pigweed / third_party / github / STMicroelectronics / cmsis_core / cb6d9400754e6c9050487dfa573949b61152ac99 / . / DSP / Source / FilteringFunctions / arm_conv_f32.c

/* ---------------------------------------------------------------------- | |

* Project: CMSIS DSP Library | |

* Title: arm_conv_f32.c | |

* Description: Convolution of floating-point sequences | |

* | |

* $Date: 27. January 2017 | |

* $Revision: V.1.5.1 | |

* | |

* Target Processor: Cortex-M cores | |

* -------------------------------------------------------------------- */ | |

/* | |

* Copyright (C) 2010-2017 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 | |

*/ | |

/** | |

* @defgroup Conv Convolution | |

* | |

* Convolution is a mathematical operation that operates on two finite length vectors to generate a finite length output vector. | |

* Convolution is similar to correlation and is frequently used in filtering and data analysis. | |

* The CMSIS DSP library contains functions for convolving Q7, Q15, Q31, and floating-point data types. | |

* The library also provides fast versions of the Q15 and Q31 functions on Cortex-M4 and Cortex-M3. | |

* | |

* \par Algorithm | |

* Let <code>a[n]</code> and <code>b[n]</code> be sequences of length <code>srcALen</code> and <code>srcBLen</code> samples respectively. | |

* Then the convolution | |

* | |

* <pre> | |

* c[n] = a[n] * b[n] | |

* </pre> | |

* | |

* \par | |

* is defined as | |

* \image html ConvolutionEquation.gif | |

* \par | |

* Note that <code>c[n]</code> is of length <code>srcALen + srcBLen - 1</code> and is defined over the interval <code>n=0, 1, 2, ..., srcALen + srcBLen - 2</code>. | |

* <code>pSrcA</code> points to the first input vector of length <code>srcALen</code> and | |

* <code>pSrcB</code> points to the second input vector of length <code>srcBLen</code>. | |

* The output result is written to <code>pDst</code> and the calling function must allocate <code>srcALen+srcBLen-1</code> words for the result. | |

* | |

* \par | |

* Conceptually, when two signals <code>a[n]</code> and <code>b[n]</code> are convolved, | |

* the signal <code>b[n]</code> slides over <code>a[n]</code>. | |

* For each offset \c n, the overlapping portions of a[n] and b[n] are multiplied and summed together. | |

* | |

* \par | |

* Note that convolution is a commutative operation: | |

* | |

* <pre> | |

* a[n] * b[n] = b[n] * a[n]. | |

* </pre> | |

* | |

* \par | |

* This means that switching the A and B arguments to the convolution functions has no effect. | |

* | |

* <b>Fixed-Point Behavior</b> | |

* | |

* \par | |

* Convolution requires summing up a large number of intermediate products. | |

* As such, the Q7, Q15, and Q31 functions run a risk of overflow and saturation. | |

* Refer to the function specific documentation below for further details of the particular algorithm used. | |

* | |

* | |

* <b>Fast Versions</b> | |

* | |

* \par | |

* Fast versions are supported for Q31 and Q15. Cycles for Fast versions are less compared to Q31 and Q15 of conv and the design requires | |

* the input signals should be scaled down to avoid intermediate overflows. | |

* | |

* | |

* <b>Opt Versions</b> | |

* | |

* \par | |

* Opt versions are supported for Q15 and Q7. Design uses internal scratch buffer for getting good optimisation. | |

* These versions are optimised in cycles and consumes more memory(Scratch memory) compared to Q15 and Q7 versions | |

*/ | |

/** | |

* @addtogroup Conv | |

* @{ | |

*/ | |

/** | |

* @brief Convolution of floating-point 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. | |

*/ | |

void arm_conv_f32( | |

float32_t * pSrcA, | |

uint32_t srcALen, | |

float32_t * pSrcB, | |

uint32_t srcBLen, | |

float32_t * pDst) | |

{ | |

#if defined (ARM_MATH_DSP) | |

/* Run the below code for Cortex-M4 and Cortex-M3 */ | |

float32_t *pIn1; /* inputA pointer */ | |

float32_t *pIn2; /* inputB pointer */ | |

float32_t *pOut = pDst; /* output pointer */ | |

float32_t *px; /* Intermediate inputA pointer */ | |

float32_t *py; /* Intermediate inputB pointer */ | |

float32_t *pSrc1, *pSrc2; /* Intermediate pointers */ | |

float32_t sum, acc0, acc1, acc2, acc3; /* Accumulator */ | |

float32_t x0, x1, x2, x3, c0; /* Temporary variables to hold state and coefficient values */ | |

uint32_t j, k, count, blkCnt, blockSize1, blockSize2, blockSize3; /* loop counters */ | |

/* 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 = pSrcB; | |

/* Initialization of inputB pointer */ | |

pIn2 = 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 = 0.0f; | |

/* 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 += *px++ * *py--; | |

/* x[1] * y[srcBLen - 2] */ | |

sum += *px++ * *py--; | |

/* x[2] * y[srcBLen - 3] */ | |

sum += *px++ * *py--; | |

/* x[3] * y[srcBLen - 4] */ | |

sum += *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 += *px++ * *py--; | |

/* Decrement the loop counter */ | |

k--; | |

} | |

/* Store the result in the accumulator in the destination buffer. */ | |

*pOut++ = sum; | |

/* 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 = 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 = 0.0f; | |

acc1 = 0.0f; | |

acc2 = 0.0f; | |

acc3 = 0.0f; | |

/* 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-accumulate */ | |

/* acc0 += x[0] * y[srcBLen - 1] */ | |

acc0 += x0 * c0; | |

/* acc1 += x[1] * y[srcBLen - 1] */ | |

acc1 += x1 * c0; | |

/* acc2 += x[2] * y[srcBLen - 1] */ | |

acc2 += x2 * c0; | |

/* acc3 += x[3] * y[srcBLen - 1] */ | |

acc3 += x3 * c0; | |

/* Read y[srcBLen - 2] sample */ | |

c0 = *(py--); | |

/* Read x[4] sample */ | |

x0 = *(px + 1U); | |

/* Perform the multiply-accumulate */ | |

/* acc0 += x[1] * y[srcBLen - 2] */ | |

acc0 += x1 * c0; | |

/* acc1 += x[2] * y[srcBLen - 2] */ | |

acc1 += x2 * c0; | |

/* acc2 += x[3] * y[srcBLen - 2] */ | |

acc2 += x3 * c0; | |

/* acc3 += x[4] * y[srcBLen - 2] */ | |

acc3 += x0 * c0; | |

/* Read y[srcBLen - 3] sample */ | |

c0 = *(py--); | |

/* Read x[5] sample */ | |

x1 = *(px + 2U); | |

/* Perform the multiply-accumulates */ | |

/* acc0 += x[2] * y[srcBLen - 3] */ | |

acc0 += x2 * c0; | |

/* acc1 += x[3] * y[srcBLen - 2] */ | |

acc1 += x3 * c0; | |

/* acc2 += x[4] * y[srcBLen - 2] */ | |

acc2 += x0 * c0; | |

/* acc3 += x[5] * y[srcBLen - 2] */ | |

acc3 += x1 * c0; | |

/* Read y[srcBLen - 4] sample */ | |

c0 = *(py--); | |

/* Read x[6] sample */ | |

x2 = *(px + 3U); | |

px += 4U; | |

/* Perform the multiply-accumulates */ | |

/* acc0 += x[3] * y[srcBLen - 4] */ | |

acc0 += x3 * c0; | |

/* acc1 += x[4] * y[srcBLen - 4] */ | |

acc1 += x0 * c0; | |

/* acc2 += x[5] * y[srcBLen - 4] */ | |

acc2 += x1 * c0; | |

/* acc3 += x[6] * y[srcBLen - 4] */ | |

acc3 += 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 += x0 * c0; | |

/* acc1 += x[5] * y[srcBLen - 5] */ | |

acc1 += x1 * c0; | |

/* acc2 += x[6] * y[srcBLen - 5] */ | |

acc2 += x2 * c0; | |

/* acc3 += x[7] * y[srcBLen - 5] */ | |

acc3 += x3 * c0; | |

/* 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++ = acc0; | |

*pOut++ = acc1; | |

*pOut++ = acc2; | |

*pOut++ = acc3; | |

/* Increment the pointer pIn1 index, count by 4 */ | |

count += 4U; | |

/* Update the inputA and inputB pointers for next MAC calculation */ | |

px = pIn1 + count; | |

py = pSrc2; | |

/* 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 = 0.0f; | |

/* 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 += *px++ * *py--; | |

sum += *px++ * *py--; | |

sum += *px++ * *py--; | |

sum += *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 += *px++ * *py--; | |

/* Decrement the loop counter */ | |

k--; | |

} | |

/* Store the result in the accumulator in the destination buffer. */ | |

*pOut++ = sum; | |

/* Increment the MAC count */ | |

count++; | |

/* Update the inputA and inputB pointers for next MAC calculation */ | |

px = pIn1 + count; | |

py = pSrc2; | |

/* 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 = 0.0f; | |

/* srcBLen number of MACS should be performed */ | |

k = srcBLen; | |

while (k > 0U) | |

{ | |

/* Perform the multiply-accumulate */ | |

sum += *px++ * *py--; | |

/* Decrement the loop counter */ | |

k--; | |

} | |

/* Store the result in the accumulator in the destination buffer. */ | |

*pOut++ = sum; | |

/* Increment the MAC count */ | |

count++; | |

/* Update the inputA and inputB pointers for next MAC calculation */ | |

px = pIn1 + count; | |

py = pSrc2; | |

/* 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 = 0.0f; | |

/* 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 += *px++ * *py--; | |

/* sum += x[srcALen - srcBLen + 2] * y[srcBLen - 2] */ | |

sum += *px++ * *py--; | |

/* sum += x[srcALen - srcBLen + 3] * y[srcBLen - 3] */ | |

sum += *px++ * *py--; | |

/* sum += x[srcALen - srcBLen + 4] * y[srcBLen - 4] */ | |

sum += *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-accumulates */ | |

/* sum += x[srcALen-1] * y[srcBLen-1] */ | |

sum += *px++ * *py--; | |

/* Decrement the loop counter */ | |

k--; | |

} | |

/* Store the result in the accumulator in the destination buffer. */ | |

*pOut++ = sum; | |

/* 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 */ | |

float32_t *pIn1 = pSrcA; /* inputA pointer */ | |

float32_t *pIn2 = pSrcB; /* inputB pointer */ | |

float32_t sum; /* Accumulator */ | |

uint32_t i, j; /* loop counters */ | |

/* Loop to calculate convolution for output length number of times */ | |

for (i = 0U; i < ((srcALen + srcBLen) - 1U); i++) | |

{ | |

/* Initialize sum with zero to carry out MAC operations */ | |

sum = 0.0f; | |

/* 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 += pIn1[j] * pIn2[i - j]; | |

} | |

} | |

/* Store the output in the destination buffer */ | |

pDst[i] = sum; | |

} | |

#endif /* #if defined (ARM_MATH_DSP) */ | |

} | |

/** | |

* @} end of Conv group | |

*/ |