csky_fir_example_f32.c

/******************************************************************************
 * @file     csky_fir_example_f32.c
 * @brief    Example code demonstrating how an FIR filter can be used
 *           as a low pass filter.
 * @version  V1.0
 * @date     20. Dec 2016
 ******************************************************************************/
/* ---------------------------------------------------------------------------
 * Copyright (C) 2016 CSKY Limited. All rights reserved.
 *
 * Redistribution and use of this software in source and binary forms,
 * with or without modification, are permitted provided that the following
 * conditions are met:
 *   * Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above copyright notice,
 *     this list of conditions and the following disclaimer in the documentation
 *     and/or other materials provided with the distribution.
 *   * Neither the name of CSKY Ltd. nor the names of CSKY's contributors may
 *     be used to endorse or promote products derived from this software without
 *     specific prior written permission of CSKY Ltd.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
 * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 * -------------------------------------------------------------------------- */

/* ----------------------------------------------------------------------
** Include Files
** ------------------------------------------------------------------- */

#include "csky_math.h"
#include "math_helper.h"

/* ----------------------------------------------------------------------
** Macro Defines
** ------------------------------------------------------------------- */

#define TEST_LENGTH_SAMPLES  320
#define SNR_THRESHOLD_F32    140.0f
#define BLOCK_SIZE            32
#define NUM_TAPS              29

/* -------------------------------------------------------------------
 * The input signal and reference output (computed with MATLAB)
 * are defined externally in csky_fir_lpf_data.c.
 * ------------------------------------------------------------------- */

extern float32_t testInput_f32_1kHz_15kHz[TEST_LENGTH_SAMPLES];
extern float32_t refOutput[TEST_LENGTH_SAMPLES];

/* -------------------------------------------------------------------
 * Declare Test output buffer
 * ------------------------------------------------------------------- */

static float32_t testOutput[TEST_LENGTH_SAMPLES];

/* -------------------------------------------------------------------
 * Declare State buffer of size (numTaps + blockSize - 1)
 * ------------------------------------------------------------------- */

static float32_t firStateF32[BLOCK_SIZE + NUM_TAPS - 1];

/* ----------------------------------------------------------------------
** FIR Coefficients buffer generated using fir1() MATLAB function.
** fir1(28, 6/24)
** ------------------------------------------------------------------- */

const float32_t firCoeffs32[NUM_TAPS] = {
  -0.0018225230f, -0.0015879294f, +0.0000000000f, +0.0036977508f, +0.0080754303f, +0.0085302217f, -0.0000000000f, -0.0173976984f,
  -0.0341458607f, -0.0333591565f, +0.0000000000f, +0.0676308395f, +0.1522061835f, +0.2229246956f, +0.2504960933f, +0.2229246956f,
  +0.1522061835f, +0.0676308395f, +0.0000000000f, -0.0333591565f, -0.0341458607f, -0.0173976984f, -0.0000000000f, +0.0085302217f,
  +0.0080754303f, +0.0036977508f, +0.0000000000f, -0.0015879294f, -0.0018225230f
};

/* ------------------------------------------------------------------
 * Global variables for FIR LPF Example
 * ------------------------------------------------------------------- */

uint32_t blockSize = BLOCK_SIZE;
uint32_t numBlocks = TEST_LENGTH_SAMPLES/BLOCK_SIZE;

float32_t  snr;

/* ----------------------------------------------------------------------
 * FIR LPF Example
 * ------------------------------------------------------------------- */

int32_t main(void)
{
  uint32_t i;
  csky_fir_instance_f32 S;
  csky_status status;
  float32_t  *inputF32, *outputF32;

  /* Initialize input and output buffer pointers */
  inputF32 = &testInput_f32_1kHz_15kHz[0];
  outputF32 = &testOutput[0];

  /* Call FIR init function to initialize the instance structure. */
  csky_fir_init_f32(&S, NUM_TAPS, (float32_t *)&firCoeffs32[0], &firStateF32[0], blockSize);

  /* ----------------------------------------------------------------------
  ** Call the FIR process function for every blockSize samples
  ** ------------------------------------------------------------------- */

  for(i=0; i < numBlocks; i++)
  {
    csky_fir_f32(&S, inputF32 + (i * blockSize), outputF32 + (i * blockSize), blockSize);
  }

  /* ----------------------------------------------------------------------
  ** Compare the generated output against the reference output computed
  ** in MATLAB.
  ** ------------------------------------------------------------------- */

  snr = csky_snr_f32(&refOutput[0], &testOutput[0], TEST_LENGTH_SAMPLES);

  if (snr < SNR_THRESHOLD_F32)
  {
    status = CSKY_MATH_TEST_FAILURE;
  }
  else
  {
    status = CSKY_MATH_SUCCESS;
  }

  /* ----------------------------------------------------------------------
  ** Loop here if the signal does not match the reference output.
  ** ------------------------------------------------------------------- */

  if( status != CSKY_MATH_SUCCESS)
  {
    while(1);
  }

  while(1);                             /* main function does not return */
}