use std::{
env, fs,
io::{Error, ErrorKind, Result},
path::PathBuf,
};
use quote::{format_ident, quote};
const SELECTED_PLATFORM_NAME: &str = "selected_platform.rs";
const BUILD_INFO_NAME: &str = "build_info.rs";
const PLATFORM_CRATE_ENV: &str = "AX_PLATFORM_CRATE";
const DEFAULT_PLATFORM_CRATE: &str = "axplat_dyn";
const DEFAULT_CPU_CAPACITY: usize = 16;
fn main() {
println!("cargo:rerun-if-env-changed=SMP");
println!("cargo:rerun-if-env-changed={PLATFORM_CRATE_ENV}");
gen_selected_platform().unwrap();
gen_build_info(read_cpu_capacity_env().unwrap()).unwrap();
}
fn gen_selected_platform() -> Result<()> {
let crate_name =
env::var(PLATFORM_CRATE_ENV).unwrap_or_else(|_| DEFAULT_PLATFORM_CRATE.to_string());
let content = selected_platform_source(&crate_name);
let out_dir = PathBuf::from(std::env::var("OUT_DIR").unwrap());
fs::write(out_dir.join(SELECTED_PLATFORM_NAME), content)
}
fn selected_platform_source(crate_name: &str) -> String {
let crate_ident = format_ident!("{crate_name}");
quote! {
pub extern crate #crate_ident as selected;
}
.to_string()
}
fn parse_usize(value: &str) -> std::result::Result<usize, std::num::ParseIntError> {
let value = value.replace('_', "");
if let Some(hex) = value.strip_prefix("0x") {
usize::from_str_radix(hex, 16)
} else {
value.parse()
}
}
fn invalid_data(error: impl std::fmt::Display) -> Error {
Error::new(ErrorKind::InvalidData, error.to_string())
}
fn read_cpu_capacity_env() -> Result<usize> {
match env::var("SMP") {
Ok(value) => parse_usize(&value)
.map_err(|err| invalid_data(format!("failed to parse SMP value `{value}`: {err}"))),
Err(_) => Ok(DEFAULT_CPU_CAPACITY),
}
}
fn gen_build_info(cpu_capacity: usize) -> Result<()> {
let out_dir = PathBuf::from(std::env::var("OUT_DIR").unwrap());
fs::write(
out_dir.join(BUILD_INFO_NAME),
build_info_source(cpu_capacity),
)
}
fn build_info_source(cpu_capacity: usize) -> String {
quote! {
#[cfg(feature = "smp")]
pub const CPU_CAPACITY: usize = #cpu_capacity;
}
.to_string()
}
#[cfg(test)]
mod tests {
use super::*;
fn semantic_source(source: &str) -> String {
source
.chars()
.filter(|character| !character.is_whitespace())
.collect()
}
#[test]
fn selected_platform_source_handles_crate_names_with_underscores() {
assert_eq!(
semantic_source(&selected_platform_source("ax_plat_loongarch64_qemu_virt")),
semantic_source("pub extern crate ax_plat_loongarch64_qemu_virt as selected;")
);
}
#[test]
fn build_info_source_generates_smp_cpu_capacity() {
assert_eq!(
semantic_source(&build_info_source(16)),
semantic_source("#[cfg(feature = \"smp\")] pub const CPU_CAPACITY: usize = 16usize;")
);
}
}