fat: rewrite makefile as snippet

Signed-off-by: James Archer <[email protected]>

components/fs/fat/fat.mk

@@ -0,0 +1,75 @@
+#
+# Copyright 2025, UNSW
+#
+# SPDX-License-Identifier: BSD-2-Clause
+#
+# This Makefile snippet builds the FAT component
+#
+# NOTES:
+# Requires variables:
+#	LIONSOS
+#	TARGET
+#	MICROKIT_SDK
+#	MICROKIT_BOARD
+#	MICROKIT_CONFIG
+#	CPU
+#	FAT_LIBC_INCLUDE
+#	FAT_LIBC_LIB
+# Generates fat.elf
+
+FAT_SRC_DIR := $(realpath $(dir $(lastword $(MAKEFILE_LIST))))
+FAT_FF15_SRC_DIR := $(LIONSOS)/dep/ff15
+FAT_LIBMICROKITCO_DIR := $(LIONSOS)/dep/libmicrokitco
+
+FAT_CFLAGS := \
+	-I$(FAT_LIBC_INCLUDE) \
+	-I$(FAT_LIBMICROKITCO_DIR) \
+	-I$(FAT_FF15_SRC_DIR) \
+	-I$(FAT_SRC_DIR)/config
+
+FAT_OBJ := \
+	fat/ff15/ff.o \
+	fat/ff15/ffunicode.o \
+	fat/event.o \
+	fat/op.o \
+	fat/io.o
+
+CHECK_FAT_FLAGS_MD5 := .fat_cflags-$(shell echo -- $(CFLAGS) $(FAT_CFLAGS) | shasum | sed 's/ *-//')
+
+$(CHECK_FAT_FLAGS_MD5):
+	-rm -f .fat_cflags-*
+	touch $@
+
+FAT_LIBMICROKITCO_OBJ := libmicrokitco/libmicrokitco.a
+FAT_LIBMICROKITCO_OPT_PATH := $(FAT_SRC_DIR)/config
+
+fat/$(FAT_LIBMICROKITCO_OBJ): fat
+	make -f $(FAT_LIBMICROKITCO_DIR)/Makefile \
+			LIBMICROKITCO_PATH=$(FAT_LIBMICROKITCO_DIR) \
+			TARGET=$(TARGET) \
+			MICROKIT_SDK:=$(MICROKIT_SDK) \
+			BUILD_DIR:=fat \
+			MICROKIT_BOARD:=$(MICROKIT_BOARD) \
+			MICROKIT_CONFIG:=$(MICROKIT_CONFIG) \
+			CPU:=$(CPU) \
+			LLVM:=1 \
+			LIBMICROKITCO_OPT_PATH=$(FAT_LIBMICROKITCO_OPT_PATH)
+
+fat:
+	mkdir -p fat
+
+fat/ff15:
+	mkdir -p fat/ff15
+
+fat/ff15/%.o: CFLAGS += $(FAT_CFLAGS)
+fat/ff15/%.o: $(FAT_FF15_SRC_DIR)/%.c $(FAT_LIBC_INCLUDE) $(CHECK_FAT_FLAGS_MD5) |fat/ff15
+	$(CC) -c $(CFLAGS) $< -o $@
+
+fat/%.o: CFLAGS += $(FAT_CFLAGS)
+fat/%.o: $(FAT_SRC_DIR)/%.c $(FAT_LIBC_INCLUDE) $(CHECK_FAT_FLAGS_MD5) |fat
+	$(CC) -c $(CFLAGS) $< -o $@
+
+fat.elf: $(FAT_OBJ) fat/$(FAT_LIBMICROKITCO_OBJ) $(FAT_LIBC_LIB)
+	$(LD) $(LDFLAGS) $^ $(LIBS) -o $@
+
+-include $(FAT_OBJ:.o=.d)

examples/fileio/fileio.mk

@@ -65,6 +65,7 @@ CFLAGS := \
 	-I$(BOARD_DIR)/include \
 	-target $(TARGET) \
 	-DBOARD_$(MICROKIT_BOARD) \
+	-I$(LIONSOS)/include \
 	-I$(SDDF)/include \
 	-I${CONFIG_INCLUDE} \
 	-DVIRTIO_MMIO_NET_OFFSET=0xc00
@@ -116,21 +117,11 @@ micropython.elf: mpy-cross libsddf_util_debug.a libco.a
 		FROZEN_MANIFEST=$(abspath ./manifest.py) \
 		V=1
 
-fat.elf: musllibc/lib/libc.a
-	make -C $(LIONSOS)/components/fs/fat \
-		CC=$(CC) \
-		LD=$(LD) \
-		CPU=$(CPU) \
-		BUILD_DIR=$(abspath .) \
-		CONFIG=$(MICROKIT_CONFIG) \
-		MICROKIT_SDK=$(MICROKIT_SDK) \
-		MICROKIT_BOARD=$(MICROKIT_BOARD) \
-		LIBC_DIR=$(abspath $(BUILD_DIR)/musllibc) \
-		BUILD_DIR=$(abspath .) \
-		CONFIG_INCLUDE=$(abspath $(CONFIG_INCLUDE)) \
-		TARGET=$(TARGET)
+FAT_LIBC_LIB := musllibc/lib/libc.a
+FAT_LIBC_INCLUDE := musllibc/include
+include $(LIONSOS)/components/fs/fat/fat.mk
 
-musllibc/lib/libc.a:
+musllibc/lib/libc.a musllibc/include:
 	make -C $(MUSL) \
 		C_COMPILER=aarch64-none-elf-gcc \
 		TOOLPREFIX=aarch64-none-elf- \