+++ /dev/null
-/* ----------------------------------------------------------------------
-* Copyright (C) 2010-2013 ARM Limited. All rights reserved.
-*
-* $Date: 17. January 2013
-* $Revision: V1.4.1
-*
-* Project: CMSIS DSP Library
-* Title: arm_correlate_fast_q31.c
-*
-* Description: Fast Q31 Correlation.
-*
-* 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 Q31 sequences (fast version) for Cortex-M3 and Cortex-M4.
- * @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.
- * @return none.
- *
- * @details
- * <b>Scaling and Overflow Behavior:</b>
- *
- * \par
- * This function is optimized for speed at the expense of fixed-point precision and overflow protection.
- * The result of each 1.31 x 1.31 multiplication is truncated to 2.30 format.
- * These intermediate results are accumulated in a 32-bit register in 2.30 format.
- * Finally, the accumulator is saturated and converted to a 1.31 result.
- *
- * \par
- * The fast version has the same overflow behavior as the standard version but provides less precision since it discards the low 32 bits of each multiplication result.
- * In order to avoid overflows completely the input signals must be scaled down.
- * The input signals should be scaled down to avoid intermediate overflows.
- * Scale down one of the inputs by 1/min(srcALen, srcBLen)to avoid overflows since a
- * maximum of min(srcALen, srcBLen) number of additions is carried internally.
- *
- * \par
- * See <code>arm_correlate_q31()</code> for a slower implementation of this function which uses 64-bit accumulation to provide higher precision.
- */
-
-void arm_correlate_fast_q31(
- q31_t * pSrcA,
- uint32_t srcALen,
- q31_t * pSrcB,
- uint32_t srcBLen,
- q31_t * pDst)
-{
- q31_t *pIn1; /* inputA pointer */
- q31_t *pIn2; /* inputB pointer */
- q31_t *pOut = pDst; /* output pointer */
- q31_t *px; /* Intermediate inputA pointer */
- q31_t *py; /* Intermediate inputB pointer */
- q31_t *pSrc1; /* Intermediate pointers */
- q31_t sum, acc0, acc1, acc2, acc3; /* Accumulators */
- q31_t x0, x1, x2, x3, c0; /* temporary variables for holding input and coefficient values */
- uint32_t j, k = 0u, count, blkCnt, outBlockSize, blockSize1, blockSize2, blockSize3; /* loop counter */
- int32_t inc = 1; /* Destination address modifier */
-
-
- /* 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);
-
- /* 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;
-
- }
-
- /* The function is internally
- * divided into three parts according to the number of multiplications that has to be
- * taken place between inputA samples and inputB samples. In the first part of the
- * algorithm, the multiplications increase by one for every iteration.
- * In the second part of the algorithm, srcBLen number of multiplications are done.
- * In the third part of the algorithm, the multiplications decrease by one
- * for every iteration.*/
- /* The algorithm is implemented in three stages.
- * The loop counters of each stage is initiated here. */
- blockSize1 = srcBLen - 1u;
- blockSize2 = srcALen - (srcBLen - 1u);
- blockSize3 = blockSize1;
-
- /* --------------------------
- * Initializations of stage1
- * -------------------------*/
-
- /* sum = x[0] * y[srcBlen - 1]
- * sum = x[0] * y[srcBlen - 2] + x[1] * y[srcBlen - 1]
- * ....
- * sum = x[0] * y[0] + x[1] * y[1] +...+ x[srcBLen - 1] * y[srcBLen - 1]
- */
-
- /* In this stage the MAC operations are increased by 1 for every iteration.
- The count variable holds the number of MAC operations performed */
- count = 1u;
-
- /* Working pointer of inputA */
- px = pIn1;
-
- /* Working pointer of inputB */
- pSrc1 = pIn2 + (srcBLen - 1u);
- py = pSrc1;
-
- /* ------------------------
- * Stage1 process
- * ----------------------*/
-
- /* The first stage starts here */
- while(blockSize1 > 0u)
- {
- /* Accumulator is made zero for every iteration */
- sum = 0;
-
- /* Apply loop unrolling and compute 4 MACs simultaneously. */
- k = count >> 2;
-
- /* First part of the processing with loop unrolling. Compute 4 MACs at a time.
- ** a second loop below computes MACs for the remaining 1 to 3 samples. */
- while(k > 0u)
- {
- /* x[0] * y[srcBLen - 4] */
- sum = (q31_t) ((((q63_t) sum << 32) +
- ((q63_t) * px++ * (*py++))) >> 32);
- /* x[1] * y[srcBLen - 3] */
- sum = (q31_t) ((((q63_t) sum << 32) +
- ((q63_t) * px++ * (*py++))) >> 32);
- /* x[2] * y[srcBLen - 2] */
- sum = (q31_t) ((((q63_t) sum << 32) +
- ((q63_t) * px++ * (*py++))) >> 32);
- /* x[3] * y[srcBLen - 1] */
- sum = (q31_t) ((((q63_t) sum << 32) +
- ((q63_t) * px++ * (*py++))) >> 32);
-
- /* Decrement the loop counter */
- k--;
- }
-
- /* If the count is not a multiple of 4, compute any remaining MACs here.
- ** No loop unrolling is used. */
- k = count % 0x4u;
-
- while(k > 0u)
- {
- /* Perform the multiply-accumulates */
- /* x[0] * y[srcBLen - 1] */
- sum = (q31_t) ((((q63_t) sum << 32) +
- ((q63_t) * px++ * (*py++))) >> 32);
-
- /* Decrement the loop counter */
- k--;
- }
-
- /* Store the result in the accumulator in the destination buffer. */
- *pOut = sum << 1;
- /* Destination pointer is updated according to the address modifier, inc */
- pOut += inc;
-
- /* Update the inputA and inputB pointers for next MAC calculation */
- py = pSrc1 - count;
- px = pIn1;
-
- /* Increment the MAC count */
- count++;
-
- /* Decrement the loop counter */
- blockSize1--;
- }
-
- /* --------------------------
- * Initializations of stage2
- * ------------------------*/
-
- /* sum = x[0] * y[0] + x[1] * y[1] +...+ x[srcBLen-1] * y[srcBLen-1]
- * sum = x[1] * y[0] + x[2] * y[1] +...+ x[srcBLen] * y[srcBLen-1]
- * ....
- * sum = x[srcALen-srcBLen-2] * y[0] + x[srcALen-srcBLen-1] * y[1] +...+ x[srcALen-1] * y[srcBLen-1]
- */
-
- /* Working pointer of inputA */
- px = pIn1;
-
- /* Working pointer of inputB */
- py = pIn2;
-
- /* count is index by which the pointer pIn1 to be incremented */
- count = 0u;
-
- /* -------------------
- * Stage2 process
- * ------------------*/
-
- /* Stage2 depends on srcBLen as in this stage srcBLen number of MACS are performed.
- * So, to loop unroll over blockSize2,
- * srcBLen should be greater than or equal to 4 */
- if(srcBLen >= 4u)
- {
- /* Loop unroll over blockSize2, by 4 */
- blkCnt = blockSize2 >> 2u;
-
- while(blkCnt > 0u)
- {
- /* Set all accumulators to zero */
- acc0 = 0;
- acc1 = 0;
- acc2 = 0;
- acc3 = 0;
-
- /* read x[0], x[1], x[2] samples */
- x0 = *(px++);
- x1 = *(px++);
- x2 = *(px++);
-
- /* Apply loop unrolling and compute 4 MACs simultaneously. */
- k = srcBLen >> 2u;
-
- /* First part of the processing with loop unrolling. Compute 4 MACs at a time.
- ** a second loop below computes MACs for the remaining 1 to 3 samples. */
- do
- {
- /* Read y[0] sample */
- c0 = *(py++);
-
- /* Read x[3] sample */
- x3 = *(px++);
-
- /* Perform the multiply-accumulate */
- /* acc0 += x[0] * y[0] */
- acc0 = (q31_t) ((((q63_t) acc0 << 32) + ((q63_t) x0 * c0)) >> 32);
- /* acc1 += x[1] * y[0] */
- acc1 = (q31_t) ((((q63_t) acc1 << 32) + ((q63_t) x1 * c0)) >> 32);
- /* acc2 += x[2] * y[0] */
- acc2 = (q31_t) ((((q63_t) acc2 << 32) + ((q63_t) x2 * c0)) >> 32);
- /* acc3 += x[3] * y[0] */
- acc3 = (q31_t) ((((q63_t) acc3 << 32) + ((q63_t) x3 * c0)) >> 32);
-
- /* Read y[1] sample */
- c0 = *(py++);
-
- /* Read x[4] sample */
- x0 = *(px++);
-
- /* Perform the multiply-accumulates */
- /* acc0 += x[1] * y[1] */
- acc0 = (q31_t) ((((q63_t) acc0 << 32) + ((q63_t) x1 * c0)) >> 32);
- /* acc1 += x[2] * y[1] */
- acc1 = (q31_t) ((((q63_t) acc1 << 32) + ((q63_t) x2 * c0)) >> 32);
- /* acc2 += x[3] * y[1] */
- acc2 = (q31_t) ((((q63_t) acc2 << 32) + ((q63_t) x3 * c0)) >> 32);
- /* acc3 += x[4] * y[1] */
- acc3 = (q31_t) ((((q63_t) acc3 << 32) + ((q63_t) x0 * c0)) >> 32);
-
- /* Read y[2] sample */
- c0 = *(py++);
-
- /* Read x[5] sample */
- x1 = *(px++);
-
- /* Perform the multiply-accumulates */
- /* acc0 += x[2] * y[2] */
- acc0 = (q31_t) ((((q63_t) acc0 << 32) + ((q63_t) x2 * c0)) >> 32);
- /* acc1 += x[3] * y[2] */
- acc1 = (q31_t) ((((q63_t) acc1 << 32) + ((q63_t) x3 * c0)) >> 32);
- /* acc2 += x[4] * y[2] */
- acc2 = (q31_t) ((((q63_t) acc2 << 32) + ((q63_t) x0 * c0)) >> 32);
- /* acc3 += x[5] * y[2] */
- acc3 = (q31_t) ((((q63_t) acc3 << 32) + ((q63_t) x1 * c0)) >> 32);
-
- /* Read y[3] sample */
- c0 = *(py++);
-
- /* Read x[6] sample */
- x2 = *(px++);
-
- /* Perform the multiply-accumulates */
- /* acc0 += x[3] * y[3] */
- acc0 = (q31_t) ((((q63_t) acc0 << 32) + ((q63_t) x3 * c0)) >> 32);
- /* acc1 += x[4] * y[3] */
- acc1 = (q31_t) ((((q63_t) acc1 << 32) + ((q63_t) x0 * c0)) >> 32);
- /* acc2 += x[5] * y[3] */
- acc2 = (q31_t) ((((q63_t) acc2 << 32) + ((q63_t) x1 * c0)) >> 32);
- /* acc3 += x[6] * y[3] */
- acc3 = (q31_t) ((((q63_t) acc3 << 32) + ((q63_t) x2 * c0)) >> 32);
-
-
- } while(--k);
-
- /* If the srcBLen is not a multiple of 4, compute any remaining MACs here.
- ** No loop unrolling is used. */
- k = srcBLen % 0x4u;
-
- while(k > 0u)
- {
- /* Read y[4] sample */
- c0 = *(py++);
-
- /* Read x[7] sample */
- x3 = *(px++);
-
- /* Perform the multiply-accumulates */
- /* acc0 += x[4] * y[4] */
- acc0 = (q31_t) ((((q63_t) acc0 << 32) + ((q63_t) x0 * c0)) >> 32);
- /* acc1 += x[5] * y[4] */
- acc1 = (q31_t) ((((q63_t) acc1 << 32) + ((q63_t) x1 * c0)) >> 32);
- /* acc2 += x[6] * y[4] */
- acc2 = (q31_t) ((((q63_t) acc2 << 32) + ((q63_t) x2 * c0)) >> 32);
- /* acc3 += x[7] * y[4] */
- acc3 = (q31_t) ((((q63_t) acc3 << 32) + ((q63_t) x3 * c0)) >> 32);
-
- /* Reuse the present samples for the next MAC */
- x0 = x1;
- x1 = x2;
- x2 = x3;
-
- /* Decrement the loop counter */
- k--;
- }
-
- /* Store the result in the accumulator in the destination buffer. */
- *pOut = (q31_t) (acc0 << 1);
- /* Destination pointer is updated according to the address modifier, inc */
- pOut += inc;
-
- *pOut = (q31_t) (acc1 << 1);
- pOut += inc;
-
- *pOut = (q31_t) (acc2 << 1);
- pOut += inc;
-
- *pOut = (q31_t) (acc3 << 1);
- pOut += inc;
-
- /* Increment the pointer pIn1 index, count by 4 */
- count += 4u;
-
- /* Update the inputA and inputB pointers for next MAC calculation */
- px = pIn1 + count;
- py = pIn2;
-
-
- /* Decrement the loop counter */
- blkCnt--;
- }
-
- /* If the blockSize2 is not a multiple of 4, compute any remaining output samples here.
- ** No loop unrolling is used. */
- blkCnt = blockSize2 % 0x4u;
-
- while(blkCnt > 0u)
- {
- /* Accumulator is made zero for every iteration */
- sum = 0;
-
- /* Apply loop unrolling and compute 4 MACs simultaneously. */
- k = srcBLen >> 2u;
-
- /* First part of the processing with loop unrolling. Compute 4 MACs at a time.
- ** a second loop below computes MACs for the remaining 1 to 3 samples. */
- while(k > 0u)
- {
- /* Perform the multiply-accumulates */
- sum = (q31_t) ((((q63_t) sum << 32) +
- ((q63_t) * px++ * (*py++))) >> 32);
- sum = (q31_t) ((((q63_t) sum << 32) +
- ((q63_t) * px++ * (*py++))) >> 32);
- sum = (q31_t) ((((q63_t) sum << 32) +
- ((q63_t) * px++ * (*py++))) >> 32);
- sum = (q31_t) ((((q63_t) sum << 32) +
- ((q63_t) * px++ * (*py++))) >> 32);
-
- /* Decrement the loop counter */
- k--;
- }
-
- /* If the srcBLen is not a multiple of 4, compute any remaining MACs here.
- ** No loop unrolling is used. */
- k = srcBLen % 0x4u;
-
- while(k > 0u)
- {
- /* Perform the multiply-accumulate */
- sum = (q31_t) ((((q63_t) sum << 32) +
- ((q63_t) * px++ * (*py++))) >> 32);
-
- /* Decrement the loop counter */
- k--;
- }
-
- /* Store the result in the accumulator in the destination buffer. */
- *pOut = sum << 1;
- /* Destination pointer is updated according to the address modifier, inc */
- pOut += inc;
-
- /* Increment the MAC count */
- count++;
-
- /* Update the inputA and inputB pointers for next MAC calculation */
- px = pIn1 + count;
- py = pIn2;
-
-
- /* Decrement the loop counter */
- blkCnt--;
- }
- }
- else
- {
- /* If the srcBLen is not a multiple of 4,
- * the blockSize2 loop cannot be unrolled by 4 */
- blkCnt = blockSize2;
-
- while(blkCnt > 0u)
- {
- /* Accumulator is made zero for every iteration */
- sum = 0;
-
- /* Loop over srcBLen */
- k = srcBLen;
-
- while(k > 0u)
- {
- /* Perform the multiply-accumulate */
- sum = (q31_t) ((((q63_t) sum << 32) +
- ((q63_t) * px++ * (*py++))) >> 32);
-
- /* Decrement the loop counter */
- k--;
- }
-
- /* Store the result in the accumulator in the destination buffer. */
- *pOut = sum << 1;
- /* Destination pointer is updated according to the address modifier, inc */
- pOut += inc;
-
- /* Increment the MAC count */
- count++;
-
- /* Update the inputA and inputB pointers for next MAC calculation */
- px = pIn1 + count;
- py = pIn2;
-
- /* Decrement the loop counter */
- blkCnt--;
- }
- }
-
- /* --------------------------
- * Initializations of stage3
- * -------------------------*/
-
- /* sum += x[srcALen-srcBLen+1] * y[0] + x[srcALen-srcBLen+2] * y[1] +...+ x[srcALen-1] * y[srcBLen-1]
- * sum += x[srcALen-srcBLen+2] * y[0] + x[srcALen-srcBLen+3] * y[1] +...+ x[srcALen-1] * y[srcBLen-1]
- * ....
- * sum += x[srcALen-2] * y[0] + x[srcALen-1] * y[1]
- * sum += x[srcALen-1] * y[0]
- */
-
- /* In this stage the MAC operations are decreased by 1 for every iteration.
- The count variable holds the number of MAC operations performed */
- count = srcBLen - 1u;
-
- /* Working pointer of inputA */
- pSrc1 = ((pIn1 + srcALen) - srcBLen) + 1u;
- px = pSrc1;
-
- /* Working pointer of inputB */
- py = pIn2;
-
- /* -------------------
- * Stage3 process
- * ------------------*/
-
- while(blockSize3 > 0u)
- {
- /* Accumulator is made zero for every iteration */
- sum = 0;
-
- /* Apply loop unrolling and compute 4 MACs simultaneously. */
- k = count >> 2u;
-
- /* First part of the processing with loop unrolling. Compute 4 MACs at a time.
- ** a second loop below computes MACs for the remaining 1 to 3 samples. */
- while(k > 0u)
- {
- /* Perform the multiply-accumulates */
- /* sum += x[srcALen - srcBLen + 4] * y[3] */
- sum = (q31_t) ((((q63_t) sum << 32) +
- ((q63_t) * px++ * (*py++))) >> 32);
- /* sum += x[srcALen - srcBLen + 3] * y[2] */
- sum = (q31_t) ((((q63_t) sum << 32) +
- ((q63_t) * px++ * (*py++))) >> 32);
- /* sum += x[srcALen - srcBLen + 2] * y[1] */
- sum = (q31_t) ((((q63_t) sum << 32) +
- ((q63_t) * px++ * (*py++))) >> 32);
- /* sum += x[srcALen - srcBLen + 1] * y[0] */
- sum = (q31_t) ((((q63_t) sum << 32) +
- ((q63_t) * px++ * (*py++))) >> 32);
-
- /* Decrement the loop counter */
- k--;
- }
-
- /* If the count is not a multiple of 4, compute any remaining MACs here.
- ** No loop unrolling is used. */
- k = count % 0x4u;
-
- while(k > 0u)
- {
- /* Perform the multiply-accumulates */
- sum = (q31_t) ((((q63_t) sum << 32) +
- ((q63_t) * px++ * (*py++))) >> 32);
-
- /* Decrement the loop counter */
- k--;
- }
-
- /* Store the result in the accumulator in the destination buffer. */
- *pOut = sum << 1;
- /* Destination pointer is updated according to the address modifier, inc */
- pOut += inc;
-
- /* Update the inputA and inputB pointers for next MAC calculation */
- px = ++pSrc1;
- py = pIn2;
-
- /* Decrement the MAC count */
- count--;
-
- /* Decrement the loop counter */
- blockSize3--;
- }
-
-}
-
-/**
- * @} end of Corr group
- */
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