From ea8131fae723ff4ba5d183f38116abbaba7cd663 Mon Sep 17 00:00:00 2001
From: Stefan Reinauer <stefan.reinauer@coreboot.org>
Date: Fri, 20 Nov 2020 17:23:09 -0800
Subject: [PATCH] Add auto-dependency generation to Makefile

Add automatic dependency generation to the Makefile. Previously, changes
to any of the header files would cause a re-link, but not a rebuild of
the source code files that include those headers.

Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
---
 .gitignore |  1 +
 Makefile   | 25 +++++++++++++++++++++----
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/.gitignore b/.gitignore
index ef281e1..1b5a9b7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 *~
 *.o
+.deps
 dpcmd
diff --git a/Makefile b/Makefile
index 0c22e16..7b764ed 100644
--- a/Makefile
+++ b/Makefile
@@ -16,13 +16,30 @@ LDFLAGS ?=
 LDFLAGS += -lpthread
 LDFLAGS += $(shell $(PKG_CONFIG) --libs libusb-1.0)
 
-PROGRAMMER_OBJS += dpcmd.o usbdriver.o FlashCommand.o SerialFlash.o parse.o board.o project.o IntelHexFile.o MotorolaFile.o
+DEPDIR := .deps
+DEPFLAGS = -MT $@ -MMD -MP -MF $(DEPDIR)/$*.d
 
-$(PROGRAM): $(PROGRAMMER_OBJS) *.h Makefile
-	$(CC) $(CFLAGS) -o $(PROGRAM) $(PROGRAMMER_OBJS) $(LDFLAGS)
+SRCS = dpcmd.c usbdriver.c FlashCommand.c SerialFlash.c parse.c board.c project.c IntelHexFile.c MotorolaFile.c
+
+PROGRAMMER_OBJS := $(SRCS:%.c=%.o)
+
+$(PROGRAM): $(PROGRAMMER_OBJS)
+	$(CC) $(CFLAGS) $(CPPFLAGS) -o $@ $^ $(LDFLAGS)
+
+%.o : %.c
+%.o : %.c $(DEPDIR)/%.d | $(DEPDIR)
+	$(CC) $(DEPFLAGS) $(CFLAGS) $(CPPFLAGS) -c -o $@ $<
+
+$(DEPDIR): ; @mkdir -p $@
+
+DEPFILES := $(SRCS:%.c=$(DEPDIR)/%.d)
+$(DEPFILES):
+
+include $(wildcard $(DEPFILES))
 
 clean:
-	@rm -vf $(PROGRAM) $(PROGRAM).exe *.o *.d
+	rm -vf $(PROGRAM) $(PROGRAM).exe *.o
+	rm -rvf $(DEPDIR)
 
 install: $(PROGRAM)
 	@[ $(shell id -u) -eq 0 ] || (echo "Error: install needs root privileges" && false)