Use rgbasm -D in the makefile.

Makefile

@@ -1,48 +1,37 @@
-# python 2.7
 PYTHON := python
-
-# md5sum -c is used to compare rom hashes. The options may vary across platforms.
 MD5 := md5sum -c --quiet
 
+2bpp     := $(PYTHON) extras/pokemontools/gfx.py 2bpp
+1bpp     := $(PYTHON) extras/pokemontools/gfx.py 1bpp
+pic      := $(PYTHON) extras/pokemontools/pic.py compress
+includes := $(PYTHON) extras/pokemontools/scan_includes.py
+
+base_obj := \
+	audio.o \
+	main.o \
+	text.o \
+	wram.o
+
+red_obj := $(base_obj:.o=_red.o)
+blue_obj := $(base_obj:.o=_blue.o)
+all_obj := $(red_obj) $(blue_obj)
+
+$(foreach obj, $(base_obj:.o=), \
+	$(eval $(obj)_dep := $(shell $(includes) $(obj).asm)) \
+)
 
-# Clear the default suffixes.
 .SUFFIXES:
 .SUFFIXES: .asm .o .gbc .png .2bpp .1bpp .pic
-
-# Secondary expansion is required for dependency variables in object rules.
 .SECONDEXPANSION:
-
 # Suppress annoying intermediate file deletion messages.
 .PRECIOUS: %.2bpp
-
 .PHONY: all clean red blue compare
 
-
-poketools := extras/pokemontools
-gfx       := $(PYTHON) $(poketools)/gfx.py
-2bpp      := $(gfx) 2bpp
-1bpp      := $(gfx) 1bpp
-pic       := $(PYTHON) $(poketools)/pic.py compress
-includes  := $(PYTHON) $(poketools)/scan_includes.py
-
-versions := red blue
-
-# Collect file dependencies for objects in red/ and blue/.
-$(foreach ver, $(versions), \
-	$(eval $(ver)_asm := $(shell find $(ver) -iname '*.asm')) \
-	$(eval $(ver)_obj := $($(ver)_asm:.asm=.o)) \
-	$(eval all_obj += $($(ver)_obj)) \
-)
-$(foreach obj, $(all_obj), \
-	$(eval $(obj:.o=)_dep := $(shell $(includes) $(obj:.o=.asm))) \
-)
-
-
 roms := pokered.gbc pokeblue.gbc
 
-all:    $(roms)
+all: $(roms)
-red:    pokered.gbc
+red: pokered.gbc
-blue:   pokeblue.gbc
+blue: pokeblue.gbc
 
 # For contributors to make sure a change didn't affect the contents of the rom.
 compare: red blue
@@ -52,29 +41,21 @@ clean:
 	rm -f $(roms) $(all_obj) $(roms:.gbc=.sym)
 	find . \( -iname '*.1bpp' -o -iname '*.2bpp' -o -iname '*.pic' \) -exec rm {} +
 
+%.asm: ;
+$(red_obj): %_red.o: %.asm $$(%_dep)
+	rgbasm -D "_RED" -h -o $@ $*.asm
+$(blue_obj): %_blue.o: %.asm $$(%_dep)
+	rgbasm -D "_BLUE" -h -o $@ $*.asm
 
-# Don't fix halts.
-asm_opt = -h
-
-# Make a symfile for debugging.
-link_opt = -n poke$*.sym
-
-# Header options for rgbfix.
 dmg_opt  = -jsv -k 01 -l 0x33 -m 0x13 -p 0 -r 03
 red_opt  = $(dmg_opt) -t "POKEMON RED"
 blue_opt = $(dmg_opt) -t "POKEMON BLUE"
 
+poke%.gbc: $$(%_obj)
+	rgblink -n poke$*.sym -o $@ $^
+	rgbfix $($*_opt) $@
 
 %.png:  ;
 %.2bpp: %.png  ; @$(2bpp) $<
 %.1bpp: %.png  ; @$(1bpp) $<
 %.pic:  %.2bpp ; @$(pic)  $<
-
-# Assemble source files into objects.
-$(all_obj): $$*.asm $$($$*_dep)
-	rgbasm $(asm_opt) -o $@ $*.asm
-
-# Link objects to produce a rom.
-poke%.gbc: $$(%_obj)
-	rgblink $(link_opt) -o $@ $^
-	rgbfix $($*_opt) $@

blue.asm

@@ -1,2 +0,0 @@
-_BLUE EQU 1
-INCLUDE "charmap.asm"

blue/audio.asm

@@ -1,2 +0,0 @@
-INCLUDE "blue.asm"
-INCLUDE "audio.asm"

blue/main.asm

@@ -1,2 +0,0 @@
-INCLUDE "blue.asm"
-INCLUDE "main.asm"

blue/text.asm

@@ -1,2 +0,0 @@
-INCLUDE "blue.asm"
-INCLUDE "text.asm"

blue/wram.asm

@@ -1,2 +0,0 @@
-INCLUDE "blue.asm"
-INCLUDE "wram.asm"

constants.asm

@@ -1,4 +1,5 @@
 INCLUDE "macros.asm"
+INCLUDE "charmap.asm"
 
 INCLUDE "hram.asm"
 INCLUDE "vram.asm"

red.asm

@@ -1,2 +0,0 @@
-_RED EQU 1
-INCLUDE "charmap.asm"

red/audio.asm

@@ -1,2 +0,0 @@
-INCLUDE "red.asm"
-INCLUDE "audio.asm"

red/main.asm

@@ -1,2 +0,0 @@
-INCLUDE "red.asm"
-INCLUDE "main.asm"

red/text.asm

@@ -1,2 +0,0 @@
-INCLUDE "red.asm"
-INCLUDE "text.asm"

red/wram.asm

@@ -1,2 +0,0 @@
-INCLUDE "red.asm"
-INCLUDE "wram.asm"

text.asm

@@ -15,6 +15,7 @@ POKEDEX_TEXT EQU TEXT_11 + 1
 MOVE_NAMES   EQU POKEDEX_TEXT + 1
 
 INCLUDE "macros.asm"
+INCLUDE "charmap.asm"
 INCLUDE "hram.asm"
 
 

yellow.asm

@@ -1,4 +0,0 @@
-_YELLOW EQU 1
-_OPTION_BEACH_HOUSE EQU 1
-_OPTION_LOWCOST_SAFARI EQU 1
-INCLUDE "charmap.asm"

yellow/audio.asm

@@ -1,2 +0,0 @@
-INCLUDE "yellow.asm"
-INCLUDE "audio.asm"

yellow/main.asm

@@ -1,2 +0,0 @@
-INCLUDE "yellow.asm"
-INCLUDE "main.asm"

yellow/text.asm

@@ -1,2 +0,0 @@
-INCLUDE "yellow.asm"
-INCLUDE "text.asm"

yellow/wram.asm

@@ -1,2 +0,0 @@
-INCLUDE "yellow.asm"
-INCLUDE "wram.asm"