91 lines
1.3 KiB
C
91 lines
1.3 KiB
C
#include <u.h>
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#include <libc.h>
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enum {
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SRATE = 44100,
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NSAMP = SRATE / 10,
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};
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void
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usage(void)
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{
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fprint(2, "%s: usage: %s [-d dev] [-v vol]\n", argv0, argv0);
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exits("usage");
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}
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int
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load(void)
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{
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static int fd = -1;
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static char buf[1024];
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int rc, sum;
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char *p, *q, *e;
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char *f[10];
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if(fd < 0)
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fd = open("/dev/sysstat", OREAD);
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if(fd < 0)
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sysfatal("open: %r");
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seek(fd, 0, 0);
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if((rc = readn(fd, buf, sizeof(buf)-1)) < 0)
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sysfatal("read: %r");
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p = buf;
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e = buf + rc;
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sum = 0;
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while(p < e){
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q = memchr(p, '\n', e - p);
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if(q == nil)
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q = e;
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*q = 0;
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rc = tokenize(p, f, nelem(f));
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if(rc >= 7)
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sum += atoi(f[7]);
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p = q;
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if(p < e)
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p++;
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}
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return sum;
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}
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void
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main(int argc, char **argv)
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{
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char *dev;
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uchar buf[4 * NSAMP], *p;
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short s;
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int vol, fd, cps;
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ulong tresh;
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dev = "/dev/audio";
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vol = 32767;
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s = 0;
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ARGBEGIN{
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case 'd':
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dev = strdup(EARGF(usage()));
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break;
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case 'v':
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vol = atoi(EARGF(usage()));
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break;
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default:
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usage();
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}ARGEND;
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if(argc != 0)
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usage();
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fd = open(dev, OWRITE);
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if(fd < 0)
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sysfatal("open: %r");
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for(;;){
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cps = 3 + load() / 3;
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tresh = umuldiv(0xFFFFFFFF, cps, SRATE);
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for(p = buf; p < buf + sizeof(buf);){
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s = lrand() < tresh ? (vol - s) : s;
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*p++ = s;
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*p++ = s >> 8;
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*p++ = s;
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*p++ = s >> 8;
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}
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if(write(fd, buf, sizeof(buf)) < 0)
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sysfatal("write: %r");
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}
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}
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