/* ----------------------------------------------------------------------
* Copyright (C) 2010 ARM Limited. All rights reserved.
*
* $Date: 15. February 2012
* $Revision: V1.1.0
*
* Project: CMSIS DSP Library
* Title: arm_fir_sparse_q15.c
*
* Description: Q15 sparse FIR filter processing function.
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Version 1.1.0 2012/02/15
* Updated with more optimizations, bug fixes and minor API changes.
*
* 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"
/**
* @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 */
#ifndef ARM_MATH_CM0
/* 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 - 1u;
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--;
}
/* 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 - 1u;
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--;
}
/* 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 /* #ifndef ARM_MATH_CM0 */
}
/**
* @} end of FIR_Sparse group
*/