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<title>/usr/web/sources/contrib/dho/mixerfs.c - Plan 9 from Bell Labs</title>


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<a href="/plan9/">Plan 9 from Bell Labs</a>’s /usr/web/sources/contrib/dho/mixerfs.c


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Copyright © 2009 Alcatel-Lucent. 
Distributed under the
<a href="/plan9/license.html">Lucent Public License version 1.02</a>.
 
<a href="/plan9/download.html">Download the Plan 9 distribution.</a>

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#include <u.h>
#include <libc.h>
#include <auth.h>
#include <fcall.h>
#include <thread.h>
#include <9p.h>

enum
{
Xmixer = 1,

Mixmax = 16,
};

Alt *a;
Channel *outchan;
int nmix;
int audiofd;

struct muxdata {
short *data;
long len;
long ptr;
};

void
buffer_thread(void *_p)
{
struct muxdata *md = mallocz(Mixmax * sizeof(struct muxdata*), 1);
int i, j, k, m, minlen, nalts;
Req *r = nil;
short *out = nil;
short *p = nil;

minlen = nalts = i = j = k = m = 0;

USED(_p);

while (1) {
while (nmix == 0) sleep(1000);

/* mux */
i = alt(a);

print("data on alt %d\n", i);

/* no more data */
if (i == nmix) {
out = mallocz(minlen, 1);

/*
* we only work on the smallest buffer we have so we don't
* over/underflow.
*/

for (j = 0; j < nalts; j++)
for (k = 0; k < minlen; k++) {
p = md[i].data + md[i].ptr;

print ("p %p\n", p);

out[k] += p[k];
md[i].ptr += minlen;
if (md[i].ptr == md[i].len) {
free(md[i].data);
md[i].data = nil;
md[i].ptr = md[i].len = 0;
}
}

print ("Sending %d bytes\n", minlen);
sendul(outchan, minlen);
sendp(outchan, out);

/* block waiting for more data */
a[i].op = CHANEND;
minlen = nalts = 0;
continue;
}

/* we're getting data, don't block anymore... */
a[nmix].op = CHANNOBLK;
r = *(Req **)a[i].v;

if (md[i].data == nil) {
md[i].data = mallocz(r->ifcall.count, 1);
md[i].ptr = 0;
} else
md[i].data = realloc(md[i].data, r->ifcall.count + md[i].len);

if (md[i].data == nil) {
respond(r, "no memory");
exits("no memory");
}

for (int m = 0; m < r->ifcall.count; m++) {
short *ptr = (short *)r->ifcall.data;
md[i].data[md[i].len] = *ptr++;
}
memcpy((char *)(md[i].data + md[i].len), r->ifcall.data, r->ifcall.count);
md[i].len += r->ifcall.count;

if (minlen == 0 || md[i].len <minlen)
minlen = md[i].len;

r->ofcall.count = r->ifcall.count;
print("oink ack %d bytes\n", r->ifcall.count);
nalts++;
}
}

void
out_thread(void *p)
{
USED(p);

while (1) {
ulong len;
short *r;

len = recvul(outchan);
r = recvp(outchan);

print("received %l bytes\n", len);

write(audiofd, r, len);
}
}

void
fsopen(Req *r)
{
int i = nmix++;

a[nmix].c = a[nmix].v = nil;
a[nmix].op = CHANEND;

if (i == 16) {
respond(r, "all channels in use");
return;
}

a[i].c = chancreate(sizeof(Req *), 0);
a[i].op = CHANRCV;
a[i].v = malloc(sizeof(Req *));
r->fid->aux = (void *)a[i].c;

respond(r, nil);
}

void
fswrite(Req *r)
{
Channel *c = (Channel *)r->fid->aux;

/* don't bother if you can't fill our minimum buffer size */
if (r->ifcall.count < 8) {
r->ofcall.count = 0;
respond(r, nil);
} else {
print("Sending %l bytes\n", r->ifcall.count);
sendp(c, r);
}

/* respond() done in buffer thread */
}

Srv fs = {
.open= fsopen,
.write= fswrite,
};

void
threadmain(int argc, char **argv)
{
char *mtpt = "/dev/";

USED(argc); USED(argv);

a = mallocz(16 * sizeof (Alt), 1);

outchan = chancreate(sizeof (char *), 0);
audiofd = open("/dev/audio", OWRITE);

proccreate(buffer_thread, a, 32768);
proccreate(out_thread, outchan, 32768);

fs.tree = alloctree(nil, nil, DMDIR|0777, nil);
closefile(createfile(fs.tree->root, "audio", nil, 0666, (void *)Xmixer));

threadpostmountsrv(&fs, "audiomux", mtpt, MBEFORE);

recvp(chancreate(sizeof(void *), 0));
}

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