| /* ---------------------------------------------------------------------- |
| * Project: CMSIS DSP Library |
| * Title: arm_correlate_q15.c |
| * Description: Correlation of Q15 sequences |
| * |
| * $Date: 18. March 2019 |
| * $Revision: V1.6.0 |
| * |
| * Target Processor: Cortex-M cores |
| * -------------------------------------------------------------------- */ |
| /* |
| * Copyright (C) 2010-2019 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 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. |
| @return none |
| |
| @par Scaling and Overflow Behavior |
| 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. |
| |
| @remark |
| Refer to \ref arm_correlate_fast_q15() for a faster but less precise version of this function. |
| @remark |
| Refer to \ref arm_correlate_opt_q15() for a faster implementation of this function using scratch buffers. |
| */ |
| |
| void arm_correlate_q15( |
| const q15_t * pSrcA, |
| uint32_t srcALen, |
| const q15_t * pSrcB, |
| uint32_t srcBLen, |
| q15_t * pDst) |
| { |
| |
| #if defined (ARM_MATH_DSP) |
| |
| const q15_t *pIn1; /* InputA pointer */ |
| const q15_t *pIn2; /* InputB pointer */ |
| q15_t *pOut = pDst; /* Output pointer */ |
| q63_t sum, acc0, acc1, acc2, acc3; /* Accumulators */ |
| const q15_t *px; /* Intermediate inputA pointer */ |
| const q15_t *py; /* Intermediate inputB pointer */ |
| const q15_t *pSrc1; /* Intermediate pointers */ |
| q31_t x0, x1, x2, x3, c0; /* Temporary input variables for holding input and coefficient values */ |
| uint32_t blockSize1, blockSize2, blockSize3; /* Loop counters */ |
| uint32_t j, k, count, blkCnt; /* Loop counters */ |
| uint32_t outBlockSize; |
| 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 = (srcALen * 2U) - 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 stages according to the number of multiplications that has to be |
| * taken place between inputA samples and inputB samples. In the first stage of the |
| * algorithm, the multiplications increase by one for every iteration. |
| * In the second stage of the algorithm, srcBLen number of multiplications are done. |
| * In the third stage 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 >> 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-accumulate */ |
| /* x[0] * y[srcBLen - 4] , x[1] * y[srcBLen - 3] */ |
| sum = __SMLALD(read_q15x2_ia ((q15_t **) &px), read_q15x2_ia ((q15_t **) &py), sum); |
| /* x[3] * y[srcBLen - 1] , x[2] * y[srcBLen - 2] */ |
| sum = __SMLALD(read_q15x2_ia ((q15_t **) &px), read_q15x2_ia ((q15_t **) &py), sum); |
| |
| /* Decrement 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-accumulate */ |
| /* x[0] * y[srcBLen - 1] */ |
| sum = __SMLALD(*px++, *py++, sum); |
| |
| /* Decrement loop counter */ |
| k--; |
| } |
| |
| /* Store the result in the accumulator in the destination buffer. */ |
| *pOut = (q15_t) (__SSAT((sum >> 15), 16)); |
| /* 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 MAC count */ |
| count++; |
| |
| /* Decrement 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 the 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 unrolling: Compute 4 outputs at a time */ |
| 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 = read_q15x2 ((q15_t *) px); |
| |
| /* read x[1], x[2] samples */ |
| x1 = read_q15x2 ((q15_t *) 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 = read_q15x2_ia ((q15_t **) &py); |
| |
| /* acc0 += x[0] * y[0] + x[1] * y[1] */ |
| acc0 = __SMLALD(x0, c0, acc0); |
| |
| /* acc1 += x[1] * y[0] + x[2] * y[1] */ |
| acc1 = __SMLALD(x1, c0, acc1); |
| |
| /* Read x[2], x[3] */ |
| x2 = read_q15x2 ((q15_t *) px); |
| |
| /* Read x[3], x[4] */ |
| x3 = read_q15x2 ((q15_t *) px + 1); |
| |
| /* acc2 += x[2] * y[0] + x[3] * y[1] */ |
| acc2 = __SMLALD(x2, c0, acc2); |
| |
| /* acc3 += x[3] * y[0] + x[4] * y[1] */ |
| acc3 = __SMLALD(x3, c0, acc3); |
| |
| /* Read y[2] and y[3] */ |
| c0 = read_q15x2_ia ((q15_t **) &py); |
| |
| /* acc0 += x[2] * y[2] + x[3] * y[3] */ |
| acc0 = __SMLALD(x2, c0, acc0); |
| |
| /* acc1 += x[3] * y[2] + x[4] * y[3] */ |
| acc1 = __SMLALD(x3, c0, acc1); |
| |
| /* Read x[4], x[5] */ |
| x0 = read_q15x2 ((q15_t *) px + 2); |
| |
| /* Read x[5], x[6] */ |
| x1 = read_q15x2 ((q15_t *) px + 3); |
| px += 4U; |
| |
| /* acc2 += x[4] * y[2] + x[5] * y[3] */ |
| acc2 = __SMLALD(x0, c0, acc2); |
| |
| /* acc3 += x[5] * y[2] + x[6] * y[3] */ |
| acc3 = __SMLALD(x1, c0, acc3); |
| |
| } while (--k); |
| |
| /* 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 = read_q15x2 ((q15_t *) px); |
| px++; |
| |
| /* Perform the multiply-accumulate */ |
| acc0 = __SMLALD (x0, c0, acc0); |
| acc1 = __SMLALD (x1, c0, acc1); |
| acc2 = __SMLALDX(x1, c0, acc2); |
| acc3 = __SMLALDX(x3, c0, acc3); |
| } |
| |
| if (k == 2U) |
| { |
| /* Read y[4], y[5] */ |
| c0 = read_q15x2 ((q15_t *) py); |
| |
| /* Read x[7], x[8] */ |
| x3 = read_q15x2 ((q15_t *) px); |
| |
| /* Read x[9] */ |
| x2 = read_q15x2 ((q15_t *) px + 1); |
| px += 2U; |
| |
| /* Perform the multiply-accumulate */ |
| acc0 = __SMLALD(x0, c0, acc0); |
| acc1 = __SMLALD(x1, c0, acc1); |
| acc2 = __SMLALD(x3, c0, acc2); |
| acc3 = __SMLALD(x2, c0, acc3); |
| } |
| |
| if (k == 3U) |
| { |
| /* Read y[4], y[5] */ |
| c0 = read_q15x2_ia ((q15_t **) &py); |
| |
| /* Read x[7], x[8] */ |
| x3 = read_q15x2 ((q15_t *) px); |
| |
| /* Read x[9] */ |
| x2 = read_q15x2 ((q15_t *) px + 1); |
| |
| /* Perform the multiply-accumulate */ |
| acc0 = __SMLALD(x0, c0, acc0); |
| acc1 = __SMLALD(x1, c0, acc1); |
| acc2 = __SMLALD(x3, c0, acc2); |
| acc3 = __SMLALD(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 = read_q15x2 ((q15_t *) px + 2); |
| px += 3U; |
| |
| /* Perform the multiply-accumulates */ |
| acc0 = __SMLALDX(x1, c0, acc0); |
| acc1 = __SMLALD (x2, c0, acc1); |
| acc2 = __SMLALDX(x2, c0, acc2); |
| acc3 = __SMLALDX(x3, c0, acc3); |
| } |
| |
| /* Store the result in the accumulator in the destination buffer. */ |
| *pOut = (q15_t) (__SSAT(acc0 >> 15, 16)); |
| /* Destination pointer is updated according to the address modifier, inc */ |
| pOut += inc; |
| |
| *pOut = (q15_t) (__SSAT(acc1 >> 15, 16)); |
| pOut += inc; |
| |
| *pOut = (q15_t) (__SSAT(acc2 >> 15, 16)); |
| pOut += inc; |
| |
| *pOut = (q15_t) (__SSAT(acc3 >> 15, 16)); |
| pOut += inc; |
| |
| /* Increment the count by 4 as 4 output values are computed */ |
| count += 4U; |
| |
| /* Update the inputA and inputB pointers for next MAC calculation */ |
| px = pIn1 + count; |
| py = pIn2; |
| |
| /* Decrement 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 += ((q63_t) *px++ * *py++); |
| sum += ((q63_t) *px++ * *py++); |
| sum += ((q63_t) *px++ * *py++); |
| sum += ((q63_t) *px++ * *py++); |
| |
| /* Decrement 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 += ((q63_t) *px++ * *py++); |
| |
| /* Decrement the loop counter */ |
| k--; |
| } |
| |
| /* Store the result in the accumulator in the destination buffer. */ |
| *pOut = (q15_t) (__SSAT(sum >> 15, 16)); |
| /* Destination pointer is updated according to the address modifier, inc */ |
| pOut += inc; |
| |
| /* Increment count by 1, as one output value is computed */ |
| 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; |
| |
| /* srcBLen number of MACS should be performed */ |
| k = srcBLen; |
| |
| while (k > 0U) |
| { |
| /* Perform the multiply-accumulate */ |
| sum += ((q63_t) *px++ * *py++); |
| |
| /* Decrement the loop counter */ |
| k--; |
| } |
| |
| /* Store the result in the accumulator in the destination buffer. */ |
| *pOut = (q15_t) (__SSAT(sum >> 15, 16)); |
| /* 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-accumulate */ |
| /* sum += x[srcALen - srcBLen + 4] * y[3] , sum += x[srcALen - srcBLen + 3] * y[2] */ |
| sum = __SMLALD(read_q15x2_ia ((q15_t **) &px), read_q15x2_ia ((q15_t **) &py), sum); |
| /* sum += x[srcALen - srcBLen + 2] * y[1] , sum += x[srcALen - srcBLen + 1] * y[0] */ |
| sum = __SMLALD(read_q15x2_ia ((q15_t **) &px), read_q15x2_ia ((q15_t **) &py), sum); |
| |
| /* Decrement 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-accumulate */ |
| sum = __SMLALD(*px++, *py++, sum); |
| |
| /* Decrement loop counter */ |
| k--; |
| } |
| |
| /* Store the result in the accumulator in the destination buffer. */ |
| *pOut = (q15_t) (__SSAT((sum >> 15), 16)); |
| /* 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 MAC count */ |
| count--; |
| |
| /* Decrement loop counter */ |
| blockSize3--; |
| } |
| |
| #else /* #if defined (ARM_MATH_DSP) */ |
| |
| const q15_t *pIn1 = pSrcA; /* InputA pointer */ |
| const q15_t *pIn2 = pSrcB + (srcBLen - 1U); /* InputB pointer */ |
| q63_t sum; /* Accumulators */ |
| uint32_t i = 0U, j; /* Loop counters */ |
| uint32_t inv = 0U; /* Reverse order flag */ |
| uint32_t tot = 0U; /* Length */ |
| |
| /* 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 a varaible, inv is set to 1 */ |
| /* If lengths are not equal then zero pad has to be done 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 */ |
| /* Once the zero padding is done the remaining of the output is calcualted |
| * using convolution but with the shorter signal time shifted. */ |
| |
| /* Calculate the length of the remaining sequence */ |
| tot = ((srcALen + srcBLen) - 2U); |
| |
| if (srcALen > srcBLen) |
| { |
| /* Calculating the number of zeros to be padded to the output */ |
| j = srcALen - srcBLen; |
| |
| /* Initialise the pointer after zero padding */ |
| pDst += j; |
| } |
| |
| else if (srcALen < srcBLen) |
| { |
| /* Initialization to inputB pointer */ |
| pIn1 = pSrcB; |
| |
| /* Initialization to the end of inputA pointer */ |
| pIn2 = pSrcA + (srcALen - 1U); |
| |
| /* Initialisation of the pointer after zero padding */ |
| pDst = pDst + tot; |
| |
| /* Swapping the lengths */ |
| j = srcALen; |
| srcALen = srcBLen; |
| srcBLen = j; |
| |
| /* Setting the reverse flag */ |
| inv = 1; |
| } |
| |
| /* Loop to calculate convolution for output length number of values */ |
| for (i = 0U; i <= tot; i++) |
| { |
| /* Initialize sum with zero to carry on MAC operations */ |
| sum = 0; |
| |
| /* Loop to perform MAC operations according to convolution equation */ |
| for (j = 0U; j <= i; j++) |
| { |
| /* Check the array limitations */ |
| if (((i - j) < srcBLen) && (j < srcALen)) |
| { |
| /* z[i] += x[i-j] * y[j] */ |
| sum += ((q31_t) pIn1[j] * pIn2[-((int32_t) i - j)]); |
| } |
| } |
| |
| /* Store the output in the destination buffer */ |
| if (inv == 1) |
| *pDst-- = (q15_t) __SSAT((sum >> 15U), 16U); |
| else |
| *pDst++ = (q15_t) __SSAT((sum >> 15U), 16U); |
| } |
| |
| #endif /* #if defined (ARM_MATH_DSP) */ |
| |
| } |
| |
| /** |
| @} end of Corr group |
| */ |
