initial commit

Makefile

@@ -0,0 +1,79 @@
+######################################################################
+# Makefile
+#
+# This makefile is the one called by user, but it's only a trampoline
+# to create the build directory and call the real Makefile.build
+#
+# make can be invoqued with 'make build=<your_build_directory> ...'
+# all other options and target are passed to the real makefile.
+#
+# As an exception to the rule of not modifying source directory, a
+# .build.mak file is created to cache the configured build directory.
+# Subsequent invocations of make could be done without passing
+# 'build=...' parameter.
+#
+# distclean target is catched to destroy both the .build.mak and
+# the whole build directory.
+#
+######################################################################
+
+# build directory is cached in BUILD_MAK file between make invocations
+BUILD_MAK = .build.mak
+ifneq ($(wildcard $(BUILD_MAK)),)
+include $(BUILD_MAK)
+endif
+
+# default build directory 'build'
+build ?= build
+
+# ($call quiet-command,CMD,MSG)
+# execute CMD and display MSG
+# if verbose mode is enabled (with 'make V=1`) print full CMD instead of MSG
+quiet-command = $(if $(V),$1,$(if $(2),@echo $2 && $1, @$1))
+
+# if the target is distclean, skip allmost rules
+# to doing anything which will be immediately
+# deleted after
+ifeq ($(filter distclean,$(MAKECMDGOALS)),)
+
+# default target (when one invokes 'make' without target)
+# so we have a non-empty target which could be catched by
+# the catch-all target below.
+default-all:
+
+# The catch-all target, which pass build to the main
+# makefile in the build directory.
+# strip-out 'default-all' for targets' list
+%: | $(build)
+	$(call quiet-command, \
+		$(MAKE) -C $(build) $(filter-out default-all,$@) \
+		, "MAKE $(filter-out default-all,$@)")
+
+# Creates the buld directory
+# and populates it with a link to the build makefile
+$(build): | $(BUILD_MAK)
+	$(call quiet-command,\
+		mkdir -p $@; \
+		ln -sf $(CURDIR)/Makefile.build $@/Makefile \
+		, "MKBUILD $@")
+
+# always create BUILD_MAK to cache build configuration
+# but don't update it if not changed
+$(BUILD_MAK): FORCE
+	@echo build=$(build) > $@.tmp
+	@cmp -s $@.tmp $@ || (mv $@.tmp $@ && echo "GEN  $@")
+	@rm -f $@.tmp
+
+else # if distclean
+
+distclean:
+	$(call quiet-command, rm -rf $(build) $(BUILD_MAK), "DISTCLEAN $(build)")
+
+endif # distclean
+
+
+.PHONY: distclean FORCE
+
+#ifndef V
+#.SILENT:
+#endif