linux_kernel/tools/build/Build.include

###
# build: Generic definitions
#
#  Lots of this code have been borrowed or heavily inspired from parts
#  of kbuild code, which is not credited, but mostly developed by:
#
#  Copyright (C) Sam Ravnborg <sam@mars.ravnborg.org>, 2015
#  Copyright (C) Linus Torvalds <torvalds@linux-foundation.org>, 2015
#

###
# Convenient variables
comma   := ,
squote  := '

###
# Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o
dot-target = $(dir $@).$(notdir $@)

###
# filename of target with directory and extension stripped
basetarget = $(basename $(notdir $@))

###
# The temporary file to save gcc -MD generated dependencies must not
# contain a comma
depfile = $(subst $(comma),_,$(dot-target).d)

###
# Check if both arguments has same arguments. Result is empty string if equal.
arg-check = $(strip $(filter-out $(cmd_$(1)), $(cmd_$@)) \
                    $(filter-out $(cmd_$@),   $(cmd_$(1))) )

###
# Escape single quote for use in echo statements
escsq = $(subst $(squote),'\$(squote)',$1)

# Echo command
# Short version is used, if $(quiet) equals `quiet_', otherwise full one.
echo-cmd = $(if $($(quiet)cmd_$(1)),\
           echo '  $(call escsq,$($(quiet)cmd_$(1)))';)

###
# Replace >$< with >$$< to preserve $ when reloading the .cmd file
# (needed for make)
# Replace >#< with >\#< to avoid starting a comment in the .cmd file
# (needed for make)
# Replace >'< with >'\''< to be able to enclose the whole string in '...'
# (needed for the shell)
make-cmd = $(call escsq,$(subst \#,\\\#,$(subst $$,$$$$,$(cmd_$(1)))))

###
# Find any prerequisites that is newer than target or that does not exist.
# PHONY targets skipped in both cases.
any-prereq = $(filter-out $(PHONY),$?) $(filter-out $(PHONY) $(wildcard $^),$^)

###
# if_changed_dep  - execute command if any prerequisite is newer than
#                   target, or command line has changed and update
#                   dependencies in the cmd file
if_changed_dep = $(if $(strip $(any-prereq) $(arg-check)),         \
	@set -e;                                                   \
	$(echo-cmd) $(cmd_$(1));                                   \
	cat $(depfile) > $(dot-target).cmd;                        \
	printf '%s\n' 'cmd_$@ := $(make-cmd)' >> $(dot-target).cmd)

# if_changed      - execute command if any prerequisite is newer than
#                   target, or command line has changed
if_changed = $(if $(strip $(any-prereq) $(arg-check)),             \
	@set -e;                                                   \
	$(echo-cmd) $(cmd_$(1));                                   \
	printf '%s\n' 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd)

###
# C flags to be used in rule definitions, includes:
# - depfile generation
# - global $(CFLAGS)
# - per target C flags
# - per object C flags
# - BUILD_STR macro to allow '-D"$(variable)"' constructs
c_flags = -Wp,-MD,$(depfile),-MT,$@ $(CFLAGS) -D"BUILD_STR(s)=\#s" $(CFLAGS_$(basetarget).o) $(CFLAGS_$(obj))