cmake: set on-by-default audio backends, make options platform-dependent

cmake >= 3.4 is now needed because of string(APPEND ...)

CMakeLists.txt

@@ -1,5 +1,5 @@
 # ########## Project setup ##########
-CMAKE_MINIMUM_REQUIRED(VERSION 3.1...3.5)
+CMAKE_MINIMUM_REQUIRED(VERSION 3.4...3.5)
 PROJECT(wildmidi LANGUAGES C VERSION 0.4.5)
 
 # WildMIDI Version
@@ -26,22 +26,39 @@ OPTION(WANT_STATIC "Build static library in addition to dynamic library" OFF)
 CMAKE_DEPENDENT_OPTION(WANT_PLAYERSTATIC "Build a statically linked WildMIDI player" ON "WANT_STATIC;WANT_PLAYER" OFF)
 
 # Player options
-OPTION(WANT_AMIGA_AHI "Include Amiga AHI support" OFF)
-OPTION(WANT_ALSA "Include ALSA (Advanced Linux Sound Architecture) support" OFF)
-OPTION(WANT_COREAUDIO "Include macOS CoreAudio support" OFF)
-OPTION(WANT_DOSSB "Include DOS SoundBlaster support" OFF)
+IF (CMAKE_SYSTEM_NAME MATCHES ".*Linux")
+    SET(ALSA_DEFAULT ON)
+ELSE()
+    SET(ALSA_DEFAULT OFF)
+ENDIF()
+IF (CMAKE_SYSTEM_NAME MATCHES "DragonFly.*|kFreeBSD.*|FreeBSD")
+    SET(OSS_DEFAULT ON)
+ELSE()
+    SET(OSS_DEFAULT OFF)
+ENDIF()
+IF (CMAKE_SYSTEM_NAME MATCHES "kOpenBSD.*|OpenBSD.*")
+    SET(SNDIO_DEFAULT ON)
+ELSE()
+    SET(SNDIO_DEFAULT OFF)
+ENDIF()
+
+CMAKE_DEPENDENT_OPTION(WANT_AMIGA_AHI "Include Amiga AHI support" ON "AMIGA" OFF)
+CMAKE_DEPENDENT_OPTION(WANT_ALSA "Include ALSA (Advanced Linux Sound Architecture) support" ${ALSA_DEFAULT} "UNIX" OFF)
+CMAKE_DEPENDENT_OPTION(WANT_COREAUDIO "Include macOS CoreAudio support" ON "APPLE" OFF)
+CMAKE_DEPENDENT_OPTION(WANT_DOSSB "Include DOS SoundBlaster support" ON "DJGPP" OFF)
+CMAKE_DEPENDENT_OPTION(WANT_OS2DART "Include OS/2 DART support" ON "OS2" OFF)
+CMAKE_DEPENDENT_OPTION(WANT_OSS "Include OSS (Open Sound System) support" ${OSS_DEFAULT} "UNIX" OFF)
+CMAKE_DEPENDENT_OPTION(WANT_SNDIO "Include OpenBSD sndio support" ${SNDIO_DEFAULT} "UNIX" OFF)
+CMAKE_DEPENDENT_OPTION(WANT_WINMM "Include Windows WinMM audio support" ON "WIN32 OR CYGWIN" OFF)
 OPTION(WANT_OPENAL "Include OpenAL (Cross Platform) support" OFF)
-OPTION(WANT_OS2DART "Include OS/2 DART support" OFF)
-OPTION(WANT_OSS "Include OSS (Open Sound System) support" OFF)
-OPTION(WANT_SNDIO "Include OpenBSD sndio support" OFF)
-OPTION(WANT_WINMM "Include Windows WinMM audio support" OFF)
 
 OPTION(WANT_DEVTEST "Build WildMIDI DevTest file to check files" OFF)
-OPTION(WANT_OSX_DEPLOYMENT "OSX Deployment" OFF)
+CMAKE_DEPENDENT_OPTION(WANT_OSX_DEPLOYMENT "OSX Deployment" OFF "APPLE" OFF)
 
 IF (WIN32 AND MSVC)
     OPTION(WANT_MP_BUILD "Build with Multiple Processes (/MP)" OFF)
 ENDIF ()
+
 IF (UNIX AND NOT APPLE AND NOT RISCOS)
     SET(WILDMIDI_CFG "/etc/wildmidi/wildmidi.cfg" CACHE STRING "default config location")
 ELSE ()
@@ -195,36 +212,44 @@ IF (APPLE)
 ENDIF (APPLE)
 
 IF(WANT_PLAYER OR WANT_PLAYERSTATIC)
+    SET(ENABLED_OUTPUT "")
+
     IF (WANT_AMIGA_AHI)
         SET(AUDIODRV_AHI 1)
+        STRING(APPEND ENABLED_OUTPUT " ahi")
     ENDIF()
 
     IF (WANT_ALSA)
         FIND_PACKAGE(ALSA REQUIRED)
         SET(AUDIODRV_ALSA 1)
         LIST(APPEND AUDIO_LIBRARY ${ALSA_LIBRARIES})
+        STRING(APPEND ENABLED_OUTPUT " alsa")
     ENDIF()
 
     IF (WANT_COREAUDIO)
         SET(AUDIODRV_COREAUDIO 1)
         LIST(APPEND AUDIO_LIBRARY -Wl,-framework,AudioToolbox)
         LIST(APPEND AUDIO_LIBRARY -Wl,-framework,AudioUnit)
         LIST(APPEND AUDIO_LIBRARY -Wl,-framework,CoreServices)
+        STRING(APPEND ENABLED_OUTPUT " coreaudio")
     ENDIF()
 
     IF (WANT_DOSSB)
         SET(AUDIODRV_DOSSB 1)
+        STRING(APPEND ENABLED_OUTPUT " dossb")
     ENDIF()
 
     IF (WANT_OPENAL)
         FIND_PACKAGE(OpenAL REQUIRED)
         SET(AUDIODRV_OPENAL 1)
         LIST(APPEND AUDIO_LIBRARY ${OPENAL_LIBRARY})
+        STRING(APPEND ENABLED_OUTPUT " openal")
     ENDIF()
 
     IF (WANT_OS2DART)
         SET(AUDIODRV_OS2DART 1)
         LIST(APPEND AUDIO_LIBRARY mmpm2)
+        STRING(APPEND ENABLED_OUTPUT " dart")
     ENDIF()
 
     IF (WANT_OSS)
@@ -233,18 +258,25 @@ IF(WANT_PLAYER OR WANT_PLAYERSTATIC)
         IF(OSS_LIBRARIES)
            LIST(APPEND AUDIO_LIBRARY ${OSS_LIBRARIES})
         ENDIF()
+        STRING(APPEND ENABLED_OUTPUT " oss")
     ENDIF()
 
     IF (WANT_SNDIO)
         FIND_PACKAGE(SNDIO REQUIRED)
         SET(AUDIODRV_SNDIO 1)
         LIST(APPEND AUDIO_LIBRARY ${SNDIO_LIBRARIES})
+        STRING(APPEND ENABLED_OUTPUT " sndio")
     ENDIF()
 
     IF (WANT_WINMM)
         SET(AUDIODRV_WINMM 1)
         LIST(APPEND AUDIO_LIBRARY winmm)
+        STRING(APPEND ENABLED_OUTPUT " winmm")
     ENDIF()
+
+    STRING(STRIP ${ENABLED_OUTPUT} ENABLED_OUTPUT)
+    STRING(APPEND ENABLED_OUTPUT " wave")
+    MESSAGE(STATUS "Enabled audio output backends: ${ENABLED_OUTPUT}")
 ENDIF()
 
 # Setup up our config file