# SPDX-License-Identifier: GPL-2.0
####
# kbuild: Generic definitions

# Convenient variables
squote  := '
empty   :=
space   := $(empty) $(empty)
space_escape := _-_SPACE_-_
pound   := \#

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

###
# dependencies
depfile = $(dot-target).d

###
# real prerequisites without phony targets
real-prereqs = $(filter-out $(PHONY), $^)

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

###
# Easy method for doing a status message
       kecho := :
 quiet_kecho := echo
silent_kecho := :
kecho := $($(quiet)kecho)

###
# filechk is used to check if the content of a generated file is updated.
# Sample usage:
#
# filechk_sample = echo $(KERNELRELEASE)
# version.h: FORCE
#	$(call filechk,sample)
#
# The rule defined shall write to stdout the content of the new file.
# The existing file will be compared with the new one.
# - If no file exist it is created
# - If the content differ the new file is used
# - If they are equal no change, and no timestamp update
define filechk
	$(Q)set -e;						\
	mkdir -p $(dir $@);					\
	trap "rm -f $(dot-target).tmp" EXIT;			\
	{ $(filechk_$(1)); } > $(dot-target).tmp;		\
	if [ ! -r $@ ] || ! cmp -s $@ $(dot-target).tmp; then	\
		$(kecho) '  UPD     $@';			\
		mv -f $(dot-target).tmp $@;			\
	fi
endef

# as-insn: Check whether assembler supports an instruction.
# Usage: cflags-y += $(call as-insn,CC FLAGS,"insn",option-yes,option-no)
as-insn = $(if $(shell echo 'void _(void) { asm volatile ( $(2) ); }' \
                       | $(filter-out -M% %.d -include %/include/xen/config.h,$(1)) \
                              -c -x c -o /dev/null - 2>&1),$(4),$(3))

# as-option-add: Conditionally add options to flags
# Usage: $(call as-option-add,CFLAGS,CC,"insn",option-yes,option-no)
as-option-add = $(eval $(call as-option-add-closure,$(1),$(2),$(3),$(4),$(5)))
define as-option-add-closure
    ifeq ($$(call as-insn,$$($(2)) $$($(1)),$$(3),y,n),y)
        $(1) += $(4)
    else
        $(1) += $(5)
    endif
endef

# $(call if-success,<command>,<then>,<else>)
# Return <then> if <command> exits with 0, <else> otherwise.
if-success = $(shell { $(1); } >/dev/null 2>&1 && echo "$(2)" || echo "$(3)")

# $(call success,<command>)
# Return y if <command> exits with 0, n otherwise
success = $(call if-success,$(1),y,n)

# $(call ld-option,<flag>)
# Return y if the linker supports <flag>, n otherwise
ld-option = $(call success,$(LD) -v $(1))

# cc-ifversion
# Usage:  EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1)
cc-ifversion = $(shell [ $(CONFIG_GCC_VERSION)0 $(1) $(2)000 ] && echo $(3) || echo $(4))

clang-ifversion = $(shell [ $(CONFIG_CLANG_VERSION)0 $(1) $(2)000 ] && echo $(3) || echo $(4))

###
# Shorthand for $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.asm-generic obj
# Usage:
# $(Q)$(MAKE) $(asm-generic)=dir
asm-generic := -f $(srctree)/scripts/Makefile.asm-generic obj

###
# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.build obj=
# Usage:
# $(Q)$(MAKE) $(build)=dir
build := -f $(srctree)/Rules.mk obj

# Shorthand for $(MAKE) clean
# Usage:
# $(Q)$(MAKE) $(clean)=dir
clean := -f $(srctree)/scripts/Makefile.clean obj

# 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)))$(echo-why)';)

# printing commands
cmd = @set -e; $(echo-cmd) $(cmd_$(1))

###
# if_changed      - execute command if any prerequisite is newer than
#                   target, or command line has changed
# if_changed_dep  - as if_changed, but uses fixdep to reveal dependencies
#                   including used config symbols
# if_changed_rule - as if_changed but execute rule instead

ifneq ($(KBUILD_NOCMDDEP),1)
# Check if both commands are the same including their order. Result is empty
# string if equal. User may override this check using make KBUILD_NOCMDDEP=1
cmd-check = $(filter-out $(subst $(space),$(space_escape),$(strip $(cmd_$@))), \
                         $(subst $(space),$(space_escape),$(strip $(cmd_$1))))
else
cmd-check = $(if $(strip $(cmd_$@)),,1)
endif

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

# Execute command if command has changed or prerequisite(s) are updated.
if_changed = $(if $(any-prereq)$(cmd-check),                                 \
        $(cmd);                                                              \
        printf '%s\n' 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd, @:)

# Execute the command and also postprocess generated .d dependencies file.
if_changed_dep = $(if $(any-prereq)$(cmd-check),$(cmd_and_fixdep),@:)

cmd_and_fixdep =                                                             \
        $(cmd);                                                              \
        tools/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).cmd;        \
        rm -f $(depfile)

# Usage: $(call if_changed_rule,foo)
# Will check if $(cmd_foo) or any of the prerequisites changed,
# and if so will execute $(rule_foo).
if_changed_rule = $(if $(any-prereq)$(cmd-check),$(rule_$(1)),@:)

###
# why - tell why a target got built
#       enabled by make V=2
#       Output (listed in the order they are checked):
#          (1) - due to target is PHONY
#          (2) - due to target missing
#          (3) - due to: file1.h file2.h
#          (4) - due to command line change
#          (5) - due to missing .cmd file
#          (6) - due to target not in $(targets)
# (1) PHONY targets are always build
# (2) No target, so we better build it
# (3) Prerequisite is newer than target
# (4) The command line stored in the file named dir/.target.cmd
#     differed from actual command line. This happens when compiler
#     options changes
# (5) No dir/.target.cmd file (used to store command line)
# (6) No dir/.target.cmd file and target not listed in $(targets)
#     This is a good hint that there is a bug in the kbuild file
ifeq ($(KBUILD_VERBOSE),2)
why =                                                                        \
    $(if $(filter $@, $(PHONY)),- due to target is PHONY,                    \
        $(if $(wildcard $@),                                                 \
            $(if $(any-prereq),- due to: $(any-prereq),                      \
                $(if $(cmd-check),                                           \
                    $(if $(cmd_$@),- due to command line change,             \
                        $(if $(filter $@, $(targets)),                       \
                            - due to missing .cmd file,                      \
                            - due to $(notdir $@) not in $$(targets)         \
                         )                                                   \
                     )                                                       \
                 )                                                           \
             ),                                                              \
             - due to target missing                                         \
         )                                                                   \
     )

echo-why = $(call escsq, $(strip $(why)))
endif

# Useful for describing the dependency of composite objects
# Usage:
#   $(call multi-depend, multi-used-targets, suffix-to-remove, suffix-to-add)
define multi-depend
$(foreach m, $(notdir $1), \
	$(eval $(obj)/$(m): \
	$(addprefix $(obj)/, $(foreach s, $3, $($(m:%$(strip $2)=%$(s)))))))
endef
