fn main() -> Result<(), Box<dyn std::error::Error>> {
println!("cargo:rerun-if-changed=build.rs");
#[cfg(feature = "haase")] {
// According to the ARMv7-M Architecture Reference Manual,
// there are two architecture extensions:
// - the DSP extension: this is what we need, it is also called
// "an ARMv7E-M implementation".
// - the floating-extension: we don't use this
//
// The Cortex-M4 processor implements the ARMV7E-M architecture,
// and according to its Technical Reference Manual (section 3.3.1),
// the UMAAL instruction takes exactly 1 cycle.
//
// In the ARMv8-M Architecture Reference Manual, we read that
// there are several extensions: main, security, floating-point,
// DSP,... and that the main extension is a prerequisite for the
// DSP extension. The Cortex-M33 Technical Reference Manual (section B1.3)
// states that the DSP extension is optional, so technically
// `thumbv8m.main-none-eabi[hf]` is not sufficiently specified.
// It does *not* contain any data on the number of cycles for UMAAL.
//
// We treat Cortex-M33 as Cortex-M4 with possibly extra features.
let target = std::env::var("TARGET")?;
if !(target.starts_with("thumbv7em") || target.starts_with("thumbv8m.main")) {
panic!(concat!(
"Target `{}` is not a Cortex-M processor with the DSP extension.\n",
"Try `--target thumbv7em-none-eabi` or `--target thumbv8m.main-none-eabi`\n",
), target);
}
let out_dir = std::path::PathBuf::from(std::env::var("OUT_DIR").unwrap());
std::fs::copy("bin/salty-asm.a", out_dir.join("libsalty-asm.a")).unwrap();
println!("cargo:rustc-link-lib=static={}", "salty-asm");
println!("cargo:rustc-link-search={}", out_dir.display());
println!("cargo:rerun-if-changed=bin/salty-asm.a");
}
Ok(())
}