(libretro) Implement error for logging

Makefile.libretro

@@ -1,5 +1,6 @@
 NTSC = 0
 DEBUG = 0
+LOGSOUND = 0
 
 GENPLUS_SRC_DIR := source
 LIBRETRO_DIR	:= libretro
@@ -124,6 +125,10 @@ LIBRETRO_SRC := $(GENPLUS_SRC_DIR)/genesis.c \
 
 LIBRETRO_OBJ := $(LIBRETRO_SRC:.c=.o)
 
+ifeq ($(LOGSOUND), 1)
+LIBRETRO_CFLAGS := -DLOGSOUND
+endif
+
 ifeq ($(platform), sncps3)
 CODE_DEFINES =
 else
@@ -133,7 +138,7 @@ endif
 DEFINES := 
 CFLAGS += $(fpic) $(DEFINES) $(CODE_DEFINES)
 
-LIBRETRO_CFLAGS := -I$(GENPLUS_SRC_DIR) \
+LIBRETRO_CFLAGS += -I$(GENPLUS_SRC_DIR) \
 		-I$(GENPLUS_SRC_DIR)/sound \
 		-I$(GENPLUS_SRC_DIR)/input_hw \
 		-I$(GENPLUS_SRC_DIR)/cart_hw \

libretro/libretro.c

@@ -2,6 +2,7 @@
 #include <stdbool.h>
 #endif
 #include <stddef.h>
+#include <stdarg.h>
 #include <stdio.h>
 
 #ifdef _MSC_VER
@@ -96,6 +97,22 @@ static uint8_t brm_format[0x40] =
  ************************************/
 #define CHUNKSIZE   (0x10000)
 
+void error(char * msg, ...)
+{
+#ifdef _XBOX1
+   char buffer[1024];
+#endif
+   va_list ap;
+   va_start(ap, msg);
+#ifdef _XBOX1
+   vsnprintf(buffer, sizeof(buffer), msg, ap);
+   OutputDebugStringA(buffer);
+#else
+   vfprintf(stderr, msg, ap);
+#endif
+   va_end(ap);
+}
+
 int load_archive(char *filename, unsigned char *buffer, int maxsize)
 {
   int size = 0;