pigweed / third_party / github / STMicroelectronics / cmsis_core / refs/heads/cm4 / . / DSP / Source / FilteringFunctions / arm_fir_interpolate_q15.c

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

* Project: CMSIS DSP Library | |

* Title: arm_fir_interpolate_q15.c | |

* Description: Q15 FIR interpolation | |

* | |

* $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 FIR_Interpolate | |

@{ | |

*/ | |

/** | |

@brief Processing function for the Q15 FIR interpolator. | |

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

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

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

@param[in] blockSize number of samples to process | |

@return none | |

@par Scaling and Overflow Behavior | |

The function is implemented using a 64-bit internal accumulator. | |

Both coefficients and state variables are represented 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. | |

There is no risk of internal overflow with this approach and the full precision of intermediate multiplications is preserved. | |

After all additions have been performed, the accumulator is truncated to 34.15 format by discarding low 15 bits. | |

Lastly, the accumulator is saturated to yield a result in 1.15 format. | |

*/ | |

void arm_fir_interpolate_q15( | |

const arm_fir_interpolate_instance_q15 * S, | |

const q15_t * pSrc, | |

q15_t * pDst, | |

uint32_t blockSize) | |

{ | |

#if (1) | |

//#if !defined(ARM_MATH_CM0_FAMILY) | |

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

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

q15_t *pStateCur; /* Points to the current sample of the state */ | |

q15_t *ptr1; /* Temporary pointer for state buffer */ | |

const q15_t *ptr2; /* Temporary pointer for coefficient buffer */ | |

q63_t sum0; /* Accumulators */ | |

uint32_t i, blkCnt, tapCnt; /* Loop counters */ | |

uint32_t phaseLen = S->phaseLength; /* Length of each polyphase filter component */ | |

uint32_t j; | |

#if defined (ARM_MATH_LOOPUNROLL) | |

q63_t acc0, acc1, acc2, acc3; | |

q15_t x0, x1, x2, x3; | |

q15_t c0, c1, c2, c3; | |

#endif | |

/* S->pState buffer contains previous frame (phaseLen - 1) samples */ | |

/* pStateCur points to the location where the new input data should be written */ | |

pStateCur = S->pState + (phaseLen - 1U); | |

#if defined (ARM_MATH_LOOPUNROLL) | |

/* Loop unrolling: Compute 4 outputs at a time */ | |

blkCnt = blockSize >> 2U; | |

while (blkCnt > 0U) | |

{ | |

/* Copy new input sample into the state buffer */ | |

*pStateCur++ = *pSrc++; | |

*pStateCur++ = *pSrc++; | |

*pStateCur++ = *pSrc++; | |

*pStateCur++ = *pSrc++; | |

/* Address modifier index of coefficient buffer */ | |

j = 1U; | |

/* Loop over the Interpolation factor. */ | |

i = (S->L); | |

while (i > 0U) | |

{ | |

/* Set accumulator to zero */ | |

acc0 = 0; | |

acc1 = 0; | |

acc2 = 0; | |

acc3 = 0; | |

/* Initialize state pointer */ | |

ptr1 = pState; | |

/* Initialize coefficient pointer */ | |

ptr2 = pCoeffs + (S->L - j); | |

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

Repeat until we've computed numTaps-(4*S->L) coefficients. */ | |

tapCnt = phaseLen >> 2U; | |

x0 = *(ptr1++); | |

x1 = *(ptr1++); | |

x2 = *(ptr1++); | |

while (tapCnt > 0U) | |

{ | |

/* Read the input sample */ | |

x3 = *(ptr1++); | |

/* Read the coefficient */ | |

c0 = *(ptr2); | |

/* Perform the multiply-accumulate */ | |

acc0 += (q63_t) x0 * c0; | |

acc1 += (q63_t) x1 * c0; | |

acc2 += (q63_t) x2 * c0; | |

acc3 += (q63_t) x3 * c0; | |

/* Read the coefficient */ | |

c1 = *(ptr2 + S->L); | |

/* Read the input sample */ | |

x0 = *(ptr1++); | |

/* Perform the multiply-accumulate */ | |

acc0 += (q63_t) x1 * c1; | |

acc1 += (q63_t) x2 * c1; | |

acc2 += (q63_t) x3 * c1; | |

acc3 += (q63_t) x0 * c1; | |

/* Read the coefficient */ | |

c2 = *(ptr2 + S->L * 2); | |

/* Read the input sample */ | |

x1 = *(ptr1++); | |

/* Perform the multiply-accumulate */ | |

acc0 += (q63_t) x2 * c2; | |

acc1 += (q63_t) x3 * c2; | |

acc2 += (q63_t) x0 * c2; | |

acc3 += (q63_t) x1 * c2; | |

/* Read the coefficient */ | |

c3 = *(ptr2 + S->L * 3); | |

/* Read the input sample */ | |

x2 = *(ptr1++); | |

/* Perform the multiply-accumulate */ | |

acc0 += (q63_t) x3 * c3; | |

acc1 += (q63_t) x0 * c3; | |

acc2 += (q63_t) x1 * c3; | |

acc3 += (q63_t) x2 * c3; | |

/* Upsampling is done by stuffing L-1 zeros between each sample. | |

* So instead of multiplying zeros with coefficients, | |

* Increment the coefficient pointer by interpolation factor times. */ | |

ptr2 += 4 * S->L; | |

/* Decrement loop counter */ | |

tapCnt--; | |

} | |

/* If the polyPhase length is not a multiple of 4, compute the remaining filter taps */ | |

tapCnt = phaseLen % 0x4U; | |

while (tapCnt > 0U) | |

{ | |

/* Read the input sample */ | |

x3 = *(ptr1++); | |

/* Read the coefficient */ | |

c0 = *(ptr2); | |

/* Perform the multiply-accumulate */ | |

acc0 += (q63_t) x0 * c0; | |

acc1 += (q63_t) x1 * c0; | |

acc2 += (q63_t) x2 * c0; | |

acc3 += (q63_t) x3 * c0; | |

/* Increment the coefficient pointer by interpolation factor times. */ | |

ptr2 += S->L; | |

/* update states for next sample processing */ | |

x0 = x1; | |

x1 = x2; | |

x2 = x3; | |

/* Decrement loop counter */ | |

tapCnt--; | |

} | |

/* The result is in the accumulator, store in the destination buffer. */ | |

*(pDst ) = (q15_t) (__SSAT((acc0 >> 15), 16)); | |

*(pDst + S->L) = (q15_t) (__SSAT((acc1 >> 15), 16)); | |

*(pDst + 2 * S->L) = (q15_t) (__SSAT((acc2 >> 15), 16)); | |

*(pDst + 3 * S->L) = (q15_t) (__SSAT((acc3 >> 15), 16)); | |

pDst++; | |

/* Increment the address modifier index of coefficient buffer */ | |

j++; | |

/* Decrement loop counter */ | |

i--; | |

} | |

/* Advance the state pointer by 1 | |

* to process the next group of interpolation factor number samples */ | |

pState = pState + 4; | |

pDst += S->L * 3; | |

/* Decrement loop counter */ | |

blkCnt--; | |

} | |

/* Loop unrolling: Compute remaining outputs */ | |

blkCnt = blockSize % 0x4U; | |

#else | |

/* Initialize blkCnt with number of samples */ | |

blkCnt = blockSize; | |

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

while (blkCnt > 0U) | |

{ | |

/* Copy new input sample into the state buffer */ | |

*pStateCur++ = *pSrc++; | |

/* Address modifier index of coefficient buffer */ | |

j = 1U; | |

/* Loop over the Interpolation factor. */ | |

i = S->L; | |

while (i > 0U) | |

{ | |

/* Set accumulator to zero */ | |

sum0 = 0; | |

/* Initialize state pointer */ | |

ptr1 = pState; | |

/* Initialize coefficient pointer */ | |

ptr2 = pCoeffs + (S->L - j); | |

/* Loop over the polyPhase length. | |

Repeat until we've computed numTaps-(4*S->L) coefficients. */ | |

#if defined (ARM_MATH_LOOPUNROLL) | |

/* Loop unrolling: Compute 4 outputs at a time */ | |

tapCnt = phaseLen >> 2U; | |

while (tapCnt > 0U) | |

{ | |

/* Perform the multiply-accumulate */ | |

sum0 += (q63_t) *ptr1++ * *ptr2; | |

/* Upsampling is done by stuffing L-1 zeros between each sample. | |

* So instead of multiplying zeros with coefficients, | |

* Increment the coefficient pointer by interpolation factor times. */ | |

ptr2 += S->L; | |

sum0 += (q63_t) *ptr1++ * *ptr2; | |

ptr2 += S->L; | |

sum0 += (q63_t) *ptr1++ * *ptr2; | |

ptr2 += S->L; | |

sum0 += (q63_t) *ptr1++ * *ptr2; | |

ptr2 += S->L; | |

/* Decrement loop counter */ | |

tapCnt--; | |

} | |

/* Loop unrolling: Compute remaining outputs */ | |

tapCnt = phaseLen % 0x4U; | |

#else | |

/* Initialize tapCnt with number of samples */ | |

tapCnt = phaseLen; | |

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

while (tapCnt > 0U) | |

{ | |

/* Perform the multiply-accumulate */ | |

sum0 += (q63_t) *ptr1++ * *ptr2; | |

/* Upsampling is done by stuffing L-1 zeros between each sample. | |

* So instead of multiplying zeros with coefficients, | |

* Increment the coefficient pointer by interpolation factor times. */ | |

ptr2 += S->L; | |

/* Decrement loop counter */ | |

tapCnt--; | |

} | |

/* The result is in the accumulator, store in the destination buffer. */ | |

*pDst++ = (q15_t) (__SSAT((sum0 >> 15), 16)); | |

/* Increment the address modifier index of coefficient buffer */ | |

j++; | |

/* Decrement the loop counter */ | |

i--; | |

} | |

/* Advance the state pointer by 1 | |

* to process the next group of interpolation factor number samples */ | |

pState = pState + 1; | |

/* Decrement the loop counter */ | |

blkCnt--; | |

} | |

/* Processing is complete. | |

Now copy the last phaseLen - 1 samples to the satrt of the state buffer. | |

This prepares the state buffer for the next function call. */ | |

/* Points to the start of the state buffer */ | |

pStateCur = S->pState; | |

#if defined (ARM_MATH_LOOPUNROLL) | |

/* Loop unrolling: Compute 4 outputs at a time */ | |

tapCnt = (phaseLen - 1U) >> 2U; | |

/* copy data */ | |

while (tapCnt > 0U) | |

{ | |

write_q15x2_ia (&pStateCur, read_q15x2_ia (&pState)); | |

write_q15x2_ia (&pStateCur, read_q15x2_ia (&pState)); | |

/* Decrement loop counter */ | |

tapCnt--; | |

} | |

/* Loop unrolling: Compute remaining outputs */ | |

tapCnt = (phaseLen - 1U) % 0x04U; | |

#else | |

/* Initialize tapCnt with number of samples */ | |

tapCnt = (phaseLen - 1U); | |

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

/* Copy data */ | |

while (tapCnt > 0U) | |

{ | |

*pStateCur++ = *pState++; | |

/* Decrement loop counter */ | |

tapCnt--; | |

} | |

#else | |

/* alternate version for CM0_FAMILY */ | |

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

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

q15_t *pStateCur; /* Points to the current sample of the state */ | |

q15_t *ptr1; /* Temporary pointer for state buffer */ | |

const q15_t *ptr2; /* Temporary pointer for coefficient buffer */ | |

q63_t sum0; /* Accumulators */ | |

uint32_t i, blkCnt, tapCnt; /* Loop counters */ | |

uint32_t phaseLen = S->phaseLength; /* Length of each polyphase filter component */ | |

/* S->pState buffer contains previous frame (phaseLen - 1) samples */ | |

/* pStateCur points to the location where the new input data should be written */ | |

pStateCur = S->pState + (phaseLen - 1U); | |

/* Total number of intput samples */ | |

blkCnt = blockSize; | |

/* Loop over the blockSize. */ | |

while (blkCnt > 0U) | |

{ | |

/* Copy new input sample into the state buffer */ | |

*pStateCur++ = *pSrc++; | |

/* Loop over the Interpolation factor. */ | |

i = S->L; | |

while (i > 0U) | |

{ | |

/* Set accumulator to zero */ | |

sum0 = 0; | |

/* Initialize state pointer */ | |

ptr1 = pState; | |

/* Initialize coefficient pointer */ | |

ptr2 = pCoeffs + (i - 1U); | |

/* Loop over the polyPhase length */ | |

tapCnt = phaseLen; | |

while (tapCnt > 0U) | |

{ | |

/* Perform the multiply-accumulate */ | |

sum0 += ((q63_t) *ptr1++ * *ptr2); | |

/* Increment the coefficient pointer by interpolation factor times. */ | |

ptr2 += S->L; | |

/* Decrement the loop counter */ | |

tapCnt--; | |

} | |

/* Store the result after converting to 1.15 format in the destination buffer. */ | |

*pDst++ = (q15_t) (__SSAT((sum0 >> 15), 16)); | |

/* Decrement loop counter */ | |

i--; | |

} | |

/* Advance the state pointer by 1 | |

* to process the next group of interpolation factor number samples */ | |

pState = pState + 1; | |

/* Decrement loop counter */ | |

blkCnt--; | |

} | |

/* Processing is complete. | |

** Now copy the last phaseLen - 1 samples to the start of the state buffer. | |

** This prepares the state buffer for the next function call. */ | |

/* Points to the start of the state buffer */ | |

pStateCur = S->pState; | |

tapCnt = phaseLen - 1U; | |

/* Copy data */ | |

while (tapCnt > 0U) | |

{ | |

*pStateCur++ = *pState++; | |

/* Decrement loop counter */ | |

tapCnt--; | |

} | |

#endif /* #if !defined(ARM_MATH_CM0_FAMILY) */ | |

} | |

/** | |

@} end of FIR_Interpolate group | |

*/ |