From f752aece31691bdf05acbbef8f206e90d1cecb80 Mon Sep 17 00:00:00 2001
From: Thomas Klaehn <thomas.klaehn@perinet.io>
Date: Sat, 13 Jul 2019 12:45:42 +0200
Subject: [PATCH] build process improved

---
 Makefile | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/Makefile b/Makefile
index 766f77c..48e6595 100644
--- a/Makefile
+++ b/Makefile
@@ -3,35 +3,40 @@ CROSS_COMPILE ?=
 TARGET_FILE ?= test
 
 CC = $(CROSS_COMPILE)gcc
+CPP = $(CROSS_COMPILE)cpp
 
 SRC_DIR = src
 OBJ_DIR = obj
 BIN_DIR = bin
 
-C_FLAGS := -O0 -g -Iinc
+INCLUDES := inc
+
+C_FLAGS := -O0 -g
+CPP_FLAGS := $(addprefix -I, $(INCLUDES))
 
 C_SRCS = $(wildcard $(SRC_DIR)/*.c)
-C_OBJS = $(patsubst %.c,$(OBJ_DIR)/%.o,$(notdir $(C_SRCS)))
+C_OBJS = $(patsubst $(SRC_DIR)%,$(OBJ_DIR)%,$(patsubst %.c,%.o,$(C_SRCS)))
 
 OBJS = $(C_OBJS)
 
 TARGET = $(BIN_DIR)/$(TARGET_FILE)
+THIS_MAKEFILE := $(lastword $(MAKEFILE_LIST))
 
 .PHONY: all
 all: $(TARGET)
 
-$(TARGET): $(OBJS)
+$(TARGET): $(OBJS) $(THIS_MAKEFILE)
 	@mkdir -p $(BIN_DIR)
 	$(CC) $(LD_FLAGS) $(OBJS) $(LIBS) -o $@
 
 .PRECIOUS: $(OBJ_DIR)/%.d
-$(OBJ_DIR)/%.d:
+$(OBJ_DIR)/%.d: $(SRC_DIR)/%.c
 	@mkdir -p $(OBJ_DIR)
-	$(CC) -MM -MF $@ -MP -MT $(patsubst %.d,%.o,$@) $(C_FLAGS) $(filter %$(patsubst %.d,%.c,$(notdir $@)),$(C_SRCS))
+	$(CPP) -MM -MF $@ -MP -MT $(patsubst %.d,%.o,$@) $(CPP_FLAGS) $(patsubst $(OBJ_DIR)/%.d,$(SRC_DIR)/%.c,$@)
 
 $(OBJ_DIR)/%.o: $(SRC_DIR)/%.c $(OBJ_DIR)/%.d
 	@mkdir -p $(OBJ_DIR)
-	$(CC) -c $(C_FLAGS) $< -o $@
+	$(CC) -c $(CPP_FLAGS) $(C_FLAGS) $< -o $@
 
 .PHONY: clean
 clean: