Makefile: start splitting into multiple .mk files

Keeping a single list of files is starting to be unwieldy.

Author: rasky

Diff for: Makefile

@@ -26,10 +26,9 @@ libdragon: LDFLAGS+=$(N64_LDFLAGS)
 libdragon: libdragon.a libdragonsys.a
 
 libdragonsys.a: $(BUILD_DIR)/system.o
-	@echo "    [AR] $@"
-	$(N64_AR) -rcs -o $@ $^
 
-libdragon.a: $(BUILD_DIR)/n64sys.o $(BUILD_DIR)/interrupt.o $(BUILD_DIR)/backtrace.o \
+LIBDRAGON_OBJS += \
+			 $(BUILD_DIR)/n64sys.o $(BUILD_DIR)/interrupt.o $(BUILD_DIR)/backtrace.o \
 			 $(BUILD_DIR)/fmath.o $(BUILD_DIR)/inthandler.o $(BUILD_DIR)/entrypoint.o \
 			 $(BUILD_DIR)/debug.o $(BUILD_DIR)/debugcpp.o $(BUILD_DIR)/usb.o $(BUILD_DIR)/libcart/cart.o $(BUILD_DIR)/fatfs/ff.o \
 			 $(BUILD_DIR)/fatfs/ffunicode.o $(BUILD_DIR)/rompak.o $(BUILD_DIR)/dragonfs.o \
@@ -56,6 +55,12 @@ libdragon.a: $(BUILD_DIR)/n64sys.o $(BUILD_DIR)/interrupt.o $(BUILD_DIR)/backtra
 			 $(BUILD_DIR)/rdpq/rdpq_rect.o $(BUILD_DIR)/rdpq/rdpq_mode.o \
 			 $(BUILD_DIR)/rdpq/rdpq_sprite.o $(BUILD_DIR)/rdpq/rdpq_tex.o \
 			 $(BUILD_DIR)/rdpq/rdpq_attach.o $(BUILD_DIR)/dlfcn.o
+
+include $(SOURCE_DIR)/audio/libdragon.mk
+
+libdragon.a: $(LIBDRAGON_OBJS)
+
+%.a:
 	@echo "    [AR] $@"
 	$(N64_AR) -rcs -o $@ $^
 

Diff for: src/audio/libdragon.mk

@@ -0,0 +1,9 @@
+LIBDRAGON_OBJS += \
+	$(BUILD_DIR)/audio/mixer.o $(BUILD_DIR)/audio/samplebuffer.o \
+	$(BUILD_DIR)/audio/rsp_mixer.o $(BUILD_DIR)/audio/wav64.o \
+	$(BUILD_DIR)/audio/xm64.o $(BUILD_DIR)/audio/libxm/play.o \
+	$(BUILD_DIR)/audio/libxm/context.o $(BUILD_DIR)/audio/libxm/load.o \
+	$(BUILD_DIR)/audio/ym64.o $(BUILD_DIR)/audio/ay8910.o \
+
+LIBDRAGON_OBJS += \
+	$(BUILD_DIR)/audio/wav64_vadpcm.o