arm_conv_fast_q15.c

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/* ----------------------------------------------------------------------      
* Copyright (C) 2011 ARM Limited. All rights reserved. 
*      
* $Date:        15. December 2011   
* $Revision:    V2.0.0  
*      
* Project:      Cortex-R DSP Library 
* Title:        arm_conv_fast_q15.c      
*      
* Description:  Fast Q15 Convolution.      
*      
* Target Processor:          Cortex-R4/R5
*
* Version 1.0.0 2011/03/08
*     Alpha release.
*
* Version 1.0.1 2011/09/30
*     Beta release.
*
* Version 2.0.0 2011/12/15
*     Final release. 
* 
* -------------------------------------------------------------------- */     
#include "arm_math.h"     
     
void arm_conv_fast_q15(     
  q15_t * pSrcA,     
  uint32_t srcALen,     
  q15_t * pSrcB,     
  uint32_t srcBLen,     
  q15_t * pDst,  
  q15_t * pScratch1,  
  q15_t *pScratch2)     
{   
  q31_t acc0, acc1, acc2, acc3;      /* Accumulators */  
  q31_t x1, x2, x3;                  /* Temporary variables to hold state and coefficient values */  
  q31_t y1, y2;                      /* State variables */  
  q15_t *pOut = pDst;                /* output pointer */  
  q15_t *pScr1 = pScratch1;          /* Temporary pointer for scratch1 */  
  q15_t *pScr2 = pScratch2;          /* Temporary pointer for scratch1 */  
  q15_t *pIn1;                       /* inputA pointer */  
  q15_t *pIn2;                       /* inputB pointer */  
  q15_t *px;                         /* Intermediate inputA pointer  */  
  q15_t *py;                         /* Intermediate inputB pointer  */  
  uint32_t j, k, blkCnt;             /* loop counter */    
  uint32_t tapCnt;                   /* loop count */    
    
  /* The algorithm implementation is based on the lengths of the inputs. */     
  /* srcB is always made to slide across srcA. */     
  /* So srcBLen is always considered as shorter or equal to srcALen */     
  if(srcALen >= srcBLen)     
  {     
    /* Initialization of inputA pointer */     
    pIn1 = pSrcA;     
     
    /* Initialization of inputB pointer */     
    pIn2 = pSrcB;     
  }     
  else     
  {     
    /* Initialization of inputA pointer */     
    pIn1 = pSrcB;     
     
    /* Initialization of inputB pointer */     
    pIn2 = pSrcA;     
     
    /* srcBLen is always considered as shorter or equal to srcALen */     
    j = srcBLen;     
    srcBLen = srcALen;     
    srcALen = j;     
  }     
  
  /* Pointer to take end of scratch2 buffer */  
  pScr2 = pScratch2 + srcBLen - 1;  
  
  /* points to smaller length sequence */  
  px = pIn2;  
  
  /* Apply loop unrolling and do 4 Copies simultaneously. */  
  k = srcBLen >> 2u;  
  
  /* First part of the processing with loop unrolling copies 4 data points at a time.     
   ** a second loop below copies for the remaining 1 to 3 samples. */  
  
  /* Copy smaller length input sequence in reverse order into second scratch buffer */  
  while(k > 0u)  
  {  
    /* copy second buffer in reversal manner */  
    *pScr2-- = *px++;  
    *pScr2-- = *px++;  
    *pScr2-- = *px++;  
    *pScr2-- = *px++;  
  
    /* Decrement the loop counter */  
    k--;  
  }  
  
  /* If the count is not a multiple of 4, copy remaining samples here.     
   ** No loop unrolling is used. */  
  k = srcBLen % 0x4u;  
  
  while(k > 0u)  
  {  
    /* copy second buffer in reversal manner for remaining samples */  
    *pScr2-- = *px++;  
  
    /* Decrement the loop counter */  
    k--;  
  }  
  
  /* Initialze temporary scratch pointer */  
  pScr1 = pScratch1;  
  
  /* Assuming scratch1 buffer is aligned by 32-bit */  
  /* Fill (srcBLen - 1u) zeros in scratch1 buffer */  
  arm_fill_q15(0, pScr1, (srcBLen - 1u));  
  
  /* Update temporary scratch pointer */  
  pScr1 += (srcBLen - 1u);  
  
  /* Copy bigger length sequence(srcALen) samples in scratch1 buffer */  
  
#ifndef UNALIGNED_SUPPORT_DISABLE  
  
  /* Copy (srcALen) samples in scratch buffer */  
  arm_copy_q15(pIn1, pScr1, srcALen);  
  
  /* Update pointers */  
  pScr1 += srcALen;  
  
#else  
  
  /* Apply loop unrolling and do 4 Copies simultaneously. */  
  k = srcALen >> 2u;  
  
  /* First part of the processing with loop unrolling copies 4 data points at a time.     
   ** a second loop below copies for the remaining 1 to 3 samples. */  
  while(k > 0u)  
  {  
    /* copy second buffer in reversal manner */  
    *pScr1++ = *pIn1++;  
    *pScr1++ = *pIn1++;  
    *pScr1++ = *pIn1++;  
    *pScr1++ = *pIn1++;  
  
    /* Decrement the loop counter */  
    k--;  
  }  
  
  /* If the count is not a multiple of 4, copy remaining samples here.     
   ** No loop unrolling is used. */  
  k = srcALen % 0x4u;  
  
  while(k > 0u)  
  {  
    /* copy second buffer in reversal manner for remaining samples */  
    *pScr1++ = *pIn1++;  
  
    /* Decrement the loop counter */  
    k--;  
  }  
  
#endif  
  
  
#ifndef UNALIGNED_SUPPORT_DISABLE  
  
  /* Fill (srcBLen - 1u) zeros at end of scratch buffer */  
  arm_fill_q15(0, pScr1, (srcBLen - 1u));  
  
  /* Update pointer */  
  pScr1 += (srcBLen - 1u);  
  
#else  
  
  /* Apply loop unrolling and do 4 Copies simultaneously. */  
  k = (srcBLen - 1u) >> 2u;  
  
  /* First part of the processing with loop unrolling copies 4 data points at a time.     
   ** a second loop below copies for the remaining 1 to 3 samples. */  
  while(k > 0u)  
  {  
    /* copy second buffer in reversal manner */  
    *pScr1++ = 0;  
    *pScr1++ = 0;  
    *pScr1++ = 0;  
    *pScr1++ = 0;  
  
    /* Decrement the loop counter */  
    k--;  
  }  
  
  /* If the count is not a multiple of 4, copy remaining samples here.     
   ** No loop unrolling is used. */  
  k = (srcBLen - 1u) % 0x4u;  
  
  while(k > 0u)  
  {  
    /* copy second buffer in reversal manner for remaining samples */  
    *pScr1++ = 0;  
  
    /* Decrement the loop counter */  
    k--;  
  }  
  
#endif  
  
  /* Temporary pointer for scratch2 */  
  py = pScratch2;  
  
  
  /* Initialization of pIn2 pointer */  
  pIn2 = py;  
  
    /* First part of the processing with loop unrolling process 4 data points at a time.     
   ** a second loop below process for the remaining 1 to 3 samples. */  
  
  /* Actual convolution process starts here */  
  blkCnt = (srcALen + srcBLen - 1u) >> 2;  
  
  while(blkCnt > 0)  
  {  
    /* Initialze temporary scratch pointer as scratch1 */  
    pScr1 = pScratch1;  
  
    /* Clear Accumlators */  
    acc0 = 0;  
    acc1 = 0;  
    acc2 = 0;  
    acc3 = 0;  
  
    /* Read two samples from scratch1 buffer */  
    x1 = *__SIMD32(pScr1)++;  
  
    /* Read next two samples from scratch1 buffer */  
    x2 = *__SIMD32(pScr1)++;  
      
    tapCnt = (srcBLen) >> 2u;  
  
    while(tapCnt > 0u)  
    {       
        
      /* Read four samples from smaller buffer */  
      y1 = _SIMD32_OFFSET(pIn2);  
      y2 = _SIMD32_OFFSET(pIn2 + 2u);  
        
      /* multiply and accumlate */  
      acc0 = __SMLAD(x1, y1, acc0);  
      acc2 = __SMLAD(x2, y1, acc2);  
  
      /* pack input data */  
#ifndef ARM_MATH_BIG_ENDIAN     
      x3 = __PKHBT(x2, x1, 0);  
#else  
      x3 = __PKHBT(x1, x2, 0);  
#endif  
  
      /* multiply and accumlate */  
      acc1 = __SMLADX(x3, y1, acc1);  
  
      /* Read next two samples from scratch1 buffer */  
      x1 = _SIMD32_OFFSET(pScr1);  
  
      /* multiply and accumlate */  
      acc0 = __SMLAD(x2, y2, acc0);  
      acc2 = __SMLAD(x1, y2, acc2);  
  
      /* pack input data */  
#ifndef ARM_MATH_BIG_ENDIAN     
      x3 = __PKHBT(x1, x2, 0);  
#else  
      x3 = __PKHBT(x2, x1, 0);  
#endif  
  
      acc3 = __SMLADX(x3, y1, acc3);  
      acc1 = __SMLADX(x3, y2, acc1);  
  
      x2 = _SIMD32_OFFSET(pScr1 + 2u);  
  
#ifndef ARM_MATH_BIG_ENDIAN     
      x3 = __PKHBT(x2, x1, 0);  
#else  
      x3 = __PKHBT(x1, x2, 0);  
#endif  
  
      acc3 = __SMLADX(x3, y2, acc3);  
  
      /* update scratch pointers */  
      pIn2 += 4u;  
      pScr1 += 4u;  
  
    
      /* Decrement the loop counter */  
      tapCnt--;  
    }      
  
    /* Update scratch pointer for remaining samples of smaller length sequence */  
    pScr1 -= 4u;    
  
    /* apply same above for remaining samples of smaller length sequence */  
    tapCnt = (srcBLen) & 3u;  
  
    while(tapCnt > 0u)  
    {  
  
      /* accumlate the results */  
      acc0 += (*pScr1++ * *pIn2);  
      acc1 += (*pScr1++ * *pIn2);  
      acc2 += (*pScr1++ * *pIn2);  
      acc3 += (*pScr1++ * *pIn2++);  
  
      pScr1 -= 3u;  
  
      /* Decrement the loop counter */  
      tapCnt--;  
    }  
  
    blkCnt--;  
  
  
    /* Store the results in the accumulators in the destination buffer. */  
  
#ifndef ARM_MATH_BIG_ENDIAN   
   
    *__SIMD32(pOut)++ =   
#ifdef CCS   
      __PKHBT(__SSATA(acc0, 15, 16), __SSATA(acc1, 15, 16), 16);   
  
    *__SIMD32(pOut)++ =   
      __PKHBT(__SSATA(acc2, 15, 16), __SSATA(acc3, 15, 16), 16);   
#else        
      __PKHBT(__SSAT((acc0 >> 15), 16), __SSAT((acc1 >> 15), 16), 16);   
  
    *__SIMD32(pOut)++ =   
      __PKHBT(__SSAT((acc2 >> 15), 16), __SSAT((acc3 >> 15), 16), 16);   
#endif   
   
#else   
   
    *__SIMD32(pOut)++ =   
#ifdef CCS       
      __PKHBT(__SSATA(acc1, 15, 16), __SSATA(acc0, 15, 16), 16);   
  
    *__SIMD32(pOut)++ =   
      __PKHBT(__SSATA(acc3, 15, 16), __SSATA(acc2, 15, 16), 16);   
#else       
      __PKHBT(__SSAT((acc1 >> 15), 16), __SSAT((acc0 >> 15), 16), 16);   
  
    *__SIMD32(pOut)++ =   
      __PKHBT(__SSAT((acc3 >> 15), 16), __SSAT((acc2 >> 15), 16), 16);   
   
#endif   
   
#endif /*      #ifndef ARM_MATH_BIG_ENDIAN       */   
  
    /* Initialization of inputB pointer */  
    pIn2 = py;  
  
    pScratch1 += 4u;  
  
  }  
  
  
  blkCnt = (srcALen + srcBLen - 1u) & 0x3;  
  
  /* Calculate convolution for remaining samples of Bigger length sequence */  
  while(blkCnt > 0)  
  {  
    /* Initialze temporary scratch pointer as scratch1 */  
    pScr1 = pScratch1;  
  
    /* Clear Accumlators */  
    acc0 = 0;  
      
    tapCnt = (srcBLen) >> 1u;  
  
    while(tapCnt > 0u)  
    {  
  
      /* Read next two samples from scratch1 buffer */  
      x1 = *__SIMD32(pScr1)++;  
        
      /* Read two samples from smaller buffer */  
      y1 = *__SIMD32(pIn2)++;   
        
      acc0 = __SMLAD(x1, y1, acc0);  
  
      /* Decrement the loop counter */  
      tapCnt--;  
    }  
  
    tapCnt = (srcBLen) & 1u;  
  
    /* apply same above for remaining samples of smaller length sequence */  
    while(tapCnt > 0u)  
    {  
  
      /* accumlate the results */  
      acc0 += (*pScr1++ * *pIn2++);  
  
      /* Decrement the loop counter */  
      tapCnt--;  
    }  
  
    blkCnt--;  
  
    /* The result is in 2.30 format.  Convert to 1.15 with saturation.     
     ** Then store the output in the destination buffer. */  
#ifdef CCS          
    *pOut++ = (q15_t) (__SSATA(acc0, 15, 16));     
#else   
    *pOut++ = (q15_t) (__SSAT((acc0 >> 15), 16));   
#endif   
  
  
    /* Initialization of inputB pointer */  
    pIn2 = py;  
  
    pScratch1 += 1u;  
  
  }      
     
}