Implement dependency generation in libtools.make.

Automatically generate dependency files for all sources so changes in headers
are picked up automatically. Use one dependency file for each source file,
since that allows to create them without using external tools (except the
compiler of course).

Change-Id: I246c1ceb525692547af22a2e32c4bab0c11507e1

rbutil/libtools.make

@@ -74,10 +74,12 @@ endif
 WINDRES = windres
 
 BUILD_DIR ?= $(TARGET_DIR)build$(COMPILETARGET)
-OBJDIR = $(abspath $(BUILD_DIR)/$(RBARCH))/
 
 ifdef RBARCH
 CFLAGS += -arch $(RBARCH)
+OBJDIR = $(abspath $(BUILD_DIR)/$(RBARCH))/
+else
+OBJDIR = $(abspath $(BUILD_DIR))/
 endif
 
 all: $(BINARY)
@@ -85,7 +87,11 @@ all: $(BINARY)
 OBJS := $(patsubst %.c,%.o,$(addprefix $(OBJDIR),$(notdir $(SOURCES))))
 LIBOBJS := $(patsubst %.c,%.o,$(addprefix $(OBJDIR),$(notdir $(LIBSOURCES))))
 
+# create dependency files. Make sure to use the same prefix as with OBJS!
 $(foreach src,$(SOURCES) $(LIBSOURCES),$(eval $(addprefix $(OBJDIR),$(subst .c,.o,$(notdir $(src)))): $(src)))
+$(foreach src,$(SOURCES) $(LIBSOURCES),$(eval $(addprefix $(OBJDIR),$(subst .c,.d,$(notdir $(src)))): $(src)))
+DEPS = $(addprefix $(OBJDIR),$(subst .c,.d,$(notdir $(SOURCES) $(LIBSOURCES))))
+-include $(DEPS)
 
 # additional link dependencies for the standalone executable
 # extra dependencies: libucl
@@ -135,6 +141,10 @@ clean:
 	rm -f $(OBJS) $(OUTPUT) $(TARGET_DIR)lib$(OUTPUT)*.a $(OUTPUT).dmg
 	rm -rf $(OUTPUT)-* i386 ppc $(OBJDIR)
 
+%.d:
+	$(SILENT)$(call mkdir,$(BUILD_DIR))
+	$(SILENT)$(CC) -MG -MM -MT $(subst .d,.o,$@) $(CFLAGS) -o $(BUILD_DIR)/$(notdir $@) $<
+
 # extra tools
 BIN2C = $(TOP)/tools/bin2c
 $(BIN2C):