/* ----------------------------------------------------------------------
* 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_q15.c
*
* Description: Correlation of Q15 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 Q15 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] *pScratch points to scratch buffer of size max(srcALen, srcBLen) + 2*min(srcALen, srcBLen) - 2.
* @return none.
*
* \par Restrictions
* If the silicon does not support unaligned memory access enable the macro UNALIGNED_SUPPORT_DISABLE
* In this case input, output, scratch buffers should be aligned by 32-bit
*
* @details
* Scaling and Overflow Behavior:
*
* \par
* The function is implemented using a 64-bit internal accumulator.
* Both inputs are in 1.15 format and multiplications yield a 2.30 result.
* The 2.30 intermediate results are accumulated in a 64-bit accumulator in 34.30 format.
* This approach provides 33 guard bits and there is no risk of overflow.
* The 34.30 result is then truncated to 34.15 format by discarding the low 15 bits and then saturated to 1.15 format.
*
* \par
* Refer to arm_correlate_fast_q15() for a faster but less precise version of this function for Cortex-M3 and Cortex-M4.
*
*
*/
void arm_correlate_opt_q15(
q15_t * pSrcA,
uint32_t srcALen,
q15_t * pSrcB,
uint32_t srcBLen,
q15_t * pDst,
q15_t * pScratch)
{
q15_t *pIn1; /* inputA pointer */
q15_t *pIn2; /* inputB pointer */
q63_t acc0, acc1, acc2, acc3; /* Accumulators */
q15_t *py; /* Intermediate inputB pointer */
q31_t x1, x2, x3; /* temporary variables for holding input1 and input2 values */
uint32_t j, blkCnt, outBlockSize; /* loop counter */
int32_t inc = 1; /* output pointer increment */
uint32_t tapCnt;
q31_t y1, y2;
q15_t *pScr; /* Intermediate pointers */
q15_t *pOut = pDst; /* output pointer */
#ifdef UNALIGNED_SUPPORT_DISABLE
q15_t a, b;
#endif /* #ifndef UNALIGNED_SUPPORT_DISABLE */
/* 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;
}
pScr = pScratch;
/* Fill (srcBLen - 1u) zeros in scratch buffer */
arm_fill_q15(0, pScr, (srcBLen - 1u));
/* Update temporary scratch pointer */
pScr += (srcBLen - 1u);
#ifndef UNALIGNED_SUPPORT_DISABLE
/* Copy (srcALen) samples in scratch buffer */
arm_copy_q15(pIn1, pScr, srcALen);
/* Update pointers */
//pIn1 += srcALen;
pScr += srcALen;
#else
/* Apply loop unrolling and do 4 Copies simultaneously. */
j = 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(j > 0u)
{
/* copy second buffer in reversal manner */
*pScr++ = *pIn1++;
*pScr++ = *pIn1++;
*pScr++ = *pIn1++;
*pScr++ = *pIn1++;
/* Decrement the loop counter */
j--;
}
/* If the count is not a multiple of 4, copy remaining samples here.
** No loop unrolling is used. */
j = srcALen % 0x4u;
while(j > 0u)
{
/* copy second buffer in reversal manner for remaining samples */
*pScr++ = *pIn1++;
/* Decrement the loop counter */
j--;
}
#endif /* #ifndef UNALIGNED_SUPPORT_DISABLE */
#ifndef UNALIGNED_SUPPORT_DISABLE
/* Fill (srcBLen - 1u) zeros at end of scratch buffer */
arm_fill_q15(0, pScr, (srcBLen - 1u));
/* Update pointer */
pScr += (srcBLen - 1u);
#else
/* Apply loop unrolling and do 4 Copies simultaneously. */
j = (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(j > 0u)
{
/* copy second buffer in reversal manner */
*pScr++ = 0;
*pScr++ = 0;
*pScr++ = 0;
*pScr++ = 0;
/* Decrement the loop counter */
j--;
}
/* If the count is not a multiple of 4, copy remaining samples here.
** No loop unrolling is used. */
j = (srcBLen - 1u) % 0x4u;
while(j > 0u)
{
/* copy second buffer in reversal manner for remaining samples */
*pScr++ = 0;
/* Decrement the loop counter */
j--;
}
#endif /* #ifndef UNALIGNED_SUPPORT_DISABLE */
/* Temporary pointer for scratch2 */
py = pIn2;
/* Actual correlation process starts here */
blkCnt = (srcALen + srcBLen - 1u) >> 2;
while(blkCnt > 0)
{
/* Initialze temporary scratch pointer as scratch1 */
pScr = pScratch;
/* Clear Accumlators */
acc0 = 0;
acc1 = 0;
acc2 = 0;
acc3 = 0;
/* Read four samples from scratch1 buffer */
x1 = *__SIMD32(pScr)++;
/* Read next four samples from scratch1 buffer */
x2 = *__SIMD32(pScr)++;
tapCnt = (srcBLen) >> 2u;
while(tapCnt > 0u)
{
#ifndef UNALIGNED_SUPPORT_DISABLE
/* Read four samples from smaller buffer */
y1 = _SIMD32_OFFSET(pIn2);
y2 = _SIMD32_OFFSET(pIn2 + 2u);
acc0 = __SMLALD(x1, y1, acc0);
acc2 = __SMLALD(x2, y1, acc2);
#ifndef ARM_MATH_BIG_ENDIAN
x3 = __PKHBT(x2, x1, 0);
#else
x3 = __PKHBT(x1, x2, 0);
#endif
acc1 = __SMLALDX(x3, y1, acc1);
x1 = _SIMD32_OFFSET(pScr);
acc0 = __SMLALD(x2, y2, acc0);
acc2 = __SMLALD(x1, y2, acc2);
#ifndef ARM_MATH_BIG_ENDIAN
x3 = __PKHBT(x1, x2, 0);
#else
x3 = __PKHBT(x2, x1, 0);
#endif
acc3 = __SMLALDX(x3, y1, acc3);
acc1 = __SMLALDX(x3, y2, acc1);
x2 = _SIMD32_OFFSET(pScr + 2u);
#ifndef ARM_MATH_BIG_ENDIAN
x3 = __PKHBT(x2, x1, 0);
#else
x3 = __PKHBT(x1, x2, 0);
#endif
acc3 = __SMLALDX(x3, y2, acc3);
#else
/* Read four samples from smaller buffer */
a = *pIn2;
b = *(pIn2 + 1);
#ifndef ARM_MATH_BIG_ENDIAN
y1 = __PKHBT(a, b, 16);
#else
y1 = __PKHBT(b, a, 16);
#endif
a = *(pIn2 + 2);
b = *(pIn2 + 3);
#ifndef ARM_MATH_BIG_ENDIAN
y2 = __PKHBT(a, b, 16);
#else
y2 = __PKHBT(b, a, 16);
#endif
acc0 = __SMLALD(x1, y1, acc0);
acc2 = __SMLALD(x2, y1, acc2);
#ifndef ARM_MATH_BIG_ENDIAN
x3 = __PKHBT(x2, x1, 0);
#else
x3 = __PKHBT(x1, x2, 0);
#endif
acc1 = __SMLALDX(x3, y1, acc1);
a = *pScr;
b = *(pScr + 1);
#ifndef ARM_MATH_BIG_ENDIAN
x1 = __PKHBT(a, b, 16);
#else
x1 = __PKHBT(b, a, 16);
#endif
acc0 = __SMLALD(x2, y2, acc0);
acc2 = __SMLALD(x1, y2, acc2);
#ifndef ARM_MATH_BIG_ENDIAN
x3 = __PKHBT(x1, x2, 0);
#else
x3 = __PKHBT(x2, x1, 0);
#endif
acc3 = __SMLALDX(x3, y1, acc3);
acc1 = __SMLALDX(x3, y2, acc1);
a = *(pScr + 2);
b = *(pScr + 3);
#ifndef ARM_MATH_BIG_ENDIAN
x2 = __PKHBT(a, b, 16);
#else
x2 = __PKHBT(b, a, 16);
#endif
#ifndef ARM_MATH_BIG_ENDIAN
x3 = __PKHBT(x2, x1, 0);
#else
x3 = __PKHBT(x1, x2, 0);
#endif
acc3 = __SMLALDX(x3, y2, acc3);
#endif /* #ifndef UNALIGNED_SUPPORT_DISABLE */
pIn2 += 4u;
pScr += 4u;
/* Decrement the loop counter */
tapCnt--;
}
/* Update scratch pointer for remaining samples of smaller length sequence */
pScr -= 4u;
/* apply same above for remaining samples of smaller length sequence */
tapCnt = (srcBLen) & 3u;
while(tapCnt > 0u)
{
/* accumlate the results */
acc0 += (*pScr++ * *pIn2);
acc1 += (*pScr++ * *pIn2);
acc2 += (*pScr++ * *pIn2);
acc3 += (*pScr++ * *pIn2++);
pScr -= 3u;
/* Decrement the loop counter */
tapCnt--;
}
blkCnt--;
/* Store the results in the accumulators in the destination buffer. */
*pOut = (__SSAT(acc0 >> 15u, 16));
pOut += inc;
*pOut = (__SSAT(acc1 >> 15u, 16));
pOut += inc;
*pOut = (__SSAT(acc2 >> 15u, 16));
pOut += inc;
*pOut = (__SSAT(acc3 >> 15u, 16));
pOut += inc;
/* Initialization of inputB pointer */
pIn2 = py;
pScratch += 4u;
}
blkCnt = (srcALen + srcBLen - 1u) & 0x3;
/* Calculate correlation for remaining samples of Bigger length sequence */
while(blkCnt > 0)
{
/* Initialze temporary scratch pointer as scratch1 */
pScr = pScratch;
/* Clear Accumlators */
acc0 = 0;
tapCnt = (srcBLen) >> 1u;
while(tapCnt > 0u)
{
acc0 += (*pScr++ * *pIn2++);
acc0 += (*pScr++ * *pIn2++);
/* 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 += (*pScr++ * *pIn2++);
/* Decrement the loop counter */
tapCnt--;
}
blkCnt--;
/* Store the result in the accumulator in the destination buffer. */
*pOut = (q15_t) (__SSAT((acc0 >> 15), 16));
pOut += inc;
/* Initialization of inputB pointer */
pIn2 = py;
pScratch += 1u;
}
}
/**
* @} end of Corr group
*/