arm_fir_interpolate_q15.c

Go to the documentation of this file.

/*-----------------------------------------------------------------------------    
* Copyright (C) 2010-2014 ARM Limited. All rights reserved.    
*    
* $Date:        19. March 2015
* $Revision:    V.1.4.5
*    
* Project:      CMSIS DSP Library    
* Title:        arm_fir_interpolate_q15.c    
*    
* Description:  Q15 FIR interpolation.    
*    
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*  
* Redistribution and use 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 ARM LIMITED nor the names of its contributors
*     may be used to endorse or promote products derived from this
*     software without specific prior written permission.
*
* 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 "arm_math.h"

#ifndef ARM_MATH_CM0_FAMILY

  /* Run the below code for Cortex-M4 and Cortex-M3 */

void arm_fir_interpolate_q15(
  const arm_fir_interpolate_instance_q15 * S,
  q15_t * pSrc,
  q15_t * pDst,
  uint32_t blockSize)
{
  q15_t *pState = S->pState;                     /* State pointer                                            */
  q15_t *pCoeffs = S->pCoeffs;                   /* Coefficient pointer                                      */
  q15_t *pStateCurnt;                            /* Points to the current sample of the state                */
  q15_t *ptr1, *ptr2;                            /* Temporary pointers for state and coefficient buffers     */
  q63_t sum0;                                    /* Accumulators                                             */
  q15_t x0, c0;                                  /* Temporary variables to hold state and coefficient values */
  uint32_t i, blkCnt, j, tapCnt;                 /* Loop counters                                            */
  uint16_t phaseLen = S->phaseLength;            /* Length of each polyphase filter component */
  uint32_t blkCntN2;
  q63_t acc0, acc1;
  q15_t x1;

  /* S->pState buffer contains previous frame (phaseLen - 1) samples */
  /* pStateCurnt points to the location where the new input data should be written */
  pStateCurnt = S->pState + ((q31_t) phaseLen - 1);

  /* Initialise  blkCnt */
  blkCnt = blockSize / 2;
  blkCntN2 = blockSize - (2 * blkCnt);

  /* Samples loop unrolled by 2 */
  while(blkCnt > 0u)
  {
    /* Copy new input sample into the state buffer */
    *pStateCurnt++ = *pSrc++;
    *pStateCurnt++ = *pSrc++;

    /* Address modifier index of coefficient buffer */
    j = 1u;

    /* Loop over the Interpolation factor. */
    i = (S->L);

    while(i > 0u)
    {
      /* Set accumulator to zero */
      acc0 = 0;
      acc1 = 0;

      /* Initialize state pointer */
      ptr1 = pState;

      /* Initialize coefficient pointer */
      ptr2 = pCoeffs + (S->L - j);

      /* Loop over the polyPhase length. Unroll by a factor of 4.        
       ** Repeat until we've computed numTaps-(4*S->L) coefficients. */
      tapCnt = phaseLen >> 2u;

      x0 = *(ptr1++);

      while(tapCnt > 0u)
      {

        /* Read the input sample */
        x1 = *(ptr1++);

        /* Read the coefficient */
        c0 = *(ptr2);

        /* Perform the multiply-accumulate */
        acc0 += (q63_t) x0 *c0;
        acc1 += (q63_t) x1 *c0;


        /* Read the coefficient */
        c0 = *(ptr2 + S->L);

        /* Read the input sample */
        x0 = *(ptr1++);

        /* Perform the multiply-accumulate */
        acc0 += (q63_t) x1 *c0;
        acc1 += (q63_t) x0 *c0;


        /* Read the coefficient */
        c0 = *(ptr2 + S->L * 2);

        /* Read the input sample */
        x1 = *(ptr1++);

        /* Perform the multiply-accumulate */
        acc0 += (q63_t) x0 *c0;
        acc1 += (q63_t) x1 *c0;

        /* Read the coefficient */
        c0 = *(ptr2 + S->L * 3);

        /* Read the input sample */
        x0 = *(ptr1++);

        /* Perform the multiply-accumulate */
        acc0 += (q63_t) x1 *c0;
        acc1 += (q63_t) x0 *c0;


        /* Upsampling is done by stuffing L-1 zeros between each sample.        
         * So instead of multiplying zeros with coefficients,        
         * Increment the coefficient pointer by interpolation factor times. */
        ptr2 += 4 * S->L;

        /* Decrement the loop counter */
        tapCnt--;
      }

      /* If the polyPhase length is not a multiple of 4, compute the remaining filter taps */
      tapCnt = phaseLen % 0x4u;

      while(tapCnt > 0u)
      {

        /* Read the input sample */
        x1 = *(ptr1++);

        /* Read the coefficient */
        c0 = *(ptr2);

        /* Perform the multiply-accumulate */
        acc0 += (q63_t) x0 *c0;
        acc1 += (q63_t) x1 *c0;

        /* Increment the coefficient pointer by interpolation factor times. */
        ptr2 += S->L;

        /* update states for next sample processing */
        x0 = x1;

        /* Decrement the loop counter */
        tapCnt--;
      }

      /* The result is in the accumulator, store in the destination buffer. */
      *pDst = (q15_t) (__SSAT((acc0 >> 15), 16));
      *(pDst + S->L) = (q15_t) (__SSAT((acc1 >> 15), 16));

      pDst++;

      /* Increment the address modifier index of coefficient buffer */
      j++;

      /* Decrement the loop counter */
      i--;
    }

    /* Advance the state pointer by 1        
     * to process the next group of interpolation factor number samples */
    pState = pState + 2;

    pDst += S->L;

    /* Decrement the loop counter */
    blkCnt--;
  }

  /* If the blockSize is not a multiple of 2, compute any remaining output samples here.        
   ** No loop unrolling is used. */
  blkCnt = blkCntN2;

  /* Loop over the blockSize. */
  while(blkCnt > 0u)
  {
    /* Copy new input sample into the state buffer */
    *pStateCurnt++ = *pSrc++;

    /* Address modifier index of coefficient buffer */
    j = 1u;

    /* Loop over the Interpolation factor. */
    i = S->L;
    while(i > 0u)
    {
      /* Set accumulator to zero */
      sum0 = 0;

      /* Initialize state pointer */
      ptr1 = pState;

      /* Initialize coefficient pointer */
      ptr2 = pCoeffs + (S->L - j);

      /* Loop over the polyPhase length. Unroll by a factor of 4.        
       ** Repeat until we've computed numTaps-(4*S->L) coefficients. */
      tapCnt = phaseLen >> 2;
      while(tapCnt > 0u)
      {

        /* Read the coefficient */
        c0 = *(ptr2);

        /* Upsampling is done by stuffing L-1 zeros between each sample.        
         * So instead of multiplying zeros with coefficients,        
         * Increment the coefficient pointer by interpolation factor times. */
        ptr2 += S->L;

        /* Read the input sample */
        x0 = *(ptr1++);

        /* Perform the multiply-accumulate */
        sum0 += (q63_t) x0 *c0;

        /* Read the coefficient */
        c0 = *(ptr2);

        /* Increment the coefficient pointer by interpolation factor times. */
        ptr2 += S->L;

        /* Read the input sample */
        x0 = *(ptr1++);

        /* Perform the multiply-accumulate */
        sum0 += (q63_t) x0 *c0;

        /* Read the coefficient */
        c0 = *(ptr2);

        /* Increment the coefficient pointer by interpolation factor times. */
        ptr2 += S->L;

        /* Read the input sample */
        x0 = *(ptr1++);

        /* Perform the multiply-accumulate */
        sum0 += (q63_t) x0 *c0;

        /* Read the coefficient */
        c0 = *(ptr2);

        /* Increment the coefficient pointer by interpolation factor times. */
        ptr2 += S->L;

        /* Read the input sample */
        x0 = *(ptr1++);

        /* Perform the multiply-accumulate */
        sum0 += (q63_t) x0 *c0;

        /* Decrement the loop counter */
        tapCnt--;
      }

      /* If the polyPhase length is not a multiple of 4, compute the remaining filter taps */
      tapCnt = phaseLen & 0x3u;

      while(tapCnt > 0u)
      {
        /* Read the coefficient */
        c0 = *(ptr2);

        /* Increment the coefficient pointer by interpolation factor times. */
        ptr2 += S->L;

        /* Read the input sample */
        x0 = *(ptr1++);

        /* Perform the multiply-accumulate */
        sum0 += (q63_t) x0 *c0;

        /* Decrement the loop counter */
        tapCnt--;
      }

      /* The result is in the accumulator, store in the destination buffer. */
      *pDst++ = (q15_t) (__SSAT((sum0 >> 15), 16));

      j++;

      /* Decrement the loop counter */
      i--;
    }

    /* Advance the state pointer by 1        
     * to process the next group of interpolation factor number samples */
    pState = pState + 1;

    /* Decrement the loop counter */
    blkCnt--;
  }


  /* Processing is complete.    
   ** Now copy the last phaseLen - 1 samples to the satrt of the state buffer.    
   ** This prepares the state buffer for the next function call. */

  /* Points to the start of the state buffer */
  pStateCurnt = S->pState;

  i = ((uint32_t) phaseLen - 1u) >> 2u;

  /* copy data */
  while(i > 0u)
  {
#ifndef UNALIGNED_SUPPORT_DISABLE

    *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;
    *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;

#else

    *pStateCurnt++ = *pState++;
    *pStateCurnt++ = *pState++;
    *pStateCurnt++ = *pState++;
    *pStateCurnt++ = *pState++;
    
#endif  /*  #ifndef UNALIGNED_SUPPORT_DISABLE   */
    
    /* Decrement the loop counter */
    i--;
  }

  i = ((uint32_t) phaseLen - 1u) % 0x04u;

  while(i > 0u)
  {
    *pStateCurnt++ = *pState++;

    /* Decrement the loop counter */
    i--;
  }
}

#else

  /* Run the below code for Cortex-M0 */

void arm_fir_interpolate_q15(
  const arm_fir_interpolate_instance_q15 * S,
  q15_t * pSrc,
  q15_t * pDst,
  uint32_t blockSize)
{
  q15_t *pState = S->pState;                     /* State pointer                                            */
  q15_t *pCoeffs = S->pCoeffs;                   /* Coefficient pointer                                      */
  q15_t *pStateCurnt;                            /* Points to the current sample of the state                */
  q15_t *ptr1, *ptr2;                            /* Temporary pointers for state and coefficient buffers     */
  q63_t sum;                                     /* Accumulator */
  q15_t x0, c0;                                  /* Temporary variables to hold state and coefficient values */
  uint32_t i, blkCnt, tapCnt;                    /* Loop counters                                            */
  uint16_t phaseLen = S->phaseLength;            /* Length of each polyphase filter component */


  /* S->pState buffer contains previous frame (phaseLen - 1) samples */
  /* pStateCurnt points to the location where the new input data should be written */
  pStateCurnt = S->pState + (phaseLen - 1u);

  /* Total number of intput samples */
  blkCnt = blockSize;

  /* Loop over the blockSize. */
  while(blkCnt > 0u)
  {
    /* Copy new input sample into the state buffer */
    *pStateCurnt++ = *pSrc++;

    /* Loop over the Interpolation factor. */
    i = S->L;

    while(i > 0u)
    {
      /* Set accumulator to zero */
      sum = 0;

      /* Initialize state pointer */
      ptr1 = pState;

      /* Initialize coefficient pointer */
      ptr2 = pCoeffs + (i - 1u);

      /* Loop over the polyPhase length */
      tapCnt = (uint32_t) phaseLen;

      while(tapCnt > 0u)
      {
        /* Read the coefficient */
        c0 = *ptr2;

        /* Increment the coefficient pointer by interpolation factor times. */
        ptr2 += S->L;

        /* Read the input sample */
        x0 = *ptr1++;

        /* Perform the multiply-accumulate */
        sum += ((q31_t) x0 * c0);

        /* Decrement the loop counter */
        tapCnt--;
      }

      /* Store the result after converting to 1.15 format in the destination buffer */
      *pDst++ = (q15_t) (__SSAT((sum >> 15), 16));

      /* Decrement the loop counter */
      i--;
    }

    /* Advance the state pointer by 1           
     * to process the next group of interpolation factor number samples */
    pState = pState + 1;

    /* Decrement the loop counter */
    blkCnt--;
  }

  /* Processing is complete.         
   ** Now copy the last phaseLen - 1 samples to the start of the state buffer.       
   ** This prepares the state buffer for the next function call. */

  /* Points to the start of the state buffer */
  pStateCurnt = S->pState;

  i = (uint32_t) phaseLen - 1u;

  while(i > 0u)
  {
    *pStateCurnt++ = *pState++;

    /* Decrement the loop counter */
    i--;
  }

}

#endif /*   #ifndef ARM_MATH_CM0_FAMILY */