*** soundbyte.c.orig	Mon Apr  8 17:39:41 1996
--- soundbyte.c	Fri Oct 25 20:36:06 1996
***************
*** 96,101 ****
--- 96,106 ----
  }
  #endif
  
+ #ifndef sun
+ #ifdef  HALF_DUPLEX
+ static int oldvol = -1;
+ #endif
+ #endif
  
  /*  SOUNDINIT  --  Open the sound peripheral and initialise for
  		   access.  Return TRUE if successful, FALSE
***************
*** 145,150 ****
--- 150,170 ----
  	    }
  	    ioctl(Audio_fd, AUDIO_SETINFO, &Audio_info);
  #endif
+ #ifndef sun
+ #ifdef  HALF_DUPLEX
+ 	    if (iomode == O_RDONLY) {
+ 		if (oldvol == -1)
+ 		    oldvol = soundgetvol();
+ 		soundplayvol(0);
+ 	    } else if (   iomode == O_WRONLY
+ 		       && oldvol != -1
+ 		      ) {
+ 		if (soundgetvol() == 0)
+ 		    soundplayvol(oldvol);
+ 		oldvol = -1;
+ 	    }
+ #endif
+ #endif
  	    return TRUE;
  	}
  	if (errno != EINTR) {
***************
*** 160,165 ****
--- 180,194 ----
  void soundterm()
  {
  	if (audiof >= 0) {
+ #ifndef sun
+ #ifdef  HALF_DUPLEX
+ 	    if (oldvol != -1) {
+ 		if (soundgetvol() == 0)
+ 		    soundplayvol(oldvol);
+ 		oldvol = -1;
+ 	    }
+ #endif
+ #endif
  	    if (close(audiof) < 0) {
                  perror("closing audio device");
  	    }
***************
*** 210,219 ****
  
     arg	 = (value << 8) | value;
  
!    if (ioctl(Audio_fd, MIXER_WRITE(SOUND_MIXER_PCM), &arg) < 0)
!         perror("SOUND_MIXER_PCM");
  #endif
  }
  
  /*  SOUNDRECGAIN  --  Set recording gain from 0 (minimum) to 100 (maximum).  */
  
--- 239,268 ----
  
     arg	 = (value << 8) | value;
  
!    if (ioctl(Audio_fd, SOUND_MIXER_WRITE_PCM, &arg) < 0)
! 	perror("SOUND_MIXER_WRITE_PCM");
  #endif
  }
+ 
+ #ifndef sun
+ #ifdef  HALF_DUPLEX
+ 
+ /*  SOUNDGETVOL -- Get current playback volume. */
+ 
+ int soundgetvol()
+ {
+    int arg, v1, v2;
+ 
+    if (ioctl(Audio_fd, SOUND_MIXER_READ_PCM, &arg) < 0) {
+ 	perror("SOUND_MIXER_READ_PCM");
+ 	return -1;
+    }
+    v1 = arg & 0xFF;
+    v2 = (arg >> 8) & 0xFF;
+    return (v1 > v2) ? v1 : v2;
+ }
+ #endif
+ #endif
  
  /*  SOUNDRECGAIN  --  Set recording gain from 0 (minimum) to 100 (maximum).  */