arm_fir_interpolate_q31.c
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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_fir_interpolate_q31.c | ||||
* | ||||
* Description: Q31 FIR interpolation. | ||||
* | ||||
* 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 FIR_Interpolate | ||||
* @{ | ||||
*/ | ||||
/** | ||||
* @brief Processing function for the Q31 FIR interpolator. | ||||
* @param[in] *S points to an instance of the Q31 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 input samples to process per call. | ||||
* @return none. | ||||
* | ||||
* <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. | ||||
* Thus, if the accumulator result overflows it wraps around rather than clip. | ||||
* In order to avoid overflows completely the input signal must be scaled down by <code>1/(numTaps/L)</code>. | ||||
* since <code>numTaps/L</code> additions occur per output sample. | ||||
* After all multiply-accumulates are performed, the 2.62 accumulator is truncated to 1.32 format and then saturated to 1.31 format. | ||||
*/ | ||||
void arm_fir_interpolate_q31( | ||||
const arm_fir_interpolate_instance_q31 * S, | ||||
q31_t * pSrc, | ||||
q31_t * pDst, | ||||
uint32_t blockSize) | ||||
{ | ||||
q31_t *pState = S->pState; /* State pointer */ | ||||
q31_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */ | ||||
q31_t *pStateCurnt; /* Points to the current sample of the state */ | ||||
q31_t *ptr1, *ptr2; /* Temporary pointers for state and coefficient buffers */ | ||||
#ifndef ARM_MATH_CM0 | ||||
/* Run the below code for Cortex-M4 and Cortex-M3 */ | ||||
q63_t sum0; /* Accumulators */ | ||||
q31_t x0, c0; /* Temporary variables to hold state and coefficient values */ | ||||
uint32_t i, blkCnt, j; /* Loop counters */ | ||||
uint16_t phaseLen = S->phaseLength, tapCnt; /* Length of each polyphase filter component */ | ||||
/* S->pState buffer contains previous frame (phaseLen - 1) samples */ | ||||
/* pStateCurnt points to the location where the new input data should be written */ | ||||
pStateCurnt = S->pState + ((q31_t) phaseLen - 1); | ||||
/* Total number of intput samples */ | ||||
blkCnt = blockSize; | ||||
/* Loop over the blockSize. */ | ||||
while(blkCnt > 0u) | ||||
{ | ||||
/* Copy new input sample into the state buffer */ | ||||
*pStateCurnt++ = *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. Unroll by a factor of 4. | ||||
** Repeat until we've computed numTaps-(4*S->L) coefficients. */ | ||||
tapCnt = phaseLen >> 2; | ||||
while(tapCnt > 0u) | ||||
{ | ||||
/* Read the coefficient */ | ||||
c0 = *(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; | ||||
/* Read the input sample */ | ||||
x0 = *(ptr1++); | ||||
/* Perform the multiply-accumulate */ | ||||
sum0 += (q63_t) x0 *c0; | ||||
/* Read the coefficient */ | ||||
c0 = *(ptr2); | ||||
/* Increment the coefficient pointer by interpolation factor times. */ | ||||
ptr2 += S->L; | ||||
/* Read the input sample */ | ||||
x0 = *(ptr1++); | ||||
/* Perform the multiply-accumulate */ | ||||
sum0 += (q63_t) x0 *c0; | ||||
/* Read the coefficient */ | ||||
c0 = *(ptr2); | ||||
/* Increment the coefficient pointer by interpolation factor times. */ | ||||
ptr2 += S->L; | ||||
/* Read the input sample */ | ||||
x0 = *(ptr1++); | ||||
/* Perform the multiply-accumulate */ | ||||
sum0 += (q63_t) x0 *c0; | ||||
/* Read the coefficient */ | ||||
c0 = *(ptr2); | ||||
/* Increment the coefficient pointer by interpolation factor times. */ | ||||
ptr2 += S->L; | ||||
/* Read the input sample */ | ||||
x0 = *(ptr1++); | ||||
/* Perform the multiply-accumulate */ | ||||
sum0 += (q63_t) x0 *c0; | ||||
/* Decrement the loop counter */ | ||||
tapCnt--; | ||||
} | ||||
/* If the polyPhase length is not a multiple of 4, compute the remaining filter taps */ | ||||
tapCnt = phaseLen & 0x3u; | ||||
while(tapCnt > 0u) | ||||
{ | ||||
/* Read the coefficient */ | ||||
c0 = *(ptr2); | ||||
/* Increment the coefficient pointer by interpolation factor times. */ | ||||
ptr2 += S->L; | ||||
/* Read the input sample */ | ||||
x0 = *(ptr1++); | ||||
/* Perform the multiply-accumulate */ | ||||
sum0 += (q63_t) x0 *c0; | ||||
/* Decrement the loop counter */ | ||||
tapCnt--; | ||||
} | ||||
/* The result is in the accumulator, store in the destination buffer. */ | ||||
*pDst++ = (q31_t) (sum0 >> 31); | ||||
/* 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 */ | ||||
pStateCurnt = S->pState; | ||||
tapCnt = (phaseLen - 1u) >> 2u; | ||||
/* copy data */ | ||||
while(tapCnt > 0u) | ||||
{ | ||||
*pStateCurnt++ = *pState++; | ||||
*pStateCurnt++ = *pState++; | ||||
*pStateCurnt++ = *pState++; | ||||
*pStateCurnt++ = *pState++; | ||||
/* Decrement the loop counter */ | ||||
tapCnt--; | ||||
} | ||||
tapCnt = (phaseLen - 1u) % 0x04u; | ||||
/* copy data */ | ||||
while(tapCnt > 0u) | ||||
{ | ||||
*pStateCurnt++ = *pState++; | ||||
/* Decrement the loop counter */ | ||||
tapCnt--; | ||||
} | ||||
#else | ||||
/* Run the below code for Cortex-M0 */ | ||||
q63_t sum; /* Accumulator */ | ||||
q31_t x0, c0; /* Temporary variables to hold state and coefficient values */ | ||||
uint32_t i, blkCnt; /* Loop counters */ | ||||
uint16_t phaseLen = S->phaseLength, tapCnt; /* Length of each polyphase filter component */ | ||||
/* S->pState buffer contains previous frame (phaseLen - 1) samples */ | ||||
/* pStateCurnt points to the location where the new input data should be written */ | ||||
pStateCurnt = S->pState + ((q31_t) phaseLen - 1); | ||||
/* Total number of intput samples */ | ||||
blkCnt = blockSize; | ||||
/* Loop over the blockSize. */ | ||||
while(blkCnt > 0u) | ||||
{ | ||||
/* Copy new input sample into the state buffer */ | ||||
*pStateCurnt++ = *pSrc++; | ||||
/* Loop over the Interpolation factor. */ | ||||
i = S->L; | ||||
while(i > 0u) | ||||
{ | ||||
/* Set accumulator to zero */ | ||||
sum = 0; | ||||
/* Initialize state pointer */ | ||||
ptr1 = pState; | ||||
/* Initialize coefficient pointer */ | ||||
ptr2 = pCoeffs + (i - 1u); | ||||
tapCnt = phaseLen; | ||||
while(tapCnt > 0u) | ||||
{ | ||||
/* Read the coefficient */ | ||||
c0 = *(ptr2); | ||||
/* Increment the coefficient pointer by interpolation factor times. */ | ||||
ptr2 += S->L; | ||||
/* Read the input sample */ | ||||
x0 = *ptr1++; | ||||
/* Perform the multiply-accumulate */ | ||||
sum += (q63_t) x0 *c0; | ||||
/* Decrement the loop counter */ | ||||
tapCnt--; | ||||
} | ||||
/* The result is in the accumulator, store in the destination buffer. */ | ||||
*pDst++ = (q31_t) (sum >> 31); | ||||
/* 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 */ | ||||
pStateCurnt = S->pState; | ||||
tapCnt = phaseLen - 1u; | ||||
/* copy data */ | ||||
while(tapCnt > 0u) | ||||
{ | ||||
*pStateCurnt++ = *pState++; | ||||
/* Decrement the loop counter */ | ||||
tapCnt--; | ||||
} | ||||
#endif /* #ifndef ARM_MATH_CM0 */ | ||||
} | ||||
/** | ||||
* @} end of FIR_Interpolate group | ||||
*/ | ||||