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functions/FilteringFunctions/arm_fir_decimate_fast_q15.c@1:24714b45cd1b, 2018-06-20 (annotated)
- Committer:
- xorjoep
- Date:
- Wed Jun 20 11:21:31 2018 +0000
- Revision:
- 1:24714b45cd1b
The newest version of the CMSIS library
Who changed what in which revision?
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xorjoep | 1:24714b45cd1b | 1 | /* ---------------------------------------------------------------------- |
xorjoep | 1:24714b45cd1b | 2 | * Project: CMSIS DSP Library |
xorjoep | 1:24714b45cd1b | 3 | * Title: arm_fir_decimate_fast_q15.c |
xorjoep | 1:24714b45cd1b | 4 | * Description: Fast Q15 FIR Decimator |
xorjoep | 1:24714b45cd1b | 5 | * |
xorjoep | 1:24714b45cd1b | 6 | * $Date: 27. January 2017 |
xorjoep | 1:24714b45cd1b | 7 | * $Revision: V.1.5.1 |
xorjoep | 1:24714b45cd1b | 8 | * |
xorjoep | 1:24714b45cd1b | 9 | * Target Processor: Cortex-M cores |
xorjoep | 1:24714b45cd1b | 10 | * -------------------------------------------------------------------- */ |
xorjoep | 1:24714b45cd1b | 11 | /* |
xorjoep | 1:24714b45cd1b | 12 | * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved. |
xorjoep | 1:24714b45cd1b | 13 | * |
xorjoep | 1:24714b45cd1b | 14 | * SPDX-License-Identifier: Apache-2.0 |
xorjoep | 1:24714b45cd1b | 15 | * |
xorjoep | 1:24714b45cd1b | 16 | * Licensed under the Apache License, Version 2.0 (the License); you may |
xorjoep | 1:24714b45cd1b | 17 | * not use this file except in compliance with the License. |
xorjoep | 1:24714b45cd1b | 18 | * You may obtain a copy of the License at |
xorjoep | 1:24714b45cd1b | 19 | * |
xorjoep | 1:24714b45cd1b | 20 | * www.apache.org/licenses/LICENSE-2.0 |
xorjoep | 1:24714b45cd1b | 21 | * |
xorjoep | 1:24714b45cd1b | 22 | * Unless required by applicable law or agreed to in writing, software |
xorjoep | 1:24714b45cd1b | 23 | * distributed under the License is distributed on an AS IS BASIS, WITHOUT |
xorjoep | 1:24714b45cd1b | 24 | * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
xorjoep | 1:24714b45cd1b | 25 | * See the License for the specific language governing permissions and |
xorjoep | 1:24714b45cd1b | 26 | * limitations under the License. |
xorjoep | 1:24714b45cd1b | 27 | */ |
xorjoep | 1:24714b45cd1b | 28 | |
xorjoep | 1:24714b45cd1b | 29 | #include "arm_math.h" |
xorjoep | 1:24714b45cd1b | 30 | |
xorjoep | 1:24714b45cd1b | 31 | /** |
xorjoep | 1:24714b45cd1b | 32 | * @ingroup groupFilters |
xorjoep | 1:24714b45cd1b | 33 | */ |
xorjoep | 1:24714b45cd1b | 34 | |
xorjoep | 1:24714b45cd1b | 35 | /** |
xorjoep | 1:24714b45cd1b | 36 | * @addtogroup FIR_decimate |
xorjoep | 1:24714b45cd1b | 37 | * @{ |
xorjoep | 1:24714b45cd1b | 38 | */ |
xorjoep | 1:24714b45cd1b | 39 | |
xorjoep | 1:24714b45cd1b | 40 | /** |
xorjoep | 1:24714b45cd1b | 41 | * @brief Processing function for the Q15 FIR decimator (fast variant) for Cortex-M3 and Cortex-M4. |
xorjoep | 1:24714b45cd1b | 42 | * @param[in] *S points to an instance of the Q15 FIR decimator structure. |
xorjoep | 1:24714b45cd1b | 43 | * @param[in] *pSrc points to the block of input data. |
xorjoep | 1:24714b45cd1b | 44 | * @param[out] *pDst points to the block of output data |
xorjoep | 1:24714b45cd1b | 45 | * @param[in] blockSize number of input samples to process per call. |
xorjoep | 1:24714b45cd1b | 46 | * @return none |
xorjoep | 1:24714b45cd1b | 47 | * |
xorjoep | 1:24714b45cd1b | 48 | * \par Restrictions |
xorjoep | 1:24714b45cd1b | 49 | * If the silicon does not support unaligned memory access enable the macro UNALIGNED_SUPPORT_DISABLE |
xorjoep | 1:24714b45cd1b | 50 | * In this case input, output, state buffers should be aligned by 32-bit |
xorjoep | 1:24714b45cd1b | 51 | * |
xorjoep | 1:24714b45cd1b | 52 | * <b>Scaling and Overflow Behavior:</b> |
xorjoep | 1:24714b45cd1b | 53 | * \par |
xorjoep | 1:24714b45cd1b | 54 | * This fast version uses a 32-bit accumulator with 2.30 format. |
xorjoep | 1:24714b45cd1b | 55 | * The accumulator maintains full precision of the intermediate multiplication results but provides only a single guard bit. |
xorjoep | 1:24714b45cd1b | 56 | * Thus, if the accumulator result overflows it wraps around and distorts the result. |
xorjoep | 1:24714b45cd1b | 57 | * In order to avoid overflows completely the input signal must be scaled down by log2(numTaps) bits (log2 is read as log to the base 2). |
xorjoep | 1:24714b45cd1b | 58 | * The 2.30 accumulator is then truncated to 2.15 format and saturated to yield the 1.15 result. |
xorjoep | 1:24714b45cd1b | 59 | * |
xorjoep | 1:24714b45cd1b | 60 | * \par |
xorjoep | 1:24714b45cd1b | 61 | * Refer to the function <code>arm_fir_decimate_q15()</code> for a slower implementation of this function which uses 64-bit accumulation to avoid wrap around distortion. |
xorjoep | 1:24714b45cd1b | 62 | * Both the slow and the fast versions use the same instance structure. |
xorjoep | 1:24714b45cd1b | 63 | * Use the function <code>arm_fir_decimate_init_q15()</code> to initialize the filter structure. |
xorjoep | 1:24714b45cd1b | 64 | */ |
xorjoep | 1:24714b45cd1b | 65 | |
xorjoep | 1:24714b45cd1b | 66 | #ifndef UNALIGNED_SUPPORT_DISABLE |
xorjoep | 1:24714b45cd1b | 67 | |
xorjoep | 1:24714b45cd1b | 68 | void arm_fir_decimate_fast_q15( |
xorjoep | 1:24714b45cd1b | 69 | const arm_fir_decimate_instance_q15 * S, |
xorjoep | 1:24714b45cd1b | 70 | q15_t * pSrc, |
xorjoep | 1:24714b45cd1b | 71 | q15_t * pDst, |
xorjoep | 1:24714b45cd1b | 72 | uint32_t blockSize) |
xorjoep | 1:24714b45cd1b | 73 | { |
xorjoep | 1:24714b45cd1b | 74 | q15_t *pState = S->pState; /* State pointer */ |
xorjoep | 1:24714b45cd1b | 75 | q15_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */ |
xorjoep | 1:24714b45cd1b | 76 | q15_t *pStateCurnt; /* Points to the current sample of the state */ |
xorjoep | 1:24714b45cd1b | 77 | q15_t *px; /* Temporary pointer for state buffer */ |
xorjoep | 1:24714b45cd1b | 78 | q15_t *pb; /* Temporary pointer coefficient buffer */ |
xorjoep | 1:24714b45cd1b | 79 | q31_t x0, x1, c0, c1; /* Temporary variables to hold state and coefficient values */ |
xorjoep | 1:24714b45cd1b | 80 | q31_t sum0; /* Accumulators */ |
xorjoep | 1:24714b45cd1b | 81 | q31_t acc0, acc1; |
xorjoep | 1:24714b45cd1b | 82 | q15_t *px0, *px1; |
xorjoep | 1:24714b45cd1b | 83 | uint32_t blkCntN3; |
xorjoep | 1:24714b45cd1b | 84 | uint32_t numTaps = S->numTaps; /* Number of taps */ |
xorjoep | 1:24714b45cd1b | 85 | uint32_t i, blkCnt, tapCnt, outBlockSize = blockSize / S->M; /* Loop counters */ |
xorjoep | 1:24714b45cd1b | 86 | |
xorjoep | 1:24714b45cd1b | 87 | |
xorjoep | 1:24714b45cd1b | 88 | /* S->pState buffer contains previous frame (numTaps - 1) samples */ |
xorjoep | 1:24714b45cd1b | 89 | /* pStateCurnt points to the location where the new input data should be written */ |
xorjoep | 1:24714b45cd1b | 90 | pStateCurnt = S->pState + (numTaps - 1U); |
xorjoep | 1:24714b45cd1b | 91 | |
xorjoep | 1:24714b45cd1b | 92 | |
xorjoep | 1:24714b45cd1b | 93 | /* Total number of output samples to be computed */ |
xorjoep | 1:24714b45cd1b | 94 | blkCnt = outBlockSize / 2; |
xorjoep | 1:24714b45cd1b | 95 | blkCntN3 = outBlockSize - (2 * blkCnt); |
xorjoep | 1:24714b45cd1b | 96 | |
xorjoep | 1:24714b45cd1b | 97 | |
xorjoep | 1:24714b45cd1b | 98 | while (blkCnt > 0U) |
xorjoep | 1:24714b45cd1b | 99 | { |
xorjoep | 1:24714b45cd1b | 100 | /* Copy decimation factor number of new input samples into the state buffer */ |
xorjoep | 1:24714b45cd1b | 101 | i = 2 * S->M; |
xorjoep | 1:24714b45cd1b | 102 | |
xorjoep | 1:24714b45cd1b | 103 | do |
xorjoep | 1:24714b45cd1b | 104 | { |
xorjoep | 1:24714b45cd1b | 105 | *pStateCurnt++ = *pSrc++; |
xorjoep | 1:24714b45cd1b | 106 | |
xorjoep | 1:24714b45cd1b | 107 | } while (--i); |
xorjoep | 1:24714b45cd1b | 108 | |
xorjoep | 1:24714b45cd1b | 109 | /* Set accumulator to zero */ |
xorjoep | 1:24714b45cd1b | 110 | acc0 = 0; |
xorjoep | 1:24714b45cd1b | 111 | acc1 = 0; |
xorjoep | 1:24714b45cd1b | 112 | |
xorjoep | 1:24714b45cd1b | 113 | /* Initialize state pointer */ |
xorjoep | 1:24714b45cd1b | 114 | px0 = pState; |
xorjoep | 1:24714b45cd1b | 115 | |
xorjoep | 1:24714b45cd1b | 116 | px1 = pState + S->M; |
xorjoep | 1:24714b45cd1b | 117 | |
xorjoep | 1:24714b45cd1b | 118 | |
xorjoep | 1:24714b45cd1b | 119 | /* Initialize coeff pointer */ |
xorjoep | 1:24714b45cd1b | 120 | pb = pCoeffs; |
xorjoep | 1:24714b45cd1b | 121 | |
xorjoep | 1:24714b45cd1b | 122 | /* Loop unrolling. Process 4 taps at a time. */ |
xorjoep | 1:24714b45cd1b | 123 | tapCnt = numTaps >> 2; |
xorjoep | 1:24714b45cd1b | 124 | |
xorjoep | 1:24714b45cd1b | 125 | /* Loop over the number of taps. Unroll by a factor of 4. |
xorjoep | 1:24714b45cd1b | 126 | ** Repeat until we've computed numTaps-4 coefficients. */ |
xorjoep | 1:24714b45cd1b | 127 | while (tapCnt > 0U) |
xorjoep | 1:24714b45cd1b | 128 | { |
xorjoep | 1:24714b45cd1b | 129 | /* Read the Read b[numTaps-1] and b[numTaps-2] coefficients */ |
xorjoep | 1:24714b45cd1b | 130 | c0 = *__SIMD32(pb)++; |
xorjoep | 1:24714b45cd1b | 131 | |
xorjoep | 1:24714b45cd1b | 132 | /* Read x[n-numTaps-1] and x[n-numTaps-2]sample */ |
xorjoep | 1:24714b45cd1b | 133 | x0 = *__SIMD32(px0)++; |
xorjoep | 1:24714b45cd1b | 134 | |
xorjoep | 1:24714b45cd1b | 135 | x1 = *__SIMD32(px1)++; |
xorjoep | 1:24714b45cd1b | 136 | |
xorjoep | 1:24714b45cd1b | 137 | /* Perform the multiply-accumulate */ |
xorjoep | 1:24714b45cd1b | 138 | acc0 = __SMLAD(x0, c0, acc0); |
xorjoep | 1:24714b45cd1b | 139 | |
xorjoep | 1:24714b45cd1b | 140 | acc1 = __SMLAD(x1, c0, acc1); |
xorjoep | 1:24714b45cd1b | 141 | |
xorjoep | 1:24714b45cd1b | 142 | /* Read the b[numTaps-3] and b[numTaps-4] coefficient */ |
xorjoep | 1:24714b45cd1b | 143 | c0 = *__SIMD32(pb)++; |
xorjoep | 1:24714b45cd1b | 144 | |
xorjoep | 1:24714b45cd1b | 145 | /* Read x[n-numTaps-2] and x[n-numTaps-3] sample */ |
xorjoep | 1:24714b45cd1b | 146 | x0 = *__SIMD32(px0)++; |
xorjoep | 1:24714b45cd1b | 147 | |
xorjoep | 1:24714b45cd1b | 148 | x1 = *__SIMD32(px1)++; |
xorjoep | 1:24714b45cd1b | 149 | |
xorjoep | 1:24714b45cd1b | 150 | /* Perform the multiply-accumulate */ |
xorjoep | 1:24714b45cd1b | 151 | acc0 = __SMLAD(x0, c0, acc0); |
xorjoep | 1:24714b45cd1b | 152 | |
xorjoep | 1:24714b45cd1b | 153 | acc1 = __SMLAD(x1, c0, acc1); |
xorjoep | 1:24714b45cd1b | 154 | |
xorjoep | 1:24714b45cd1b | 155 | /* Decrement the loop counter */ |
xorjoep | 1:24714b45cd1b | 156 | tapCnt--; |
xorjoep | 1:24714b45cd1b | 157 | } |
xorjoep | 1:24714b45cd1b | 158 | |
xorjoep | 1:24714b45cd1b | 159 | /* If the filter length is not a multiple of 4, compute the remaining filter taps */ |
xorjoep | 1:24714b45cd1b | 160 | tapCnt = numTaps % 0x4U; |
xorjoep | 1:24714b45cd1b | 161 | |
xorjoep | 1:24714b45cd1b | 162 | while (tapCnt > 0U) |
xorjoep | 1:24714b45cd1b | 163 | { |
xorjoep | 1:24714b45cd1b | 164 | /* Read coefficients */ |
xorjoep | 1:24714b45cd1b | 165 | c0 = *pb++; |
xorjoep | 1:24714b45cd1b | 166 | |
xorjoep | 1:24714b45cd1b | 167 | /* Fetch 1 state variable */ |
xorjoep | 1:24714b45cd1b | 168 | x0 = *px0++; |
xorjoep | 1:24714b45cd1b | 169 | |
xorjoep | 1:24714b45cd1b | 170 | x1 = *px1++; |
xorjoep | 1:24714b45cd1b | 171 | |
xorjoep | 1:24714b45cd1b | 172 | /* Perform the multiply-accumulate */ |
xorjoep | 1:24714b45cd1b | 173 | acc0 = __SMLAD(x0, c0, acc0); |
xorjoep | 1:24714b45cd1b | 174 | acc1 = __SMLAD(x1, c0, acc1); |
xorjoep | 1:24714b45cd1b | 175 | |
xorjoep | 1:24714b45cd1b | 176 | /* Decrement the loop counter */ |
xorjoep | 1:24714b45cd1b | 177 | tapCnt--; |
xorjoep | 1:24714b45cd1b | 178 | } |
xorjoep | 1:24714b45cd1b | 179 | |
xorjoep | 1:24714b45cd1b | 180 | /* Advance the state pointer by the decimation factor |
xorjoep | 1:24714b45cd1b | 181 | * to process the next group of decimation factor number samples */ |
xorjoep | 1:24714b45cd1b | 182 | pState = pState + S->M * 2; |
xorjoep | 1:24714b45cd1b | 183 | |
xorjoep | 1:24714b45cd1b | 184 | /* Store filter output, smlad returns the values in 2.14 format */ |
xorjoep | 1:24714b45cd1b | 185 | /* so downsacle by 15 to get output in 1.15 */ |
xorjoep | 1:24714b45cd1b | 186 | *pDst++ = (q15_t) (__SSAT((acc0 >> 15), 16)); |
xorjoep | 1:24714b45cd1b | 187 | *pDst++ = (q15_t) (__SSAT((acc1 >> 15), 16)); |
xorjoep | 1:24714b45cd1b | 188 | |
xorjoep | 1:24714b45cd1b | 189 | /* Decrement the loop counter */ |
xorjoep | 1:24714b45cd1b | 190 | blkCnt--; |
xorjoep | 1:24714b45cd1b | 191 | } |
xorjoep | 1:24714b45cd1b | 192 | |
xorjoep | 1:24714b45cd1b | 193 | |
xorjoep | 1:24714b45cd1b | 194 | |
xorjoep | 1:24714b45cd1b | 195 | while (blkCntN3 > 0U) |
xorjoep | 1:24714b45cd1b | 196 | { |
xorjoep | 1:24714b45cd1b | 197 | /* Copy decimation factor number of new input samples into the state buffer */ |
xorjoep | 1:24714b45cd1b | 198 | i = S->M; |
xorjoep | 1:24714b45cd1b | 199 | |
xorjoep | 1:24714b45cd1b | 200 | do |
xorjoep | 1:24714b45cd1b | 201 | { |
xorjoep | 1:24714b45cd1b | 202 | *pStateCurnt++ = *pSrc++; |
xorjoep | 1:24714b45cd1b | 203 | |
xorjoep | 1:24714b45cd1b | 204 | } while (--i); |
xorjoep | 1:24714b45cd1b | 205 | |
xorjoep | 1:24714b45cd1b | 206 | /*Set sum to zero */ |
xorjoep | 1:24714b45cd1b | 207 | sum0 = 0; |
xorjoep | 1:24714b45cd1b | 208 | |
xorjoep | 1:24714b45cd1b | 209 | /* Initialize state pointer */ |
xorjoep | 1:24714b45cd1b | 210 | px = pState; |
xorjoep | 1:24714b45cd1b | 211 | |
xorjoep | 1:24714b45cd1b | 212 | /* Initialize coeff pointer */ |
xorjoep | 1:24714b45cd1b | 213 | pb = pCoeffs; |
xorjoep | 1:24714b45cd1b | 214 | |
xorjoep | 1:24714b45cd1b | 215 | /* Loop unrolling. Process 4 taps at a time. */ |
xorjoep | 1:24714b45cd1b | 216 | tapCnt = numTaps >> 2; |
xorjoep | 1:24714b45cd1b | 217 | |
xorjoep | 1:24714b45cd1b | 218 | /* Loop over the number of taps. Unroll by a factor of 4. |
xorjoep | 1:24714b45cd1b | 219 | ** Repeat until we've computed numTaps-4 coefficients. */ |
xorjoep | 1:24714b45cd1b | 220 | while (tapCnt > 0U) |
xorjoep | 1:24714b45cd1b | 221 | { |
xorjoep | 1:24714b45cd1b | 222 | /* Read the Read b[numTaps-1] and b[numTaps-2] coefficients */ |
xorjoep | 1:24714b45cd1b | 223 | c0 = *__SIMD32(pb)++; |
xorjoep | 1:24714b45cd1b | 224 | |
xorjoep | 1:24714b45cd1b | 225 | /* Read x[n-numTaps-1] and x[n-numTaps-2]sample */ |
xorjoep | 1:24714b45cd1b | 226 | x0 = *__SIMD32(px)++; |
xorjoep | 1:24714b45cd1b | 227 | |
xorjoep | 1:24714b45cd1b | 228 | /* Read the b[numTaps-3] and b[numTaps-4] coefficient */ |
xorjoep | 1:24714b45cd1b | 229 | c1 = *__SIMD32(pb)++; |
xorjoep | 1:24714b45cd1b | 230 | |
xorjoep | 1:24714b45cd1b | 231 | /* Perform the multiply-accumulate */ |
xorjoep | 1:24714b45cd1b | 232 | sum0 = __SMLAD(x0, c0, sum0); |
xorjoep | 1:24714b45cd1b | 233 | |
xorjoep | 1:24714b45cd1b | 234 | /* Read x[n-numTaps-2] and x[n-numTaps-3] sample */ |
xorjoep | 1:24714b45cd1b | 235 | x0 = *__SIMD32(px)++; |
xorjoep | 1:24714b45cd1b | 236 | |
xorjoep | 1:24714b45cd1b | 237 | /* Perform the multiply-accumulate */ |
xorjoep | 1:24714b45cd1b | 238 | sum0 = __SMLAD(x0, c1, sum0); |
xorjoep | 1:24714b45cd1b | 239 | |
xorjoep | 1:24714b45cd1b | 240 | /* Decrement the loop counter */ |
xorjoep | 1:24714b45cd1b | 241 | tapCnt--; |
xorjoep | 1:24714b45cd1b | 242 | } |
xorjoep | 1:24714b45cd1b | 243 | |
xorjoep | 1:24714b45cd1b | 244 | /* If the filter length is not a multiple of 4, compute the remaining filter taps */ |
xorjoep | 1:24714b45cd1b | 245 | tapCnt = numTaps % 0x4U; |
xorjoep | 1:24714b45cd1b | 246 | |
xorjoep | 1:24714b45cd1b | 247 | while (tapCnt > 0U) |
xorjoep | 1:24714b45cd1b | 248 | { |
xorjoep | 1:24714b45cd1b | 249 | /* Read coefficients */ |
xorjoep | 1:24714b45cd1b | 250 | c0 = *pb++; |
xorjoep | 1:24714b45cd1b | 251 | |
xorjoep | 1:24714b45cd1b | 252 | /* Fetch 1 state variable */ |
xorjoep | 1:24714b45cd1b | 253 | x0 = *px++; |
xorjoep | 1:24714b45cd1b | 254 | |
xorjoep | 1:24714b45cd1b | 255 | /* Perform the multiply-accumulate */ |
xorjoep | 1:24714b45cd1b | 256 | sum0 = __SMLAD(x0, c0, sum0); |
xorjoep | 1:24714b45cd1b | 257 | |
xorjoep | 1:24714b45cd1b | 258 | /* Decrement the loop counter */ |
xorjoep | 1:24714b45cd1b | 259 | tapCnt--; |
xorjoep | 1:24714b45cd1b | 260 | } |
xorjoep | 1:24714b45cd1b | 261 | |
xorjoep | 1:24714b45cd1b | 262 | /* Advance the state pointer by the decimation factor |
xorjoep | 1:24714b45cd1b | 263 | * to process the next group of decimation factor number samples */ |
xorjoep | 1:24714b45cd1b | 264 | pState = pState + S->M; |
xorjoep | 1:24714b45cd1b | 265 | |
xorjoep | 1:24714b45cd1b | 266 | /* Store filter output, smlad returns the values in 2.14 format */ |
xorjoep | 1:24714b45cd1b | 267 | /* so downsacle by 15 to get output in 1.15 */ |
xorjoep | 1:24714b45cd1b | 268 | *pDst++ = (q15_t) (__SSAT((sum0 >> 15), 16)); |
xorjoep | 1:24714b45cd1b | 269 | |
xorjoep | 1:24714b45cd1b | 270 | /* Decrement the loop counter */ |
xorjoep | 1:24714b45cd1b | 271 | blkCntN3--; |
xorjoep | 1:24714b45cd1b | 272 | } |
xorjoep | 1:24714b45cd1b | 273 | |
xorjoep | 1:24714b45cd1b | 274 | /* Processing is complete. |
xorjoep | 1:24714b45cd1b | 275 | ** Now copy the last numTaps - 1 samples to the satrt of the state buffer. |
xorjoep | 1:24714b45cd1b | 276 | ** This prepares the state buffer for the next function call. */ |
xorjoep | 1:24714b45cd1b | 277 | |
xorjoep | 1:24714b45cd1b | 278 | /* Points to the start of the state buffer */ |
xorjoep | 1:24714b45cd1b | 279 | pStateCurnt = S->pState; |
xorjoep | 1:24714b45cd1b | 280 | |
xorjoep | 1:24714b45cd1b | 281 | i = (numTaps - 1U) >> 2U; |
xorjoep | 1:24714b45cd1b | 282 | |
xorjoep | 1:24714b45cd1b | 283 | /* copy data */ |
xorjoep | 1:24714b45cd1b | 284 | while (i > 0U) |
xorjoep | 1:24714b45cd1b | 285 | { |
xorjoep | 1:24714b45cd1b | 286 | *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++; |
xorjoep | 1:24714b45cd1b | 287 | *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++; |
xorjoep | 1:24714b45cd1b | 288 | |
xorjoep | 1:24714b45cd1b | 289 | /* Decrement the loop counter */ |
xorjoep | 1:24714b45cd1b | 290 | i--; |
xorjoep | 1:24714b45cd1b | 291 | } |
xorjoep | 1:24714b45cd1b | 292 | |
xorjoep | 1:24714b45cd1b | 293 | i = (numTaps - 1U) % 0x04U; |
xorjoep | 1:24714b45cd1b | 294 | |
xorjoep | 1:24714b45cd1b | 295 | /* copy data */ |
xorjoep | 1:24714b45cd1b | 296 | while (i > 0U) |
xorjoep | 1:24714b45cd1b | 297 | { |
xorjoep | 1:24714b45cd1b | 298 | *pStateCurnt++ = *pState++; |
xorjoep | 1:24714b45cd1b | 299 | |
xorjoep | 1:24714b45cd1b | 300 | /* Decrement the loop counter */ |
xorjoep | 1:24714b45cd1b | 301 | i--; |
xorjoep | 1:24714b45cd1b | 302 | } |
xorjoep | 1:24714b45cd1b | 303 | } |
xorjoep | 1:24714b45cd1b | 304 | |
xorjoep | 1:24714b45cd1b | 305 | #else |
xorjoep | 1:24714b45cd1b | 306 | |
xorjoep | 1:24714b45cd1b | 307 | |
xorjoep | 1:24714b45cd1b | 308 | void arm_fir_decimate_fast_q15( |
xorjoep | 1:24714b45cd1b | 309 | const arm_fir_decimate_instance_q15 * S, |
xorjoep | 1:24714b45cd1b | 310 | q15_t * pSrc, |
xorjoep | 1:24714b45cd1b | 311 | q15_t * pDst, |
xorjoep | 1:24714b45cd1b | 312 | uint32_t blockSize) |
xorjoep | 1:24714b45cd1b | 313 | { |
xorjoep | 1:24714b45cd1b | 314 | q15_t *pState = S->pState; /* State pointer */ |
xorjoep | 1:24714b45cd1b | 315 | q15_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */ |
xorjoep | 1:24714b45cd1b | 316 | q15_t *pStateCurnt; /* Points to the current sample of the state */ |
xorjoep | 1:24714b45cd1b | 317 | q15_t *px; /* Temporary pointer for state buffer */ |
xorjoep | 1:24714b45cd1b | 318 | q15_t *pb; /* Temporary pointer coefficient buffer */ |
xorjoep | 1:24714b45cd1b | 319 | q15_t x0, x1, c0; /* Temporary variables to hold state and coefficient values */ |
xorjoep | 1:24714b45cd1b | 320 | q31_t sum0; /* Accumulators */ |
xorjoep | 1:24714b45cd1b | 321 | q31_t acc0, acc1; |
xorjoep | 1:24714b45cd1b | 322 | q15_t *px0, *px1; |
xorjoep | 1:24714b45cd1b | 323 | uint32_t blkCntN3; |
xorjoep | 1:24714b45cd1b | 324 | uint32_t numTaps = S->numTaps; /* Number of taps */ |
xorjoep | 1:24714b45cd1b | 325 | uint32_t i, blkCnt, tapCnt, outBlockSize = blockSize / S->M; /* Loop counters */ |
xorjoep | 1:24714b45cd1b | 326 | |
xorjoep | 1:24714b45cd1b | 327 | |
xorjoep | 1:24714b45cd1b | 328 | /* S->pState buffer contains previous frame (numTaps - 1) samples */ |
xorjoep | 1:24714b45cd1b | 329 | /* pStateCurnt points to the location where the new input data should be written */ |
xorjoep | 1:24714b45cd1b | 330 | pStateCurnt = S->pState + (numTaps - 1U); |
xorjoep | 1:24714b45cd1b | 331 | |
xorjoep | 1:24714b45cd1b | 332 | |
xorjoep | 1:24714b45cd1b | 333 | /* Total number of output samples to be computed */ |
xorjoep | 1:24714b45cd1b | 334 | blkCnt = outBlockSize / 2; |
xorjoep | 1:24714b45cd1b | 335 | blkCntN3 = outBlockSize - (2 * blkCnt); |
xorjoep | 1:24714b45cd1b | 336 | |
xorjoep | 1:24714b45cd1b | 337 | while (blkCnt > 0U) |
xorjoep | 1:24714b45cd1b | 338 | { |
xorjoep | 1:24714b45cd1b | 339 | /* Copy decimation factor number of new input samples into the state buffer */ |
xorjoep | 1:24714b45cd1b | 340 | i = 2 * S->M; |
xorjoep | 1:24714b45cd1b | 341 | |
xorjoep | 1:24714b45cd1b | 342 | do |
xorjoep | 1:24714b45cd1b | 343 | { |
xorjoep | 1:24714b45cd1b | 344 | *pStateCurnt++ = *pSrc++; |
xorjoep | 1:24714b45cd1b | 345 | |
xorjoep | 1:24714b45cd1b | 346 | } while (--i); |
xorjoep | 1:24714b45cd1b | 347 | |
xorjoep | 1:24714b45cd1b | 348 | /* Set accumulator to zero */ |
xorjoep | 1:24714b45cd1b | 349 | acc0 = 0; |
xorjoep | 1:24714b45cd1b | 350 | acc1 = 0; |
xorjoep | 1:24714b45cd1b | 351 | |
xorjoep | 1:24714b45cd1b | 352 | /* Initialize state pointer */ |
xorjoep | 1:24714b45cd1b | 353 | px0 = pState; |
xorjoep | 1:24714b45cd1b | 354 | |
xorjoep | 1:24714b45cd1b | 355 | px1 = pState + S->M; |
xorjoep | 1:24714b45cd1b | 356 | |
xorjoep | 1:24714b45cd1b | 357 | |
xorjoep | 1:24714b45cd1b | 358 | /* Initialize coeff pointer */ |
xorjoep | 1:24714b45cd1b | 359 | pb = pCoeffs; |
xorjoep | 1:24714b45cd1b | 360 | |
xorjoep | 1:24714b45cd1b | 361 | /* Loop unrolling. Process 4 taps at a time. */ |
xorjoep | 1:24714b45cd1b | 362 | tapCnt = numTaps >> 2; |
xorjoep | 1:24714b45cd1b | 363 | |
xorjoep | 1:24714b45cd1b | 364 | /* Loop over the number of taps. Unroll by a factor of 4. |
xorjoep | 1:24714b45cd1b | 365 | ** Repeat until we've computed numTaps-4 coefficients. */ |
xorjoep | 1:24714b45cd1b | 366 | while (tapCnt > 0U) |
xorjoep | 1:24714b45cd1b | 367 | { |
xorjoep | 1:24714b45cd1b | 368 | /* Read the Read b[numTaps-1] coefficients */ |
xorjoep | 1:24714b45cd1b | 369 | c0 = *pb++; |
xorjoep | 1:24714b45cd1b | 370 | |
xorjoep | 1:24714b45cd1b | 371 | /* Read x[n-numTaps-1] for sample 0 and for sample 1 */ |
xorjoep | 1:24714b45cd1b | 372 | x0 = *px0++; |
xorjoep | 1:24714b45cd1b | 373 | x1 = *px1++; |
xorjoep | 1:24714b45cd1b | 374 | |
xorjoep | 1:24714b45cd1b | 375 | /* Perform the multiply-accumulate */ |
xorjoep | 1:24714b45cd1b | 376 | acc0 += x0 * c0; |
xorjoep | 1:24714b45cd1b | 377 | acc1 += x1 * c0; |
xorjoep | 1:24714b45cd1b | 378 | |
xorjoep | 1:24714b45cd1b | 379 | /* Read the b[numTaps-2] coefficient */ |
xorjoep | 1:24714b45cd1b | 380 | c0 = *pb++; |
xorjoep | 1:24714b45cd1b | 381 | |
xorjoep | 1:24714b45cd1b | 382 | /* Read x[n-numTaps-2] for sample 0 and sample 1 */ |
xorjoep | 1:24714b45cd1b | 383 | x0 = *px0++; |
xorjoep | 1:24714b45cd1b | 384 | x1 = *px1++; |
xorjoep | 1:24714b45cd1b | 385 | |
xorjoep | 1:24714b45cd1b | 386 | /* Perform the multiply-accumulate */ |
xorjoep | 1:24714b45cd1b | 387 | acc0 += x0 * c0; |
xorjoep | 1:24714b45cd1b | 388 | acc1 += x1 * c0; |
xorjoep | 1:24714b45cd1b | 389 | |
xorjoep | 1:24714b45cd1b | 390 | /* Read the b[numTaps-3] coefficients */ |
xorjoep | 1:24714b45cd1b | 391 | c0 = *pb++; |
xorjoep | 1:24714b45cd1b | 392 | |
xorjoep | 1:24714b45cd1b | 393 | /* Read x[n-numTaps-3] for sample 0 and sample 1 */ |
xorjoep | 1:24714b45cd1b | 394 | x0 = *px0++; |
xorjoep | 1:24714b45cd1b | 395 | x1 = *px1++; |
xorjoep | 1:24714b45cd1b | 396 | |
xorjoep | 1:24714b45cd1b | 397 | /* Perform the multiply-accumulate */ |
xorjoep | 1:24714b45cd1b | 398 | acc0 += x0 * c0; |
xorjoep | 1:24714b45cd1b | 399 | acc1 += x1 * c0; |
xorjoep | 1:24714b45cd1b | 400 | |
xorjoep | 1:24714b45cd1b | 401 | /* Read the b[numTaps-4] coefficient */ |
xorjoep | 1:24714b45cd1b | 402 | c0 = *pb++; |
xorjoep | 1:24714b45cd1b | 403 | |
xorjoep | 1:24714b45cd1b | 404 | /* Read x[n-numTaps-4] for sample 0 and sample 1 */ |
xorjoep | 1:24714b45cd1b | 405 | x0 = *px0++; |
xorjoep | 1:24714b45cd1b | 406 | x1 = *px1++; |
xorjoep | 1:24714b45cd1b | 407 | |
xorjoep | 1:24714b45cd1b | 408 | /* Perform the multiply-accumulate */ |
xorjoep | 1:24714b45cd1b | 409 | acc0 += x0 * c0; |
xorjoep | 1:24714b45cd1b | 410 | acc1 += x1 * c0; |
xorjoep | 1:24714b45cd1b | 411 | |
xorjoep | 1:24714b45cd1b | 412 | /* Decrement the loop counter */ |
xorjoep | 1:24714b45cd1b | 413 | tapCnt--; |
xorjoep | 1:24714b45cd1b | 414 | } |
xorjoep | 1:24714b45cd1b | 415 | |
xorjoep | 1:24714b45cd1b | 416 | /* If the filter length is not a multiple of 4, compute the remaining filter taps */ |
xorjoep | 1:24714b45cd1b | 417 | tapCnt = numTaps % 0x4U; |
xorjoep | 1:24714b45cd1b | 418 | |
xorjoep | 1:24714b45cd1b | 419 | while (tapCnt > 0U) |
xorjoep | 1:24714b45cd1b | 420 | { |
xorjoep | 1:24714b45cd1b | 421 | /* Read coefficients */ |
xorjoep | 1:24714b45cd1b | 422 | c0 = *pb++; |
xorjoep | 1:24714b45cd1b | 423 | |
xorjoep | 1:24714b45cd1b | 424 | /* Fetch 1 state variable */ |
xorjoep | 1:24714b45cd1b | 425 | x0 = *px0++; |
xorjoep | 1:24714b45cd1b | 426 | x1 = *px1++; |
xorjoep | 1:24714b45cd1b | 427 | |
xorjoep | 1:24714b45cd1b | 428 | /* Perform the multiply-accumulate */ |
xorjoep | 1:24714b45cd1b | 429 | acc0 += x0 * c0; |
xorjoep | 1:24714b45cd1b | 430 | acc1 += x1 * c0; |
xorjoep | 1:24714b45cd1b | 431 | |
xorjoep | 1:24714b45cd1b | 432 | /* Decrement the loop counter */ |
xorjoep | 1:24714b45cd1b | 433 | tapCnt--; |
xorjoep | 1:24714b45cd1b | 434 | } |
xorjoep | 1:24714b45cd1b | 435 | |
xorjoep | 1:24714b45cd1b | 436 | /* Advance the state pointer by the decimation factor |
xorjoep | 1:24714b45cd1b | 437 | * to process the next group of decimation factor number samples */ |
xorjoep | 1:24714b45cd1b | 438 | pState = pState + S->M * 2; |
xorjoep | 1:24714b45cd1b | 439 | |
xorjoep | 1:24714b45cd1b | 440 | /* Store filter output, smlad returns the values in 2.14 format */ |
xorjoep | 1:24714b45cd1b | 441 | /* so downsacle by 15 to get output in 1.15 */ |
xorjoep | 1:24714b45cd1b | 442 | |
xorjoep | 1:24714b45cd1b | 443 | *pDst++ = (q15_t) (__SSAT((acc0 >> 15), 16)); |
xorjoep | 1:24714b45cd1b | 444 | *pDst++ = (q15_t) (__SSAT((acc1 >> 15), 16)); |
xorjoep | 1:24714b45cd1b | 445 | |
xorjoep | 1:24714b45cd1b | 446 | |
xorjoep | 1:24714b45cd1b | 447 | /* Decrement the loop counter */ |
xorjoep | 1:24714b45cd1b | 448 | blkCnt--; |
xorjoep | 1:24714b45cd1b | 449 | } |
xorjoep | 1:24714b45cd1b | 450 | |
xorjoep | 1:24714b45cd1b | 451 | while (blkCntN3 > 0U) |
xorjoep | 1:24714b45cd1b | 452 | { |
xorjoep | 1:24714b45cd1b | 453 | /* Copy decimation factor number of new input samples into the state buffer */ |
xorjoep | 1:24714b45cd1b | 454 | i = S->M; |
xorjoep | 1:24714b45cd1b | 455 | |
xorjoep | 1:24714b45cd1b | 456 | do |
xorjoep | 1:24714b45cd1b | 457 | { |
xorjoep | 1:24714b45cd1b | 458 | *pStateCurnt++ = *pSrc++; |
xorjoep | 1:24714b45cd1b | 459 | |
xorjoep | 1:24714b45cd1b | 460 | } while (--i); |
xorjoep | 1:24714b45cd1b | 461 | |
xorjoep | 1:24714b45cd1b | 462 | /*Set sum to zero */ |
xorjoep | 1:24714b45cd1b | 463 | sum0 = 0; |
xorjoep | 1:24714b45cd1b | 464 | |
xorjoep | 1:24714b45cd1b | 465 | /* Initialize state pointer */ |
xorjoep | 1:24714b45cd1b | 466 | px = pState; |
xorjoep | 1:24714b45cd1b | 467 | |
xorjoep | 1:24714b45cd1b | 468 | /* Initialize coeff pointer */ |
xorjoep | 1:24714b45cd1b | 469 | pb = pCoeffs; |
xorjoep | 1:24714b45cd1b | 470 | |
xorjoep | 1:24714b45cd1b | 471 | /* Loop unrolling. Process 4 taps at a time. */ |
xorjoep | 1:24714b45cd1b | 472 | tapCnt = numTaps >> 2; |
xorjoep | 1:24714b45cd1b | 473 | |
xorjoep | 1:24714b45cd1b | 474 | /* Loop over the number of taps. Unroll by a factor of 4. |
xorjoep | 1:24714b45cd1b | 475 | ** Repeat until we've computed numTaps-4 coefficients. */ |
xorjoep | 1:24714b45cd1b | 476 | while (tapCnt > 0U) |
xorjoep | 1:24714b45cd1b | 477 | { |
xorjoep | 1:24714b45cd1b | 478 | /* Read the Read b[numTaps-1] coefficients */ |
xorjoep | 1:24714b45cd1b | 479 | c0 = *pb++; |
xorjoep | 1:24714b45cd1b | 480 | |
xorjoep | 1:24714b45cd1b | 481 | /* Read x[n-numTaps-1] and sample */ |
xorjoep | 1:24714b45cd1b | 482 | x0 = *px++; |
xorjoep | 1:24714b45cd1b | 483 | |
xorjoep | 1:24714b45cd1b | 484 | /* Perform the multiply-accumulate */ |
xorjoep | 1:24714b45cd1b | 485 | sum0 += x0 * c0; |
xorjoep | 1:24714b45cd1b | 486 | |
xorjoep | 1:24714b45cd1b | 487 | /* Read the b[numTaps-2] coefficient */ |
xorjoep | 1:24714b45cd1b | 488 | c0 = *pb++; |
xorjoep | 1:24714b45cd1b | 489 | |
xorjoep | 1:24714b45cd1b | 490 | /* Read x[n-numTaps-2] and sample */ |
xorjoep | 1:24714b45cd1b | 491 | x0 = *px++; |
xorjoep | 1:24714b45cd1b | 492 | |
xorjoep | 1:24714b45cd1b | 493 | /* Perform the multiply-accumulate */ |
xorjoep | 1:24714b45cd1b | 494 | sum0 += x0 * c0; |
xorjoep | 1:24714b45cd1b | 495 | |
xorjoep | 1:24714b45cd1b | 496 | /* Read the b[numTaps-3] coefficients */ |
xorjoep | 1:24714b45cd1b | 497 | c0 = *pb++; |
xorjoep | 1:24714b45cd1b | 498 | |
xorjoep | 1:24714b45cd1b | 499 | /* Read x[n-numTaps-3] sample */ |
xorjoep | 1:24714b45cd1b | 500 | x0 = *px++; |
xorjoep | 1:24714b45cd1b | 501 | |
xorjoep | 1:24714b45cd1b | 502 | /* Perform the multiply-accumulate */ |
xorjoep | 1:24714b45cd1b | 503 | sum0 += x0 * c0; |
xorjoep | 1:24714b45cd1b | 504 | |
xorjoep | 1:24714b45cd1b | 505 | /* Read the b[numTaps-4] coefficient */ |
xorjoep | 1:24714b45cd1b | 506 | c0 = *pb++; |
xorjoep | 1:24714b45cd1b | 507 | |
xorjoep | 1:24714b45cd1b | 508 | /* Read x[n-numTaps-4] sample */ |
xorjoep | 1:24714b45cd1b | 509 | x0 = *px++; |
xorjoep | 1:24714b45cd1b | 510 | |
xorjoep | 1:24714b45cd1b | 511 | /* Perform the multiply-accumulate */ |
xorjoep | 1:24714b45cd1b | 512 | sum0 += x0 * c0; |
xorjoep | 1:24714b45cd1b | 513 | |
xorjoep | 1:24714b45cd1b | 514 | /* Decrement the loop counter */ |
xorjoep | 1:24714b45cd1b | 515 | tapCnt--; |
xorjoep | 1:24714b45cd1b | 516 | } |
xorjoep | 1:24714b45cd1b | 517 | |
xorjoep | 1:24714b45cd1b | 518 | /* If the filter length is not a multiple of 4, compute the remaining filter taps */ |
xorjoep | 1:24714b45cd1b | 519 | tapCnt = numTaps % 0x4U; |
xorjoep | 1:24714b45cd1b | 520 | |
xorjoep | 1:24714b45cd1b | 521 | while (tapCnt > 0U) |
xorjoep | 1:24714b45cd1b | 522 | { |
xorjoep | 1:24714b45cd1b | 523 | /* Read coefficients */ |
xorjoep | 1:24714b45cd1b | 524 | c0 = *pb++; |
xorjoep | 1:24714b45cd1b | 525 | |
xorjoep | 1:24714b45cd1b | 526 | /* Fetch 1 state variable */ |
xorjoep | 1:24714b45cd1b | 527 | x0 = *px++; |
xorjoep | 1:24714b45cd1b | 528 | |
xorjoep | 1:24714b45cd1b | 529 | /* Perform the multiply-accumulate */ |
xorjoep | 1:24714b45cd1b | 530 | sum0 += x0 * c0; |
xorjoep | 1:24714b45cd1b | 531 | |
xorjoep | 1:24714b45cd1b | 532 | /* Decrement the loop counter */ |
xorjoep | 1:24714b45cd1b | 533 | tapCnt--; |
xorjoep | 1:24714b45cd1b | 534 | } |
xorjoep | 1:24714b45cd1b | 535 | |
xorjoep | 1:24714b45cd1b | 536 | /* Advance the state pointer by the decimation factor |
xorjoep | 1:24714b45cd1b | 537 | * to process the next group of decimation factor number samples */ |
xorjoep | 1:24714b45cd1b | 538 | pState = pState + S->M; |
xorjoep | 1:24714b45cd1b | 539 | |
xorjoep | 1:24714b45cd1b | 540 | /* Store filter output, smlad returns the values in 2.14 format */ |
xorjoep | 1:24714b45cd1b | 541 | /* so downsacle by 15 to get output in 1.15 */ |
xorjoep | 1:24714b45cd1b | 542 | *pDst++ = (q15_t) (__SSAT((sum0 >> 15), 16)); |
xorjoep | 1:24714b45cd1b | 543 | |
xorjoep | 1:24714b45cd1b | 544 | /* Decrement the loop counter */ |
xorjoep | 1:24714b45cd1b | 545 | blkCntN3--; |
xorjoep | 1:24714b45cd1b | 546 | } |
xorjoep | 1:24714b45cd1b | 547 | |
xorjoep | 1:24714b45cd1b | 548 | /* Processing is complete. |
xorjoep | 1:24714b45cd1b | 549 | ** Now copy the last numTaps - 1 samples to the satrt of the state buffer. |
xorjoep | 1:24714b45cd1b | 550 | ** This prepares the state buffer for the next function call. */ |
xorjoep | 1:24714b45cd1b | 551 | |
xorjoep | 1:24714b45cd1b | 552 | /* Points to the start of the state buffer */ |
xorjoep | 1:24714b45cd1b | 553 | pStateCurnt = S->pState; |
xorjoep | 1:24714b45cd1b | 554 | |
xorjoep | 1:24714b45cd1b | 555 | i = (numTaps - 1U) >> 2U; |
xorjoep | 1:24714b45cd1b | 556 | |
xorjoep | 1:24714b45cd1b | 557 | /* copy data */ |
xorjoep | 1:24714b45cd1b | 558 | while (i > 0U) |
xorjoep | 1:24714b45cd1b | 559 | { |
xorjoep | 1:24714b45cd1b | 560 | *pStateCurnt++ = *pState++; |
xorjoep | 1:24714b45cd1b | 561 | *pStateCurnt++ = *pState++; |
xorjoep | 1:24714b45cd1b | 562 | *pStateCurnt++ = *pState++; |
xorjoep | 1:24714b45cd1b | 563 | *pStateCurnt++ = *pState++; |
xorjoep | 1:24714b45cd1b | 564 | |
xorjoep | 1:24714b45cd1b | 565 | /* Decrement the loop counter */ |
xorjoep | 1:24714b45cd1b | 566 | i--; |
xorjoep | 1:24714b45cd1b | 567 | } |
xorjoep | 1:24714b45cd1b | 568 | |
xorjoep | 1:24714b45cd1b | 569 | i = (numTaps - 1U) % 0x04U; |
xorjoep | 1:24714b45cd1b | 570 | |
xorjoep | 1:24714b45cd1b | 571 | /* copy data */ |
xorjoep | 1:24714b45cd1b | 572 | while (i > 0U) |
xorjoep | 1:24714b45cd1b | 573 | { |
xorjoep | 1:24714b45cd1b | 574 | *pStateCurnt++ = *pState++; |
xorjoep | 1:24714b45cd1b | 575 | |
xorjoep | 1:24714b45cd1b | 576 | /* Decrement the loop counter */ |
xorjoep | 1:24714b45cd1b | 577 | i--; |
xorjoep | 1:24714b45cd1b | 578 | } |
xorjoep | 1:24714b45cd1b | 579 | } |
xorjoep | 1:24714b45cd1b | 580 | |
xorjoep | 1:24714b45cd1b | 581 | |
xorjoep | 1:24714b45cd1b | 582 | #endif /* #ifndef UNALIGNED_SUPPORT_DISABLE */ |
xorjoep | 1:24714b45cd1b | 583 | |
xorjoep | 1:24714b45cd1b | 584 | /** |
xorjoep | 1:24714b45cd1b | 585 | * @} end of FIR_decimate group |
xorjoep | 1:24714b45cd1b | 586 | */ |