<title>Using GNU Make with cc65 <author>Oliver Schmidt, <date>2009-06-26

How to build your program using the GNU Make utility.

<toc> <sect>Overview<p> This document describes how to build your programs using the cc65 development tools and the GNU Make utility. The cc65 development package doesn't come with a make utility. However this is no issue because GNU Make works very nicely with cc65. <sect>What is GNU Make?<p> GNU Make is a both very powerful and very popular make utility. It might even be called the de facto standard for make utilities. For more information see the GNU Make home page: The cc65 development package is available as binaries for several host systems and can easily built for quite some additional systems. The very same is true for GNU Make so a cc65-based project coming with a GNU Make Makefile can easily be built by any cc65 developer no matter what host system is used. Because of the strong alignment of the cc65 compiler with the ISO C standard it is very well feasible to compile a single C code base both with the cc65 compiler and other C compilers like for example GCC. GNU Make turns out to be very well suited to build projects for several target systems using multiple compilers as it isn't tied to any C compiler. <sect>A sample Makefile<p> This Makefile is a fully functional sample for compiling several C sources (here <tt/foo.c/ and <tt/bar.c/) and link the resulting object files into an executable program (here <tt/foobar/): <tscreen> SOURCES = foo.c bar.c PROGRAM = foobar ifdef CC65_TARGET CC = $(CC65_HOME)/bin/cl65 CFLAGS = -t $(CC65_TARGET) --create-dep -O LDFLAGS = -t $(CC65_TARGET) -m $(PROGRAM).map else CC = gcc CFLAGS = -MMD -MP -O LDFLAGS = -Wl,-Map,$(PROGRAM).map endif ######################################## ifdef CC65_TARGET define MAKEDEPEND sed -e"s!$(<:.c=.s)!$@!p" -e"s![^:]*:.\(.*\)!\1:!" < $(<:.c=.u) > $(@:.o=.d) $(RM) $(<:.c=.u) endef endif .SUFFIXES: .PHONY: all clean all: $(PROGRAM) ifneq ($(MAKECMDGOALS),clean) -include $(SOURCES:.c=.d) endif %.o: %.c $(CC) -c $(CFLAGS) -o $@ $< @$(MAKEDEPEND) $(PROGRAM): $(SOURCES:.c=.o) $(CC) $(LDFLAGS) -o $@ $^ clean: $(RM) $(SOURCES:.c=.o) $(SOURCES:.c=.d) $(PROGRAM) $(PROGRAM).map <bf/Important:/ When using the sample Makefile above via copy & paste it is necessary to replace the eight spaces at the beginning of command lines (lines 33, 34, 37 and 40) with a tab character (ASCII code 9). <sect1>Invoking the sample Makefile<p> Without any specific configuration the sample Makefile will compile and link using GCC. In order to rather use cc65 the variable <tt/CC65_TARGET/ needs to be defined. This may by done as an environment variable or simply as part of the Makefile. However to quickly switch between compilers and/or cc65 targets it is best done on the GNU Make command line like this: <tscreen> make CC65_TARGET=c64 The sample Makefile doesn't require cc65 to be "installed" in any way. Rather it only presumes the single variable <tt/CC65_HOME/ to point to the directory the cc65 packages were unpacked into. Again there are several ways to define this variable but as its value typically won't change often it is best done as an environment variable. <sect1>Understanding the sample Makefile<p> Most parts of the sample Makefile follow the guidelines in the that can be searched online for background information. The automatic generation of dependency however rather works as described by the GNU Make maintainer Paul D. Smith in . In the meantime GCC supports this method directly with the preprocessor option <tt/-MP/ while cc65 requires some post-processing of the dependency file with <tt/sed/ adding a second line like in this example: <tscreen> foo.o: foo.c foo.h bar.h foo.c foo.h bar.h: <sect1>Invoking the sample Makefile on Windows<p> The recommended way to use GNU Make on Windows is to install it as part of a Cygwin environment. For more information see the Cygwin home page: If however installing Cygwin shouldn't be an option for one or the other reason then the sample Makefile may be invoked from the Windows Command Prompt (cmd.exe) by downloading the following programs: <item>make.exe: <item>sed.exe: <item>rm.exe: <sect>Target-specific Variable Values<p> The very limited resources of the cc65 target machines now and then require manual optimization of the build process by compiling individual source files with different compiler options. GNU Make offers perfectly suited for doing so. For example placing the code of the two modules <tt/foo/ and <tt/bar/ in the segment <tt/FOOBAR/ can be archived with this target-specific variable definition: <tscreen> foo.o bar.o: CFLAGS += --code-name FOOBAR