audio/mixfs: implement Tstat to obtain buffer size, better underrun handling

diff --git a/sys/src/cmd/audio/mixfs/mixfs.c b/sys/src/cmd/audio/mixfs/mixfs.c
index 6e3b722eafe6516132b00311528a85ea0c0dd220..537bfca8f42f8942a82c94193f5b7c4bc0b53d17 100644 (file)
--- a/sys/src/cmd/audio/mixfs/mixfs.c
+++ b/sys/src/cmd/audio/mixfs/mixfs.c
@@ -8,6 +8,7 @@ enum {
        NBUF = 8*1024,
        NDELAY = 2048,
        NCHAN = 2,
+       FREQ = 44100,
 };
 
 typedef struct Stream Stream;
@@ -83,21 +84,21 @@ void
 audioproc(void *)
 {
        static uchar buf[NBUF*NCHAN*2];
-       int nsleep, fd, i, j, n, m, v;
+       int sweep, fd, i, j, n, m, v;
        Stream *s;
        uchar *p;
 
        threadsetname("audioproc");
 
        fd = -1;
-       nsleep = 0;
+       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 && nsleep > 4)
+                               if(n <= 0 && (s->used == 0 || sweep))
                                        s->run = 0;
                                else if(n < m)
                                        m = n;
@@ -109,20 +110,34 @@ audioproc(void *)
                m %= NBUF;
 
                if(m == 0){
-                       sleep(1<<nsleep);
-                       if(nsleep < 7)
-                               nsleep++;
-                       else {
-                               close(fd);
-                               fd = -1;
+                       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)
-                               continue;
-
-               nsleep = 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++){
@@ -179,6 +194,28 @@ fswrite(Req *r)
        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 *)
 {
@@ -200,6 +237,7 @@ fsend(Srv *)
 Srv fs = {
        .open=          fsopen,
        .write=         fswrite,
+       .stat=          fsstat,
        .destroyfid=    fsclunk,
        .start=         fsstart,
        .end=           fsend,