->flush = 1;
rwakeup(s);
}
qunlock(s);
}
respond(r, nil);
}
void
fsclunk(Fid *f)
{
Stream *s;
if(f->file != nil && strcmp(f->file->name, "audio") == 0 && (s = f->aux) != nil)
s->used = 0;
f->aux = nil;
}
void
audioproc(void *)
{
static uchar buf[NBUF*NCHAN*2];
int sweep, fd, i, j, n, m, v;
ulong rp;
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){
if(s->mode & OWRITE){
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);
} else {
n = (long)(mixrp - s->rp);
if(n > NBUF && (s->used == 0 || sweep))
s->run = 0;
if(n > 0)
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;
rp = mixrp;
for(i=0; i<m; i++){
for(j=0; j<NCHAN; j++){
v = clip16(mixbuf[rp % NBUF][j])*vol64k[j] / 65536;
lbbuf[rp % NBUF][j] = v;
mixbuf[rp % NBUF][j] = 0;
*p++ = v & 0xFF;
*p++ = v >> 8;
}
rp++;
}
/* barrier */
lock(&rplock);
mixrp = rp;
unlock(&rplock);
write(fd, buf, p - buf);
}
}
void
fsread(Req *r)
{
Srv *srv;
int i, j, n, m, v;
Stream *s;
uchar *p;
if(r->fid->file->aux == &volfd){
static char svol[4096];
if(r->ifcall.offset == 0){
m = snprint(svol, sizeof(svol), "mix %d %d\n", volume[0], volume[1]);
if((n = pread(volfd, svol+m, sizeof(svol)-m-1, 0)) > 0)
svol[m+n] = 0;
}
readstr(r, svol);
respond(r, nil);
return;
}
p = (uchar*)r->ofcall.data;
n = r->ifcall.count;
n &= ~(NCHAN*2 - 1);
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->rp = mixrp;
s->run = 1;
}
m = (long)(mixrp - s->rp);
if(m <= 0){
if(s->flush)
break;
s->run = 1;
rsleep(s);
continue;
}
if(m > NBUF){
m = NBUF;
s->rp = mixrp - m;
}
if(m > n)
m = n;
for(i=0; i<m; i++){
for(j=0; j<NCHAN; j++){
v = lbbuf[s->rp % NBUF][j];
*p++ = v & 0xFF;
*p++ = v >> 8;
}
s->rp++;
}
n -= m;
}
s->flush = 0;
qunlock(s);
respond(r, nil);
srvacquire(srv);
}
void
fswrite(Req *r)
{
Srv *srv;
int i, j, n, m;
Stream *s;
uchar *p;
if(r->fid->file->aux == &volfd){
char msg[64], *f[5];
int x[2], nf;
r->ofcall.count = r->ifcall.count;
snprint(msg, sizeof(msg), "%.*s",
utfnlen((char*)r->ifcall.data, r->ifcall.count), (char*)r->ifcall.data);
nf = tokenize(msg, f, nelem(f));
if(nf > 1 && strcmp(f[0], "mix") == 0){
x[0] = atoi(f[1]);
x[1] = nf < 3 ? x[0] : atoi(f[2]);
if(f[1][0] == '+' || f[1][0] == '-'){
x[0] += volume[0];
x[1] += volume[1];
}
volume[0] = MIN(MAX(0, x[0]), 100);
volume[1] = MIN(MAX(0, x[1]), 100);
/* ≈60dB dynamic range; [0-100] → [0-65536] */
vol64k[0] = 65.536 * (exp(volume[0] * 0.0690876) - 1.0);
vol64k[1] = 65.536 * (exp(volume[1] * 0.0690876) - 1.0);
}else if(volfd >= 0){
if(write(volfd, r->ifcall.data, r->ifcall.count) < 0){
responderror(r);
return;
}
}else{
respond(r, "bad msg");
return;
}
respond(r, nil);
return;
}
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){
if(s->flush)
break;
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->flush){
s->run = 1;
rsleep(s);
}
s->flush = 0;
qunlock(s);
respond(r, nil);
srvacquire(srv);
}
void
fsstat(Req *r)
{
Stream *s;
r->d.length = 0;
if(r->fid->file != nil && 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;
}
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,
.read= fsread,
.write= fswrite,
.stat= fsstat,
.destroyfid= fsclunk,
.flush= fsflush,
.start= fsstart,
.end= fsend,
};
void
usage(void)
{
fprint(2, "usage: %s [-D] [-v] [-s srvname] [-m mtpt]\n", argv0);
exits("usage");
}
void
threadmain(int argc, char **argv)
{
char *srv = nil;
char *m, *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();
volfd = open("/dev/volume", ORDWR);
fs.tree = alloctree(nil, nil, DMDIR|0777, nil);
createfile(fs.tree->root, "audio", nil, 0666, nil);
createfile(fs.tree->root, "volume", nil, 0666, &volfd);
threadpostmountsrv(&fs, srv, mtpt, MREPL);
m = smprint("%s/audio", mtpt);
if(bind(m, "/dev/audio", MREPL) < 0)
sysfatal("bind: %r");
free(m);
if(volfd >= 0){
m = smprint("%s/volume", mtpt);
if(bind(m, "/dev/volume", MREPL) < 0)
sysfatal("bind: %r");
free(m);
}
threadexits(0);
}