Some work on the lowlevel sound support

- ALSA driver is now default on Linux (if present)
- SDL sound driver is now default if no platform-specific driver is available
  and the SDL gui is enabled
- soundlnx.cc: sendwavepacket() now exits with error if device is not opened
- soundmod.cc: exit beep loop if sendwavepacket() returns error

bochs/config.h.in

@@ -850,12 +850,13 @@ typedef
 #define BX_SUPPORT_SOUNDLOW 0
 
 #if BX_SUPPORT_SOUNDLOW
-// Determines which sound lowlevel class is to be used.
+// Determines which sound lowlevel class is to be used as the default.
 // Currently the following are available:
+//    bx_sound_alsa_c       Output for Linux with ALSA PCM and sequencer interface
 //    bx_sound_linux_c      Output for Linux, to /dev/dsp and /dev/midi00
-//                          or ALSA PCM and sequencer interface
 //    bx_sound_windows_c    Output for Windows midi and wave mappers
 //    bx_sound_osx_c        Output for MacOSX midi and wave device
+//    bx_sound_sdl_c        Wave output with SDL
 //    bx_sound_lowlevel_c   Dummy functions, no output
 #define BX_SOUND_LOWLEVEL_C bx_sound_lowlevel_c
 // Use ALSA sound interface on Linux

bochs/configure.in

@@ -1767,6 +1767,8 @@ AC_SUBST(CDROM_OBJS)
 SOUNDCARD_OBJS=''
 SOUNDLOW_OBJS=''
 GAME_OBJS=''
+soundlow_drivers=''
+soundlow_default=''
 soundcard_present=0
 gameport_present=0
 AC_MSG_CHECKING(for Sound Blaster 16 support)
@@ -1814,17 +1816,20 @@ AC_ARG_ENABLE(es1370,
   )
 
 if test "$soundcard_present" = 1; then
-  AC_MSG_CHECKING(for sound lowlevel module)
   AC_DEFINE(BX_SUPPORT_SOUNDLOW, 1)
   case "$target" in
     *-linux* | *-freebsd*)
       SOUNDLOW_OBJS='soundlnx.o'
       AC_DEFINE(BX_SOUND_LOWLEVEL_C, bx_sound_linux_c)
-      AC_MSG_RESULT(linux)
+      soundlow_drivers="oss"
+      soundlow_default="oss"
       bx_have_alsa=0
       AC_CHECK_HEADER([alsa/asoundlib.h], [bx_have_alsa=1])
       if test "$bx_have_alsa" = 1; then
         SOUNDLOW_OBJS="$SOUNDLOW_OBJS soundalsa.o"
+        AC_DEFINE(BX_SOUND_LOWLEVEL_C, bx_sound_alsa_c)
+        soundlow_default="alsa"
+        soundlow_drivers="alsa $soundlow_drivers"
         AC_DEFINE(BX_HAVE_ALSASOUND, 1)
         if test "$bx_plugins" = 1; then
           SOUND_LINK_OPTS="$SOUND_LINK_OPTS -lasound"
@@ -1837,40 +1842,47 @@ if test "$soundcard_present" = 1; then
       SOUNDLOW_OBJS='soundwin.o'
       AC_DEFINE(BX_SOUND_LOWLEVEL_C, bx_sound_windows_c)
       DEVICE_LINK_OPTS="$DEVICE_LINK_OPTS winmm.lib"
-      AC_MSG_RESULT(win)
+      soundlow_drivers="win"
+      soundlow_default="win"
       ;;
     *-cygwin* | *-mingw32*)
       SOUNDLOW_OBJS='soundwin.o'
       AC_DEFINE(BX_SOUND_LOWLEVEL_C, bx_sound_windows_c)
       DEVICE_LINK_OPTS="$DEVICE_LINK_OPTS -lwinmm"
-      AC_MSG_RESULT(win)
+      soundlow_drivers="win"
+      soundlow_default="win"
       ;;
     *-macosx* | *-macos* | *-apple-darwin*)
       SOUNDLOW_OBJS='soundosx.o'
       AC_DEFINE(BX_SOUND_LOWLEVEL_C, bx_sound_osx_c)
       DEVICE_LINK_OPTS="$DEVICE_LINK_OPTS -framework CoreServices -framework AudioUnit -framework AudioToolbox"
-      AC_MSG_RESULT(osx)
+      soundlow_drivers="osx"
+      soundlow_default="osx"
       ;;
     *)
       SOUNDLOW_OBJS=''
       AC_DEFINE(BX_SOUND_LOWLEVEL_C, bx_sound_lowlevel_c)
-      AC_MSG_RESULT(dummy)
+      soundlow_default="dummy"
       ;;
   esac
-  AC_MSG_CHECKING(for additional sound lowlevel modules)
   if test "$with_sdl" = yes; then
     SOUNDLOW_OBJS="$SOUNDLOW_OBJS soundsdl.o"
     if test "$bx_plugins" = 1; then
       SOUND_LINK_OPTS="$SOUND_LINK_OPTS `sdl-config --libs`"
     fi
-    AC_MSG_RESULT(sdl)
-  else
-    AC_MSG_RESULT(none)
+    soundlow_drivers="$soundlow_drivers sdl"
+    if test "$soundlow_default" = "dummy"; then
+      soundlow_default="sdl"
+    fi
   fi
   if test "$bx_plugins" = 0; then
     SOUND_LIB_VAR='iodev/sound/libsound.a'
     AC_SUBST(SOUND_LIB_VAR)
   fi
+  AC_MSG_CHECKING(for sound lowlevel modules)
+  AC_MSG_RESULT($soundlow_drivers)
+  AC_MSG_CHECKING(for default sound lowlevel module)
+  AC_MSG_RESULT($soundlow_default)
 else
   AC_DEFINE(BX_SUPPORT_SOUNDLOW, 0)
 fi

bochs/iodev/sound/soundlnx.cc

@@ -193,8 +193,11 @@ int bx_sound_linux_c::startwaveplayback(int frequency, int bits, bx_bool stereo,
 
 int bx_sound_linux_c::sendwavepacket(int length, Bit8u data[])
 {
-  int ret = write(wave_fd[0], data, length);
+  if (wave_fd[0] == -1) {
+    return BX_SOUNDLOW_ERR;
+  }
 
+  int ret = write(wave_fd[0], data, length);
   if (ret == length) {
     return BX_SOUNDLOW_OK;
   } else {

bochs/iodev/sound/soundmod.cc

@@ -138,7 +138,7 @@ void beep_thread(void *indata)
 #endif
 {
   Bit8u level;
-  int i, j;
+  int i, j, ret;
 
   bx_sound_lowlevel_c *soundmod = (bx_sound_lowlevel_c*)indata;
   level = 0x40;
@@ -149,7 +149,8 @@ void beep_thread(void *indata)
       beep_buffer[j++] = level;
       if ((++i % beep_bytes) == 0) level ^= 0x40;
     } while (j < beep_bufsize);
-    soundmod->sendwavepacket(beep_bufsize, beep_buffer);
+    ret = soundmod->sendwavepacket(beep_bufsize, beep_buffer);
+    if (ret == BX_SOUNDLOW_ERR) break;
     if (soundmod->get_type() == BX_SOUNDLOW_WIN) {
 #ifdef WIN32
       Sleep(100);