# tk.mk — the kernel build entry point.
#
# A project Makefile sets PROJECT + SRCS, then includes this file:
#
#     PROJECT := my_app
#     SRCS    := main.c
#     include ../../make/tk.mk        # in-tree example (path relative to the project)
#
# Out-of-tree (a project copied outside the kernel tree)? Point TK_DIR at the tree and include from
# there — tk.mk self-locates its root from its OWN path (TK_ROOT below), so nothing downstream needs
# to change:
#
#     TK_DIR ?= /opt/tk-0.1.2         # absolute or relative; override from the environment / CLI
#     include $(TK_DIR)/make/tk.mk
#
#     make BOARD=host                 # build + `make run` on the desktop (arch/pthread)
#     make boards                     # list every board BOARD= accepts, with a one-line description
#     make BOARD=host PROFILE=<root>/profiles/tk_profile_nano.h
#     make BOARD=host print-config    # show the resolved board/arch/flags
#
# Resolution: BOARD -> make/board/<board>.mk (sets TK_ARCH + toolchain + flags + run/flash)
#             -> make/arch/<arch>.mk (sets the arch source list + arch flags/includes).
# Add a board or arch = drop in one .mk — nothing here changes. The kernel core is constant.
#
# Single-pass compile (kernel + arch + board + app in one $(CC) call) — simple and fine for a
# small kernel; a prebuilt libtk.a variant is a later refinement.

TK_ROOT := $(abspath $(dir $(lastword $(MAKEFILE_LIST)))/..)

# Windows: Cygwin make emits /cygdrive/<d>/... paths that a NATIVE (non-Cygwin) cross-compiler —
# e.g. the xPack riscv-none-elf-gcc used by the qemu_riscv32_virt board — cannot open. Rewrite
# TK_ROOT to <d>:/... with pure-make string ops (NOT cygpath: the ambient cygpath is often
# MSYS/Git's, which mis-resolves /cygdrive). Cygwin make's include and drive-colon prerequisites
# both accept c:/... form. No-op off Windows — a Mac/Linux abspath contains no '/cygdrive/'.
ifneq (,$(findstring /cygdrive/,$(TK_ROOT)))
tk_drive := $(word 2,$(subst /, ,$(TK_ROOT)))
TK_ROOT  := $(tk_drive):/$(patsubst /cygdrive/$(tk_drive)/%,%,$(TK_ROOT))
endif

BOARD   ?= host
PROJECT ?= app

include $(TK_ROOT)/make/board/$(BOARD).mk
include $(TK_ROOT)/make/arch/$(TK_ARCH).mk

# The portable kernel core — constant across every board and arch.
TK_KERNEL_SRCS := $(TK_ROOT)/kernel/tk_kernel.c $(TK_ROOT)/kernel/tk_sync.c \
                  $(TK_ROOT)/kernel/tk_trace_ring.c $(TK_ROOT)/kernel/tk_stack.c

TK_SRCS := $(TK_KERNEL_SRCS) $(TK_ARCH_SRCS) $(TK_BOARD_SRCS)
TK_INC  := -I$(TK_ROOT)/kernel -I$(TK_ROOT)/arch/$(TK_ARCH) $(TK_ARCH_INC) $(TK_BOARD_INC)

PROFILE_CFLAGS := $(if $(PROFILE),-include $(PROFILE),)

# Language standard, pinned PROJECT-WIDE for build reproducibility. Left unset, GCC's default -std
# drifts across releases (gnu11 -> gnu17 -> gnu23), silently changing which conformance/UB rules
# apply when the toolchain is upgraded or swapped. C99 is the floor the whole tree is verified clean
# against under -pedantic-errors. `?=` lets a board that needs GNU/POSIX extensions override it
# *before* this point — the host board (pthreads) sets TK_STD := -std=gnu11. Placed first in
# ALL_CFLAGS so any residual board-local -std (last one wins in GCC) still takes precedence.
TK_STD ?= -std=c99

# Strictness, applied PROJECT-WIDE — no exceptions, vendored SEGGER included (each board's own
# -Wall -Wextra stay in TK_CFLAGS). `?=` keeps it overridable for a one-off (e.g. `make TK_WARNINGS=`).
TK_WARNINGS ?= -Werror -pedantic-errors
ALL_CFLAGS := $(TK_STD) $(TK_CFLAGS) $(TK_ARCH_CFLAGS) $(TK_BOARD_CFLAGS) $(TK_WARNINGS) $(TK_INC) $(PROFILE_CFLAGS) $(CFLAGS)

BIN := $(PROJECT)$(TK_BIN_EXT)
TK_SIZE ?= $(CROSS)size   # footprint tool; boards set CROSS (host -> plain 'size')

.PHONY: all run flash size clean print-config boards
all: $(BIN)

$(BIN): $(SRCS) $(TK_SRCS)
	$(TK_CC) $(ALL_CFLAGS) $(SRCS) $(TK_SRCS) $(TK_LDFLAGS) -o $@

run: all
	$(TK_RUN)

flash: all
	$(TK_FLASH)

# Footprint: text (code, in flash) / data / bss (RAM). Add PROFILE=$(TK_ROOT)/profiles/tk_profile_nano.h
# for the minimal-kernel figure on this arch.
size: all
	$(TK_SIZE) $(BIN)

clean:
	rm -f $(BIN) $(PROJECT) $(PROJECT).exe $(PROJECT).elf $(PROJECT).bin $(PROJECT).hex $(PROJECT).map

print-config:
	@echo "BOARD   = $(BOARD)   ARCH = $(TK_ARCH)"
	@echo "CC      = $(TK_CC)"
	@echo "CFLAGS  = $(ALL_CFLAGS)"
	@echo "LDFLAGS = $(TK_LDFLAGS)"
	@echo "APP     = $(SRCS)"
	@echo "KERNEL  = $(TK_KERNEL_SRCS)"
	@echo "ARCH    = $(TK_ARCH_SRCS)"
	@echo "BOARD_SRCS = $(TK_BOARD_SRCS)"

# List every board BOARD= accepts, with a one-line description scraped from each fragment's header
# comment (no build; works from any project dir). Add a board = drop in make/board/<name>.mk and it
# shows up here automatically — nothing to register.
boards:
	@echo 'Supported boards (build with BOARD=<name>):'
	@for f in $(sort $(wildcard $(TK_ROOT)/make/board/*.mk)); do \
	    b=$$(basename $$f .mk); \
	    d=$$(sed -n '1s/.*\.mk[^A-Za-z0-9]*//p' $$f); \
	    printf '  %-24s %s\n' "$$b" "$${d:-(no description)}"; \
	done