sdr-0.1.0.0: c_sources/resample.c

/*
 * FIR rational resampling of complex and real data with real coefficients.
 * These exist because the pure Haskell implementations are slow.
 * Uses SIMD instructions for performance.
 */

#include <stdio.h>
#include <stdint.h>
#include <x86intrin.h>

#include "common.h"

/*
 * Rational downsampling
 */
void resample(int buf_size, int coeff_size, int interpolation, int decimation, int filter_offset, float *coeffs, float *in_buf, float *out_buf){
    int j, k, l;
    int input_offset = 0;
    for(k=0; k<buf_size; k++) {
        float accum = 0;

        for(l=0, j=filter_offset; j<coeff_size; l++, j+=interpolation) {
            accum += in_buf[input_offset + l] * coeffs[j];
        }

        int filter_offset_new = interpolation - 1 - (decimation - filter_offset - 1) % interpolation;
        input_offset += (decimation - filter_offset - 1) / interpolation + 1;
        filter_offset = filter_offset_new;

        out_buf[k] = accum;
    }
}

int resample2(int buf_size, int num_coeffs, int starting_group, int num_groups, int *increments, float **coeffs, float *in_buf, float *out_buf){
    int   i, j;
    int   group      = starting_group;
    float *start_ptr = in_buf;

    for(i=0; i<buf_size; i++){
        out_buf[i]  = dotprod_R(num_coeffs, coeffs[group], start_ptr);

        start_ptr  += increments[group];
        group++;
        if(group == num_groups) 
            group = 0;
    }

    return group;
}

int resampleSSERR(int buf_size, int num_coeffs, int starting_group, int num_groups, int *increments, float **coeffs, float *in_buf, float *out_buf){
    int   i, j;
    int   group      = starting_group;
    float *startPtr  = in_buf;

    for(i=0; i<buf_size; i++){
        __m128 accum = sse_dotprod_R(num_coeffs, coeffs[group], startPtr);
        accum = sse_hadd_R(accum);
        _mm_store_ss(out_buf + i, accum);

        startPtr  += increments[group];
        group++;
        if(group == num_groups) 
            group = 0;
    }

    return group;
}

int resampleAVXRR(int buf_size, int num_coeffs, int starting_group, int num_groups, int *increments, float **coeffs, float *in_buf, float *out_buf){
    int   i, j;
    int   group      = starting_group;
    float *startPtr  = in_buf;

    for(i=0; i<buf_size; i++){
        __m256 accum = avx_dotprod_R(num_coeffs, coeffs[group], startPtr);
        __m128 res   = avx_hadd_R(accum);
        _mm_store_ss(out_buf + i, res);

        startPtr  += increments[group];
        group++;
        if(group == num_groups) 
            group = 0;
    }

    return group;
}