Eli Hughes
V4.0.1 of the ARM CMSIS DSP libraries. Note that arm_bitreversal2.s, arm_cfft_f32.c and arm_rfft_fast_f32.c had to be removed. arm_bitreversal2.s will not assemble with the online tools. So, the fast f32 FFT functions are not yet available. All the other FFT functions are available.
Dependents: MPU9150_Example fir_f32 fir_f32 MPU9150_nucleo_noni2cdev ... more
Diff: FilteringFunctions/arm_correlate_fast_q15.c
- Revision:
- 0:3d9c67d97d6f
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/FilteringFunctions/arm_correlate_fast_q15.c Mon Jul 28 15:03:15 2014 +0000
@@ -0,0 +1,1319 @@
+/* ----------------------------------------------------------------------
+* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
+*
+* $Date: 12. March 2014
+* $Revision: V1.4.3
+*
+* Project: CMSIS DSP Library
+* Title: arm_correlate_fast_q15.c
+*
+* Description: Fast Q15 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 Q15 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.
+ *
+ * <b>Scaling and Overflow Behavior:</b>
+ *
+ * \par
+ * This fast version uses a 32-bit accumulator with 2.30 format.
+ * The accumulator maintains full precision of the intermediate multiplication results but provides only a single guard bit.
+ * There is no saturation on intermediate additions.
+ * Thus, if the accumulator overflows it wraps around and distorts the result.
+ * The input signals should be scaled down to avoid intermediate overflows.
+ * Scale down one of the inputs by 1/min(srcALen, srcBLen) to avoid overflow since a
+ * maximum of min(srcALen, srcBLen) number of additions is carried internally.
+ * The 2.30 accumulator is right shifted by 15 bits and then saturated to 1.15 format to yield the final result.
+ *
+ * \par
+ * See <code>arm_correlate_q15()</code> for a slower implementation of this function which uses a 64-bit accumulator to avoid wrap around distortion.
+ */
+
+void arm_correlate_fast_q15(
+ q15_t * pSrcA,
+ uint32_t srcALen,
+ q15_t * pSrcB,
+ uint32_t srcBLen,
+ q15_t * pDst)
+{
+#ifndef UNALIGNED_SUPPORT_DISABLE
+
+ q15_t *pIn1; /* inputA pointer */
+ q15_t *pIn2; /* inputB pointer */
+ q15_t *pOut = pDst; /* output pointer */
+ q31_t sum, acc0, acc1, acc2, acc3; /* Accumulators */
+ q15_t *px; /* Intermediate inputA pointer */
+ q15_t *py; /* Intermediate inputB pointer */
+ q15_t *pSrc1; /* Intermediate pointers */
+ 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 */
+ /* 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;
+
+ }
+
+ /* 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 loop 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] , x[1] * y[srcBLen - 3] */
+ sum = __SMLAD(*__SIMD32(px)++, *__SIMD32(py)++, sum);
+ /* x[3] * y[srcBLen - 1] , x[2] * y[srcBLen - 2] */
+ sum = __SMLAD(*__SIMD32(px)++, *__SIMD32(py)++, sum);
+
+ /* 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 = __SMLAD(*px++, *py++, sum);
+
+ /* Decrement the loop counter */
+ k--;
+ }
+
+ /* Store the result in the accumulator in the destination buffer. */
+ *pOut = (q15_t) (sum >> 15);
+ /* 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, to loop unroll the srcBLen loop */
+ 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] samples */
+ x0 = *__SIMD32(px);
+ /* read x[1], x[2] samples */
+ x1 = _SIMD32_OFFSET(px + 1);
+ px += 2u;
+
+ /* 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 the first two inputB samples using SIMD:
+ * y[0] and y[1] */
+ c0 = *__SIMD32(py)++;
+
+ /* acc0 += x[0] * y[0] + x[1] * y[1] */
+ acc0 = __SMLAD(x0, c0, acc0);
+
+ /* acc1 += x[1] * y[0] + x[2] * y[1] */
+ acc1 = __SMLAD(x1, c0, acc1);
+
+ /* Read x[2], x[3] */
+ x2 = *__SIMD32(px);
+
+ /* Read x[3], x[4] */
+ x3 = _SIMD32_OFFSET(px + 1);
+
+ /* acc2 += x[2] * y[0] + x[3] * y[1] */
+ acc2 = __SMLAD(x2, c0, acc2);
+
+ /* acc3 += x[3] * y[0] + x[4] * y[1] */
+ acc3 = __SMLAD(x3, c0, acc3);
+
+ /* Read y[2] and y[3] */
+ c0 = *__SIMD32(py)++;
+
+ /* acc0 += x[2] * y[2] + x[3] * y[3] */
+ acc0 = __SMLAD(x2, c0, acc0);
+
+ /* acc1 += x[3] * y[2] + x[4] * y[3] */
+ acc1 = __SMLAD(x3, c0, acc1);
+
+ /* Read x[4], x[5] */
+ x0 = _SIMD32_OFFSET(px + 2);
+
+ /* Read x[5], x[6] */
+ x1 = _SIMD32_OFFSET(px + 3);
+ px += 4u;
+
+ /* acc2 += x[4] * y[2] + x[5] * y[3] */
+ acc2 = __SMLAD(x0, c0, acc2);
+
+ /* acc3 += x[5] * y[2] + x[6] * y[3] */
+ acc3 = __SMLAD(x1, c0, acc3);
+
+ } while(--k);
+
+ /* For the next MAC operations, SIMD is not used
+ * So, the 16 bit pointer if inputB, py is updated */
+
+ /* If the srcBLen is not a multiple of 4, compute any remaining MACs here.
+ ** No loop unrolling is used. */
+ k = srcBLen % 0x4u;
+
+ if(k == 1u)
+ {
+ /* Read y[4] */
+ c0 = *py;
+#ifdef ARM_MATH_BIG_ENDIAN
+
+ c0 = c0 << 16u;
+
+#else
+
+ c0 = c0 & 0x0000FFFF;
+
+#endif /* #ifdef ARM_MATH_BIG_ENDIAN */
+
+ /* Read x[7] */
+ x3 = *__SIMD32(px);
+ px++;
+
+ /* Perform the multiply-accumulates */
+ acc0 = __SMLAD(x0, c0, acc0);
+ acc1 = __SMLAD(x1, c0, acc1);
+ acc2 = __SMLADX(x1, c0, acc2);
+ acc3 = __SMLADX(x3, c0, acc3);
+ }
+
+ if(k == 2u)
+ {
+ /* Read y[4], y[5] */
+ c0 = *__SIMD32(py);
+
+ /* Read x[7], x[8] */
+ x3 = *__SIMD32(px);
+
+ /* Read x[9] */
+ x2 = _SIMD32_OFFSET(px + 1);
+ px += 2u;
+
+ /* Perform the multiply-accumulates */
+ acc0 = __SMLAD(x0, c0, acc0);
+ acc1 = __SMLAD(x1, c0, acc1);
+ acc2 = __SMLAD(x3, c0, acc2);
+ acc3 = __SMLAD(x2, c0, acc3);
+ }
+
+ if(k == 3u)
+ {
+ /* Read y[4], y[5] */
+ c0 = *__SIMD32(py)++;
+
+ /* Read x[7], x[8] */
+ x3 = *__SIMD32(px);
+
+ /* Read x[9] */
+ x2 = _SIMD32_OFFSET(px + 1);
+
+ /* Perform the multiply-accumulates */
+ acc0 = __SMLAD(x0, c0, acc0);
+ acc1 = __SMLAD(x1, c0, acc1);
+ acc2 = __SMLAD(x3, c0, acc2);
+ acc3 = __SMLAD(x2, c0, acc3);
+
+ c0 = (*py);
+ /* Read y[6] */
+#ifdef ARM_MATH_BIG_ENDIAN
+
+ c0 = c0 << 16u;
+#else
+
+ c0 = c0 & 0x0000FFFF;
+#endif /* #ifdef ARM_MATH_BIG_ENDIAN */
+
+ /* Read x[10] */
+ x3 = _SIMD32_OFFSET(px + 2);
+ px += 3u;
+
+ /* Perform the multiply-accumulates */
+ acc0 = __SMLADX(x1, c0, acc0);
+ acc1 = __SMLAD(x2, c0, acc1);
+ acc2 = __SMLADX(x2, c0, acc2);
+ acc3 = __SMLADX(x3, c0, acc3);
+ }
+
+ /* Store the result in the accumulator in the destination buffer. */
+ *pOut = (q15_t) (acc0 >> 15);
+ /* Destination pointer is updated according to the address modifier, inc */
+ pOut += inc;
+
+ *pOut = (q15_t) (acc1 >> 15);
+ pOut += inc;
+
+ *pOut = (q15_t) (acc2 >> 15);
+ pOut += inc;
+
+ *pOut = (q15_t) (acc3 >> 15);
+ pOut += inc;
+
+ /* Increment the pointer pIn1 index, count by 1 */
+ 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) * px++ * *py++);
+ sum += ((q31_t) * px++ * *py++);
+ sum += ((q31_t) * px++ * *py++);
+ sum += ((q31_t) * px++ * *py++);
+
+ /* 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-accumulates */
+ sum += ((q31_t) * px++ * *py++);
+
+ /* Decrement the loop counter */
+ k--;
+ }
+
+ /* Store the result in the accumulator in the destination buffer. */
+ *pOut = (q15_t) (sum >> 15);
+ /* Destination pointer is updated according to the address modifier, inc */
+ pOut += inc;
+
+ /* Increment the pointer pIn1 index, count by 1 */
+ 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) * px++ * *py++);
+
+ /* Decrement the loop counter */
+ k--;
+ }
+
+ /* Store the result in the accumulator in the destination buffer. */
+ *pOut = (q15_t) (sum >> 15);
+ /* 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 += x[srcALen - srcBLen + 3] * y[2] */
+ sum = __SMLAD(*__SIMD32(px)++, *__SIMD32(py)++, sum);
+ /* sum += x[srcALen - srcBLen + 2] * y[1] , sum += x[srcALen - srcBLen + 1] * y[0] */
+ sum = __SMLAD(*__SIMD32(px)++, *__SIMD32(py)++, sum);
+
+ /* 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 = __SMLAD(*px++, *py++, sum);
+
+ /* Decrement the loop counter */
+ k--;
+ }
+
+ /* Store the result in the accumulator in the destination buffer. */
+ *pOut = (q15_t) (sum >> 15);
+ /* 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--;
+ }
+
+#else
+
+ q15_t *pIn1; /* inputA pointer */
+ q15_t *pIn2; /* inputB pointer */
+ q15_t *pOut = pDst; /* output pointer */
+ q31_t sum, acc0, acc1, acc2, acc3; /* Accumulators */
+ q15_t *px; /* Intermediate inputA pointer */
+ q15_t *py; /* Intermediate inputB pointer */
+ q15_t *pSrc1; /* Intermediate pointers */
+ 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 */
+ q15_t a, b;
+
+
+ /* 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;
+
+ }
+
+ /* 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 loop 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] , x[1] * y[srcBLen - 3] */
+ sum += ((q31_t) * px++ * *py++);
+ sum += ((q31_t) * px++ * *py++);
+ sum += ((q31_t) * px++ * *py++);
+ sum += ((q31_t) * px++ * *py++);
+
+ /* 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) * px++ * *py++);
+
+ /* Decrement the loop counter */
+ k--;
+ }
+
+ /* Store the result in the accumulator in the destination buffer. */
+ *pOut = (q15_t) (sum >> 15);
+ /* 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, to loop unroll the srcBLen loop */
+ 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 */
+ a = *px;
+ b = *(px + 1);
+
+#ifndef ARM_MATH_BIG_ENDIAN
+
+ x0 = __PKHBT(a, b, 16);
+ a = *(px + 2);
+ x1 = __PKHBT(b, a, 16);
+
+#else
+
+ x0 = __PKHBT(b, a, 16);
+ a = *(px + 2);
+ x1 = __PKHBT(a, b, 16);
+
+#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
+
+ px += 2u;
+
+ /* 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 the first two inputB samples using SIMD:
+ * y[0] and y[1] */
+ a = *py;
+ b = *(py + 1);
+
+#ifndef ARM_MATH_BIG_ENDIAN
+
+ c0 = __PKHBT(a, b, 16);
+
+#else
+
+ c0 = __PKHBT(b, a, 16);
+
+#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
+
+ /* acc0 += x[0] * y[0] + x[1] * y[1] */
+ acc0 = __SMLAD(x0, c0, acc0);
+
+ /* acc1 += x[1] * y[0] + x[2] * y[1] */
+ acc1 = __SMLAD(x1, c0, acc1);
+
+ /* Read x[2], x[3], x[4] */
+ a = *px;
+ b = *(px + 1);
+
+#ifndef ARM_MATH_BIG_ENDIAN
+
+ x2 = __PKHBT(a, b, 16);
+ a = *(px + 2);
+ x3 = __PKHBT(b, a, 16);
+
+#else
+
+ x2 = __PKHBT(b, a, 16);
+ a = *(px + 2);
+ x3 = __PKHBT(a, b, 16);
+
+#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
+
+ /* acc2 += x[2] * y[0] + x[3] * y[1] */
+ acc2 = __SMLAD(x2, c0, acc2);
+
+ /* acc3 += x[3] * y[0] + x[4] * y[1] */
+ acc3 = __SMLAD(x3, c0, acc3);
+
+ /* Read y[2] and y[3] */
+ a = *(py + 2);
+ b = *(py + 3);
+
+ py += 4u;
+
+#ifndef ARM_MATH_BIG_ENDIAN
+
+ c0 = __PKHBT(a, b, 16);
+
+#else
+
+ c0 = __PKHBT(b, a, 16);
+
+#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
+
+ /* acc0 += x[2] * y[2] + x[3] * y[3] */
+ acc0 = __SMLAD(x2, c0, acc0);
+
+ /* acc1 += x[3] * y[2] + x[4] * y[3] */
+ acc1 = __SMLAD(x3, c0, acc1);
+
+ /* Read x[4], x[5], x[6] */
+ a = *(px + 2);
+ b = *(px + 3);
+
+#ifndef ARM_MATH_BIG_ENDIAN
+
+ x0 = __PKHBT(a, b, 16);
+ a = *(px + 4);
+ x1 = __PKHBT(b, a, 16);
+
+#else
+
+ x0 = __PKHBT(b, a, 16);
+ a = *(px + 4);
+ x1 = __PKHBT(a, b, 16);
+
+#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
+
+ px += 4u;
+
+ /* acc2 += x[4] * y[2] + x[5] * y[3] */
+ acc2 = __SMLAD(x0, c0, acc2);
+
+ /* acc3 += x[5] * y[2] + x[6] * y[3] */
+ acc3 = __SMLAD(x1, c0, acc3);
+
+ } while(--k);
+
+ /* For the next MAC operations, SIMD is not used
+ * So, the 16 bit pointer if inputB, py is updated */
+
+ /* If the srcBLen is not a multiple of 4, compute any remaining MACs here.
+ ** No loop unrolling is used. */
+ k = srcBLen % 0x4u;
+
+ if(k == 1u)
+ {
+ /* Read y[4] */
+ c0 = *py;
+#ifdef ARM_MATH_BIG_ENDIAN
+
+ c0 = c0 << 16u;
+
+#else
+
+ c0 = c0 & 0x0000FFFF;
+
+#endif /* #ifdef ARM_MATH_BIG_ENDIAN */
+
+ /* Read x[7] */
+ a = *px;
+ b = *(px + 1);
+
+ px++;;
+
+#ifndef ARM_MATH_BIG_ENDIAN
+
+ x3 = __PKHBT(a, b, 16);
+
+#else
+
+ x3 = __PKHBT(b, a, 16);
+
+#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
+
+ px++;
+
+ /* Perform the multiply-accumulates */
+ acc0 = __SMLAD(x0, c0, acc0);
+ acc1 = __SMLAD(x1, c0, acc1);
+ acc2 = __SMLADX(x1, c0, acc2);
+ acc3 = __SMLADX(x3, c0, acc3);
+ }
+
+ if(k == 2u)
+ {
+ /* Read y[4], y[5] */
+ a = *py;
+ b = *(py + 1);
+
+#ifndef ARM_MATH_BIG_ENDIAN
+
+ c0 = __PKHBT(a, b, 16);
+
+#else
+
+ c0 = __PKHBT(b, a, 16);
+
+#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
+
+ /* Read x[7], x[8], x[9] */
+ a = *px;
+ b = *(px + 1);
+
+#ifndef ARM_MATH_BIG_ENDIAN
+
+ x3 = __PKHBT(a, b, 16);
+ a = *(px + 2);
+ x2 = __PKHBT(b, a, 16);
+
+#else
+
+ x3 = __PKHBT(b, a, 16);
+ a = *(px + 2);
+ x2 = __PKHBT(a, b, 16);
+
+#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
+
+ px += 2u;
+
+ /* Perform the multiply-accumulates */
+ acc0 = __SMLAD(x0, c0, acc0);
+ acc1 = __SMLAD(x1, c0, acc1);
+ acc2 = __SMLAD(x3, c0, acc2);
+ acc3 = __SMLAD(x2, c0, acc3);
+ }
+
+ if(k == 3u)
+ {
+ /* Read y[4], y[5] */
+ a = *py;
+ b = *(py + 1);
+
+#ifndef ARM_MATH_BIG_ENDIAN
+
+ c0 = __PKHBT(a, b, 16);
+
+#else
+
+ c0 = __PKHBT(b, a, 16);
+
+#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
+
+ py += 2u;
+
+ /* Read x[7], x[8], x[9] */
+ a = *px;
+ b = *(px + 1);
+
+#ifndef ARM_MATH_BIG_ENDIAN
+
+ x3 = __PKHBT(a, b, 16);
+ a = *(px + 2);
+ x2 = __PKHBT(b, a, 16);
+
+#else
+
+ x3 = __PKHBT(b, a, 16);
+ a = *(px + 2);
+ x2 = __PKHBT(a, b, 16);
+
+#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
+
+ /* Perform the multiply-accumulates */
+ acc0 = __SMLAD(x0, c0, acc0);
+ acc1 = __SMLAD(x1, c0, acc1);
+ acc2 = __SMLAD(x3, c0, acc2);
+ acc3 = __SMLAD(x2, c0, acc3);
+
+ c0 = (*py);
+ /* Read y[6] */
+#ifdef ARM_MATH_BIG_ENDIAN
+
+ c0 = c0 << 16u;
+#else
+
+ c0 = c0 & 0x0000FFFF;
+#endif /* #ifdef ARM_MATH_BIG_ENDIAN */
+
+ /* Read x[10] */
+ b = *(px + 3);
+
+#ifndef ARM_MATH_BIG_ENDIAN
+
+ x3 = __PKHBT(a, b, 16);
+
+#else
+
+ x3 = __PKHBT(b, a, 16);
+
+#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
+
+ px += 3u;
+
+ /* Perform the multiply-accumulates */
+ acc0 = __SMLADX(x1, c0, acc0);
+ acc1 = __SMLAD(x2, c0, acc1);
+ acc2 = __SMLADX(x2, c0, acc2);
+ acc3 = __SMLADX(x3, c0, acc3);
+ }
+
+ /* Store the result in the accumulator in the destination buffer. */
+ *pOut = (q15_t) (acc0 >> 15);
+ /* Destination pointer is updated according to the address modifier, inc */
+ pOut += inc;
+
+ *pOut = (q15_t) (acc1 >> 15);
+ pOut += inc;
+
+ *pOut = (q15_t) (acc2 >> 15);
+ pOut += inc;
+
+ *pOut = (q15_t) (acc3 >> 15);
+ pOut += inc;
+
+ /* Increment the pointer pIn1 index, count by 1 */
+ 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) * px++ * *py++);
+ sum += ((q31_t) * px++ * *py++);
+ sum += ((q31_t) * px++ * *py++);
+ sum += ((q31_t) * px++ * *py++);
+
+ /* 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-accumulates */
+ sum += ((q31_t) * px++ * *py++);
+
+ /* Decrement the loop counter */
+ k--;
+ }
+
+ /* Store the result in the accumulator in the destination buffer. */
+ *pOut = (q15_t) (sum >> 15);
+ /* Destination pointer is updated according to the address modifier, inc */
+ pOut += inc;
+
+ /* Increment the pointer pIn1 index, count by 1 */
+ 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) * px++ * *py++);
+
+ /* Decrement the loop counter */
+ k--;
+ }
+
+ /* Store the result in the accumulator in the destination buffer. */
+ *pOut = (q15_t) (sum >> 15);
+ /* 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 += ((q31_t) * px++ * *py++);
+ sum += ((q31_t) * px++ * *py++);
+ sum += ((q31_t) * px++ * *py++);
+ sum += ((q31_t) * px++ * *py++);
+
+ /* 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) * px++ * *py++);
+
+ /* Decrement the loop counter */
+ k--;
+ }
+
+ /* Store the result in the accumulator in the destination buffer. */
+ *pOut = (q15_t) (sum >> 15);
+ /* 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--;
+ }
+
+#endif /* #ifndef UNALIGNED_SUPPORT_DISABLE */
+
+}
+
+/**
+ * @} end of Corr group
+ */