cmsis-dsp-sys

rust bindings for the prebuilt cmsis-dsp math

prereqs

Until 5730 is solved some day currently requires three commands to be present. I'd be happy to take requests to swap them around to that works well across platforms.

• unzip
• curl
• bindgen

usage

use cmsis_dsp_sys::{arm_sin_f32};

let sin = unsafe { arm_sin_f32(core::f32::consts::PI) };
assert_eq!(sin, 0f32);

the dirty details

Its complicated. Im currently not building any c files that accompany the arm dsp libraries. Bringing the necessary libc, libm and abstracting against every possible architecture and build flag seems hopeless atm. As a result you're going to have to do some work on your end.

When you start to do anything complicated you're probably going to see something like:

  = note: rust-lld: error: undefined symbol: sqrtf
          >>> referenced by arm_math.h:6841 (../../Include/arm_math.h:6841)
          >>>               arm_cmplx_mag_f32.o:(arm_cmplx_mag_f32) in archive /home/jacob/Downloads/dsp-discoveryf4-rust/lab4/libarm_cortexM4lf_math.a

Which means you need to bring some libm type function with you. Possibilitie pure rust options I've seen include libm or micromath with differing tradeoffs. Stub one in with:

use cmsis_dsp_sys::{arm_cfft_sR_f32_len16, arm_cfft_f32, arm_cfft_instance_f32, arm_cmplx_mag_f32};
use micromath::F32Ext;

//C needs access to a sqrt fn, lets use micromath
#[no_mangle]
pub extern "C" fn sqrtf(x: f32) -> f32 {
    x.sqrt()
}
...
    //your data as stored as real and imaginary pairs here
    let mut dtfsecoef = [0f32; 32];

    let mut mag = [0f32; 16];

    //Coefficient calculation with CFFT function
    unsafe {

        //CFFT calculation
        arm_cfft_f32(&arm_cfft_sR_f32_len16, dtfsecoef.as_mut_ptr(), 0, 1);

        // Magnitude calculation
        arm_cmplx_mag_f32(s.as_ptr(), mag.as_mut_ptr(), N::to_usize() as uint32_t);

    }
...