pigweed / third_party / github / STMicroelectronics / cmsis_core / cb6d9400754e6c9050487dfa573949b61152ac99 / . / DSP / Source / FilteringFunctions / arm_fir_sparse_q15.c

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

* Project: CMSIS DSP Library | |

* Title: arm_fir_sparse_q15.c | |

* Description: Q15 sparse FIR filter processing function | |

* | |

* $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" | |

/** | |

* @addtogroup FIR_Sparse | |

* @{ | |

*/ | |

/** | |

* @brief Processing function for the Q15 sparse FIR filter. | |

* @param[in] *S points to an instance of the Q15 sparse FIR structure. | |

* @param[in] *pSrc points to the block of input data. | |

* @param[out] *pDst points to the block of output data | |

* @param[in] *pScratchIn points to a temporary buffer of size blockSize. | |

* @param[in] *pScratchOut points to a temporary buffer of size blockSize. | |

* @param[in] blockSize number of input samples to process per call. | |

* @return none. | |

* | |

* <b>Scaling and Overflow Behavior:</b> | |

* \par | |

* The function is implemented using an internal 32-bit accumulator. | |

* The 1.15 x 1.15 multiplications yield a 2.30 result and these are added to a 2.30 accumulator. | |

* Thus the full precision of the multiplications is maintained but there is only a single guard bit in the accumulator. | |

* If the accumulator result overflows it will wrap around rather than saturate. | |

* After all multiply-accumulates are performed, the 2.30 accumulator is truncated to 2.15 format and then saturated to 1.15 format. | |

* In order to avoid overflows the input signal or coefficients must be scaled down by log2(numTaps) bits. | |

*/ | |

void arm_fir_sparse_q15( | |

arm_fir_sparse_instance_q15 * S, | |

q15_t * pSrc, | |

q15_t * pDst, | |

q15_t * pScratchIn, | |

q31_t * pScratchOut, | |

uint32_t blockSize) | |

{ | |

q15_t *pState = S->pState; /* State pointer */ | |

q15_t *pIn = pSrc; /* Working pointer for input */ | |

q15_t *pOut = pDst; /* Working pointer for output */ | |

q15_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */ | |

q15_t *px; /* Temporary pointers for scratch buffer */ | |

q15_t *pb = pScratchIn; /* Temporary pointers for scratch buffer */ | |

q15_t *py = pState; /* Temporary pointers for state buffer */ | |

int32_t *pTapDelay = S->pTapDelay; /* Pointer to the array containing offset of the non-zero tap values. */ | |

uint32_t delaySize = S->maxDelay + blockSize; /* state length */ | |

uint16_t numTaps = S->numTaps; /* Filter order */ | |

int32_t readIndex; /* Read index of the state buffer */ | |

uint32_t tapCnt, blkCnt; /* loop counters */ | |

q15_t coeff = *pCoeffs++; /* Read the first coefficient value */ | |

q31_t *pScr2 = pScratchOut; /* Working pointer for pScratchOut */ | |

#if defined (ARM_MATH_DSP) | |

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

q31_t in1, in2; /* Temporary variables */ | |

/* BlockSize of Input samples are copied into the state buffer */ | |

/* StateIndex points to the starting position to write in the state buffer */ | |

arm_circularWrite_q15(py, delaySize, &S->stateIndex, 1, pIn, 1, blockSize); | |

/* Loop over the number of taps. */ | |

tapCnt = numTaps; | |

/* Read Index, from where the state buffer should be read, is calculated. */ | |

readIndex = (S->stateIndex - blockSize) - *pTapDelay++; | |

/* Wraparound of readIndex */ | |

if (readIndex < 0) | |

{ | |

readIndex += (int32_t) delaySize; | |

} | |

/* Working pointer for state buffer is updated */ | |

py = pState; | |

/* blockSize samples are read from the state buffer */ | |

arm_circularRead_q15(py, delaySize, &readIndex, 1, | |

pb, pb, blockSize, 1, blockSize); | |

/* Working pointer for the scratch buffer of state values */ | |

px = pb; | |

/* Working pointer for scratch buffer of output values */ | |

pScratchOut = pScr2; | |

/* Loop over the blockSize. Unroll by a factor of 4. | |

* Compute 4 multiplications at a time. */ | |

blkCnt = blockSize >> 2; | |

while (blkCnt > 0U) | |

{ | |

/* Perform multiplication and store in the scratch buffer */ | |

*pScratchOut++ = ((q31_t) * px++ * coeff); | |

*pScratchOut++ = ((q31_t) * px++ * coeff); | |

*pScratchOut++ = ((q31_t) * px++ * coeff); | |

*pScratchOut++ = ((q31_t) * px++ * coeff); | |

/* Decrement the loop counter */ | |

blkCnt--; | |

} | |

/* If the blockSize is not a multiple of 4, | |

* compute the remaining samples */ | |

blkCnt = blockSize % 0x4U; | |

while (blkCnt > 0U) | |

{ | |

/* Perform multiplication and store in the scratch buffer */ | |

*pScratchOut++ = ((q31_t) * px++ * coeff); | |

/* Decrement the loop counter */ | |

blkCnt--; | |

} | |

/* Load the coefficient value and | |

* increment the coefficient buffer for the next set of state values */ | |

coeff = *pCoeffs++; | |

/* Read Index, from where the state buffer should be read, is calculated. */ | |

readIndex = (S->stateIndex - blockSize) - *pTapDelay++; | |

/* Wraparound of readIndex */ | |

if (readIndex < 0) | |

{ | |

readIndex += (int32_t) delaySize; | |

} | |

/* Loop over the number of taps. */ | |

tapCnt = (uint32_t) numTaps - 2U; | |

while (tapCnt > 0U) | |

{ | |

/* Working pointer for state buffer is updated */ | |

py = pState; | |

/* blockSize samples are read from the state buffer */ | |

arm_circularRead_q15(py, delaySize, &readIndex, 1, | |

pb, pb, blockSize, 1, blockSize); | |

/* Working pointer for the scratch buffer of state values */ | |

px = pb; | |

/* Working pointer for scratch buffer of output values */ | |

pScratchOut = pScr2; | |

/* Loop over the blockSize. Unroll by a factor of 4. | |

* Compute 4 MACS at a time. */ | |

blkCnt = blockSize >> 2; | |

while (blkCnt > 0U) | |

{ | |

/* Perform Multiply-Accumulate */ | |

*pScratchOut++ += (q31_t) * px++ * coeff; | |

*pScratchOut++ += (q31_t) * px++ * coeff; | |

*pScratchOut++ += (q31_t) * px++ * coeff; | |

*pScratchOut++ += (q31_t) * px++ * coeff; | |

/* Decrement the loop counter */ | |

blkCnt--; | |

} | |

/* If the blockSize is not a multiple of 4, | |

* compute the remaining samples */ | |

blkCnt = blockSize % 0x4U; | |

while (blkCnt > 0U) | |

{ | |

/* Perform Multiply-Accumulate */ | |

*pScratchOut++ += (q31_t) * px++ * coeff; | |

/* Decrement the loop counter */ | |

blkCnt--; | |

} | |

/* Load the coefficient value and | |

* increment the coefficient buffer for the next set of state values */ | |

coeff = *pCoeffs++; | |

/* Read Index, from where the state buffer should be read, is calculated. */ | |

readIndex = (S->stateIndex - blockSize) - *pTapDelay++; | |

/* Wraparound of readIndex */ | |

if (readIndex < 0) | |

{ | |

readIndex += (int32_t) delaySize; | |

} | |

/* Decrement the tap loop counter */ | |

tapCnt--; | |

} | |

/* Compute last tap without the final read of pTapDelay */ | |

/* Working pointer for state buffer is updated */ | |

py = pState; | |

/* blockSize samples are read from the state buffer */ | |

arm_circularRead_q15(py, delaySize, &readIndex, 1, | |

pb, pb, blockSize, 1, blockSize); | |

/* Working pointer for the scratch buffer of state values */ | |

px = pb; | |

/* Working pointer for scratch buffer of output values */ | |

pScratchOut = pScr2; | |

/* Loop over the blockSize. Unroll by a factor of 4. | |

* Compute 4 MACS at a time. */ | |

blkCnt = blockSize >> 2; | |

while (blkCnt > 0U) | |

{ | |

/* Perform Multiply-Accumulate */ | |

*pScratchOut++ += (q31_t) * px++ * coeff; | |

*pScratchOut++ += (q31_t) * px++ * coeff; | |

*pScratchOut++ += (q31_t) * px++ * coeff; | |

*pScratchOut++ += (q31_t) * px++ * coeff; | |

/* Decrement the loop counter */ | |

blkCnt--; | |

} | |

/* If the blockSize is not a multiple of 4, | |

* compute the remaining samples */ | |

blkCnt = blockSize % 0x4U; | |

while (blkCnt > 0U) | |

{ | |

/* Perform Multiply-Accumulate */ | |

*pScratchOut++ += (q31_t) * px++ * coeff; | |

/* Decrement the loop counter */ | |

blkCnt--; | |

} | |

/* All the output values are in pScratchOut buffer. | |

Convert them into 1.15 format, saturate and store in the destination buffer. */ | |

/* Loop over the blockSize. */ | |

blkCnt = blockSize >> 2; | |

while (blkCnt > 0U) | |

{ | |

in1 = *pScr2++; | |

in2 = *pScr2++; | |

#ifndef ARM_MATH_BIG_ENDIAN | |

*__SIMD32(pOut)++ = | |

__PKHBT((q15_t) __SSAT(in1 >> 15, 16), (q15_t) __SSAT(in2 >> 15, 16), | |

16); | |

#else | |

*__SIMD32(pOut)++ = | |

__PKHBT((q15_t) __SSAT(in2 >> 15, 16), (q15_t) __SSAT(in1 >> 15, 16), | |

16); | |

#endif /* #ifndef ARM_MATH_BIG_ENDIAN */ | |

in1 = *pScr2++; | |

in2 = *pScr2++; | |

#ifndef ARM_MATH_BIG_ENDIAN | |

*__SIMD32(pOut)++ = | |

__PKHBT((q15_t) __SSAT(in1 >> 15, 16), (q15_t) __SSAT(in2 >> 15, 16), | |

16); | |

#else | |

*__SIMD32(pOut)++ = | |

__PKHBT((q15_t) __SSAT(in2 >> 15, 16), (q15_t) __SSAT(in1 >> 15, 16), | |

16); | |

#endif /* #ifndef ARM_MATH_BIG_ENDIAN */ | |

blkCnt--; | |

} | |

/* If the blockSize is not a multiple of 4, | |

remaining samples are processed in the below loop */ | |

blkCnt = blockSize % 0x4U; | |

while (blkCnt > 0U) | |

{ | |

*pOut++ = (q15_t) __SSAT(*pScr2++ >> 15, 16); | |

blkCnt--; | |

} | |

#else | |

/* Run the below code for Cortex-M0 */ | |

/* BlockSize of Input samples are copied into the state buffer */ | |

/* StateIndex points to the starting position to write in the state buffer */ | |

arm_circularWrite_q15(py, delaySize, &S->stateIndex, 1, pIn, 1, blockSize); | |

/* Loop over the number of taps. */ | |

tapCnt = numTaps; | |

/* Read Index, from where the state buffer should be read, is calculated. */ | |

readIndex = (S->stateIndex - blockSize) - *pTapDelay++; | |

/* Wraparound of readIndex */ | |

if (readIndex < 0) | |

{ | |

readIndex += (int32_t) delaySize; | |

} | |

/* Working pointer for state buffer is updated */ | |

py = pState; | |

/* blockSize samples are read from the state buffer */ | |

arm_circularRead_q15(py, delaySize, &readIndex, 1, | |

pb, pb, blockSize, 1, blockSize); | |

/* Working pointer for the scratch buffer of state values */ | |

px = pb; | |

/* Working pointer for scratch buffer of output values */ | |

pScratchOut = pScr2; | |

blkCnt = blockSize; | |

while (blkCnt > 0U) | |

{ | |

/* Perform multiplication and store in the scratch buffer */ | |

*pScratchOut++ = ((q31_t) * px++ * coeff); | |

/* Decrement the loop counter */ | |

blkCnt--; | |

} | |

/* Load the coefficient value and | |

* increment the coefficient buffer for the next set of state values */ | |

coeff = *pCoeffs++; | |

/* Read Index, from where the state buffer should be read, is calculated. */ | |

readIndex = (S->stateIndex - blockSize) - *pTapDelay++; | |

/* Wraparound of readIndex */ | |

if (readIndex < 0) | |

{ | |

readIndex += (int32_t) delaySize; | |

} | |

/* Loop over the number of taps. */ | |

tapCnt = (uint32_t) numTaps - 2U; | |

while (tapCnt > 0U) | |

{ | |

/* Working pointer for state buffer is updated */ | |

py = pState; | |

/* blockSize samples are read from the state buffer */ | |

arm_circularRead_q15(py, delaySize, &readIndex, 1, | |

pb, pb, blockSize, 1, blockSize); | |

/* Working pointer for the scratch buffer of state values */ | |

px = pb; | |

/* Working pointer for scratch buffer of output values */ | |

pScratchOut = pScr2; | |

blkCnt = blockSize; | |

while (blkCnt > 0U) | |

{ | |

/* Perform Multiply-Accumulate */ | |

*pScratchOut++ += (q31_t) * px++ * coeff; | |

/* Decrement the loop counter */ | |

blkCnt--; | |

} | |

/* Load the coefficient value and | |

* increment the coefficient buffer for the next set of state values */ | |

coeff = *pCoeffs++; | |

/* Read Index, from where the state buffer should be read, is calculated. */ | |

readIndex = (S->stateIndex - blockSize) - *pTapDelay++; | |

/* Wraparound of readIndex */ | |

if (readIndex < 0) | |

{ | |

readIndex += (int32_t) delaySize; | |

} | |

/* Decrement the tap loop counter */ | |

tapCnt--; | |

} | |

/* Compute last tap without the final read of pTapDelay */ | |

/* Working pointer for state buffer is updated */ | |

py = pState; | |

/* blockSize samples are read from the state buffer */ | |

arm_circularRead_q15(py, delaySize, &readIndex, 1, | |

pb, pb, blockSize, 1, blockSize); | |

/* Working pointer for the scratch buffer of state values */ | |

px = pb; | |

/* Working pointer for scratch buffer of output values */ | |

pScratchOut = pScr2; | |

blkCnt = blockSize; | |

while (blkCnt > 0U) | |

{ | |

/* Perform Multiply-Accumulate */ | |

*pScratchOut++ += (q31_t) * px++ * coeff; | |

/* Decrement the loop counter */ | |

blkCnt--; | |

} | |

/* All the output values are in pScratchOut buffer. | |

Convert them into 1.15 format, saturate and store in the destination buffer. */ | |

/* Loop over the blockSize. */ | |

blkCnt = blockSize; | |

while (blkCnt > 0U) | |

{ | |

*pOut++ = (q15_t) __SSAT(*pScr2++ >> 15, 16); | |

blkCnt--; | |

} | |

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

} | |

/** | |

* @} end of FIR_Sparse group | |

*/ |