arm_conv_q31.c
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CLexer
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r41 | /* ---------------------------------------------------------------------- | ||
* Copyright (C) 2010 ARM Limited. All rights reserved. | ||||
* | ||||
* $Date: 15. July 2011 | ||||
* $Revision: V1.0.10 | ||||
* | ||||
* Project: CMSIS DSP Library | ||||
* Title: arm_conv_q31.c | ||||
* | ||||
* Description: Convolution of Q31 sequences. | ||||
* | ||||
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 | ||||
* | ||||
* Version 1.0.10 2011/7/15 | ||||
* Big Endian support added and Merged M0 and M3/M4 Source code. | ||||
* | ||||
* Version 1.0.3 2010/11/29 | ||||
* Re-organized the CMSIS folders and updated documentation. | ||||
* | ||||
* Version 1.0.2 2010/11/11 | ||||
* Documentation updated. | ||||
* | ||||
* Version 1.0.1 2010/10/05 | ||||
* Production release and review comments incorporated. | ||||
* | ||||
* Version 1.0.0 2010/09/20 | ||||
* Production release and review comments incorporated | ||||
* | ||||
* Version 0.0.7 2010/06/10 | ||||
* Misra-C changes done | ||||
* | ||||
* -------------------------------------------------------------------- */ | ||||
#include "arm_math.h" | ||||
/** | ||||
* @ingroup groupFilters | ||||
*/ | ||||
/** | ||||
* @addtogroup Conv | ||||
* @{ | ||||
*/ | ||||
/** | ||||
* @brief Convolution of Q31 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 srcALen+srcBLen-1. | ||||
* @return none. | ||||
* | ||||
* @details | ||||
* <b>Scaling and Overflow Behavior:</b> | ||||
* | ||||
* \par | ||||
* The function is implemented using an internal 64-bit accumulator. | ||||
* The accumulator has a 2.62 format and 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 the inputs by log2(min(srcALen, srcBLen)) (log2 is read as log to the base 2) times to avoid overflows, | ||||
* as maximum of min(srcALen, srcBLen) number of additions are carried internally. | ||||
* The 2.62 accumulator is right shifted by 31 bits and saturated to 1.31 format to yield the final result. | ||||
* | ||||
* \par | ||||
* See <code>arm_conv_fast_q31()</code> for a faster but less precise implementation of this function for Cortex-M3 and Cortex-M4. | ||||
*/ | ||||
void arm_conv_q31( | ||||
q31_t * pSrcA, | ||||
uint32_t srcALen, | ||||
q31_t * pSrcB, | ||||
uint32_t srcBLen, | ||||
q31_t * pDst) | ||||
{ | ||||
#ifndef ARM_MATH_CM0 | ||||
/* Run the below code for Cortex-M4 and Cortex-M3 */ | ||||
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, *pSrc2; /* Intermediate pointers */ | ||||
q63_t sum; /* Accumulator */ | ||||
q63_t acc0, acc1, acc2, acc3; /* Accumulator */ | ||||
q31_t x0, x1, x2, x3, c0; /* Temporary variables to hold state and coefficient values */ | ||||
uint32_t j, k, count, blkCnt, blockSize1, blockSize2, blockSize3; /* loop counter */ | ||||
/* 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; | ||||
} | ||||
else | ||||
{ | ||||
/* Initialization of inputA pointer */ | ||||
pIn1 = (q31_t *) pSrcB; | ||||
/* Initialization of inputB pointer */ | ||||
pIn2 = (q31_t *) pSrcA; | ||||
/* srcBLen is always considered as shorter or equal to srcALen */ | ||||
j = srcBLen; | ||||
srcBLen = srcALen; | ||||
srcALen = j; | ||||
} | ||||
/* conv(x,y) at n = x[n] * y[0] + x[n-1] * y[1] + x[n-2] * y[2] + ...+ x[n-N+1] * y[N -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[0] | ||||
* sum = x[0] * y[1] + x[1] * y[0] | ||||
* .... | ||||
* sum = x[0] * y[srcBlen - 1] + x[1] * y[srcBlen - 2] +...+ x[srcBLen - 1] * y[0] | ||||
*/ | ||||
/* 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 */ | ||||
py = pIn2; | ||||
/* ------------------------ | ||||
* 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 >> 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) | ||||
{ | ||||
/* x[0] * y[srcBLen - 1] */ | ||||
sum += (q63_t) * px++ * (*py--); | ||||
/* x[1] * y[srcBLen - 2] */ | ||||
sum += (q63_t) * px++ * (*py--); | ||||
/* x[2] * y[srcBLen - 3] */ | ||||
sum += (q63_t) * px++ * (*py--); | ||||
/* x[3] * y[srcBLen - 4] */ | ||||
sum += (q63_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-accumulate */ | ||||
sum += (q63_t) * px++ * (*py--); | ||||
/* Decrement the loop counter */ | ||||
k--; | ||||
} | ||||
/* Store the result in the accumulator in the destination buffer. */ | ||||
*pOut++ = (q31_t) (sum >> 31); | ||||
/* Update the inputA and inputB pointers for next MAC calculation */ | ||||
py = pIn2 + count; | ||||
px = pIn1; | ||||
/* Increment the MAC count */ | ||||
count++; | ||||
/* Decrement the loop counter */ | ||||
blockSize1--; | ||||
} | ||||
/* -------------------------- | ||||
* Initializations of stage2 | ||||
* ------------------------*/ | ||||
/* sum = x[0] * y[srcBLen-1] + x[1] * y[srcBLen-2] +...+ x[srcBLen-1] * y[0] | ||||
* sum = x[1] * y[srcBLen-1] + x[2] * y[srcBLen-2] +...+ x[srcBLen] * y[0] | ||||
* .... | ||||
* sum = x[srcALen-srcBLen-2] * y[srcBLen-1] + x[srcALen] * y[srcBLen-2] +...+ x[srcALen-1] * y[0] | ||||
*/ | ||||
/* Working pointer of inputA */ | ||||
px = pIn1; | ||||
/* Working pointer of inputB */ | ||||
pSrc2 = pIn2 + (srcBLen - 1u); | ||||
py = pSrc2; | ||||
/* count is index by which the pointer pIn1 to be incremented */ | ||||
count = 1u; | ||||
/* ------------------- | ||||
* 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[srcBLen - 1] sample */ | ||||
c0 = *(py--); | ||||
/* Read x[3] sample */ | ||||
x3 = *(px++); | ||||
/* Perform the multiply-accumulates */ | ||||
/* acc0 += x[0] * y[srcBLen - 1] */ | ||||
acc0 += ((q63_t) x0 * c0); | ||||
/* acc1 += x[1] * y[srcBLen - 1] */ | ||||
acc1 += ((q63_t) x1 * c0); | ||||
/* acc2 += x[2] * y[srcBLen - 1] */ | ||||
acc2 += ((q63_t) x2 * c0); | ||||
/* acc3 += x[3] * y[srcBLen - 1] */ | ||||
acc3 += ((q63_t) x3 * c0); | ||||
/* Read y[srcBLen - 2] sample */ | ||||
c0 = *(py--); | ||||
/* Read x[4] sample */ | ||||
x0 = *(px++); | ||||
/* Perform the multiply-accumulate */ | ||||
/* acc0 += x[1] * y[srcBLen - 2] */ | ||||
acc0 += ((q63_t) x1 * c0); | ||||
/* acc1 += x[2] * y[srcBLen - 2] */ | ||||
acc1 += ((q63_t) x2 * c0); | ||||
/* acc2 += x[3] * y[srcBLen - 2] */ | ||||
acc2 += ((q63_t) x3 * c0); | ||||
/* acc3 += x[4] * y[srcBLen - 2] */ | ||||
acc3 += ((q63_t) x0 * c0); | ||||
/* Read y[srcBLen - 3] sample */ | ||||
c0 = *(py--); | ||||
/* Read x[5] sample */ | ||||
x1 = *(px++); | ||||
/* Perform the multiply-accumulates */ | ||||
/* acc0 += x[2] * y[srcBLen - 3] */ | ||||
acc0 += ((q63_t) x2 * c0); | ||||
/* acc1 += x[3] * y[srcBLen - 2] */ | ||||
acc1 += ((q63_t) x3 * c0); | ||||
/* acc2 += x[4] * y[srcBLen - 2] */ | ||||
acc2 += ((q63_t) x0 * c0); | ||||
/* acc3 += x[5] * y[srcBLen - 2] */ | ||||
acc3 += ((q63_t) x1 * c0); | ||||
/* Read y[srcBLen - 4] sample */ | ||||
c0 = *(py--); | ||||
/* Read x[6] sample */ | ||||
x2 = *(px++); | ||||
/* Perform the multiply-accumulates */ | ||||
/* acc0 += x[3] * y[srcBLen - 4] */ | ||||
acc0 += ((q63_t) x3 * c0); | ||||
/* acc1 += x[4] * y[srcBLen - 4] */ | ||||
acc1 += ((q63_t) x0 * c0); | ||||
/* acc2 += x[5] * y[srcBLen - 4] */ | ||||
acc2 += ((q63_t) x1 * c0); | ||||
/* acc3 += x[6] * y[srcBLen - 4] */ | ||||
acc3 += ((q63_t) x2 * c0); | ||||
} 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[srcBLen - 5] sample */ | ||||
c0 = *(py--); | ||||
/* Read x[7] sample */ | ||||
x3 = *(px++); | ||||
/* Perform the multiply-accumulates */ | ||||
/* acc0 += x[4] * y[srcBLen - 5] */ | ||||
acc0 += ((q63_t) x0 * c0); | ||||
/* acc1 += x[5] * y[srcBLen - 5] */ | ||||
acc1 += ((q63_t) x1 * c0); | ||||
/* acc2 += x[6] * y[srcBLen - 5] */ | ||||
acc2 += ((q63_t) x2 * c0); | ||||
/* acc3 += x[7] * y[srcBLen - 5] */ | ||||
acc3 += ((q63_t) x3 * c0); | ||||
/* Reuse the present samples for the next MAC */ | ||||
x0 = x1; | ||||
x1 = x2; | ||||
x2 = x3; | ||||
/* Decrement the loop counter */ | ||||
k--; | ||||
} | ||||
/* Store the results in the accumulators in the destination buffer. */ | ||||
*pOut++ = (q31_t) (acc0 >> 31); | ||||
*pOut++ = (q31_t) (acc1 >> 31); | ||||
*pOut++ = (q31_t) (acc2 >> 31); | ||||
*pOut++ = (q31_t) (acc3 >> 31); | ||||
/* Update the inputA and inputB pointers for next MAC calculation */ | ||||
px = pIn1 + (count * 4u); | ||||
py = pSrc2; | ||||
/* Increment the pointer pIn1 index, count by 1 */ | ||||
count++; | ||||
/* 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 += (q63_t) * px++ * (*py--); | ||||
sum += (q63_t) * px++ * (*py--); | ||||
sum += (q63_t) * px++ * (*py--); | ||||
sum += (q63_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-accumulate */ | ||||
sum += (q63_t) * px++ * (*py--); | ||||
/* Decrement the loop counter */ | ||||
k--; | ||||
} | ||||
/* Store the result in the accumulator in the destination buffer. */ | ||||
*pOut++ = (q31_t) (sum >> 31); | ||||
/* Update the inputA and inputB pointers for next MAC calculation */ | ||||
px = pIn1 + count; | ||||
py = pSrc2; | ||||
/* Increment the MAC count */ | ||||
count++; | ||||
/* 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++ = (q31_t) (sum >> 31); | ||||
/* Update the inputA and inputB pointers for next MAC calculation */ | ||||
px = pIn1 + count; | ||||
py = pSrc2; | ||||
/* Increment the MAC count */ | ||||
count++; | ||||
/* Decrement the loop counter */ | ||||
blkCnt--; | ||||
} | ||||
} | ||||
/* -------------------------- | ||||
* Initializations of stage3 | ||||
* -------------------------*/ | ||||
/* sum += x[srcALen-srcBLen+1] * y[srcBLen-1] + x[srcALen-srcBLen+2] * y[srcBLen-2] +...+ x[srcALen-1] * y[1] | ||||
* sum += x[srcALen-srcBLen+2] * y[srcBLen-1] + x[srcALen-srcBLen+3] * y[srcBLen-2] +...+ x[srcALen-1] * y[2] | ||||
* .... | ||||
* sum += x[srcALen-2] * y[srcBLen-1] + x[srcALen-1] * y[srcBLen-2] | ||||
* sum += x[srcALen-1] * y[srcBLen-1] | ||||
*/ | ||||
/* In this stage the MAC operations are decreased by 1 for every iteration. | ||||
The blockSize3 variable holds the number of MAC operations performed */ | ||||
/* Working pointer of inputA */ | ||||
pSrc1 = (pIn1 + srcALen) - (srcBLen - 1u); | ||||
px = pSrc1; | ||||
/* Working pointer of inputB */ | ||||
pSrc2 = pIn2 + (srcBLen - 1u); | ||||
py = pSrc2; | ||||
/* ------------------- | ||||
* Stage3 process | ||||
* ------------------*/ | ||||
while(blockSize3 > 0u) | ||||
{ | ||||
/* Accumulator is made zero for every iteration */ | ||||
sum = 0; | ||||
/* Apply loop unrolling and compute 4 MACs simultaneously. */ | ||||
k = blockSize3 >> 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) | ||||
{ | ||||
/* sum += x[srcALen - srcBLen + 1] * y[srcBLen - 1] */ | ||||
sum += (q63_t) * px++ * (*py--); | ||||
/* sum += x[srcALen - srcBLen + 2] * y[srcBLen - 2] */ | ||||
sum += (q63_t) * px++ * (*py--); | ||||
/* sum += x[srcALen - srcBLen + 3] * y[srcBLen - 3] */ | ||||
sum += (q63_t) * px++ * (*py--); | ||||
/* sum += x[srcALen - srcBLen + 4] * y[srcBLen - 4] */ | ||||
sum += (q63_t) * px++ * (*py--); | ||||
/* Decrement the loop counter */ | ||||
k--; | ||||
} | ||||
/* If the blockSize3 is not a multiple of 4, compute any remaining MACs here. | ||||
** No loop unrolling is used. */ | ||||
k = blockSize3 % 0x4u; | ||||
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++ = (q31_t) (sum >> 31); | ||||
/* Update the inputA and inputB pointers for next MAC calculation */ | ||||
px = ++pSrc1; | ||||
py = pSrc2; | ||||
/* Decrement the loop counter */ | ||||
blockSize3--; | ||||
} | ||||
#else | ||||
/* Run the below code for Cortex-M0 */ | ||||
q31_t *pIn1 = pSrcA; /* input pointer */ | ||||
q31_t *pIn2 = pSrcB; /* coefficient pointer */ | ||||
q63_t sum; /* Accumulator */ | ||||
uint32_t i, j; /* loop counter */ | ||||
/* Loop to calculate output of convolution for output length number of times */ | ||||
for (i = 0; i < (srcALen + srcBLen - 1); i++) | ||||
{ | ||||
/* Initialize sum with zero to carry on MAC operations */ | ||||
sum = 0; | ||||
/* Loop to perform MAC operations according to convolution equation */ | ||||
for (j = 0; j <= i; j++) | ||||
{ | ||||
/* Check the array limitations */ | ||||
if(((i - j) < srcBLen) && (j < srcALen)) | ||||
{ | ||||
/* z[i] += x[i-j] * y[j] */ | ||||
sum += ((q63_t) pIn1[j] * (pIn2[i - j])); | ||||
} | ||||
} | ||||
/* Store the output in the destination buffer */ | ||||
pDst[i] = (q31_t) (sum >> 31u); | ||||
} | ||||
#endif /* #ifndef ARM_MATH_CM0 */ | ||||
} | ||||
/** | ||||
* @} end of Conv group | ||||
*/ | ||||