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# Copyright 2020 The Pigweed Authors
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may not
# use this file except in compliance with the License. You may obtain a copy of
# the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations under
# the License.
import("$dir_pw_build/exec.gni")
# Preprocess a linker script and turn it into a target.
#
# Note: to use this template, pw_cc_command must be specified in your target's
# config. It should match the name of the C compiler your target uses (e.g.
# arm-none-eabi-gcc).
#
# In lieu of direct GN support for linker scripts, this template makes it
# possible to run the C Preprocessor on a linker script file so defines can
# be properly evaluated before the linker script is passed to the dir_pw_build
#
# TODO(pwbug/53): This template serves as a stand-in until native GN support for
# linker scripts is added.
#
# Args:
# linker_script: The linker script to send through the C preprocessor.
#
# defines: Preprocessor defines to apply when running the C preprocessor.
#
# cflags: Flags to pass to the C compiler.
#
# inputs: Files that, when changed, should trigger a re-build of the linker
# script. linker_script is implicitly added to this by the template.
#
# Example:
#
# pw_linker_script("generic_linker_script") {
# defines = [
# "PW_HEAP_SIZE=1K",
# "PW_NOINIT_SIZE=512"
# ]
# linker_script = "basic_script.ld"
# }
#
template("pw_linker_script") {
assert(
defined(pw_cc_command) && pw_cc_command != "",
"pw_cc_command has not been properly configured. This variable must be " +
"defined to enable linker script preprocessing.")
assert(
defined(invoker.linker_script) && invoker.linker_script != "",
"$target_name did not set `linker_script` to refer to a valid linker " +
"script. This variable is required for linker script targets.")
_final_linker_script = "${target_gen_dir}/${target_name}_final.ld"
# This action invokes the C compiler provided by the target to preprocess the
# linker script.
pw_exec("${target_name}_preprocess") {
program = pw_cc_command
inputs = [ invoker.linker_script ]
args = [
# Run compiler in preprocessor-only mode.
"-E",
# Do not generate linemarkers in output.
"-P",
# Do not discard comments.
"-C",
# Treat the following file as a C file.
"-x",
"c",
get_path_info(invoker.linker_script, "abspath"),
]
# Include any explicitly listed c flags.
if (defined(invoker.cflags)) {
args += cflags
}
# Add defines.
if (defined(invoker.defines)) {
args += process_file_template(invoker.defines, "-D{{source_name_part}}")
}
# Set output file.
args += [
"-o",
_final_linker_script,
]
outputs = [ _final_linker_script ]
}
# This config adds a the linker script produced by the preprocess action to
# the linker flags.
config("${target_name}_config") {
inputs = [ invoker.linker_script ]
if (!defined(invoker.ldflags)) {
ldflags = []
}
ldflags += [ "-T" + rebase_path(_final_linker_script) ]
}
# The target that adds the linker script config to this library and everything
# that depends on it.
source_set(target_name) {
inputs = [ _final_linker_script ]
if (defined(invoker.inputs)) {
inputs += invoker.inputs
}
all_dependent_configs = [ ":${target_name}_config" ]
deps = [ ":${target_name}_preprocess" ]
}
}