MAKEFLAGS += -R -r

CROSS     = riscv32-unknown-elf-
prefix   := $(CURDIR)
target_flags = -fvisibility=hidden -fno-pic -mshorten-memrefs \
	       -frename-registers -mdiv -mno-strict-align \
	       -ffunction-sections -fdata-sections

tooldir   = riscv-gnu-toolchain

# --disable-gdb because the gdb with riscv-gnu-toolchain seems really broken
config    = --prefix=$(prefix)/gnu \
	    --with-arch=rv32imc --with-abi=ilp32 \
	    --with-target-cflags='$(target_flags)' \
	    --with-target-cxxflags='$(target_flags)' \
	    --with-system-zlib \
	    --disable-gdb \
	    --enable-multilib --with-multilib-generator='rv32imc-ilp32--'

# The tools don't seem to build correctly without buildin rules (sigh)
# There isn't even an option to cancel them, so use this hideousness
# to strip out the r and R option from MAKEFLAGS.
_tail = $(wordlist 2,$(words $(1)),$(1))
_strip_flags = $(if $(1),$(call _strip_flags,$(call _tail,$(1)),$(subst $(word 1,$(1)),,$(2))),$(2))
strip_flags  = $(if $(findstring -,$(word 1,$(2))),$(2),$(call _strip_flags,$(1),$(word 1,$(2))) $(call _tail,$(2)))

RMAKE = $(MAKE) MAKEFLAGS='$(call strip_flags,r R,$(MAKEFLAGS))'

export target_configargs := --enable-lite-exit --disable-newlib-register-fini

export PATH := $(prefix)/gnu/bin:$(PATH)

all: gnu

clean:
	rm -rf gnu *.build

# Note: the riscv-gnu-toolchain repo has bugs when building in
# parallel, so spoon feed it a sequence to avoid dependency problems.
.PHONY: gnu
gnu:
	[ ! -f ../../.gitmodules ] || \
		git submodule update --init --recursive
	mkdir -p gnu.build
	cd gnu.build && ../$(tooldir)/configure $(config)
	$(RMAKE) -C gnu.build build-binutils
	$(RMAKE) -C gnu.build newlib