arm_fir_sparse_f32.c
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r71 | /* ---------------------------------------------------------------------- | |||
* Copyright (C) 2010 ARM Limited. All rights reserved. | ||||
* | ||||
* $Date: 15. July 2011 | ||||
* $Revision: V1.0.10 | ||||
* | ||||
* Project: CMSIS DSP Library | ||||
* Title: arm_fir_sparse_f32.c | ||||
* | ||||
* Description: Floating-point sparse FIR filter processing function. | ||||
* | ||||
* 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 | ||||
*/ | ||||
/** | ||||
* @defgroup FIR_Sparse Finite Impulse Response (FIR) Sparse Filters | ||||
* | ||||
* This group of functions implements sparse FIR filters. | ||||
* Sparse FIR filters are equivalent to standard FIR filters except that most of the coefficients are equal to zero. | ||||
* Sparse filters are used for simulating reflections in communications and audio applications. | ||||
* | ||||
* There are separate functions for Q7, Q15, Q31, and floating-point data types. | ||||
* The functions operate on blocks of input and output data and each call to the function processes | ||||
* <code>blockSize</code> samples through the filter. <code>pSrc</code> and | ||||
* <code>pDst</code> points to input and output arrays respectively containing <code>blockSize</code> values. | ||||
* | ||||
* \par Algorithm: | ||||
* The sparse filter instant structure contains an array of tap indices <code>pTapDelay</code> which specifies the locations of the non-zero coefficients. | ||||
* This is in addition to the coefficient array <code>b</code>. | ||||
* The implementation essentially skips the multiplications by zero and leads to an efficient realization. | ||||
* <pre> | ||||
* y[n] = b[0] * x[n-pTapDelay[0]] + b[1] * x[n-pTapDelay[1]] + b[2] * x[n-pTapDelay[2]] + ...+ b[numTaps-1] * x[n-pTapDelay[numTaps-1]] | ||||
* </pre> | ||||
* \par | ||||
* \image html FIRSparse.gif "Sparse FIR filter. b[n] represents the filter coefficients" | ||||
* \par | ||||
* <code>pCoeffs</code> points to a coefficient array of size <code>numTaps</code>; | ||||
* <code>pTapDelay</code> points to an array of nonzero indices and is also of size <code>numTaps</code>; | ||||
* <code>pState</code> points to a state array of size <code>maxDelay + blockSize</code>, where | ||||
* <code>maxDelay</code> is the largest offset value that is ever used in the <code>pTapDelay</code> array. | ||||
* Some of the processing functions also require temporary working buffers. | ||||
* | ||||
* \par Instance Structure | ||||
* The coefficients and state variables for a filter are stored together in an instance data structure. | ||||
* A separate instance structure must be defined for each filter. | ||||
* Coefficient and offset arrays may be shared among several instances while state variable arrays cannot be shared. | ||||
* There are separate instance structure declarations for each of the 4 supported data types. | ||||
* | ||||
* \par Initialization Functions | ||||
* There is also an associated initialization function for each data type. | ||||
* The initialization function performs the following operations: | ||||
* - Sets the values of the internal structure fields. | ||||
* - Zeros out the values in the state buffer. | ||||
* | ||||
* \par | ||||
* Use of the initialization function is optional. | ||||
* However, if the initialization function is used, then the instance structure cannot be placed into a const data section. | ||||
* To place an instance structure into a const data section, the instance structure must be manually initialized. | ||||
* Set the values in the state buffer to zeros before static initialization. | ||||
* The code below statically initializes each of the 4 different data type filter instance structures | ||||
* <pre> | ||||
*arm_fir_sparse_instance_f32 S = {numTaps, 0, pState, pCoeffs, maxDelay, pTapDelay}; | ||||
*arm_fir_sparse_instance_q31 S = {numTaps, 0, pState, pCoeffs, maxDelay, pTapDelay}; | ||||
*arm_fir_sparse_instance_q15 S = {numTaps, 0, pState, pCoeffs, maxDelay, pTapDelay}; | ||||
*arm_fir_sparse_instance_q7 S = {numTaps, 0, pState, pCoeffs, maxDelay, pTapDelay}; | ||||
* </pre> | ||||
* \par | ||||
* | ||||
* \par Fixed-Point Behavior | ||||
* Care must be taken when using the fixed-point versions of the sparse FIR filter functions. | ||||
* In particular, the overflow and saturation behavior of the accumulator used in each function must be considered. | ||||
* Refer to the function specific documentation below for usage guidelines. | ||||
*/ | ||||
/** | ||||
* @addtogroup FIR_Sparse | ||||
* @{ | ||||
*/ | ||||
/** | ||||
* @brief Processing function for the floating-point sparse FIR filter. | ||||
* @param[in] *S points to an instance of the floating-point 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] blockSize number of input samples to process per call. | ||||
* @return none. | ||||
*/ | ||||
void arm_fir_sparse_f32( | ||||
arm_fir_sparse_instance_f32 * S, | ||||
float32_t * pSrc, | ||||
float32_t * pDst, | ||||
float32_t * pScratchIn, | ||||
uint32_t blockSize) | ||||
{ | ||||
float32_t *pState = S->pState; /* State pointer */ | ||||
float32_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */ | ||||
float32_t *px; /* Scratch buffer pointer */ | ||||
float32_t *py = pState; /* Temporary pointers for state buffer */ | ||||
float32_t *pb = pScratchIn; /* Temporary pointers for scratch buffer */ | ||||
float32_t *pOut; /* Destination pointer */ | ||||
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; /* Number of filter coefficients in the filter */ | ||||
int32_t readIndex; /* Read index of the state buffer */ | ||||
uint32_t tapCnt, blkCnt; /* loop counters */ | ||||
float32_t coeff = *pCoeffs++; /* Read the first coefficient value */ | ||||
/* BlockSize of Input samples are copied into the state buffer */ | ||||
/* StateIndex points to the starting position to write in the state buffer */ | ||||
arm_circularWrite_f32((int32_t *) py, delaySize, &S->stateIndex, 1, | ||||
(int32_t *) pSrc, 1, blockSize); | ||||
/* Read Index, from where the state buffer should be read, is calculated. */ | ||||
readIndex = ((int32_t) S->stateIndex - (int32_t) 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_f32((int32_t *) py, delaySize, &readIndex, 1, | ||||
(int32_t *) pb, (int32_t *) pb, blockSize, 1, | ||||
blockSize); | ||||
/* Working pointer for the scratch buffer */ | ||||
px = pb; | ||||
/* Working pointer for destination buffer */ | ||||
pOut = pDst; | ||||
#ifndef ARM_MATH_CM0 | ||||
/* Run the below code for Cortex-M4 and Cortex-M3 */ | ||||
/* Loop over the blockSize. Unroll by a factor of 4. | ||||
* Compute 4 Multiplications at a time. */ | ||||
blkCnt = blockSize >> 2u; | ||||
while(blkCnt > 0u) | ||||
{ | ||||
/* Perform Multiplications and store in destination buffer */ | ||||
*pOut++ = *px++ * coeff; | ||||
*pOut++ = *px++ * coeff; | ||||
*pOut++ = *px++ * coeff; | ||||
*pOut++ = *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 Multiplications and store in destination buffer */ | ||||
*pOut++ = *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 = ((int32_t) S->stateIndex - (int32_t) blockSize) - *pTapDelay++; | ||||
/* Wraparound of readIndex */ | ||||
if(readIndex < 0) | ||||
{ | ||||
readIndex += (int32_t) delaySize; | ||||
} | ||||
/* Loop over the number of taps. */ | ||||
tapCnt = (uint32_t) numTaps - 1u; | ||||
while(tapCnt > 0u) | ||||
{ | ||||
/* Working pointer for state buffer is updated */ | ||||
py = pState; | ||||
/* blockSize samples are read from the state buffer */ | ||||
arm_circularRead_f32((int32_t *) py, delaySize, &readIndex, 1, | ||||
(int32_t *) pb, (int32_t *) pb, blockSize, 1, | ||||
blockSize); | ||||
/* Working pointer for the scratch buffer */ | ||||
px = pb; | ||||
/* Working pointer for destination buffer */ | ||||
pOut = pDst; | ||||
/* Loop over the blockSize. Unroll by a factor of 4. | ||||
* Compute 4 MACS at a time. */ | ||||
blkCnt = blockSize >> 2u; | ||||
while(blkCnt > 0u) | ||||
{ | ||||
/* Perform Multiply-Accumulate */ | ||||
*pOut++ += *px++ * coeff; | ||||
*pOut++ += *px++ * coeff; | ||||
*pOut++ += *px++ * coeff; | ||||
*pOut++ += *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 */ | ||||
*pOut++ += *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 = ((int32_t) S->stateIndex - | ||||
(int32_t) blockSize) - *pTapDelay++; | ||||
/* Wraparound of readIndex */ | ||||
if(readIndex < 0) | ||||
{ | ||||
readIndex += (int32_t) delaySize; | ||||
} | ||||
/* Decrement the tap loop counter */ | ||||
tapCnt--; | ||||
} | ||||
#else | ||||
/* Run the below code for Cortex-M0 */ | ||||
blkCnt = blockSize; | ||||
while(blkCnt > 0u) | ||||
{ | ||||
/* Perform Multiplications and store in destination buffer */ | ||||
*pOut++ = *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 = ((int32_t) S->stateIndex - (int32_t) blockSize) - *pTapDelay++; | ||||
/* Wraparound of readIndex */ | ||||
if(readIndex < 0) | ||||
{ | ||||
readIndex += (int32_t) delaySize; | ||||
} | ||||
/* Loop over the number of taps. */ | ||||
tapCnt = (uint32_t) numTaps - 1u; | ||||
while(tapCnt > 0u) | ||||
{ | ||||
/* Working pointer for state buffer is updated */ | ||||
py = pState; | ||||
/* blockSize samples are read from the state buffer */ | ||||
arm_circularRead_f32((int32_t *) py, delaySize, &readIndex, 1, | ||||
(int32_t *) pb, (int32_t *) pb, blockSize, 1, | ||||
blockSize); | ||||
/* Working pointer for the scratch buffer */ | ||||
px = pb; | ||||
/* Working pointer for destination buffer */ | ||||
pOut = pDst; | ||||
blkCnt = blockSize; | ||||
while(blkCnt > 0u) | ||||
{ | ||||
/* Perform Multiply-Accumulate */ | ||||
*pOut++ += *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 = | ||||
((int32_t) S->stateIndex - (int32_t) blockSize) - *pTapDelay++; | ||||
/* Wraparound of readIndex */ | ||||
if(readIndex < 0) | ||||
{ | ||||
readIndex += (int32_t) delaySize; | ||||
} | ||||
/* Decrement the tap loop counter */ | ||||
tapCnt--; | ||||
} | ||||
#endif /* #ifndef ARM_MATH_CM0 */ | ||||
} | ||||
/** | ||||
* @} end of FIR_Sparse group | ||||
*/ | ||||