Rearchitect Makefile to support dependency tracking / fast incremental builds. Lua now built and linked as static library via its own Makefile. .gitignore modified to ignore *.d Makefile fragments with dependency info.

.gitignore

@@ -2,6 +2,7 @@
 # Ignore files ending in the following #
 ########################################
 *.o
+*.d
 *.swp
 *.swo
 *.bin
@@ -14,3 +15,6 @@ firmware/source/shared_*.h
 
 # ignore trash/temp files stored in host/ignore
 host/ignore
+
+# OS X Metadata
+.DS_Store

host/Makefile

@@ -1,25 +1,39 @@
 #compiler flags: -Wall Warnings all,  -g gdb debug markings, 
 CFLAGS=-Wall -O
+LDFLAGS= -llua -lusb-1.0 -Lsource/lua
 INCLUDE= -I ./include -I ../shared
-WINLIB= -L ./winlib
-LIBUSB= -lusb-1.0
+LDFLAGS_WINDOWS= -L ./winlib $(LDFLAGS)
+LDFLAGS_UNIX= -lm $(LDFLAGS)
 CC= gcc
 
-SOURCES=$(wildcard source/*.c source/lua/*.c)
-OBJECTS=$(patsubst %.c,%.o,$(SOURCES))
+SOURCES=$(wildcard source/*.c)
+OBJECTS=$(SOURCES:.c=.o)
 
-LUAOBJ=$(wildcard source/lua/*.o)
+# Use GCC preprocessor to determine dependencies for all source files.
+DEPS=$(OBJECTS:.o=.d)
+%.d: %.c
+	@$(CC) $(CFLAGS) $(INCLUDE) $< -MM -MT $(@:.d=.o) >$@
+# Include generated .d Makefile fragments to manage object dependencies.
+-include $(DEPS)
+
+# Provide recipes for building all objects, dependencies managed via earlier inclusion.
+%.o: %.c
+	$(CC) $(CFLAGS) $(INCLUDE) -o $@ -c $<
+
+# TODO: Pass through platform when building liblua.
+liblua:
+	$(MAKE) -C source/lua a
 
 TARGET=inlretro
 
 #default to windows build
-all:
-	$(CC) $(INCLUDE) $(LUAOBJ) $(SOURCES) -o $(TARGET) $(WINLIB) $(CFLAGS) $(LIBUSB) 
+all: liblua $(DEPS) $(OBJECTS)
+	$(CC) $(INCLUDE) $(OBJECTS) -o $(TARGET) $(CFLAGS) $(LDFLAGS_WINDOWS)
 
 #unix build doesn't need winlib directory as libusb should be installed on OS.
 #sudo apt-get install libusb-1.0-0-dev
-unix:
-	$(CC) $(INCLUDE) $(LUAOBJ) $(SOURCES) -o $(TARGET) $(CFLAGS) -lm $(LIBUSB)
+unix: liblua $(DEPS) $(OBJECTS)
+	$(CC) $(INCLUDE) $(OBJECTS) -o $(TARGET) $(CFLAGS) $(LDFLAGS_UNIX)
 
 # "make debug" will build program with debug print messages
 # -DDEBUG show debug logs
@@ -31,7 +45,8 @@ debug: all
 unixdebug: CFLAGS += -DDEBUG -g
 unixdebug: unix
 
-
 #clean on unix and windows(.exe)
+.PHONY: clean
 clean:
-	rm -f $(TARGET) $(TARGET).exe $(OBJECTS) $(LUAOBJ)
+	$(MAKE) -C source/lua clean
+	rm -f $(TARGET) $(TARGET).exe $(OBJECTS) $(DEPS) $(LUAOBJ) source/lua/liblua.a