configure.ac: Improve alsa checks.

On non-Linux systems, do not check for alsa, and do not print the
warning message stating that alsa could not be found.

Also, skip further alsa-checks on the first failure.

diff --git a/configure.ac b/configure.ac
index 8e9ca7d05527463fc916e4880dd7ad6ba1b95662..6c55553827adf916e4a5ecf9a5c028c112713aa9 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -36,8 +36,6 @@ AC_CHECK_HEADERS([arpa/inet.h ctype.h fcntl.h limits.h netdb.h netinet/in.h \
        sys/ipc.h unistd.h utime.h stddef.h],
        [], [AC_MSG_ERROR([$ac_header not found])])
 
-AC_CHECK_HEADER(linux/soundcard.h, [extras="$extras para_fade"],
-       [AC_MSG_WARN([linux/soundcard.h not found, cannot build para_fade])])
 
 # Checks for typedefs, structures, and compiler characteristics.
 AC_C_CONST
@@ -427,15 +425,34 @@ have_alsa="yes"
 OLD_CPPFLAGS="$CPPFLAGS"
 OLD_LD_FLAGS="$LDFLAGS"
 OLD_LIBS="$LIBS"
-msg="=> no alsa support for para_audiod/para_write"
-AC_CHECK_HEADERS([alsa/asoundlib.h], [], [
-       AC_MSG_WARN([no alsa/asoundlib $msg])
+if test "$OSTYPE" != "Linux"; then
        have_alsa="no"
-])
-AC_CHECK_LIB([asound], [snd_pcm_open], [], [
-       AC_MSG_WARN([no libasound $msg])
-       have_alsa="no"
-])
+fi
+msg="=> can not build para_fade, and no alsa support for para_audiod/para_write"
+if test "$have_alsa" = "yes"; then
+       AC_CHECK_HEADER(linux/soundcard.h,
+               [extras="$extras para_fade"],
+               [
+                       have_alsa="no"
+                       AC_MSG_WARN([no linux/soundcard.h $msg])
+               ]
+       )
+fi
+
+if test "$have_alsa" = "yes"; then
+       AC_CHECK_HEADERS([alsa/asoundlib.h], [], [
+               have_alsa="no"
+               AC_MSG_WARN([no alsa/asoundlib $msg])
+       ])
+fi
+
+if test "$have_alsa" = "yes"; then
+       AC_CHECK_LIB([asound], [snd_pcm_open], [], [
+               have_alsa="no"
+               AC_MSG_WARN([no libasound $msg])
+       ])
+fi
+
 if test "$have_alsa" = "yes"; then
        all_errlist_objs="$all_errlist_objs alsa_write"
        audiod_errlist_objs="$audiod_errlist_objs alsa_write"