Convert sound.cpp to C

Makefile.common

@@ -39,7 +39,6 @@ SOURCES_CXX := \
 	$(CORE_DIR)/graphics.cpp \
 	$(CORE_DIR)/main.cpp \
 	$(CORE_DIR)/state.cpp \
-	$(CORE_DIR)/sound.cpp \
 	$(CORE_DIR)/libretro/libretro.cpp \
 	$(CORE_DIR)/libretro/log.cpp
 
@@ -47,6 +46,7 @@ SOURCES_C += \
 	$(CORE_DIR)/input.c \
 	$(CORE_DIR)/race-memory.c \
 	$(CORE_DIR)/ngpBios.c \
+	$(CORE_DIR)/sound.c \
 	$(CORE_DIR)/neopopsound.c
 
 ifeq ($(DRZ80),1)

sound.cpp → sound.c

@@ -9,10 +9,7 @@
 
 /* sound.cpp: implementation of the sound class. */
 
-#include "main.h"
 #include "types.h"
-#include "sound.h"
-#include "memory.h"
 
 #ifdef DRZ80
 #include "DrZ80_support.h"

sound.h

@@ -12,13 +12,13 @@
 #ifndef AFX_SOUND_H
 #define AFX_SOUND_H
 
-#if _MSC_VER > 1000
-#pragma once
-#endif /* _MSC_VER > 1000 */
-
 #include "types.h"
 #include "main.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 int initSound(void);
 void soundCleanup(void);
 
@@ -48,4 +48,8 @@ void ngpSoundExecute(void);
 void ngpSoundOff(void);
 void ngpSoundInterrupt(void);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* !defined(AFX_SOUND_H) */