arm_fir_example_f32.c

/* ---------------------------------------------------------------------- 
 * Copyright (C) 2010 ARM Limited. All rights reserved.   
 *  
 * $Date:           29. November 2010  
 * $Revision:       V1.0.3  
 *  
 * Project:         CMSIS DSP Library  
 * Title:               arm_fir_example_f32.c             
 *  
 * Description: Example code demonstrating how an FIR filter can be used
 *               as a low pass filter.
 * 
 * Target Processor: Cortex-M4/Cortex-M3  
 *
 *
 * Version 1.0.3 2010/11/29 
 *    Re-organized the CMSIS folders and updated documentation. 
 * 
 * Version 1.0.1 2010/10/05 KK 
 *    Production release and review comments incorporated.  
 *
 * Version 1.0.0 2010/09/20 KK
 *    Production release and review comments incorporated.
 * ------------------------------------------------------------------- */ 
 
/* ---------------------------------------------------------------------- 
** Include Files  
** ------------------------------------------------------------------- */ 

#include "arm_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 arm_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; 
  arm_fir_instance_f32 S; 
  arm_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. */
  arm_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++)  
    {    
      arm_fir_f32(&S, inputF32 + (i * blockSize), outputF32 + (i * blockSize), blockSize);  
    } 
 
  /* ---------------------------------------------------------------------- 
  ** Compare the generated output against the reference output computed
  ** in MATLAB.
  ** ------------------------------------------------------------------- */ 

  snr = arm_snr_f32(&refOutput[0], &testOutput[0], TEST_LENGTH_SAMPLES); 
 
  if (snr < SNR_THRESHOLD_F32) 
    { 
      status = ARM_MATH_TEST_FAILURE; 
    } 
  else
    {
      status = ARM_MATH_SUCCESS; 
    }
         
  /* ---------------------------------------------------------------------- 
  ** Loop here if the signal does not match the reference output.
  ** ------------------------------------------------------------------- */ 
         
  if( status != ARM_MATH_SUCCESS) 
    { 
      while(1); 
    } 

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