/* ----------------------------------------------------------------------
* Copyright (C) 2010-2013 ARM Limited. All rights reserved.
*
* $Date: 17. January 2013
* $Revision: V1.4.1
*
* Project: CMSIS DSP Library
* Title: arm_correlate_opt_q7.c
*
* Description: Correlation of Q7 sequences.
*
* Target Processor: Cortex-M4/Cortex-M3
*
* 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"
/**
* @ingroup groupFilters
*/
/**
* @addtogroup Corr
* @{
*/
/**
* @brief Correlation of Q7 sequences.
* @param[in] *pSrcA points to the first input sequence.
* @param[in] srcALen length of the first input sequence.
* @param[in] *pSrcB points to the second input sequence.
* @param[in] srcBLen length of the second input sequence.
* @param[out] *pDst points to the location where the output result is written. Length 2 * max(srcALen, srcBLen) - 1.
* @param[in] *pScratch1 points to scratch buffer(of type q15_t) of size max(srcALen, srcBLen) + 2*min(srcALen, srcBLen) - 2.
* @param[in] *pScratch2 points to scratch buffer (of type q15_t) of size min(srcALen, srcBLen).
* @return none.
*
*
* \par Restrictions
* If the silicon does not support unaligned memory access enable the macro UNALIGNED_SUPPORT_DISABLE
* In this case input, output, scratch1 and scratch2 buffers should be aligned by 32-bit
*
* @details
* Scaling and Overflow Behavior:
*
* \par
* The function is implemented using a 32-bit internal accumulator.
* Both the inputs are represented in 1.7 format and multiplications yield a 2.14 result.
* The 2.14 intermediate results are accumulated in a 32-bit accumulator in 18.14 format.
* This approach provides 17 guard bits and there is no risk of overflow as long as max(srcALen, srcBLen)<131072.
* The 18.14 result is then truncated to 18.7 format by discarding the low 7 bits and saturated to 1.7 format.
*
*
*/
void arm_correlate_opt_q7(
q7_t * pSrcA,
uint32_t srcALen,
q7_t * pSrcB,
uint32_t srcBLen,
q7_t * pDst,
q15_t * pScratch1,
q15_t * pScratch2)
{
q7_t *pOut = pDst; /* output pointer */
q15_t *pScr1 = pScratch1; /* Temporary pointer for scratch */
q15_t *pScr2 = pScratch2; /* Temporary pointer for scratch */
q7_t *pIn1; /* inputA pointer */
q7_t *pIn2; /* inputB pointer */
q15_t *py; /* Intermediate inputB pointer */
q31_t acc0, acc1, acc2, acc3; /* Accumulators */
uint32_t j, k = 0u, blkCnt; /* loop counter */
int32_t inc = 1; /* output pointer increment */
uint32_t outBlockSize; /* loop counter */
q15_t x4; /* Temporary input variable */
uint32_t tapCnt; /* loop counter */
q31_t x1, x2, x3, y1; /* Temporary input variables */
/* 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 */
/* But CORR(x, y) is reverse of CORR(y, x) */
/* So, when srcBLen > srcALen, output pointer is made to point to the end of the output buffer */
/* and the destination pointer modifier, inc is set to -1 */
/* If srcALen > srcBLen, zero pad has to be done to srcB to make the two inputs of same length */
/* But to improve the performance,
* we include zeroes in the output instead of zero padding either of the the inputs*/
/* If srcALen > srcBLen,
* (srcALen - srcBLen) zeroes has to included in the starting of the output buffer */
/* If srcALen < srcBLen,
* (srcALen - srcBLen) zeroes has to included in the ending of the output buffer */
if(srcALen >= srcBLen)
{
/* Initialization of inputA pointer */
pIn1 = (pSrcA);
/* Initialization of inputB pointer */
pIn2 = (pSrcB);
/* Number of output samples is calculated */
outBlockSize = (2u * srcALen) - 1u;
/* When srcALen > srcBLen, zero padding is done to srcB
* to make their lengths equal.
* Instead, (outBlockSize - (srcALen + srcBLen - 1))
* number of output samples are made zero */
j = outBlockSize - (srcALen + (srcBLen - 1u));
/* Updating the pointer position to non zero value */
pOut += j;
}
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;
/* CORR(x, y) = Reverse order(CORR(y, x)) */
/* Hence set the destination pointer to point to the last output sample */
pOut = pDst + ((srcALen + srcBLen) - 2u);
/* Destination address modifier is set to -1 */
inc = -1;
}
/* Copy (srcBLen) samples in scratch buffer */
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. */
while(k > 0u)
{
/* copy second buffer in reversal manner */
x4 = (q15_t) * pIn2++;
*pScr2++ = x4;
x4 = (q15_t) * pIn2++;
*pScr2++ = x4;
x4 = (q15_t) * pIn2++;
*pScr2++ = x4;
x4 = (q15_t) * pIn2++;
*pScr2++ = x4;
/* 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 */
x4 = (q15_t) * pIn2++;
*pScr2++ = x4;
/* Decrement the loop counter */
k--;
}
/* Fill (srcBLen - 1u) zeros in scratch buffer */
arm_fill_q15(0, pScr1, (srcBLen - 1u));
/* Update temporary scratch pointer */
pScr1 += (srcBLen - 1u);
/* Copy (srcALen) samples in scratch buffer */
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 */
x4 = (q15_t) * pIn1++;
*pScr1++ = x4;
x4 = (q15_t) * pIn1++;
*pScr1++ = x4;
x4 = (q15_t) * pIn1++;
*pScr1++ = x4;
x4 = (q15_t) * pIn1++;
*pScr1++ = x4;
/* 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 */
x4 = (q15_t) * pIn1++;
*pScr1++ = x4;
/* Decrement the loop counter */
k--;
}
#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 /* #ifndef UNALIGNED_SUPPORT_DISABLE */
/* Temporary pointer for second sequence */
py = pScratch2;
/* Initialization of pScr2 pointer */
pScr2 = pScratch2;
/* Actual correlation 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(pScr2);
/* 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(pScr1)++;
/* 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);
/* Read four samples from smaller buffer */
y1 = _SIMD32_OFFSET(pScr2 + 2u);
acc0 = __SMLAD(x2, y1, acc0);
acc2 = __SMLAD(x1, y1, acc2);
acc1 = __SMLADX(x3, y1, acc1);
x2 = *__SIMD32(pScr1)++;
#ifndef ARM_MATH_BIG_ENDIAN
x3 = __PKHBT(x2, x1, 0);
#else
x3 = __PKHBT(x1, x2, 0);
#endif
acc3 = __SMLADX(x3, y1, acc3);
pScr2 += 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++ * *pScr2);
acc1 += (*pScr1++ * *pScr2);
acc2 += (*pScr1++ * *pScr2);
acc3 += (*pScr1++ * *pScr2++);
pScr1 -= 3u;
/* Decrement the loop counter */
tapCnt--;
}
blkCnt--;
/* Store the result in the accumulator in the destination buffer. */
*pOut = (q7_t) (__SSAT(acc0 >> 7u, 8));
pOut += inc;
*pOut = (q7_t) (__SSAT(acc1 >> 7u, 8));
pOut += inc;
*pOut = (q7_t) (__SSAT(acc2 >> 7u, 8));
pOut += inc;
*pOut = (q7_t) (__SSAT(acc3 >> 7u, 8));
pOut += inc;
/* Initialization of inputB pointer */
pScr2 = py;
pScratch1 += 4u;
}
blkCnt = (srcALen + srcBLen - 1u) & 0x3;
/* Calculate correlation 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)
{
acc0 += (*pScr1++ * *pScr2++);
acc0 += (*pScr1++ * *pScr2++);
/* 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++ * *pScr2++);
/* Decrement the loop counter */
tapCnt--;
}
blkCnt--;
/* Store the result in the accumulator in the destination buffer. */
*pOut = (q7_t) (__SSAT(acc0 >> 7u, 8));
pOut += inc;
/* Initialization of inputB pointer */
pScr2 = py;
pScratch1 += 1u;
}
}
/**
* @} end of Corr group
*/