| /* ---------------------------------------------------------------------- |
| * 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_lattice_q31.c |
| * |
| * Description: Q31 FIR lattice filter processing function. |
| * |
| * 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_Lattice |
| * @{ |
| */ |
| |
| |
| /** |
| * @brief Processing function for the Q31 FIR lattice filter. |
| * @param[in] *S points to an instance of the Q31 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. |
| * |
| * @details |
| * <b>Scaling and Overflow Behavior:</b> |
| * In order to avoid overflows the input signal must be scaled down by 2*log2(numStages) bits. |
| */ |
| |
| #ifndef ARM_MATH_CM0_FAMILY |
| |
| /* Run the below code for Cortex-M4 and Cortex-M3 */ |
| |
| void arm_fir_lattice_q31( |
| const arm_fir_lattice_instance_q31 * S, |
| q31_t * pSrc, |
| q31_t * pDst, |
| uint32_t blockSize) |
| { |
| q31_t *pState; /* State pointer */ |
| q31_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */ |
| q31_t *px; /* temporary state pointer */ |
| q31_t *pk; /* temporary coefficient pointer */ |
| q31_t fcurr1, fnext1, gcurr1 = 0, gnext1; /* temporary variables for first sample in loop unrolling */ |
| q31_t fcurr2, fnext2, gnext2; /* temporary variables for second sample in loop unrolling */ |
| uint32_t numStages = S->numStages; /* Length of the filter */ |
| uint32_t blkCnt, stageCnt; /* temporary variables for counts */ |
| q31_t k; |
| |
| pState = &S->pState[0]; |
| |
| blkCnt = blockSize >> 1u; |
| |
| /* First part of the processing with loop unrolling. Compute 2 outputs at a time. |
| a second loop below computes the remaining 1 sample. */ |
| while(blkCnt > 0u) |
| { |
| /* f0(n) = x(n) */ |
| fcurr1 = *pSrc++; |
| |
| /* f0(n) = x(n) */ |
| fcurr2 = *pSrc++; |
| |
| /* Initialize coeff pointer */ |
| pk = (pCoeffs); |
| |
| /* Initialize state pointer */ |
| px = pState; |
| |
| /* read g0(n - 1) from state buffer */ |
| gcurr1 = *px; |
| |
| /* Read the reflection coefficient */ |
| k = *pk++; |
| |
| /* for sample 1 processing */ |
| /* f1(n) = f0(n) + K1 * g0(n-1) */ |
| fnext1 = (q31_t) (((q63_t) gcurr1 * k) >> 32); |
| |
| /* g1(n) = f0(n) * K1 + g0(n-1) */ |
| gnext1 = (q31_t) (((q63_t) fcurr1 * (k)) >> 32); |
| fnext1 = fcurr1 + (fnext1 << 1u); |
| gnext1 = gcurr1 + (gnext1 << 1u); |
| |
| /* for sample 1 processing */ |
| /* f1(n) = f0(n) + K1 * g0(n-1) */ |
| fnext2 = (q31_t) (((q63_t) fcurr1 * k) >> 32); |
| |
| /* g1(n) = f0(n) * K1 + g0(n-1) */ |
| gnext2 = (q31_t) (((q63_t) fcurr2 * (k)) >> 32); |
| fnext2 = fcurr2 + (fnext2 << 1u); |
| gnext2 = fcurr1 + (gnext2 << 1u); |
| |
| /* save g1(n) in state buffer */ |
| *px++ = fcurr2; |
| |
| /* f1(n) is saved in fcurr1 |
| for next stage processing */ |
| fcurr1 = fnext1; |
| fcurr2 = fnext2; |
| |
| stageCnt = (numStages - 1u); |
| |
| /* stage loop */ |
| while(stageCnt > 0u) |
| { |
| |
| /* Read the reflection coefficient */ |
| k = *pk++; |
| |
| /* read g2(n) from state buffer */ |
| gcurr1 = *px; |
| |
| /* save g1(n) in state buffer */ |
| *px++ = gnext2; |
| |
| /* Sample processing for K2, K3.... */ |
| /* f2(n) = f1(n) + K2 * g1(n-1) */ |
| fnext1 = (q31_t) (((q63_t) gcurr1 * k) >> 32); |
| fnext2 = (q31_t) (((q63_t) gnext1 * k) >> 32); |
| |
| fnext1 = fcurr1 + (fnext1 << 1u); |
| fnext2 = fcurr2 + (fnext2 << 1u); |
| |
| /* g2(n) = f1(n) * K2 + g1(n-1) */ |
| gnext2 = (q31_t) (((q63_t) fcurr2 * (k)) >> 32); |
| gnext2 = gnext1 + (gnext2 << 1u); |
| |
| /* g2(n) = f1(n) * K2 + g1(n-1) */ |
| gnext1 = (q31_t) (((q63_t) fcurr1 * (k)) >> 32); |
| gnext1 = gcurr1 + (gnext1 << 1u); |
| |
| /* f1(n) is saved in fcurr1 |
| for next stage processing */ |
| fcurr1 = fnext1; |
| fcurr2 = fnext2; |
| |
| stageCnt--; |
| |
| } |
| |
| /* y(n) = fN(n) */ |
| *pDst++ = fcurr1; |
| *pDst++ = fcurr2; |
| |
| blkCnt--; |
| |
| } |
| |
| /* If the blockSize is not a multiple of 4, compute any remaining output samples here. |
| ** No loop unrolling is used. */ |
| blkCnt = blockSize % 0x2u; |
| |
| while(blkCnt > 0u) |
| { |
| /* f0(n) = x(n) */ |
| fcurr1 = *pSrc++; |
| |
| /* Initialize coeff pointer */ |
| pk = (pCoeffs); |
| |
| /* Initialize state pointer */ |
| px = pState; |
| |
| /* read g0(n - 1) from state buffer */ |
| gcurr1 = *px; |
| |
| /* Read the reflection coefficient */ |
| k = *pk++; |
| |
| /* for sample 1 processing */ |
| /* f1(n) = f0(n) + K1 * g0(n-1) */ |
| fnext1 = (q31_t) (((q63_t) gcurr1 * k) >> 32); |
| fnext1 = fcurr1 + (fnext1 << 1u); |
| |
| /* g1(n) = f0(n) * K1 + g0(n-1) */ |
| gnext1 = (q31_t) (((q63_t) fcurr1 * (k)) >> 32); |
| gnext1 = gcurr1 + (gnext1 << 1u); |
| |
| /* save g1(n) in state buffer */ |
| *px++ = fcurr1; |
| |
| /* f1(n) is saved in fcurr1 |
| for next stage processing */ |
| fcurr1 = fnext1; |
| |
| stageCnt = (numStages - 1u); |
| |
| /* stage loop */ |
| while(stageCnt > 0u) |
| { |
| /* Read the reflection coefficient */ |
| k = *pk++; |
| |
| /* read g2(n) from state buffer */ |
| gcurr1 = *px; |
| |
| /* save g1(n) in state buffer */ |
| *px++ = gnext1; |
| |
| /* Sample processing for K2, K3.... */ |
| /* f2(n) = f1(n) + K2 * g1(n-1) */ |
| fnext1 = (q31_t) (((q63_t) gcurr1 * k) >> 32); |
| fnext1 = fcurr1 + (fnext1 << 1u); |
| |
| /* g2(n) = f1(n) * K2 + g1(n-1) */ |
| gnext1 = (q31_t) (((q63_t) fcurr1 * (k)) >> 32); |
| gnext1 = gcurr1 + (gnext1 << 1u); |
| |
| /* f1(n) is saved in fcurr1 |
| for next stage processing */ |
| fcurr1 = fnext1; |
| |
| stageCnt--; |
| |
| } |
| |
| |
| /* y(n) = fN(n) */ |
| *pDst++ = fcurr1; |
| |
| blkCnt--; |
| |
| } |
| |
| |
| } |
| |
| |
| #else |
| |
| /* Run the below code for Cortex-M0 */ |
| |
| void arm_fir_lattice_q31( |
| const arm_fir_lattice_instance_q31 * S, |
| q31_t * pSrc, |
| q31_t * pDst, |
| uint32_t blockSize) |
| { |
| q31_t *pState; /* State pointer */ |
| q31_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */ |
| q31_t *px; /* temporary state pointer */ |
| q31_t *pk; /* temporary coefficient pointer */ |
| q31_t fcurr, fnext, gcurr, 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) */ |
| fcurr = *pSrc++; |
| |
| /* Initialize coeff pointer */ |
| pk = (pCoeffs); |
| |
| /* Initialize state pointer */ |
| px = pState; |
| |
| /* read g0(n-1) from state buffer */ |
| gcurr = *px; |
| |
| /* for sample 1 processing */ |
| /* f1(n) = f0(n) + K1 * g0(n-1) */ |
| fnext = (q31_t) (((q63_t) gcurr * (*pk)) >> 31) + fcurr; |
| /* g1(n) = f0(n) * K1 + g0(n-1) */ |
| gnext = (q31_t) (((q63_t) fcurr * (*pk++)) >> 31) + gcurr; |
| /* save g1(n) in state buffer */ |
| *px++ = fcurr; |
| |
| /* f1(n) is saved in fcurr1 |
| for next stage processing */ |
| fcurr = fnext; |
| |
| stageCnt = (numStages - 1u); |
| |
| /* stage loop */ |
| while(stageCnt > 0u) |
| { |
| /* read g2(n) from state buffer */ |
| gcurr = *px; |
| |
| /* save g1(n) in state buffer */ |
| *px++ = gnext; |
| |
| /* Sample processing for K2, K3.... */ |
| /* f2(n) = f1(n) + K2 * g1(n-1) */ |
| fnext = (q31_t) (((q63_t) gcurr * (*pk)) >> 31) + fcurr; |
| /* g2(n) = f1(n) * K2 + g1(n-1) */ |
| gnext = (q31_t) (((q63_t) fcurr * (*pk++)) >> 31) + gcurr; |
| |
| /* f1(n) is saved in fcurr1 |
| for next stage processing */ |
| fcurr = fnext; |
| |
| stageCnt--; |
| |
| } |
| |
| /* y(n) = fN(n) */ |
| *pDst++ = fcurr; |
| |
| blkCnt--; |
| |
| } |
| |
| } |
| |
| #endif /* #ifndef ARM_MATH_CM0_FAMILY */ |
| |
| |
| /** |
| * @} end of FIR_Lattice group |
| */ |
