| /* ---------------------------------------------------------------------- |
| * Project: CMSIS DSP Library |
| * Title: arm_fir_lattice_q15.c |
| * Description: Q15 FIR lattice filter processing function |
| * |
| * $Date: 27. January 2017 |
| * $Revision: V.1.5.1 |
| * |
| * Target Processor: Cortex-M cores |
| * -------------------------------------------------------------------- */ |
| /* |
| * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved. |
| * |
| * SPDX-License-Identifier: Apache-2.0 |
| * |
| * Licensed under the Apache License, Version 2.0 (the License); you may |
| * not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an AS IS BASIS, WITHOUT |
| * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include "arm_math.h" |
| |
| /** |
| * @ingroup groupFilters |
| */ |
| |
| /** |
| * @addtogroup FIR_Lattice |
| * @{ |
| */ |
| |
| |
| /** |
| * @brief Processing function for the Q15 FIR lattice filter. |
| * @param[in] *S points to an instance of the Q15 FIR lattice 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 samples to process. |
| * @return none. |
| */ |
| |
| void arm_fir_lattice_q15( |
| const arm_fir_lattice_instance_q15 * S, |
| q15_t * pSrc, |
| q15_t * pDst, |
| uint32_t blockSize) |
| { |
| q15_t *pState; /* State pointer */ |
| q15_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */ |
| q15_t *px; /* temporary state pointer */ |
| q15_t *pk; /* temporary coefficient pointer */ |
| |
| |
| #if defined (ARM_MATH_DSP) |
| |
| /* Run the below code for Cortex-M4 and Cortex-M3 */ |
| |
| q31_t fcurnt1, fnext1, gcurnt1 = 0, gnext1; /* temporary variables for first sample in loop unrolling */ |
| q31_t fcurnt2, fnext2, gnext2; /* temporary variables for second sample in loop unrolling */ |
| q31_t fcurnt3, fnext3, gnext3; /* temporary variables for third sample in loop unrolling */ |
| q31_t fcurnt4, fnext4, gnext4; /* temporary variables for fourth sample in loop unrolling */ |
| uint32_t numStages = S->numStages; /* Number of stages in the filter */ |
| uint32_t blkCnt, stageCnt; /* temporary variables for counts */ |
| |
| pState = &S->pState[0]; |
| |
| blkCnt = blockSize >> 2U; |
| |
| /* First part of the processing with loop unrolling. Compute 4 outputs at a time. |
| ** a second loop below computes the remaining 1 to 3 samples. */ |
| while (blkCnt > 0U) |
| { |
| |
| /* Read two samples from input buffer */ |
| /* f0(n) = x(n) */ |
| fcurnt1 = *pSrc++; |
| fcurnt2 = *pSrc++; |
| |
| /* Initialize coeff pointer */ |
| pk = (pCoeffs); |
| |
| /* Initialize state pointer */ |
| px = pState; |
| |
| /* Read g0(n-1) from state */ |
| gcurnt1 = *px; |
| |
| /* Process first sample for first tap */ |
| /* f1(n) = f0(n) + K1 * g0(n-1) */ |
| fnext1 = (q31_t) ((gcurnt1 * (*pk)) >> 15U) + fcurnt1; |
| fnext1 = __SSAT(fnext1, 16); |
| |
| /* g1(n) = f0(n) * K1 + g0(n-1) */ |
| gnext1 = (q31_t) ((fcurnt1 * (*pk)) >> 15U) + gcurnt1; |
| gnext1 = __SSAT(gnext1, 16); |
| |
| /* Process second sample for first tap */ |
| /* for sample 2 processing */ |
| fnext2 = (q31_t) ((fcurnt1 * (*pk)) >> 15U) + fcurnt2; |
| fnext2 = __SSAT(fnext2, 16); |
| |
| gnext2 = (q31_t) ((fcurnt2 * (*pk)) >> 15U) + fcurnt1; |
| gnext2 = __SSAT(gnext2, 16); |
| |
| |
| /* Read next two samples from input buffer */ |
| /* f0(n+2) = x(n+2) */ |
| fcurnt3 = *pSrc++; |
| fcurnt4 = *pSrc++; |
| |
| /* Copy only last input samples into the state buffer |
| which is used for next four samples processing */ |
| *px++ = (q15_t) fcurnt4; |
| |
| /* Process third sample for first tap */ |
| fnext3 = (q31_t) ((fcurnt2 * (*pk)) >> 15U) + fcurnt3; |
| fnext3 = __SSAT(fnext3, 16); |
| gnext3 = (q31_t) ((fcurnt3 * (*pk)) >> 15U) + fcurnt2; |
| gnext3 = __SSAT(gnext3, 16); |
| |
| /* Process fourth sample for first tap */ |
| fnext4 = (q31_t) ((fcurnt3 * (*pk)) >> 15U) + fcurnt4; |
| fnext4 = __SSAT(fnext4, 16); |
| gnext4 = (q31_t) ((fcurnt4 * (*pk++)) >> 15U) + fcurnt3; |
| gnext4 = __SSAT(gnext4, 16); |
| |
| /* Update of f values for next coefficient set processing */ |
| fcurnt1 = fnext1; |
| fcurnt2 = fnext2; |
| fcurnt3 = fnext3; |
| fcurnt4 = fnext4; |
| |
| |
| /* Loop unrolling. Process 4 taps at a time . */ |
| stageCnt = (numStages - 1U) >> 2; |
| |
| |
| /* Loop over the number of taps. Unroll by a factor of 4. |
| ** Repeat until we've computed numStages-3 coefficients. */ |
| |
| /* Process 2nd, 3rd, 4th and 5th taps ... here */ |
| while (stageCnt > 0U) |
| { |
| /* Read g1(n-1), g3(n-1) .... from state */ |
| gcurnt1 = *px; |
| |
| /* save g1(n) in state buffer */ |
| *px++ = (q15_t) gnext4; |
| |
| /* Process first sample for 2nd, 6th .. tap */ |
| /* Sample processing for K2, K6.... */ |
| /* f1(n) = f0(n) + K1 * g0(n-1) */ |
| fnext1 = (q31_t) ((gcurnt1 * (*pk)) >> 15U) + fcurnt1; |
| fnext1 = __SSAT(fnext1, 16); |
| |
| |
| /* Process second sample for 2nd, 6th .. tap */ |
| /* for sample 2 processing */ |
| fnext2 = (q31_t) ((gnext1 * (*pk)) >> 15U) + fcurnt2; |
| fnext2 = __SSAT(fnext2, 16); |
| /* Process third sample for 2nd, 6th .. tap */ |
| fnext3 = (q31_t) ((gnext2 * (*pk)) >> 15U) + fcurnt3; |
| fnext3 = __SSAT(fnext3, 16); |
| /* Process fourth sample for 2nd, 6th .. tap */ |
| /* fnext4 = fcurnt4 + (*pk) * gnext3; */ |
| fnext4 = (q31_t) ((gnext3 * (*pk)) >> 15U) + fcurnt4; |
| fnext4 = __SSAT(fnext4, 16); |
| |
| /* g1(n) = f0(n) * K1 + g0(n-1) */ |
| /* Calculation of state values for next stage */ |
| gnext4 = (q31_t) ((fcurnt4 * (*pk)) >> 15U) + gnext3; |
| gnext4 = __SSAT(gnext4, 16); |
| gnext3 = (q31_t) ((fcurnt3 * (*pk)) >> 15U) + gnext2; |
| gnext3 = __SSAT(gnext3, 16); |
| |
| gnext2 = (q31_t) ((fcurnt2 * (*pk)) >> 15U) + gnext1; |
| gnext2 = __SSAT(gnext2, 16); |
| |
| gnext1 = (q31_t) ((fcurnt1 * (*pk++)) >> 15U) + gcurnt1; |
| gnext1 = __SSAT(gnext1, 16); |
| |
| |
| /* Read g2(n-1), g4(n-1) .... from state */ |
| gcurnt1 = *px; |
| |
| /* save g1(n) in state buffer */ |
| *px++ = (q15_t) gnext4; |
| |
| /* Sample processing for K3, K7.... */ |
| /* Process first sample for 3rd, 7th .. tap */ |
| /* f3(n) = f2(n) + K3 * g2(n-1) */ |
| fcurnt1 = (q31_t) ((gcurnt1 * (*pk)) >> 15U) + fnext1; |
| fcurnt1 = __SSAT(fcurnt1, 16); |
| |
| /* Process second sample for 3rd, 7th .. tap */ |
| fcurnt2 = (q31_t) ((gnext1 * (*pk)) >> 15U) + fnext2; |
| fcurnt2 = __SSAT(fcurnt2, 16); |
| |
| /* Process third sample for 3rd, 7th .. tap */ |
| fcurnt3 = (q31_t) ((gnext2 * (*pk)) >> 15U) + fnext3; |
| fcurnt3 = __SSAT(fcurnt3, 16); |
| |
| /* Process fourth sample for 3rd, 7th .. tap */ |
| fcurnt4 = (q31_t) ((gnext3 * (*pk)) >> 15U) + fnext4; |
| fcurnt4 = __SSAT(fcurnt4, 16); |
| |
| /* Calculation of state values for next stage */ |
| /* g3(n) = f2(n) * K3 + g2(n-1) */ |
| gnext4 = (q31_t) ((fnext4 * (*pk)) >> 15U) + gnext3; |
| gnext4 = __SSAT(gnext4, 16); |
| |
| gnext3 = (q31_t) ((fnext3 * (*pk)) >> 15U) + gnext2; |
| gnext3 = __SSAT(gnext3, 16); |
| |
| gnext2 = (q31_t) ((fnext2 * (*pk)) >> 15U) + gnext1; |
| gnext2 = __SSAT(gnext2, 16); |
| |
| gnext1 = (q31_t) ((fnext1 * (*pk++)) >> 15U) + gcurnt1; |
| gnext1 = __SSAT(gnext1, 16); |
| |
| /* Read g1(n-1), g3(n-1) .... from state */ |
| gcurnt1 = *px; |
| |
| /* save g1(n) in state buffer */ |
| *px++ = (q15_t) gnext4; |
| |
| /* Sample processing for K4, K8.... */ |
| /* Process first sample for 4th, 8th .. tap */ |
| /* f4(n) = f3(n) + K4 * g3(n-1) */ |
| fnext1 = (q31_t) ((gcurnt1 * (*pk)) >> 15U) + fcurnt1; |
| fnext1 = __SSAT(fnext1, 16); |
| |
| /* Process second sample for 4th, 8th .. tap */ |
| /* for sample 2 processing */ |
| fnext2 = (q31_t) ((gnext1 * (*pk)) >> 15U) + fcurnt2; |
| fnext2 = __SSAT(fnext2, 16); |
| |
| /* Process third sample for 4th, 8th .. tap */ |
| fnext3 = (q31_t) ((gnext2 * (*pk)) >> 15U) + fcurnt3; |
| fnext3 = __SSAT(fnext3, 16); |
| |
| /* Process fourth sample for 4th, 8th .. tap */ |
| fnext4 = (q31_t) ((gnext3 * (*pk)) >> 15U) + fcurnt4; |
| fnext4 = __SSAT(fnext4, 16); |
| |
| /* g4(n) = f3(n) * K4 + g3(n-1) */ |
| /* Calculation of state values for next stage */ |
| gnext4 = (q31_t) ((fcurnt4 * (*pk)) >> 15U) + gnext3; |
| gnext4 = __SSAT(gnext4, 16); |
| |
| gnext3 = (q31_t) ((fcurnt3 * (*pk)) >> 15U) + gnext2; |
| gnext3 = __SSAT(gnext3, 16); |
| |
| gnext2 = (q31_t) ((fcurnt2 * (*pk)) >> 15U) + gnext1; |
| gnext2 = __SSAT(gnext2, 16); |
| gnext1 = (q31_t) ((fcurnt1 * (*pk++)) >> 15U) + gcurnt1; |
| gnext1 = __SSAT(gnext1, 16); |
| |
| |
| /* Read g2(n-1), g4(n-1) .... from state */ |
| gcurnt1 = *px; |
| |
| /* save g4(n) in state buffer */ |
| *px++ = (q15_t) gnext4; |
| |
| /* Sample processing for K5, K9.... */ |
| /* Process first sample for 5th, 9th .. tap */ |
| /* f5(n) = f4(n) + K5 * g4(n-1) */ |
| fcurnt1 = (q31_t) ((gcurnt1 * (*pk)) >> 15U) + fnext1; |
| fcurnt1 = __SSAT(fcurnt1, 16); |
| |
| /* Process second sample for 5th, 9th .. tap */ |
| fcurnt2 = (q31_t) ((gnext1 * (*pk)) >> 15U) + fnext2; |
| fcurnt2 = __SSAT(fcurnt2, 16); |
| |
| /* Process third sample for 5th, 9th .. tap */ |
| fcurnt3 = (q31_t) ((gnext2 * (*pk)) >> 15U) + fnext3; |
| fcurnt3 = __SSAT(fcurnt3, 16); |
| |
| /* Process fourth sample for 5th, 9th .. tap */ |
| fcurnt4 = (q31_t) ((gnext3 * (*pk)) >> 15U) + fnext4; |
| fcurnt4 = __SSAT(fcurnt4, 16); |
| |
| /* Calculation of state values for next stage */ |
| /* g5(n) = f4(n) * K5 + g4(n-1) */ |
| gnext4 = (q31_t) ((fnext4 * (*pk)) >> 15U) + gnext3; |
| gnext4 = __SSAT(gnext4, 16); |
| gnext3 = (q31_t) ((fnext3 * (*pk)) >> 15U) + gnext2; |
| gnext3 = __SSAT(gnext3, 16); |
| gnext2 = (q31_t) ((fnext2 * (*pk)) >> 15U) + gnext1; |
| gnext2 = __SSAT(gnext2, 16); |
| gnext1 = (q31_t) ((fnext1 * (*pk++)) >> 15U) + gcurnt1; |
| gnext1 = __SSAT(gnext1, 16); |
| |
| stageCnt--; |
| } |
| |
| /* If the (filter length -1) is not a multiple of 4, compute the remaining filter taps */ |
| stageCnt = (numStages - 1U) % 0x4U; |
| |
| while (stageCnt > 0U) |
| { |
| gcurnt1 = *px; |
| |
| /* save g value in state buffer */ |
| *px++ = (q15_t) gnext4; |
| |
| /* Process four samples for last three taps here */ |
| fnext1 = (q31_t) ((gcurnt1 * (*pk)) >> 15U) + fcurnt1; |
| fnext1 = __SSAT(fnext1, 16); |
| fnext2 = (q31_t) ((gnext1 * (*pk)) >> 15U) + fcurnt2; |
| fnext2 = __SSAT(fnext2, 16); |
| |
| fnext3 = (q31_t) ((gnext2 * (*pk)) >> 15U) + fcurnt3; |
| fnext3 = __SSAT(fnext3, 16); |
| |
| fnext4 = (q31_t) ((gnext3 * (*pk)) >> 15U) + fcurnt4; |
| fnext4 = __SSAT(fnext4, 16); |
| |
| /* g1(n) = f0(n) * K1 + g0(n-1) */ |
| gnext4 = (q31_t) ((fcurnt4 * (*pk)) >> 15U) + gnext3; |
| gnext4 = __SSAT(gnext4, 16); |
| gnext3 = (q31_t) ((fcurnt3 * (*pk)) >> 15U) + gnext2; |
| gnext3 = __SSAT(gnext3, 16); |
| gnext2 = (q31_t) ((fcurnt2 * (*pk)) >> 15U) + gnext1; |
| gnext2 = __SSAT(gnext2, 16); |
| gnext1 = (q31_t) ((fcurnt1 * (*pk++)) >> 15U) + gcurnt1; |
| gnext1 = __SSAT(gnext1, 16); |
| |
| /* Update of f values for next coefficient set processing */ |
| fcurnt1 = fnext1; |
| fcurnt2 = fnext2; |
| fcurnt3 = fnext3; |
| fcurnt4 = fnext4; |
| |
| stageCnt--; |
| |
| } |
| |
| /* The results in the 4 accumulators, store in the destination buffer. */ |
| /* y(n) = fN(n) */ |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| |
| *__SIMD32(pDst)++ = __PKHBT(fcurnt1, fcurnt2, 16); |
| *__SIMD32(pDst)++ = __PKHBT(fcurnt3, fcurnt4, 16); |
| |
| #else |
| |
| *__SIMD32(pDst)++ = __PKHBT(fcurnt2, fcurnt1, 16); |
| *__SIMD32(pDst)++ = __PKHBT(fcurnt4, fcurnt3, 16); |
| |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| blkCnt--; |
| } |
| |
| /* If the blockSize is not a multiple of 4, compute any remaining output samples here. |
| ** No loop unrolling is used. */ |
| blkCnt = blockSize % 0x4U; |
| |
| while (blkCnt > 0U) |
| { |
| /* f0(n) = x(n) */ |
| fcurnt1 = *pSrc++; |
| |
| /* Initialize coeff pointer */ |
| pk = (pCoeffs); |
| |
| /* Initialize state pointer */ |
| px = pState; |
| |
| /* read g2(n) from state buffer */ |
| gcurnt1 = *px; |
| |
| /* for sample 1 processing */ |
| /* f1(n) = f0(n) + K1 * g0(n-1) */ |
| fnext1 = (((q31_t) gcurnt1 * (*pk)) >> 15U) + fcurnt1; |
| fnext1 = __SSAT(fnext1, 16); |
| |
| |
| /* g1(n) = f0(n) * K1 + g0(n-1) */ |
| gnext1 = (((q31_t) fcurnt1 * (*pk++)) >> 15U) + gcurnt1; |
| gnext1 = __SSAT(gnext1, 16); |
| |
| /* save g1(n) in state buffer */ |
| *px++ = (q15_t) fcurnt1; |
| |
| /* f1(n) is saved in fcurnt1 |
| for next stage processing */ |
| fcurnt1 = fnext1; |
| |
| stageCnt = (numStages - 1U); |
| |
| /* stage loop */ |
| while (stageCnt > 0U) |
| { |
| /* read g2(n) from state buffer */ |
| gcurnt1 = *px; |
| |
| /* save g1(n) in state buffer */ |
| *px++ = (q15_t) gnext1; |
| |
| /* Sample processing for K2, K3.... */ |
| /* f2(n) = f1(n) + K2 * g1(n-1) */ |
| fnext1 = (((q31_t) gcurnt1 * (*pk)) >> 15U) + fcurnt1; |
| fnext1 = __SSAT(fnext1, 16); |
| |
| /* g2(n) = f1(n) * K2 + g1(n-1) */ |
| gnext1 = (((q31_t) fcurnt1 * (*pk++)) >> 15U) + gcurnt1; |
| gnext1 = __SSAT(gnext1, 16); |
| |
| |
| /* f1(n) is saved in fcurnt1 |
| for next stage processing */ |
| fcurnt1 = fnext1; |
| |
| stageCnt--; |
| |
| } |
| |
| /* y(n) = fN(n) */ |
| *pDst++ = __SSAT(fcurnt1, 16); |
| |
| |
| blkCnt--; |
| |
| } |
| |
| #else |
| |
| /* Run the below code for Cortex-M0 */ |
| |
| q31_t fcurnt, fnext, gcurnt, gnext; /* temporary variables */ |
| uint32_t numStages = S->numStages; /* Length of the filter */ |
| uint32_t blkCnt, stageCnt; /* temporary variables for counts */ |
| |
| pState = &S->pState[0]; |
| |
| blkCnt = blockSize; |
| |
| while (blkCnt > 0U) |
| { |
| /* f0(n) = x(n) */ |
| fcurnt = *pSrc++; |
| |
| /* Initialize coeff pointer */ |
| pk = (pCoeffs); |
| |
| /* Initialize state pointer */ |
| px = pState; |
| |
| /* read g0(n-1) from state buffer */ |
| gcurnt = *px; |
| |
| /* for sample 1 processing */ |
| /* f1(n) = f0(n) + K1 * g0(n-1) */ |
| fnext = ((gcurnt * (*pk)) >> 15U) + fcurnt; |
| fnext = __SSAT(fnext, 16); |
| |
| |
| /* g1(n) = f0(n) * K1 + g0(n-1) */ |
| gnext = ((fcurnt * (*pk++)) >> 15U) + gcurnt; |
| gnext = __SSAT(gnext, 16); |
| |
| /* save f0(n) in state buffer */ |
| *px++ = (q15_t) fcurnt; |
| |
| /* f1(n) is saved in fcurnt |
| for next stage processing */ |
| fcurnt = fnext; |
| |
| stageCnt = (numStages - 1U); |
| |
| /* stage loop */ |
| while (stageCnt > 0U) |
| { |
| /* read g1(n-1) from state buffer */ |
| gcurnt = *px; |
| |
| /* save g0(n-1) in state buffer */ |
| *px++ = (q15_t) gnext; |
| |
| /* Sample processing for K2, K3.... */ |
| /* f2(n) = f1(n) + K2 * g1(n-1) */ |
| fnext = ((gcurnt * (*pk)) >> 15U) + fcurnt; |
| fnext = __SSAT(fnext, 16); |
| |
| /* g2(n) = f1(n) * K2 + g1(n-1) */ |
| gnext = ((fcurnt * (*pk++)) >> 15U) + gcurnt; |
| gnext = __SSAT(gnext, 16); |
| |
| |
| /* f1(n) is saved in fcurnt |
| for next stage processing */ |
| fcurnt = fnext; |
| |
| stageCnt--; |
| |
| } |
| |
| /* y(n) = fN(n) */ |
| *pDst++ = __SSAT(fcurnt, 16); |
| |
| |
| blkCnt--; |
| |
| } |
| |
| #endif /* #if defined (ARM_MATH_DSP) */ |
| |
| } |
| |
| /** |
| * @} end of FIR_Lattice group |
| */ |
