##
# A set of makefile rules loosely based on kbuild.

default: compile

all: compile docs

test check:

ifndef build

toplevelrun:=yes

##
# Disable default rules and make output pretty.

MAKEFLAGS += -rR --no-print-directory

Makefile: ;

ifdef V
  ifeq ("$(origin V)", "command line")
    VERBOSE = $(V)
  endif
endif
ifndef VERBOSE
  VERBOSE = 0
endif

ifeq ($(VERBOSE),1)
  quiet =
  Q =
else
  quiet=quiet_
  Q = @
endif

ifneq ($(findstring s,$(MAKEFLAGS)),)
  quiet=silent_
endif

export quiet Q VERBOSE

##
# Recursion helpers.
srctree		:= $(CURDIR)
objtree		:= $(CURDIR)

export srctree objtree

##
# Consult SCM for better version string.

TAGPREFIX	?= v

ifneq ($(CI_COMMIT_TAG),)
FULL_VERSION	:= $(CI_COMMIT_TAG)
else ifneq ($(CI_COMMIT_REF_NAME),)
# GitLab but no tag info, use the 'git describe' from environment variable
# once https://gitlab.com/gitlab-org/gitlab-runner/-/merge_requests/1633
# gets completed and merged upstream.
FULL_VERSION	:= $(VERSION)
else ifneq ($(wildcard .git),)
FULL_VERSION	:= $(patsubst $(TAGPREFIX)%,%,$(shell git describe))
else
FULL_VERSION	:= $(VERSION)
endif

RCS_FIND_IGNORE := \( -name SCCS -o -name BitKeeper -o -name .svn -o -name CVS -o -name .pc -o -name .hg -o -name .git \) -prune -o

export FULL_VERSION RCS_FIND_IGNORE

##
# Utilities and default flags for them.

CROSS_COMPILE	?=
CC		:= $(CROSS_COMPILE)gcc
AR		:= $(CROSS_COMPILE)ar
LD		:= $(CROSS_COMPILE)ld
LN		:= ln -sf
SCDOC		:= scdoc
SED		:= sed
INSTALL		:= install
INSTALLDIR	:= $(INSTALL) -d

CFLAGS		?= -g -O2
CFLAGS_ALL	:= -Werror -Wall -Wstrict-prototypes -D_GNU_SOURCE -std=gnu99 -fPIC
CFLAGS_ALL	+= $(CFLAGS)

LDFLAGS		?= -g
LDFLAGS_ALL	+= $(LDFLAGS)

export CC AR LD LN SCDOC SED INSTALL INSTALLDIR CFLAGS_ALL LDFLAGS_ALL

build		:=

endif

##
# Reset all variables.
ifneq ($(origin subdirs),file)
subdirs		:=
endif
ifneq ($(origin targets),file)
targets		:=
endif
ifneq ($(origin nontargets),file)
nontargets	:=
endif

src		:=
obj		:=

src		+= $(build)
obj		:= $(build)

##
# Include directory specific stuff

ifneq ($(build),)
$(build)/Makefile: ;
include $(build)/Makefile
endif

##
# Rules and helpers

PHONY += all compile install clean docs FORCE

# Convinient variables
comma   := ,
squote  := '
empty   :=
space   := $(empty) $(empty)

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

build-dir  = $(patsubst %/,%,$(dir $@))
target-dir = $(dir $@)

##
# Build rules

ifneq ($(NOCMDDEP),1)
# Check if both arguments has same arguments. Result in empty string if equal
# User may override this check using make NOCMDDEP=1
# Check if both arguments has same arguments. Result is empty string if equal.
# User may override this check using make KBUILD_NOCMDDEP=1
arg-check = $(strip $(filter-out $(cmd_$(1)), $(cmd_$@)) \
                    $(filter-out $(cmd_$@),   $(cmd_$(1))) )
endif

# 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)';)

make-cmd = $(subst \#,\\\#,$(subst $$,$$$$,$(call escsq,$(cmd_$(1)))))

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

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

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

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

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

# Execute command if command has changed or prerequisite(s) are updated.
#
if_changed = $(if $(strip $(any-prereq) $(arg-check)),                       \
	@set -e;                                                             \
	$(echo-cmd) $(cmd_$(1));                                             \
	echo 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd)

# 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 $(strip $(any-prereq) $(arg-check) ),                 \
	@set -e;                                                             \
	$(rule_$(1)))

#####
# Handle options to gcc.

c_flags		= -Wp,-MD,$(depfile) -Wp,-MT,$@ $(CPPFLAGS) \
		  $(CFLAGS_ALL) $(CFLAGS_EXTRA) $(CFLAGS_$(notdir $@))
ld_flags	= $(LDFLAGS_ALL) $(LDFLAGS_EXTRA) $(LDFLAGS_$(notdir $@))

#####
# Generated targets
generate: $(addprefix $(obj)/,$(sort $(generate-y)))

#####
# Compile c-files.
quiet_cmd_cc_o_c = CC      $@

cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<

define rule_cc_o_c
	$(call echo-cmd,cc_o_c) $(cmd_cc_o_c);		\
	(echo 'cmd_$@ := $(call make-cmd,cc_o_c)'; echo; cat $(depfile)) \
		> $(dot-target).cmd ; \
	rm $(depfile)
endef

$(obj)/%.o: override local-target-prereqs=%

$(obj)/%.o: $(src)/%.c FORCE | generate
	$(call if_changed_rule,cc_o_c)

#####
# Link static libraries
#
__arlibs := $(addprefix $(obj)/,$(sort $(libs-y)))
arobjs	 := $(addprefix $(obj)/,$(sort $(foreach m,$(libs-y),$($(m)-objs))))

# link shared library
quiet_cmd_ar	= AR      $@
      cmd_ar = $(AR) rcs $@ $(addprefix $(obj)/,$($(@F)-objs))

$(__arlibs): override local-target-prereqs=$(addprefix $(obj)/,$($(*F)-objs))

$(__arlibs): $(obj)/%: $(arobjs) FORCE
	$(call if_changed,ar)

targets += $(__arlibs) $(arobjs)

#####
# Link shared libraries
#
__shlibs := $(addprefix $(obj)/,$(sort $(shlibs-y)))
shobjs	 := $(addprefix $(obj)/,$(sort $(foreach m,$(shlibs-y),$($(m)-objs)))) $(sort $(foreach m,$(shlibs-y),$($(m)-libs)))

# link shared library
quiet_cmd_shlib	= LD -shared $@
      cmd_shlib = $(CC) $(ld_flags) -shared -o $@ \
		  $(addprefix $(obj)/,$($(@F)-objs)) \
		  $($(@F)-libs) \
		  $(LIBS) $(LIBS_$(@F))

$(__shlibs): override local-target-prereqs=$(addprefix $(obj)/,$($(*F)-objs)) $($(*F)-libs)

$(__shlibs): $(obj)/%: $(shobjs) FORCE
	$(call if_changed,shlib)

targets += $(__shlibs) $(shobjs)

#####
# Link programs

# Link an executable based on list of .o files, all plain c
# host-cmulti -> executable
__progs	:= $(addprefix $(obj)/,$(sort $(progs-y)))
cobjs	:= $(addprefix $(obj)/,$(sort $(foreach m,$(progs-y),$($(m)-objs)))) $(sort $(foreach m,$(progs-y),$($(m)-libs)))

quiet_cmd_ld	= LD      $@
      cmd_ld	= $(CC) $(ld_flags) -o $@ \
			  $(addprefix $(obj)/,$($(@F)-objs)) $($(@F)-libs) \
			  $(LIBS) $(LIBS_$(@F))

$(__progs): override local-target-prereqs=$(addprefix $(obj)/,$($(*F)-objs)) $($(*F)-libs)

$(__progs): $(obj)/%: $(cobjs) FORCE
	$(call if_changed,ld)

targets += $(__progs) $(cobjs)

#####
# Man pages

quiet_cmd_scdoc = SCDOC   $@
      cmd_scdoc = $(SCDOC) < $< > $@

__scdocs	:= $(addprefix $(obj)/,$(sort $(scdocs-y)))
nontargets	+= $(__scdocs)
docs		+= $(__scdocs)

$(__scdocs): $(obj)/%: $(src)/%.scd FORCE
	$(call if_changed,scdoc)

####
# Template (.in) files

quiet_cmd_sed = SED     $@
      cmd_sed = $(SED) \
		-e "s|@EXEC_DIR@|$(SBINDIR)|" \
		-e "s|@LIB_DIR@|$(LIBDIR)|" \
		-e "s|@INCLUDE_DIR@|$(INCLUDEDIR)|" \
		-e "s|@VERSION@|$(VERSION)|" \
		$< > $@

$(obj)/%: $(src)/%.in FORCE
	$(call if_changed,sed)


nontargets	+= $(addprefix $(obj)/,$(sort $(generate-y)))

###
# why - tell why a a target got build
ifeq ($(VERBOSE),2)
why =                                                                        \
    $(if $(filter $@, $(PHONY)),- due to target is PHONY,                    \
        $(if $(wildcard $@),                                                 \
            $(if $(strip $(any-prereq)),- due to: $(any-prereq),             \
                $(if $(arg-check),                                           \
                    $(if $(cmd_$@),- due to command line change: $(arg-check),             \
                        $(if $(filter $@, $(targets) $(nontargets)),         \
                            - due to missing .cmd file,                      \
                            - due to $(notdir $@) not in $$(targets) or $$(nontargets) \
                         )                                                   \
                     )                                                       \
                 )                                                           \
             ),                                                              \
             - due to target missing                                         \
         )                                                                   \
     )

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

##
# Top level rules.

%/: FORCE
	$(Q)$(MAKE) -f Make.rules build=$(build-dir) $(MAKECMDGOALS)

compile: generate $(targets) $(subdirs)
	@:

docs: $(docs) $(subdirs)
	@:

install: compile docs $(subdirs) FORCE

tag:

generate:

clean: $(subdirs)
ifeq ($(toplevelrun),yes)
	$(Q)find . $(RCS_FIND_IGNORE) \
		\( -name '*.[oas]' -o -name '.*.cmd' -o -name '.*.d' \) \
		-type f -print | xargs rm -f
endif
	$(Q)rm -rf $(addprefix $(obj)/, \
		$(sort	$(progs-y) $(progs-n) $(progs-) \
			$(shlibs-y) $(shlibs-n) $(shlibs-) \
			$(libs-y) $(libs-n) $(libs-) \
			$(generate-y) $(generate-n) $(generate-) \
			$(scdocs-y) $(scdocs-n) $(scdocs-)))

ifeq ($(origin VERSION),command line)
DIST_VERSION=$(VERSION)
else
DIST_VERSION=$(FULL_VERSION)
endif

dist:
	git archive --format tar --prefix=$(PACKAGE)-$(DIST_VERSION)/ \
		$(TAGPREFIX)$(DIST_VERSION) \
		| bzip2 -9 > $(PACKAGE)-$(DIST_VERSION).tar.bz2

FORCE:

# Read all saved command lines and dependencies for the $(targets) we
# may be building above, using $(if_changed{,_dep}). As an
# optimization, we don't need to read them if the target does not
# exist, we will rebuild anyway in that case.

targets := $(wildcard $(sort $(targets)))
docs := $(wildcard $(sort $(docs)))
cmd_files := $(wildcard $(foreach f,$(targets) $(nontargets),$(dir $(f)).$(notdir $(f)).cmd))

ifneq ($(cmd_files),)
  include $(cmd_files)
endif

# Declare the contents of the .PHONY variable as phony.  We keep that
# information in a variable se we can use it in if_changed and friends.

.PHONY: $(PHONY)