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NE10_iir.c
/*
* Copyright 2012-15 ARM Limited and Contributors.
* All rights reserved.
*
* 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 ARM LIMITED 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 ARM LIMITED AND 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.
*/
/*
* NE10 Library : dsp/NE10_iir.c
*/
#include "NE10_types.h"
void ne10_iir_lattice_float_c (const ne10_iir_lattice_instance_f32_t * S,
ne10_float32_t * pSrc,
ne10_float32_t * pDst,
ne10_uint32_t blockSize)
{
ne10_float32_t fcurr, fnext = 0, gcurr, gnext; /* Temporary variables for lattice stages */
ne10_float32_t acc; /* Accumlator */
ne10_uint32_t blkCnt, tapCnt; /* temporary variables for counts */
ne10_float32_t *px1, *px2, *pk, *pv; /* temporary pointers for state and coef */
ne10_uint32_t numStages = S->numStages; /* number of stages */
ne10_float32_t *pState; /* State pointer */
ne10_float32_t *pStateCurnt; /* State current pointer */
/* Run the below code for Cortex-M4 and Cortex-M3 */
gcurr = 0.0f;
blkCnt = blockSize;
pState = &S->pState[0];
/* Sample processing */
while (blkCnt > 0u)
{
/* Read Sample from input buffer */
/* fN(n) = x(n) */
fcurr = *pSrc++;
/* Initialize state read pointer */
px1 = pState;
/* Initialize state write pointer */
px2 = pState;
/* Set accumulator to zero */
acc = 0.0f;
/* Initialize Ladder coeff pointer */
pv = &S->pvCoeffs[S->numStages];
/* Initialize Reflection coeff pointer */
pk = &S->pkCoeffs[0];
/* Process sample for first tap */
gcurr = *px1++;
/* fN-1(n) = fN(n) - kN * gN-1(n-1) */
fnext = fcurr - ( (*pk) * gcurr);
/* gN(n) = kN * fN-1(n) + gN-1(n-1) */
gnext = (fnext * (*pk++)) + gcurr;
/* write gN(n) into state for next sample processing */
*px2++ = gnext;
/* y(n) += gN(n) * vN */
acc += (gnext * (*pv--));
/* Update f values for next coefficient processing */
fcurr = fnext;
/* Loop unrolling. Process 4 taps at a time. */
tapCnt = (numStages - 1u) >> 2;
while (tapCnt > 0u)
{
/* Process sample for 2nd, 6th ...taps */
/* Read gN-2(n-1) from state buffer */
gcurr = *px1++;
/* Process sample for 2nd, 6th .. taps */
/* fN-2(n) = fN-1(n) - kN-1 * gN-2(n-1) */
fnext = fcurr - ( (*pk) * gcurr);
/* gN-1(n) = kN-1 * fN-2(n) + gN-2(n-1) */
gnext = (fnext * (*pk++)) + gcurr;
/* y(n) += gN-1(n) * vN-1 */
/* process for gN-5(n) * vN-5, gN-9(n) * vN-9 ... */
acc += (gnext * (*pv--));
/* write gN-1(n) into state for next sample processing */
*px2++ = gnext;
/* Process sample for 3nd, 7th ...taps */
/* Read gN-3(n-1) from state buffer */
gcurr = *px1++;
/* Process sample for 3rd, 7th .. taps */
/* fN-3(n) = fN-2(n) - kN-2 * gN-3(n-1) */
fcurr = fnext - ( (*pk) * gcurr);
/* gN-2(n) = kN-2 * fN-3(n) + gN-3(n-1) */
gnext = (fcurr * (*pk++)) + gcurr;
/* y(n) += gN-2(n) * vN-2 */
/* process for gN-6(n) * vN-6, gN-10(n) * vN-10 ... */
acc += (gnext * (*pv--));
/* write gN-2(n) into state for next sample processing */
*px2++ = gnext;
/* Process sample for 4th, 8th ...taps */
/* Read gN-4(n-1) from state buffer */
gcurr = *px1++;
/* Process sample for 4th, 8th .. taps */
/* fN-4(n) = fN-3(n) - kN-3 * gN-4(n-1) */
fnext = fcurr - ( (*pk) * gcurr);
/* gN-3(n) = kN-3 * fN-4(n) + gN-4(n-1) */
gnext = (fnext * (*pk++)) + gcurr;
/* y(n) += gN-3(n) * vN-3 */
/* process for gN-7(n) * vN-7, gN-11(n) * vN-11 ... */
acc += (gnext * (*pv--));
/* write gN-3(n) into state for next sample processing */
*px2++ = gnext;
/* Process sample for 5th, 9th ...taps */
/* Read gN-5(n-1) from state buffer */
gcurr = *px1++;
/* Process sample for 5th, 9th .. taps */
/* fN-5(n) = fN-4(n) - kN-4 * gN-1(n-1) */
fcurr = fnext - ( (*pk) * gcurr);
/* gN-4(n) = kN-4 * fN-5(n) + gN-5(n-1) */
gnext = (fcurr * (*pk++)) + gcurr;
/* y(n) += gN-4(n) * vN-4 */
/* process for gN-8(n) * vN-8, gN-12(n) * vN-12 ... */
acc += (gnext * (*pv--));
/* write gN-4(n) into state for next sample processing */
*px2++ = gnext;
tapCnt--;
}
fnext = fcurr;
/* If the filter length is not a multiple of 4, compute the remaining filter taps */
tapCnt = (numStages - 1u) % 0x4u;
while (tapCnt > 0u)
{
gcurr = *px1++;
/* Process sample for last taps */
fnext = fcurr - ( (*pk) * gcurr);
gnext = (fnext * (*pk++)) + gcurr;
/* Output samples for last taps */
acc += (gnext * (*pv--));
*px2++ = gnext;
fcurr = fnext;
tapCnt--;
}
/* y(n) += g0(n) * v0 */
acc += (fnext * (*pv));
*px2++ = fnext;
/* write out into pDst */
*pDst++ = acc;
/* Advance the state pointer by 4 to process the next group of 4 samples */
pState = pState + 1u;
blkCnt--;
}
/* Processing is complete. Now copy last S->numStages samples to start of the buffer
for the preperation of next frame process */
/* Points to the start of the state buffer */
pStateCurnt = &S->pState[0];
pState = &S->pState[blockSize];
tapCnt = numStages >> 2u;
/* copy data */
while (tapCnt > 0u)
{
*pStateCurnt++ = *pState++;
*pStateCurnt++ = *pState++;
*pStateCurnt++ = *pState++;
*pStateCurnt++ = *pState++;
/* Decrement the loop counter */
tapCnt--;
}
/* Calculate remaining number of copies */
tapCnt = (numStages) % 0x4u;
/* Copy the remaining q31_t data */
while (tapCnt > 0u)
{
*pStateCurnt++ = *pState++;
/* Decrement the loop counter */
tapCnt--;
}
}
//end of IIR_Lattice group
ne10_iir_lattice_float_c
void ne10_iir_lattice_float_c(const ne10_iir_lattice_instance_f32_t *S, ne10_float32_t *pSrc, ne10_float32_t *pDst, ne10_uint32_t blockSize)
Processing function for the floating-point IIR lattice filter.
Definition NE10_iir.c:118
ne10_iir_lattice_instance_f32_t
Instance structure for the floating point IIR Lattice filter.
Definition NE10_types.h:420
ne10_iir_lattice_instance_f32_t::pState
ne10_float32_t * pState
Points to the state variable array.
Definition NE10_types.h:422
ne10_iir_lattice_instance_f32_t::pkCoeffs
ne10_float32_t * pkCoeffs
Points to the reflection coefficient array.
Definition NE10_types.h:423
ne10_iir_lattice_instance_f32_t::numStages
ne10_uint16_t numStages
numStages of the of lattice filter.
Definition NE10_types.h:421
ne10_iir_lattice_instance_f32_t::pvCoeffs
ne10_float32_t * pvCoeffs
Points to the ladder coefficient array.
Definition NE10_types.h:424