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NucleoTNC/Src/arm_fir_interpolate_q15.c

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/*-----------------------------------------------------------------------------
* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
*
* $Date: 19. March 2015
* $Revision: V.1.4.5
*
* Project: CMSIS DSP Library
* Title: arm_fir_interpolate_q15.c
*
* Description: Q15 FIR interpolation.
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* - Neither the name of ARM LIMITED nor the names of its contributors
* may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
* ---------------------------------------------------------------------------*/
#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 input samples to process per call.
* @return none.
*
* <b>Scaling and Overflow Behavior:</b>
* \par
* 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.
*/
#ifndef ARM_MATH_CM0_FAMILY
/* Run the below code for Cortex-M4 and Cortex-M3 */
void arm_fir_interpolate_q15(
const arm_fir_interpolate_instance_q15 * S,
q15_t * pSrc,
q15_t * pDst,
uint32_t blockSize)
{
q15_t *pState = S->pState; /* State pointer */
q15_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
q15_t *pStateCurnt; /* Points to the current sample of the state */
q15_t *ptr1, *ptr2; /* Temporary pointers for state and coefficient buffers */
q63_t sum0; /* Accumulators */
q15_t x0, c0; /* Temporary variables to hold state and coefficient values */
uint32_t i, blkCnt, j, tapCnt; /* Loop counters */
uint16_t phaseLen = S->phaseLength; /* Length of each polyphase filter component */
uint32_t blkCntN2;
q63_t acc0, acc1;
q15_t x1;
/* 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);
/* Initialise blkCnt */
blkCnt = blockSize / 2;
blkCntN2 = blockSize - (2 * blkCnt);
/* Samples loop unrolled by 2 */
while(blkCnt > 0u)
{
/* Copy new input sample into the state buffer */
*pStateCurnt++ = *pSrc++;
*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 */
acc0 = 0;
acc1 = 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++);
while(tapCnt > 0u)
{
/* Read the input sample */
x1 = *(ptr1++);
/* Read the coefficient */
c0 = *(ptr2);
/* Perform the multiply-accumulate */
acc0 += (q63_t) x0 *c0;
acc1 += (q63_t) x1 *c0;
/* Read the coefficient */
c0 = *(ptr2 + S->L);
/* Read the input sample */
x0 = *(ptr1++);
/* Perform the multiply-accumulate */
acc0 += (q63_t) x1 *c0;
acc1 += (q63_t) x0 *c0;
/* Read the coefficient */
c0 = *(ptr2 + S->L * 2);
/* Read the input sample */
x1 = *(ptr1++);
/* Perform the multiply-accumulate */
acc0 += (q63_t) x0 *c0;
acc1 += (q63_t) x1 *c0;
/* Read the coefficient */
c0 = *(ptr2 + S->L * 3);
/* Read the input sample */
x0 = *(ptr1++);
/* Perform the multiply-accumulate */
acc0 += (q63_t) x1 *c0;
acc1 += (q63_t) x0 *c0;
/* 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 the 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 */
x1 = *(ptr1++);
/* Read the coefficient */
c0 = *(ptr2);
/* Perform the multiply-accumulate */
acc0 += (q63_t) x0 *c0;
acc1 += (q63_t) x1 *c0;
/* Increment the coefficient pointer by interpolation factor times. */
ptr2 += S->L;
/* update states for next sample processing */
x0 = x1;
/* Decrement the 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++;
/* 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 + 2;
pDst += S->L;
/* Decrement the loop counter */
blkCnt--;
}
/* If the blockSize is not a multiple of 2, compute any remaining output samples here.
** No loop unrolling is used. */
blkCnt = blkCntN2;
/* 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++ = (q15_t) (__SSAT((sum0 >> 15), 16));
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;
i = ((uint32_t) phaseLen - 1u) >> 2u;
/* copy data */
while(i > 0u)
{
#ifndef UNALIGNED_SUPPORT_DISABLE
*__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;
*__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;
#else
*pStateCurnt++ = *pState++;
*pStateCurnt++ = *pState++;
*pStateCurnt++ = *pState++;
*pStateCurnt++ = *pState++;
#endif /* #ifndef UNALIGNED_SUPPORT_DISABLE */
/* Decrement the loop counter */
i--;
}
i = ((uint32_t) phaseLen - 1u) % 0x04u;
while(i > 0u)
{
*pStateCurnt++ = *pState++;
/* Decrement the loop counter */
i--;
}
}
#else
/* Run the below code for Cortex-M0 */
void arm_fir_interpolate_q15(
const arm_fir_interpolate_instance_q15 * S,
q15_t * pSrc,
q15_t * pDst,
uint32_t blockSize)
{
q15_t *pState = S->pState; /* State pointer */
q15_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
q15_t *pStateCurnt; /* Points to the current sample of the state */
q15_t *ptr1, *ptr2; /* Temporary pointers for state and coefficient buffers */
q63_t sum; /* Accumulator */
q15_t x0, c0; /* Temporary variables to hold state and coefficient values */
uint32_t i, blkCnt, tapCnt; /* Loop counters */
uint16_t phaseLen = S->phaseLength; /* 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 + (phaseLen - 1u);
/* 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);
/* Loop over the polyPhase length */
tapCnt = (uint32_t) 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 += ((q31_t) x0 * c0);
/* Decrement the loop counter */
tapCnt--;
}
/* Store the result after converting to 1.15 format in the destination buffer */
*pDst++ = (q15_t) (__SSAT((sum >> 15), 16));
/* 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 start 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;
i = (uint32_t) phaseLen - 1u;
while(i > 0u)
{
*pStateCurnt++ = *pState++;
/* Decrement the loop counter */
i--;
}
}
#endif /* #ifndef ARM_MATH_CM0_FAMILY */
/**
* @} end of FIR_Interpolate group
*/
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