convolve.c

/* shoves new samples onto a kernel-sized history buffer */
float convolve(const float input,
              const float* kernel, const size_t kernel_length,
              float* history){
    int index = kernel_length -1;
    /* XXX: replace with better data structure without data copying
       this is really inefficient! It does work though.
    */
    for(; index > 0; index--){
        history[index] = history[index - 1];
    }
    history[0] = input;
    float output = 0.0;
    for(index = 0; index < kernel_length; index++){
        output += history[index] * kernel[index];
    }

    return output;
}