[WIP] Switch to PortAudio

Switch to PortAudio for cross-platform and cross backend compatibility.

Yet, there are two known limitations for current sound playback implementation:
1. The last period of sound is lost.
2. You cannot play sound twice or the device will crash thus
whole system crashes.

Author: Cuda-Chen

.gitmodules

@@ -1,8 +1,8 @@
-[submodule "cnfa"]
-    path = cnfa
-    url = https://github.com/cntools/cnfa
-    shallow = true
 [submodule "mini-gdbstub"]
     path = mini-gdbstub
     url = https://github.com/RinHizakura/mini-gdbstub
     shallow = true
+[submodule "portaudio"]
+	path = portaudio
+    url = https://github.com/PortAudio/portaudio
+    shallow = true

Makefile

@@ -14,7 +14,7 @@ OBJS_EXTRA :=
 # command line option
 OPTS :=
 
-LDFLAGS := -lm
+LDFLAGS :=
 
 # virtio-blk
 ENABLE_VIRTIOBLK ?= 1
@@ -55,37 +55,61 @@ endif
 
 # virtio-snd
 ENABLE_VIRTIOSND ?= 1
-ifneq ($(UNAME_S),$(filter $(UNAME_S),Linux))
+ifneq ($(UNAME_S),$(filter $(UNAME_S),Linux Darwin))
     ENABLE_VIRTIOSND := 0
 endif
 
-# Check ALSA installation
 ifeq ($(UNAME_S),Linux)
+    # Check ALSA installation
     ifeq (0, $(call check-alsa))
         $(warning No libasound installed. Check libasound in advance.)
         ENABLE_VIRTIOSND := 0
     endif
 endif
+ifeq ($(UNAME_S),Darwin)
+    ifeq (0, $(call check-ca))
+        $(warning No CoreAudio installed Check AudioToolbox in advance.)
+        ENABLE_VIRTIOSND := 0
+    endif
+endif
 $(call set-feature, VIRTIOSND)
 ifeq ($(call has, VIRTIOSND), 1)
     OBJS_EXTRA += virtio-snd.o
 
-    LDFLAGS += -lasound -lpthread
-    CFLAGS += -Icnfa
+    PORTAUDIOLIB := portaudio/lib/.libs/libportaudio.a
+    LDFLAGS += $(PORTAUDIOLIB)
 
-cnfa/Makefile:
-	git submodule update --init cnfa
-cnfa/os_generic: cnfa/Makefile
-	$(MAKE) -C $(dir $<) os_generic.h
-CNFA_LIB := cnfa/CNFA_sf.h
-$(CNFA_LIB): cnfa/Makefile cnfa/os_generic
-	$(MAKE) -C $(dir $<) CNFA_sf.h
-main.o: $(CNFA_LIB)
+    ifeq ($(UNAME_S),Linux)
+        LDFLAGS += -lasound -lrt
+        # Check PulseAudio installation
+        ifeq (0, $(call check-pa))
+            LDFLAGS += -lpulse
+        endif
+    endif
+    ifeq ($(UNAME_S),Darwin)
+        LDFLAGS += -framework CoreServices -framework CoreFoundation -framework AudioUnit -framework AudioToolbox -framework CoreAudio
+    endif
 
-# suppress warning when compiling CNFA
-virtio-snd.o: CFLAGS += -Wno-unused-parameter -Wno-sign-compare
+    CFLAGS += -Iportaudio/include
+	# PortAudio requires libm, yet we set -lm in the end of LDFLAGS
+	# so that the other libraries will be benefited for no need to set
+	# -lm separately.
+    LDFLAGS += -lpthread
+
+portaudio/Makefile:
+	git submodule update --init portaudio
+$(PORTAUDIOLIB): portaudio/Makefile
+	cd $(dir $<) && ./configure
+	$(MAKE) -C $(dir $<)
+main.o: $(PORTAUDIOLIB)
+
+# suppress warning when compiling PortAudio
+virtio-snd.o: CFLAGS += -Wno-unused-parameter
 endif
 
+# Set libm as the last dependency so that no need to set -lm seperately.
+LDFLAGS += -lm
+
 # .DEFAULT_GOAL should be set to all since the very first target is not all
 # after git submodule.
 .DEFAULT_GOAL := all

README.md

@@ -12,8 +12,8 @@ A minimalist RISC-V system emulator capable of running Linux the kernel and corr
 - Three types of I/O support using VirtIO standard:
     - virtio-blk acquires disk image from the host.
     - virtio-net is mapped as TAP interface.
-    - virtio-snd uses ALSA for sound operation with the following limitations:
-        - The emulator will hang if PulseAudio is enabled on host.
+    - virtio-snd uses PortAudio for sound operation with the following limitations:
+        - The emulator will crash after playing sound twice.
         - The playback may plays with repeating artifact.
 
 ## Prerequisites

cnfa

@@ -10,8 +10,41 @@ int main(){\n\
 }\n'
 endef
 
+# Create a mininal PulseAudio program
+define create-pa-prog
+echo '\
+#include <pulse/mainloop.h>\n\
+int main(){\n\
+    pa_mainloop *m;\n\
+    return 0;\n\
+}\n'
+endef
+
+# Create a mininal CoreAudio program
+define create-ca-prog
+echo '\
+#include <CoreAudio/CoreAudio.h>\n\
+#include <AudioToolbox/AudioQueue.h>
+int main(){\n\
+    AudioQueueRef queue;\n\
+    AudioQueueDispose(queue, TRUE);\n\
+    return 0;\n\
+}\n'
+endef
+
 # Check ALSA installation
 define check-alsa
 $(shell $(call create-alsa-prog) | $(CC) -x c -lasound -o /dev/null > /dev/null 2> /dev/null - 
 	&& echo $$?)
 endef
+
+# Check PulseAudio installation
+define check-pa
+$(shell $(call create-pa-prog) | $(CC) -x c -lpulse -o /dev/null - && echo 0 || echo 1)
+endef
+
+# Check CoreAudio installation
+define check-ca
+$(shell $(call create-ca-prog) | $(CC) -x c -framework AudioToolbox -o /dev/null > /dev/null 2> /dev/null - 
+	&& echo $$?)
+endef