# SPDX-License-Identifier: GPL-2.0-or-later
# Copyright (C) 2026 Richard Qin
#
# scripts/Kbuild.include — shared Make helpers for LumeOS.
#
# Mirrors a small, useful subset of Linux's scripts/Kbuild.include.
# Provides:
#
#   - Q / KBUILD_VERBOSE        : `make V=1` shows full commands,
#                                  default V=0 prints a one-line summary
#   - $(call cmd,<name>)        : echo a quiet summary, then run cmd_<name>
#   - $(call if_changed,<name>) : currently a thin alias for $(cmd) —
#                                  no .cmd-file hashing yet (Linux's full
#                                  if_changed uses fixdep to detect both
#                                  recipe-text and header changes; LumeOS
#                                  relies on `-MMD -MP` for headers and
#                                  on `make clean` for flag changes).
#   - $(call kbuild-objs,...)   : translate Kbuild-style `obj-y := foo.o`
#                                  entries into SRCS_C / SRCS_CC.
#
# Naming convention adopted from Linux: each command has both a
# `quiet_cmd_<name>` (single-line summary) and a `cmd_<name>` (full
# command line).  $(quiet) selects which prefix to display:
#   V=0  ->  quiet := quiet_   ->  echoes "  CC  foo.c"
#   V=1  ->  quiet :=          ->  echoes the full $(CC) $(CFLAGS) ...
# ----------------------------------------------------------------------

# --- Verbosity ---------------------------------------------------------
# Override at the command line: `make V=1`.  Default V=0 = quiet.
KBUILD_VERBOSE ?= $(V)
KBUILD_VERBOSE ?= 0

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

# --- echo-cmd / cmd / if_changed ---------------------------------------
#
# echo-cmd prints the recipe's one-line summary (when quiet) or its full
# command line (when verbose).  Implementation uses $($(quiet)cmd_<name>)
# so the right form is picked up automatically.
#
# cmd is the workhorse: print summary, then execute the real command.
echo-cmd = $(if $($(quiet)cmd_$(1)),echo '  $($(quiet)cmd_$(1))';)

cmd = @$(echo-cmd) $(cmd_$(1))

# if_changed currently degenerates to `cmd` — full Linux semantics
# require tracking the command-line via per-target .<file>.cmd files
# and comparing on every rebuild, which needs fixdep.  Until LumeOS
# grows that infrastructure, `make clean` after editing CFLAGS suffices.
if_changed = $(cmd)

# --- Standard quiet_cmd_* / cmd_* templates ---------------------------
#
# Subdir Makefiles and the top-level Makefile can reference these by
# name via $(call cmd,<name>).  Add new pairs here as new recipe shapes
# show up (e.g., cmd_lz / cmd_gz / cmd_zstd for compressed Image targets).

   quiet_cmd_cc_o_c   = CC      $<
         cmd_cc_o_c   = $(CC) $(CFLAGS_LIBC) -c $< -o $@

   quiet_cmd_cxx_o_cc = CXX     $<
         cmd_cxx_o_cc = $(CXX) $(CXXFLAGS) -c $< -o $@

   quiet_cmd_as_o_S   = AS      $<
         cmd_as_o_S   = $(CC) $(ASFLAGS) -c $< -o $@

   quiet_cmd_cc_s_c   = CC -S   $<
         cmd_cc_s_c   = $(CC) $(CFLAGS_LIBC) -S $< -o $@

   quiet_cmd_objcopy_bin = OBJCOPY $@
         cmd_objcopy_bin = $(OBJCOPY) -O binary $< $@

# Objcopy with custom flags via per-target OBJCOPYFLAGS variable —
# used by the .pi.o post-processing rule (--prefix-symbols=__pi_ etc.).
   quiet_cmd_objcopy  = OBJCOPY $@
         cmd_objcopy  = $(OBJCOPY) $(OBJCOPYFLAGS) $< $@

   quiet_cmd_ld_kernel = LD      $@
         cmd_ld_kernel = $(LD) $(LDFLAGS) -T $(LINKER_SCRIPT) -o $@ $^

# --- kbuild-objs: obj-y -> SRCS_C / SRCS_CC ---------------------------
#
# Usage from a subdir Makefile (e.g. arch/riscv/kernel/pi/Makefile):
#
#     obj-dir := arch/riscv/kernel/pi
#     obj-y   := fdt_early.pi.o cmdline_early.pi.o archrandom_early.pi.o
#     $(eval $(call kbuild-objs,$(obj-dir),$(obj-y:.pi.o=.o)))
#
# For each <name>.o entry, looks up <dir>/<name>.cc first, then
# <dir>/<name>.c, and appends to SRCS_CC / SRCS_C respectively.
# Pure .pi.o entries should be passed through `:.pi.o=.o` first by the
# caller so the .pi suffix doesn't confuse the source-file lookup.

define _kbuild-find-src
$(if $(wildcard $(1)/$(basename $(2)).cc),\
  $(eval SRCS_CC += $(1)/$(basename $(2)).cc),\
  $(if $(wildcard $(1)/$(basename $(2)).c),\
    $(eval SRCS_C += $(1)/$(basename $(2)).c),\
    $(error kbuild-objs: no $(1)/$(basename $(2)).{c,cc} for obj $(2))))
endef

define kbuild-objs
$(foreach _obj,$(2),$(call _kbuild-find-src,$(1),$(_obj)))
endef