#include <stdio.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include <signal.h>
#include <strings.h>
#include <sys/audioio.h>

extern const char *__progname;

static int afd = -1;

static signed short int data[65536];
static int ptr;
static int len;

/* QSIZE should be a bit more than enough samples to fill up DELAY at 8kHz */
#define QSIZE 250 /* samples */
#define DELAY 20000 /* usec */

static int scount[QSIZE];

static void readsound(void)
{
 int c1;
 int c2;

 len = 0;
 ptr = 0;
 while (1)
  { if (len >= 65536) break;
    c1 = getchar();
    if (c1 == EOF) break;
    c2 = getchar();
    if (c2 == EOF) break;
    data[len++] = (c1 << 8) | c2;
  }
 bzero(&scount,sizeof(scount));
}

/* mulaw seems to be a floating-point format that splits up eight bits as
   sign(1), exponent(3), mantissa(4) - and for then some incomprehensible
   reason bit-complements the whole thing. */
static unsigned char linear_to_ulaw(signed long int linear)
{
 unsigned char sign;
 unsigned char exp;
 unsigned char mant;
 static unsigned exptbl[128] = { 0,1,2,2,3,3,3,3,4,4,4,4,4,4,4,4,
				 5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
				 6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
				 6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
				 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
				 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
				 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
				 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7 };

 if (linear < 0)
  { linear = - linear;
    sign = 0x80;
  }
 else
  { sign = 0;
  }
 linear += 0x84; /* where does this magic number come from?? */
 if (linear > 32767) linear = 32767;
 exp = exptbl[linear>>8];
 mant = (linear >> (exp+3)) & 0xf;
 return(~(sign|(exp<<4)|mant));
}

static void playsome(int n)
{
 signed long int linear[QSIZE];
 unsigned char ulaw[QSIZE];
 int i;
 int j;
 int c;

 if (n < 1) return;
 for (i=0;i<n;i++) linear[i] = 0;
 j = ptr;
 c = len;
 for (i=0;i<n;i++)
  { linear[i] += data[j];
    j ++;
    if (j >= c) j = 0;
  }
 ptr = j;
 for (i=0;i<n;i++) ulaw[i] = linear_to_ulaw(linear[i]);
 write(afd,&ulaw[0],n);
 scount[n] ++;
}

static void die(int sig __attribute__((__unused__)))
{
 int i;
 for (i=0;i<QSIZE;i++)
  { if (scount[i])
     { printf("%d: %d\n",i,scount[i]);
     }
  }
 exit(0);
}

int main(void);
int main(void)
{
 audio_info_t ai;
 struct timeval wait;

 signal(SIGINT,die);
 readsound();
 afd = open("/dev/audio",O_WRONLY,0);
 AUDIO_INITINFO(&ai);
 ai.blocksize = 1;
 if (ioctl(afd,AUDIO_SETINFO,&ai) < 0)
  { fprintf(stderr,"%s: AUDIO_SETINFO: %s\n",__progname,strerror(errno));
    exit(1);
  }
 if (ai.blocksize > 50)
  { fprintf(stderr,"%s: audio blocksize too large\n",__progname);
    exit(1);
  }
 while (1)
  { if (ioctl(afd,AUDIO_GETINFO,&ai) < 0)
     { fprintf(stderr,"%s: AUDIO_GETINFO: %s\n",__progname,strerror(errno));
       exit(1);
     }
    playsome(QSIZE-ai.play.seek);
    wait.tv_sec = 0;
    wait.tv_usec = DELAY;
    if (select(1,0,0,0,&wait) < 0)
     { if (errno == EINTR) continue;
       fprintf(stderr,"%s: select: %s\n",__progname,strerror(errno));
       exit(1);
     }
  }
}