Use make primitives for enumerating source files

tests/Makefile

@@ -205,13 +205,16 @@ LDFLAGS+=$(foreach MOCK,$(MD_MOCKS),-Wl,--wrap=$(MOCK))
 SYSTEM_TEST_LDFLAGS=$(LDFLAGS)
 UNIT_TEST_LDFLAGS=$(LDFLAGS) $(foreach MOCK,$(MOCKS),-Wl,--wrap=$(MOCK))
 
-SRC=$(shell find ../src/* -maxdepth 0 -type f -name '*.c' ! -name '*main.c*' -printf '%f\n')
-SRC+=$(shell find ../src/comm/* -maxdepth 0 -type f -name '*.c' ! -name '*main.c*' -printf 'comm/%f\n')
-COMMON_TEST_SRC=$(shell find * -maxdepth 0 -type f -name '*.c' -print)
-UNIT_TEST_SRC=$(shell find ./unit/* -maxdepth 0 -type f -name '*.c' -print)
-SYSTEM_TEST_SRC=$(shell find ./system/* -maxdepth 0 -type f -name '*.c' -print)
+SRC=$(wildcard ../src/*.c)
+SRC+=$(wildcard ../src/*/*.c)
+SRC:=$(filter-out ../src/boot/rom_head.c,$(SRC))
+SRC:=$(filter-out ../src/main.c,$(SRC))
 
-SRC_OBJ=$(patsubst %.c,obj/%.o,$(SRC))
+COMMON_TEST_SRC=$(wildcard *.c)
+UNIT_TEST_SRC+=$(wildcard unit/*.c)
+SYSTEM_TEST_SRC+=$(wildcard system/*.c)
+
+SRC_OBJ=$(patsubst ../src/%.c,obj/%.o,$(SRC))
 COMMON_TEST_OBJ=$(patsubst %.c,obj/%.o,$(COMMON_TEST_SRC))
 UNIT_TEST_OBJ=$(patsubst %.c,obj/%.o,$(UNIT_TEST_SRC))
 SYSTEM_TEST_OBJ=$(patsubst %.c,obj/%.o,$(SYSTEM_TEST_SRC))
@@ -237,20 +240,18 @@ system: $(SYSTEM_TESTS_TARGET)
 $(SRC_OBJ): | $(OBJ_DIR) $(CMOCKA_DIR)
 
 $(OBJ_DIR):
-	mkdir -p $@
-	mkdir -p $@/comm
-	mkdir -p $@/unit
-	mkdir -p $@/system
+	mkdir -p $(dir $@)
 
 $(OBJ_DIR)/%.o: %.c
+	mkdir -p $(dir $@)
 	$(CC) $(CFLAGS) -c $< -o $@
 
 $(UNIT_TESTS_TARGET): $(SRC_OBJ) $(UNIT_TEST_OBJ) $(COMMON_TEST_OBJ)
-	mkdir -p $(BIN_DIR)
+	mkdir -p $(dir $@)
 	$(CC) -o $@ $^ $(UNIT_TEST_LDFLAGS)
 
 $(SYSTEM_TESTS_TARGET): $(SRC_OBJ) $(SYSTEM_TEST_OBJ) $(COMMON_TEST_OBJ)
-	mkdir -p $(BIN_DIR)
+	mkdir -p $(dir $@)
 	$(CC) -o $@ $^ $(SYSTEM_TEST_LDFLAGS)
 
 $(CMOCKA_DIR):