/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_correlate_opt_q7.c
* Description: Correlation of Q7 sequences
*
* $Date: 27. January 2017
* $Revision: V.1.5.1
*
* Target Processor: Cortex-M cores
* -------------------------------------------------------------------- */
/*
* Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
*
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the License); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an AS IS BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#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
*/