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CMSIS DSP library

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cmsis_dsp/FilteringFunctions/arm_fir_decimate_q15.c@5:3762170b6d4d, 2015-11-20 (annotated)

Committer:
mbed_official
Date:
Fri Nov 20 08:45:18 2015 +0000
Revision:
5:3762170b6d4d
Parent:
3:7a284390b0ce 
Synchronized with git revision 2eb940b9a73af188d3004a2575fdfbb05febe62b



Full URL: https://github.com/mbedmicro/mbed/commit/2eb940b9a73af188d3004a2575fdfbb05febe62b/



Added option to build rpc library. closes #1426

Who changed what in which revision?

UserRevisionLine numberNew contents of line
emilmont 1:fdd22bb7aa52 1 /* ----------------------------------------------------------------------
mbed_official 5:3762170b6d4d 2 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.
emilmont 1:fdd22bb7aa52 3 *
mbed_official 5:3762170b6d4d 4 * $Date: 19. March 2015
mbed_official 5:3762170b6d4d 5 * $Revision: V.1.4.5
emilmont 1:fdd22bb7aa52 6 *
emilmont 2:da51fb522205 7 * Project: CMSIS DSP Library
emilmont 2:da51fb522205 8 * Title: arm_fir_decimate_q15.c
emilmont 1:fdd22bb7aa52 9 *
emilmont 2:da51fb522205 10 * Description: Q15 FIR Decimator.
emilmont 1:fdd22bb7aa52 11 *
emilmont 1:fdd22bb7aa52 12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
emilmont 1:fdd22bb7aa52 13 *
mbed_official 3:7a284390b0ce 14 * Redistribution and use in source and binary forms, with or without
mbed_official 3:7a284390b0ce 15 * modification, are permitted provided that the following conditions
mbed_official 3:7a284390b0ce 16 * are met:
mbed_official 3:7a284390b0ce 17 * - Redistributions of source code must retain the above copyright
mbed_official 3:7a284390b0ce 18 * notice, this list of conditions and the following disclaimer.
mbed_official 3:7a284390b0ce 19 * - Redistributions in binary form must reproduce the above copyright
mbed_official 3:7a284390b0ce 20 * notice, this list of conditions and the following disclaimer in
mbed_official 3:7a284390b0ce 21 * the documentation and/or other materials provided with the
mbed_official 3:7a284390b0ce 22 * distribution.
mbed_official 3:7a284390b0ce 23 * - Neither the name of ARM LIMITED nor the names of its contributors
mbed_official 3:7a284390b0ce 24 * may be used to endorse or promote products derived from this
mbed_official 3:7a284390b0ce 25 * software without specific prior written permission.
mbed_official 3:7a284390b0ce 26 *
mbed_official 3:7a284390b0ce 27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
mbed_official 3:7a284390b0ce 28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
mbed_official 3:7a284390b0ce 29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
mbed_official 3:7a284390b0ce 30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
mbed_official 3:7a284390b0ce 31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
mbed_official 3:7a284390b0ce 32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
mbed_official 3:7a284390b0ce 33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
mbed_official 3:7a284390b0ce 34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
mbed_official 3:7a284390b0ce 35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
mbed_official 3:7a284390b0ce 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
mbed_official 3:7a284390b0ce 37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
mbed_official 3:7a284390b0ce 38 * POSSIBILITY OF SUCH DAMAGE.
emilmont 1:fdd22bb7aa52 39 * -------------------------------------------------------------------- */
emilmont 1:fdd22bb7aa52 40
emilmont 1:fdd22bb7aa52 41 #include "arm_math.h"
emilmont 1:fdd22bb7aa52 42
emilmont 1:fdd22bb7aa52 43 /**
emilmont 1:fdd22bb7aa52 44 * @ingroup groupFilters
emilmont 1:fdd22bb7aa52 45 */
emilmont 1:fdd22bb7aa52 46
emilmont 1:fdd22bb7aa52 47 /**
emilmont 1:fdd22bb7aa52 48 * @addtogroup FIR_decimate
emilmont 1:fdd22bb7aa52 49 * @{
emilmont 1:fdd22bb7aa52 50 */
emilmont 1:fdd22bb7aa52 51
emilmont 1:fdd22bb7aa52 52 /**
emilmont 1:fdd22bb7aa52 53 * @brief Processing function for the Q15 FIR decimator.
emilmont 1:fdd22bb7aa52 54 * @param[in] *S points to an instance of the Q15 FIR decimator structure.
emilmont 1:fdd22bb7aa52 55 * @param[in] *pSrc points to the block of input data.
emilmont 1:fdd22bb7aa52 56 * @param[out] *pDst points to the location where the output result is written.
emilmont 1:fdd22bb7aa52 57 * @param[in] blockSize number of input samples to process per call.
emilmont 1:fdd22bb7aa52 58 * @return none.
emilmont 1:fdd22bb7aa52 59 *
emilmont 1:fdd22bb7aa52 60 * <b>Scaling and Overflow Behavior:</b>
emilmont 1:fdd22bb7aa52 61 * \par
emilmont 1:fdd22bb7aa52 62 * The function is implemented using a 64-bit internal accumulator.
emilmont 1:fdd22bb7aa52 63 * Both coefficients and state variables are represented in 1.15 format and multiplications yield a 2.30 result.
emilmont 1:fdd22bb7aa52 64 * The 2.30 intermediate results are accumulated in a 64-bit accumulator in 34.30 format.
emilmont 1:fdd22bb7aa52 65 * There is no risk of internal overflow with this approach and the full precision of intermediate multiplications is preserved.
emilmont 1:fdd22bb7aa52 66 * After all additions have been performed, the accumulator is truncated to 34.15 format by discarding low 15 bits.
emilmont 1:fdd22bb7aa52 67 * Lastly, the accumulator is saturated to yield a result in 1.15 format.
emilmont 1:fdd22bb7aa52 68 *
emilmont 1:fdd22bb7aa52 69 * \par
emilmont 1:fdd22bb7aa52 70 * Refer to the function <code>arm_fir_decimate_fast_q15()</code> for a faster but less precise implementation of this function for Cortex-M3 and Cortex-M4.
emilmont 1:fdd22bb7aa52 71 */
emilmont 1:fdd22bb7aa52 72
mbed_official 3:7a284390b0ce 73 #ifndef ARM_MATH_CM0_FAMILY
emilmont 1:fdd22bb7aa52 74
emilmont 1:fdd22bb7aa52 75 #ifndef UNALIGNED_SUPPORT_DISABLE
emilmont 1:fdd22bb7aa52 76
emilmont 1:fdd22bb7aa52 77 void arm_fir_decimate_q15(
emilmont 1:fdd22bb7aa52 78 const arm_fir_decimate_instance_q15 * S,
emilmont 1:fdd22bb7aa52 79 q15_t * pSrc,
emilmont 1:fdd22bb7aa52 80 q15_t * pDst,
emilmont 1:fdd22bb7aa52 81 uint32_t blockSize)
emilmont 1:fdd22bb7aa52 82 {
emilmont 1:fdd22bb7aa52 83 q15_t *pState = S->pState; /* State pointer */
emilmont 1:fdd22bb7aa52 84 q15_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
emilmont 1:fdd22bb7aa52 85 q15_t *pStateCurnt; /* Points to the current sample of the state */
emilmont 1:fdd22bb7aa52 86 q15_t *px; /* Temporary pointer for state buffer */
emilmont 1:fdd22bb7aa52 87 q15_t *pb; /* Temporary pointer coefficient buffer */
emilmont 1:fdd22bb7aa52 88 q31_t x0, x1, c0, c1; /* Temporary variables to hold state and coefficient values */
emilmont 1:fdd22bb7aa52 89 q63_t sum0; /* Accumulators */
emilmont 1:fdd22bb7aa52 90 q63_t acc0, acc1;
emilmont 1:fdd22bb7aa52 91 q15_t *px0, *px1;
emilmont 1:fdd22bb7aa52 92 uint32_t blkCntN3;
emilmont 1:fdd22bb7aa52 93 uint32_t numTaps = S->numTaps; /* Number of taps */
emilmont 1:fdd22bb7aa52 94 uint32_t i, blkCnt, tapCnt, outBlockSize = blockSize / S->M; /* Loop counters */
emilmont 1:fdd22bb7aa52 95
emilmont 1:fdd22bb7aa52 96
emilmont 1:fdd22bb7aa52 97 /* S->pState buffer contains previous frame (numTaps - 1) samples */
emilmont 1:fdd22bb7aa52 98 /* pStateCurnt points to the location where the new input data should be written */
emilmont 1:fdd22bb7aa52 99 pStateCurnt = S->pState + (numTaps - 1u);
emilmont 1:fdd22bb7aa52 100
emilmont 1:fdd22bb7aa52 101
emilmont 1:fdd22bb7aa52 102 /* Total number of output samples to be computed */
emilmont 1:fdd22bb7aa52 103 blkCnt = outBlockSize / 2;
emilmont 1:fdd22bb7aa52 104 blkCntN3 = outBlockSize - (2 * blkCnt);
emilmont 1:fdd22bb7aa52 105
emilmont 1:fdd22bb7aa52 106
emilmont 1:fdd22bb7aa52 107 while(blkCnt > 0u)
emilmont 1:fdd22bb7aa52 108 {
emilmont 1:fdd22bb7aa52 109 /* Copy decimation factor number of new input samples into the state buffer */
emilmont 1:fdd22bb7aa52 110 i = 2 * S->M;
emilmont 1:fdd22bb7aa52 111
emilmont 1:fdd22bb7aa52 112 do
emilmont 1:fdd22bb7aa52 113 {
emilmont 1:fdd22bb7aa52 114 *pStateCurnt++ = *pSrc++;
emilmont 1:fdd22bb7aa52 115
emilmont 1:fdd22bb7aa52 116 } while(--i);
emilmont 1:fdd22bb7aa52 117
emilmont 1:fdd22bb7aa52 118 /* Set accumulator to zero */
emilmont 1:fdd22bb7aa52 119 acc0 = 0;
emilmont 1:fdd22bb7aa52 120 acc1 = 0;
emilmont 1:fdd22bb7aa52 121
emilmont 1:fdd22bb7aa52 122 /* Initialize state pointer */
emilmont 1:fdd22bb7aa52 123 px0 = pState;
emilmont 1:fdd22bb7aa52 124
emilmont 1:fdd22bb7aa52 125 px1 = pState + S->M;
emilmont 1:fdd22bb7aa52 126
emilmont 1:fdd22bb7aa52 127
emilmont 1:fdd22bb7aa52 128 /* Initialize coeff pointer */
emilmont 1:fdd22bb7aa52 129 pb = pCoeffs;
emilmont 1:fdd22bb7aa52 130
emilmont 1:fdd22bb7aa52 131 /* Loop unrolling. Process 4 taps at a time. */
emilmont 1:fdd22bb7aa52 132 tapCnt = numTaps >> 2;
emilmont 1:fdd22bb7aa52 133
emilmont 1:fdd22bb7aa52 134 /* Loop over the number of taps. Unroll by a factor of 4.
emilmont 1:fdd22bb7aa52 135 ** Repeat until we've computed numTaps-4 coefficients. */
emilmont 1:fdd22bb7aa52 136 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 137 {
emilmont 1:fdd22bb7aa52 138 /* Read the Read b[numTaps-1] and b[numTaps-2] coefficients */
emilmont 1:fdd22bb7aa52 139 c0 = *__SIMD32(pb)++;
emilmont 1:fdd22bb7aa52 140
emilmont 1:fdd22bb7aa52 141 /* Read x[n-numTaps-1] and x[n-numTaps-2]sample */
emilmont 1:fdd22bb7aa52 142 x0 = *__SIMD32(px0)++;
emilmont 1:fdd22bb7aa52 143
emilmont 1:fdd22bb7aa52 144 x1 = *__SIMD32(px1)++;
emilmont 1:fdd22bb7aa52 145
emilmont 1:fdd22bb7aa52 146 /* Perform the multiply-accumulate */
emilmont 1:fdd22bb7aa52 147 acc0 = __SMLALD(x0, c0, acc0);
emilmont 1:fdd22bb7aa52 148
emilmont 1:fdd22bb7aa52 149 acc1 = __SMLALD(x1, c0, acc1);
emilmont 1:fdd22bb7aa52 150
emilmont 1:fdd22bb7aa52 151 /* Read the b[numTaps-3] and b[numTaps-4] coefficient */
emilmont 1:fdd22bb7aa52 152 c0 = *__SIMD32(pb)++;
emilmont 1:fdd22bb7aa52 153
emilmont 1:fdd22bb7aa52 154 /* Read x[n-numTaps-2] and x[n-numTaps-3] sample */
emilmont 1:fdd22bb7aa52 155 x0 = *__SIMD32(px0)++;
emilmont 1:fdd22bb7aa52 156
emilmont 1:fdd22bb7aa52 157 x1 = *__SIMD32(px1)++;
emilmont 1:fdd22bb7aa52 158
emilmont 1:fdd22bb7aa52 159 /* Perform the multiply-accumulate */
emilmont 1:fdd22bb7aa52 160 acc0 = __SMLALD(x0, c0, acc0);
emilmont 1:fdd22bb7aa52 161
emilmont 1:fdd22bb7aa52 162 acc1 = __SMLALD(x1, c0, acc1);
emilmont 1:fdd22bb7aa52 163
emilmont 1:fdd22bb7aa52 164 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 165 tapCnt--;
emilmont 1:fdd22bb7aa52 166 }
emilmont 1:fdd22bb7aa52 167
emilmont 1:fdd22bb7aa52 168 /* If the filter length is not a multiple of 4, compute the remaining filter taps */
emilmont 1:fdd22bb7aa52 169 tapCnt = numTaps % 0x4u;
emilmont 1:fdd22bb7aa52 170
emilmont 1:fdd22bb7aa52 171 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 172 {
emilmont 1:fdd22bb7aa52 173 /* Read coefficients */
emilmont 1:fdd22bb7aa52 174 c0 = *pb++;
emilmont 1:fdd22bb7aa52 175
emilmont 1:fdd22bb7aa52 176 /* Fetch 1 state variable */
emilmont 1:fdd22bb7aa52 177 x0 = *px0++;
emilmont 1:fdd22bb7aa52 178
emilmont 1:fdd22bb7aa52 179 x1 = *px1++;
emilmont 1:fdd22bb7aa52 180
emilmont 1:fdd22bb7aa52 181 /* Perform the multiply-accumulate */
emilmont 1:fdd22bb7aa52 182 acc0 = __SMLALD(x0, c0, acc0);
emilmont 1:fdd22bb7aa52 183 acc1 = __SMLALD(x1, c0, acc1);
emilmont 1:fdd22bb7aa52 184
emilmont 1:fdd22bb7aa52 185 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 186 tapCnt--;
emilmont 1:fdd22bb7aa52 187 }
emilmont 1:fdd22bb7aa52 188
emilmont 1:fdd22bb7aa52 189 /* Advance the state pointer by the decimation factor
emilmont 1:fdd22bb7aa52 190 * to process the next group of decimation factor number samples */
emilmont 1:fdd22bb7aa52 191 pState = pState + S->M * 2;
emilmont 1:fdd22bb7aa52 192
emilmont 1:fdd22bb7aa52 193 /* Store filter output, smlad returns the values in 2.14 format */
emilmont 1:fdd22bb7aa52 194 /* so downsacle by 15 to get output in 1.15 */
emilmont 1:fdd22bb7aa52 195 *pDst++ = (q15_t) (__SSAT((acc0 >> 15), 16));
emilmont 1:fdd22bb7aa52 196 *pDst++ = (q15_t) (__SSAT((acc1 >> 15), 16));
emilmont 1:fdd22bb7aa52 197
emilmont 1:fdd22bb7aa52 198 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 199 blkCnt--;
emilmont 1:fdd22bb7aa52 200 }
emilmont 1:fdd22bb7aa52 201
emilmont 1:fdd22bb7aa52 202
emilmont 1:fdd22bb7aa52 203
emilmont 1:fdd22bb7aa52 204 while(blkCntN3 > 0u)
emilmont 1:fdd22bb7aa52 205 {
emilmont 1:fdd22bb7aa52 206 /* Copy decimation factor number of new input samples into the state buffer */
emilmont 1:fdd22bb7aa52 207 i = S->M;
emilmont 1:fdd22bb7aa52 208
emilmont 1:fdd22bb7aa52 209 do
emilmont 1:fdd22bb7aa52 210 {
emilmont 1:fdd22bb7aa52 211 *pStateCurnt++ = *pSrc++;
emilmont 1:fdd22bb7aa52 212
emilmont 1:fdd22bb7aa52 213 } while(--i);
emilmont 1:fdd22bb7aa52 214
emilmont 1:fdd22bb7aa52 215 /*Set sum to zero */
emilmont 1:fdd22bb7aa52 216 sum0 = 0;
emilmont 1:fdd22bb7aa52 217
emilmont 1:fdd22bb7aa52 218 /* Initialize state pointer */
emilmont 1:fdd22bb7aa52 219 px = pState;
emilmont 1:fdd22bb7aa52 220
emilmont 1:fdd22bb7aa52 221 /* Initialize coeff pointer */
emilmont 1:fdd22bb7aa52 222 pb = pCoeffs;
emilmont 1:fdd22bb7aa52 223
emilmont 1:fdd22bb7aa52 224 /* Loop unrolling. Process 4 taps at a time. */
emilmont 1:fdd22bb7aa52 225 tapCnt = numTaps >> 2;
emilmont 1:fdd22bb7aa52 226
emilmont 1:fdd22bb7aa52 227 /* Loop over the number of taps. Unroll by a factor of 4.
emilmont 1:fdd22bb7aa52 228 ** Repeat until we've computed numTaps-4 coefficients. */
emilmont 1:fdd22bb7aa52 229 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 230 {
emilmont 1:fdd22bb7aa52 231 /* Read the Read b[numTaps-1] and b[numTaps-2] coefficients */
emilmont 1:fdd22bb7aa52 232 c0 = *__SIMD32(pb)++;
emilmont 1:fdd22bb7aa52 233
emilmont 1:fdd22bb7aa52 234 /* Read x[n-numTaps-1] and x[n-numTaps-2]sample */
emilmont 1:fdd22bb7aa52 235 x0 = *__SIMD32(px)++;
emilmont 1:fdd22bb7aa52 236
emilmont 1:fdd22bb7aa52 237 /* Read the b[numTaps-3] and b[numTaps-4] coefficient */
emilmont 1:fdd22bb7aa52 238 c1 = *__SIMD32(pb)++;
emilmont 1:fdd22bb7aa52 239
emilmont 1:fdd22bb7aa52 240 /* Perform the multiply-accumulate */
emilmont 1:fdd22bb7aa52 241 sum0 = __SMLALD(x0, c0, sum0);
emilmont 1:fdd22bb7aa52 242
emilmont 1:fdd22bb7aa52 243 /* Read x[n-numTaps-2] and x[n-numTaps-3] sample */
emilmont 1:fdd22bb7aa52 244 x0 = *__SIMD32(px)++;
emilmont 1:fdd22bb7aa52 245
emilmont 1:fdd22bb7aa52 246 /* Perform the multiply-accumulate */
emilmont 1:fdd22bb7aa52 247 sum0 = __SMLALD(x0, c1, sum0);
emilmont 1:fdd22bb7aa52 248
emilmont 1:fdd22bb7aa52 249 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 250 tapCnt--;
emilmont 1:fdd22bb7aa52 251 }
emilmont 1:fdd22bb7aa52 252
emilmont 1:fdd22bb7aa52 253 /* If the filter length is not a multiple of 4, compute the remaining filter taps */
emilmont 1:fdd22bb7aa52 254 tapCnt = numTaps % 0x4u;
emilmont 1:fdd22bb7aa52 255
emilmont 1:fdd22bb7aa52 256 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 257 {
emilmont 1:fdd22bb7aa52 258 /* Read coefficients */
emilmont 1:fdd22bb7aa52 259 c0 = *pb++;
emilmont 1:fdd22bb7aa52 260
emilmont 1:fdd22bb7aa52 261 /* Fetch 1 state variable */
emilmont 1:fdd22bb7aa52 262 x0 = *px++;
emilmont 1:fdd22bb7aa52 263
emilmont 1:fdd22bb7aa52 264 /* Perform the multiply-accumulate */
emilmont 1:fdd22bb7aa52 265 sum0 = __SMLALD(x0, c0, sum0);
emilmont 1:fdd22bb7aa52 266
emilmont 1:fdd22bb7aa52 267 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 268 tapCnt--;
emilmont 1:fdd22bb7aa52 269 }
emilmont 1:fdd22bb7aa52 270
emilmont 1:fdd22bb7aa52 271 /* Advance the state pointer by the decimation factor
emilmont 1:fdd22bb7aa52 272 * to process the next group of decimation factor number samples */
emilmont 1:fdd22bb7aa52 273 pState = pState + S->M;
emilmont 1:fdd22bb7aa52 274
emilmont 1:fdd22bb7aa52 275 /* Store filter output, smlad returns the values in 2.14 format */
emilmont 1:fdd22bb7aa52 276 /* so downsacle by 15 to get output in 1.15 */
emilmont 1:fdd22bb7aa52 277 *pDst++ = (q15_t) (__SSAT((sum0 >> 15), 16));
emilmont 1:fdd22bb7aa52 278
emilmont 1:fdd22bb7aa52 279 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 280 blkCntN3--;
emilmont 1:fdd22bb7aa52 281 }
emilmont 1:fdd22bb7aa52 282
emilmont 1:fdd22bb7aa52 283 /* Processing is complete.
emilmont 1:fdd22bb7aa52 284 ** Now copy the last numTaps - 1 samples to the satrt of the state buffer.
emilmont 1:fdd22bb7aa52 285 ** This prepares the state buffer for the next function call. */
emilmont 1:fdd22bb7aa52 286
emilmont 1:fdd22bb7aa52 287 /* Points to the start of the state buffer */
emilmont 1:fdd22bb7aa52 288 pStateCurnt = S->pState;
emilmont 1:fdd22bb7aa52 289
emilmont 1:fdd22bb7aa52 290 i = (numTaps - 1u) >> 2u;
emilmont 1:fdd22bb7aa52 291
emilmont 1:fdd22bb7aa52 292 /* copy data */
emilmont 1:fdd22bb7aa52 293 while(i > 0u)
emilmont 1:fdd22bb7aa52 294 {
emilmont 1:fdd22bb7aa52 295 *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;
emilmont 1:fdd22bb7aa52 296 *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;
emilmont 1:fdd22bb7aa52 297
emilmont 1:fdd22bb7aa52 298 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 299 i--;
emilmont 1:fdd22bb7aa52 300 }
emilmont 1:fdd22bb7aa52 301
emilmont 1:fdd22bb7aa52 302 i = (numTaps - 1u) % 0x04u;
emilmont 1:fdd22bb7aa52 303
emilmont 1:fdd22bb7aa52 304 /* copy data */
emilmont 1:fdd22bb7aa52 305 while(i > 0u)
emilmont 1:fdd22bb7aa52 306 {
emilmont 1:fdd22bb7aa52 307 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 308
emilmont 1:fdd22bb7aa52 309 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 310 i--;
emilmont 1:fdd22bb7aa52 311 }
emilmont 1:fdd22bb7aa52 312 }
emilmont 1:fdd22bb7aa52 313
emilmont 1:fdd22bb7aa52 314 #else
emilmont 1:fdd22bb7aa52 315
emilmont 1:fdd22bb7aa52 316
emilmont 1:fdd22bb7aa52 317 void arm_fir_decimate_q15(
emilmont 1:fdd22bb7aa52 318 const arm_fir_decimate_instance_q15 * S,
emilmont 1:fdd22bb7aa52 319 q15_t * pSrc,
emilmont 1:fdd22bb7aa52 320 q15_t * pDst,
emilmont 1:fdd22bb7aa52 321 uint32_t blockSize)
emilmont 1:fdd22bb7aa52 322 {
emilmont 1:fdd22bb7aa52 323 q15_t *pState = S->pState; /* State pointer */
emilmont 1:fdd22bb7aa52 324 q15_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
emilmont 1:fdd22bb7aa52 325 q15_t *pStateCurnt; /* Points to the current sample of the state */
emilmont 1:fdd22bb7aa52 326 q15_t *px; /* Temporary pointer for state buffer */
emilmont 1:fdd22bb7aa52 327 q15_t *pb; /* Temporary pointer coefficient buffer */
emilmont 1:fdd22bb7aa52 328 q15_t x0, x1, c0; /* Temporary variables to hold state and coefficient values */
emilmont 1:fdd22bb7aa52 329 q63_t sum0; /* Accumulators */
emilmont 1:fdd22bb7aa52 330 q63_t acc0, acc1;
emilmont 1:fdd22bb7aa52 331 q15_t *px0, *px1;
emilmont 1:fdd22bb7aa52 332 uint32_t blkCntN3;
emilmont 1:fdd22bb7aa52 333 uint32_t numTaps = S->numTaps; /* Number of taps */
emilmont 1:fdd22bb7aa52 334 uint32_t i, blkCnt, tapCnt, outBlockSize = blockSize / S->M; /* Loop counters */
emilmont 1:fdd22bb7aa52 335
emilmont 1:fdd22bb7aa52 336
emilmont 1:fdd22bb7aa52 337 /* S->pState buffer contains previous frame (numTaps - 1) samples */
emilmont 1:fdd22bb7aa52 338 /* pStateCurnt points to the location where the new input data should be written */
emilmont 1:fdd22bb7aa52 339 pStateCurnt = S->pState + (numTaps - 1u);
emilmont 1:fdd22bb7aa52 340
emilmont 1:fdd22bb7aa52 341
emilmont 1:fdd22bb7aa52 342 /* Total number of output samples to be computed */
emilmont 1:fdd22bb7aa52 343 blkCnt = outBlockSize / 2;
emilmont 1:fdd22bb7aa52 344 blkCntN3 = outBlockSize - (2 * blkCnt);
emilmont 1:fdd22bb7aa52 345
emilmont 1:fdd22bb7aa52 346 while(blkCnt > 0u)
emilmont 1:fdd22bb7aa52 347 {
emilmont 1:fdd22bb7aa52 348 /* Copy decimation factor number of new input samples into the state buffer */
emilmont 1:fdd22bb7aa52 349 i = 2 * S->M;
emilmont 1:fdd22bb7aa52 350
emilmont 1:fdd22bb7aa52 351 do
emilmont 1:fdd22bb7aa52 352 {
emilmont 1:fdd22bb7aa52 353 *pStateCurnt++ = *pSrc++;
emilmont 1:fdd22bb7aa52 354
emilmont 1:fdd22bb7aa52 355 } while(--i);
emilmont 1:fdd22bb7aa52 356
emilmont 1:fdd22bb7aa52 357 /* Set accumulator to zero */
emilmont 1:fdd22bb7aa52 358 acc0 = 0;
emilmont 1:fdd22bb7aa52 359 acc1 = 0;
emilmont 1:fdd22bb7aa52 360
emilmont 1:fdd22bb7aa52 361 /* Initialize state pointer */
emilmont 1:fdd22bb7aa52 362 px0 = pState;
emilmont 1:fdd22bb7aa52 363
emilmont 1:fdd22bb7aa52 364 px1 = pState + S->M;
emilmont 1:fdd22bb7aa52 365
emilmont 1:fdd22bb7aa52 366
emilmont 1:fdd22bb7aa52 367 /* Initialize coeff pointer */
emilmont 1:fdd22bb7aa52 368 pb = pCoeffs;
emilmont 1:fdd22bb7aa52 369
emilmont 1:fdd22bb7aa52 370 /* Loop unrolling. Process 4 taps at a time. */
emilmont 1:fdd22bb7aa52 371 tapCnt = numTaps >> 2;
emilmont 1:fdd22bb7aa52 372
emilmont 1:fdd22bb7aa52 373 /* Loop over the number of taps. Unroll by a factor of 4.
emilmont 1:fdd22bb7aa52 374 ** Repeat until we've computed numTaps-4 coefficients. */
emilmont 1:fdd22bb7aa52 375 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 376 {
emilmont 1:fdd22bb7aa52 377 /* Read the Read b[numTaps-1] coefficients */
emilmont 1:fdd22bb7aa52 378 c0 = *pb++;
emilmont 1:fdd22bb7aa52 379
emilmont 1:fdd22bb7aa52 380 /* Read x[n-numTaps-1] for sample 0 and for sample 1 */
emilmont 1:fdd22bb7aa52 381 x0 = *px0++;
emilmont 1:fdd22bb7aa52 382 x1 = *px1++;
emilmont 1:fdd22bb7aa52 383
emilmont 1:fdd22bb7aa52 384 /* Perform the multiply-accumulate */
emilmont 1:fdd22bb7aa52 385 acc0 += x0 * c0;
emilmont 1:fdd22bb7aa52 386 acc1 += x1 * c0;
emilmont 1:fdd22bb7aa52 387
emilmont 1:fdd22bb7aa52 388 /* Read the b[numTaps-2] coefficient */
emilmont 1:fdd22bb7aa52 389 c0 = *pb++;
emilmont 1:fdd22bb7aa52 390
emilmont 1:fdd22bb7aa52 391 /* Read x[n-numTaps-2] for sample 0 and sample 1 */
emilmont 1:fdd22bb7aa52 392 x0 = *px0++;
emilmont 1:fdd22bb7aa52 393 x1 = *px1++;
emilmont 1:fdd22bb7aa52 394
emilmont 1:fdd22bb7aa52 395 /* Perform the multiply-accumulate */
emilmont 1:fdd22bb7aa52 396 acc0 += x0 * c0;
emilmont 1:fdd22bb7aa52 397 acc1 += x1 * c0;
emilmont 1:fdd22bb7aa52 398
emilmont 1:fdd22bb7aa52 399 /* Read the b[numTaps-3] coefficients */
emilmont 1:fdd22bb7aa52 400 c0 = *pb++;
emilmont 1:fdd22bb7aa52 401
emilmont 1:fdd22bb7aa52 402 /* Read x[n-numTaps-3] for sample 0 and sample 1 */
emilmont 1:fdd22bb7aa52 403 x0 = *px0++;
emilmont 1:fdd22bb7aa52 404 x1 = *px1++;
emilmont 1:fdd22bb7aa52 405
emilmont 1:fdd22bb7aa52 406 /* Perform the multiply-accumulate */
emilmont 1:fdd22bb7aa52 407 acc0 += x0 * c0;
emilmont 1:fdd22bb7aa52 408 acc1 += x1 * c0;
emilmont 1:fdd22bb7aa52 409
emilmont 1:fdd22bb7aa52 410 /* Read the b[numTaps-4] coefficient */
emilmont 1:fdd22bb7aa52 411 c0 = *pb++;
emilmont 1:fdd22bb7aa52 412
emilmont 1:fdd22bb7aa52 413 /* Read x[n-numTaps-4] for sample 0 and sample 1 */
emilmont 1:fdd22bb7aa52 414 x0 = *px0++;
emilmont 1:fdd22bb7aa52 415 x1 = *px1++;
emilmont 1:fdd22bb7aa52 416
emilmont 1:fdd22bb7aa52 417 /* Perform the multiply-accumulate */
emilmont 1:fdd22bb7aa52 418 acc0 += x0 * c0;
emilmont 1:fdd22bb7aa52 419 acc1 += x1 * c0;
emilmont 1:fdd22bb7aa52 420
emilmont 1:fdd22bb7aa52 421 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 422 tapCnt--;
emilmont 1:fdd22bb7aa52 423 }
emilmont 1:fdd22bb7aa52 424
emilmont 1:fdd22bb7aa52 425 /* If the filter length is not a multiple of 4, compute the remaining filter taps */
emilmont 1:fdd22bb7aa52 426 tapCnt = numTaps % 0x4u;
emilmont 1:fdd22bb7aa52 427
emilmont 1:fdd22bb7aa52 428 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 429 {
emilmont 1:fdd22bb7aa52 430 /* Read coefficients */
emilmont 1:fdd22bb7aa52 431 c0 = *pb++;
emilmont 1:fdd22bb7aa52 432
emilmont 1:fdd22bb7aa52 433 /* Fetch 1 state variable */
emilmont 1:fdd22bb7aa52 434 x0 = *px0++;
emilmont 1:fdd22bb7aa52 435 x1 = *px1++;
emilmont 1:fdd22bb7aa52 436
emilmont 1:fdd22bb7aa52 437 /* Perform the multiply-accumulate */
emilmont 1:fdd22bb7aa52 438 acc0 += x0 * c0;
emilmont 1:fdd22bb7aa52 439 acc1 += x1 * c0;
emilmont 1:fdd22bb7aa52 440
emilmont 1:fdd22bb7aa52 441 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 442 tapCnt--;
emilmont 1:fdd22bb7aa52 443 }
emilmont 1:fdd22bb7aa52 444
emilmont 1:fdd22bb7aa52 445 /* Advance the state pointer by the decimation factor
emilmont 1:fdd22bb7aa52 446 * to process the next group of decimation factor number samples */
emilmont 1:fdd22bb7aa52 447 pState = pState + S->M * 2;
emilmont 1:fdd22bb7aa52 448
emilmont 1:fdd22bb7aa52 449 /* Store filter output, smlad returns the values in 2.14 format */
emilmont 1:fdd22bb7aa52 450 /* so downsacle by 15 to get output in 1.15 */
emilmont 1:fdd22bb7aa52 451
emilmont 1:fdd22bb7aa52 452 *pDst++ = (q15_t) (__SSAT((acc0 >> 15), 16));
emilmont 1:fdd22bb7aa52 453 *pDst++ = (q15_t) (__SSAT((acc1 >> 15), 16));
emilmont 1:fdd22bb7aa52 454
emilmont 1:fdd22bb7aa52 455 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 456 blkCnt--;
emilmont 1:fdd22bb7aa52 457 }
emilmont 1:fdd22bb7aa52 458
emilmont 1:fdd22bb7aa52 459 while(blkCntN3 > 0u)
emilmont 1:fdd22bb7aa52 460 {
emilmont 1:fdd22bb7aa52 461 /* Copy decimation factor number of new input samples into the state buffer */
emilmont 1:fdd22bb7aa52 462 i = S->M;
emilmont 1:fdd22bb7aa52 463
emilmont 1:fdd22bb7aa52 464 do
emilmont 1:fdd22bb7aa52 465 {
emilmont 1:fdd22bb7aa52 466 *pStateCurnt++ = *pSrc++;
emilmont 1:fdd22bb7aa52 467
emilmont 1:fdd22bb7aa52 468 } while(--i);
emilmont 1:fdd22bb7aa52 469
emilmont 1:fdd22bb7aa52 470 /*Set sum to zero */
emilmont 1:fdd22bb7aa52 471 sum0 = 0;
emilmont 1:fdd22bb7aa52 472
emilmont 1:fdd22bb7aa52 473 /* Initialize state pointer */
emilmont 1:fdd22bb7aa52 474 px = pState;
emilmont 1:fdd22bb7aa52 475
emilmont 1:fdd22bb7aa52 476 /* Initialize coeff pointer */
emilmont 1:fdd22bb7aa52 477 pb = pCoeffs;
emilmont 1:fdd22bb7aa52 478
emilmont 1:fdd22bb7aa52 479 /* Loop unrolling. Process 4 taps at a time. */
emilmont 1:fdd22bb7aa52 480 tapCnt = numTaps >> 2;
emilmont 1:fdd22bb7aa52 481
emilmont 1:fdd22bb7aa52 482 /* Loop over the number of taps. Unroll by a factor of 4.
emilmont 1:fdd22bb7aa52 483 ** Repeat until we've computed numTaps-4 coefficients. */
emilmont 1:fdd22bb7aa52 484 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 485 {
emilmont 1:fdd22bb7aa52 486 /* Read the Read b[numTaps-1] coefficients */
emilmont 1:fdd22bb7aa52 487 c0 = *pb++;
emilmont 1:fdd22bb7aa52 488
emilmont 1:fdd22bb7aa52 489 /* Read x[n-numTaps-1] and sample */
emilmont 1:fdd22bb7aa52 490 x0 = *px++;
emilmont 1:fdd22bb7aa52 491
emilmont 1:fdd22bb7aa52 492 /* Perform the multiply-accumulate */
emilmont 1:fdd22bb7aa52 493 sum0 += x0 * c0;
emilmont 1:fdd22bb7aa52 494
emilmont 1:fdd22bb7aa52 495 /* Read the b[numTaps-2] coefficient */
emilmont 1:fdd22bb7aa52 496 c0 = *pb++;
emilmont 1:fdd22bb7aa52 497
emilmont 1:fdd22bb7aa52 498 /* Read x[n-numTaps-2] and sample */
emilmont 1:fdd22bb7aa52 499 x0 = *px++;
emilmont 1:fdd22bb7aa52 500
emilmont 1:fdd22bb7aa52 501 /* Perform the multiply-accumulate */
emilmont 1:fdd22bb7aa52 502 sum0 += x0 * c0;
emilmont 1:fdd22bb7aa52 503
emilmont 1:fdd22bb7aa52 504 /* Read the b[numTaps-3] coefficients */
emilmont 1:fdd22bb7aa52 505 c0 = *pb++;
emilmont 1:fdd22bb7aa52 506
emilmont 1:fdd22bb7aa52 507 /* Read x[n-numTaps-3] sample */
emilmont 1:fdd22bb7aa52 508 x0 = *px++;
emilmont 1:fdd22bb7aa52 509
emilmont 1:fdd22bb7aa52 510 /* Perform the multiply-accumulate */
emilmont 1:fdd22bb7aa52 511 sum0 += x0 * c0;
emilmont 1:fdd22bb7aa52 512
emilmont 1:fdd22bb7aa52 513 /* Read the b[numTaps-4] coefficient */
emilmont 1:fdd22bb7aa52 514 c0 = *pb++;
emilmont 1:fdd22bb7aa52 515
emilmont 1:fdd22bb7aa52 516 /* Read x[n-numTaps-4] sample */
emilmont 1:fdd22bb7aa52 517 x0 = *px++;
emilmont 1:fdd22bb7aa52 518
emilmont 1:fdd22bb7aa52 519 /* Perform the multiply-accumulate */
emilmont 1:fdd22bb7aa52 520 sum0 += x0 * c0;
emilmont 1:fdd22bb7aa52 521
emilmont 1:fdd22bb7aa52 522 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 523 tapCnt--;
emilmont 1:fdd22bb7aa52 524 }
emilmont 1:fdd22bb7aa52 525
emilmont 1:fdd22bb7aa52 526 /* If the filter length is not a multiple of 4, compute the remaining filter taps */
emilmont 1:fdd22bb7aa52 527 tapCnt = numTaps % 0x4u;
emilmont 1:fdd22bb7aa52 528
emilmont 1:fdd22bb7aa52 529 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 530 {
emilmont 1:fdd22bb7aa52 531 /* Read coefficients */
emilmont 1:fdd22bb7aa52 532 c0 = *pb++;
emilmont 1:fdd22bb7aa52 533
emilmont 1:fdd22bb7aa52 534 /* Fetch 1 state variable */
emilmont 1:fdd22bb7aa52 535 x0 = *px++;
emilmont 1:fdd22bb7aa52 536
emilmont 1:fdd22bb7aa52 537 /* Perform the multiply-accumulate */
emilmont 1:fdd22bb7aa52 538 sum0 += x0 * c0;
emilmont 1:fdd22bb7aa52 539
emilmont 1:fdd22bb7aa52 540 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 541 tapCnt--;
emilmont 1:fdd22bb7aa52 542 }
emilmont 1:fdd22bb7aa52 543
emilmont 1:fdd22bb7aa52 544 /* Advance the state pointer by the decimation factor
emilmont 1:fdd22bb7aa52 545 * to process the next group of decimation factor number samples */
emilmont 1:fdd22bb7aa52 546 pState = pState + S->M;
emilmont 1:fdd22bb7aa52 547
emilmont 1:fdd22bb7aa52 548 /* Store filter output, smlad returns the values in 2.14 format */
emilmont 1:fdd22bb7aa52 549 /* so downsacle by 15 to get output in 1.15 */
emilmont 1:fdd22bb7aa52 550 *pDst++ = (q15_t) (__SSAT((sum0 >> 15), 16));
emilmont 1:fdd22bb7aa52 551
emilmont 1:fdd22bb7aa52 552 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 553 blkCntN3--;
emilmont 1:fdd22bb7aa52 554 }
emilmont 1:fdd22bb7aa52 555
emilmont 1:fdd22bb7aa52 556 /* Processing is complete.
emilmont 1:fdd22bb7aa52 557 ** Now copy the last numTaps - 1 samples to the satrt of the state buffer.
emilmont 1:fdd22bb7aa52 558 ** This prepares the state buffer for the next function call. */
emilmont 1:fdd22bb7aa52 559
emilmont 1:fdd22bb7aa52 560 /* Points to the start of the state buffer */
emilmont 1:fdd22bb7aa52 561 pStateCurnt = S->pState;
emilmont 1:fdd22bb7aa52 562
emilmont 1:fdd22bb7aa52 563 i = (numTaps - 1u) >> 2u;
emilmont 1:fdd22bb7aa52 564
emilmont 1:fdd22bb7aa52 565 /* copy data */
emilmont 1:fdd22bb7aa52 566 while(i > 0u)
emilmont 1:fdd22bb7aa52 567 {
emilmont 1:fdd22bb7aa52 568 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 569 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 570 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 571 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 572
emilmont 1:fdd22bb7aa52 573 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 574 i--;
emilmont 1:fdd22bb7aa52 575 }
emilmont 1:fdd22bb7aa52 576
emilmont 1:fdd22bb7aa52 577 i = (numTaps - 1u) % 0x04u;
emilmont 1:fdd22bb7aa52 578
emilmont 1:fdd22bb7aa52 579 /* copy data */
emilmont 1:fdd22bb7aa52 580 while(i > 0u)
emilmont 1:fdd22bb7aa52 581 {
emilmont 1:fdd22bb7aa52 582 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 583
emilmont 1:fdd22bb7aa52 584 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 585 i--;
emilmont 1:fdd22bb7aa52 586 }
emilmont 1:fdd22bb7aa52 587 }
emilmont 1:fdd22bb7aa52 588
emilmont 1:fdd22bb7aa52 589
emilmont 2:da51fb522205 590 #endif /* #ifndef UNALIGNED_SUPPORT_DISABLE */
emilmont 1:fdd22bb7aa52 591
emilmont 1:fdd22bb7aa52 592 #else
emilmont 1:fdd22bb7aa52 593
emilmont 1:fdd22bb7aa52 594
emilmont 1:fdd22bb7aa52 595 void arm_fir_decimate_q15(
emilmont 1:fdd22bb7aa52 596 const arm_fir_decimate_instance_q15 * S,
emilmont 1:fdd22bb7aa52 597 q15_t * pSrc,
emilmont 1:fdd22bb7aa52 598 q15_t * pDst,
emilmont 1:fdd22bb7aa52 599 uint32_t blockSize)
emilmont 1:fdd22bb7aa52 600 {
emilmont 1:fdd22bb7aa52 601 q15_t *pState = S->pState; /* State pointer */
emilmont 1:fdd22bb7aa52 602 q15_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
emilmont 1:fdd22bb7aa52 603 q15_t *pStateCurnt; /* Points to the current sample of the state */
emilmont 1:fdd22bb7aa52 604 q15_t *px; /* Temporary pointer for state buffer */
emilmont 1:fdd22bb7aa52 605 q15_t *pb; /* Temporary pointer coefficient buffer */
emilmont 1:fdd22bb7aa52 606 q31_t x0, c0; /* Temporary variables to hold state and coefficient values */
emilmont 1:fdd22bb7aa52 607 q63_t sum0; /* Accumulators */
emilmont 1:fdd22bb7aa52 608 uint32_t numTaps = S->numTaps; /* Number of taps */
emilmont 1:fdd22bb7aa52 609 uint32_t i, blkCnt, tapCnt, outBlockSize = blockSize / S->M; /* Loop counters */
emilmont 1:fdd22bb7aa52 610
emilmont 1:fdd22bb7aa52 611
emilmont 1:fdd22bb7aa52 612
emilmont 1:fdd22bb7aa52 613 /* Run the below code for Cortex-M0 */
emilmont 1:fdd22bb7aa52 614
emilmont 1:fdd22bb7aa52 615 /* S->pState buffer contains previous frame (numTaps - 1) samples */
emilmont 1:fdd22bb7aa52 616 /* pStateCurnt points to the location where the new input data should be written */
emilmont 1:fdd22bb7aa52 617 pStateCurnt = S->pState + (numTaps - 1u);
emilmont 1:fdd22bb7aa52 618
emilmont 1:fdd22bb7aa52 619 /* Total number of output samples to be computed */
emilmont 1:fdd22bb7aa52 620 blkCnt = outBlockSize;
emilmont 1:fdd22bb7aa52 621
emilmont 1:fdd22bb7aa52 622 while(blkCnt > 0u)
emilmont 1:fdd22bb7aa52 623 {
emilmont 1:fdd22bb7aa52 624 /* Copy decimation factor number of new input samples into the state buffer */
emilmont 1:fdd22bb7aa52 625 i = S->M;
emilmont 1:fdd22bb7aa52 626
emilmont 1:fdd22bb7aa52 627 do
emilmont 1:fdd22bb7aa52 628 {
emilmont 1:fdd22bb7aa52 629 *pStateCurnt++ = *pSrc++;
emilmont 1:fdd22bb7aa52 630
emilmont 1:fdd22bb7aa52 631 } while(--i);
emilmont 1:fdd22bb7aa52 632
emilmont 1:fdd22bb7aa52 633 /*Set sum to zero */
emilmont 1:fdd22bb7aa52 634 sum0 = 0;
emilmont 1:fdd22bb7aa52 635
emilmont 1:fdd22bb7aa52 636 /* Initialize state pointer */
emilmont 1:fdd22bb7aa52 637 px = pState;
emilmont 1:fdd22bb7aa52 638
emilmont 1:fdd22bb7aa52 639 /* Initialize coeff pointer */
emilmont 1:fdd22bb7aa52 640 pb = pCoeffs;
emilmont 1:fdd22bb7aa52 641
emilmont 1:fdd22bb7aa52 642 tapCnt = numTaps;
emilmont 1:fdd22bb7aa52 643
emilmont 1:fdd22bb7aa52 644 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 645 {
emilmont 1:fdd22bb7aa52 646 /* Read coefficients */
emilmont 1:fdd22bb7aa52 647 c0 = *pb++;
emilmont 1:fdd22bb7aa52 648
emilmont 1:fdd22bb7aa52 649 /* Fetch 1 state variable */
emilmont 1:fdd22bb7aa52 650 x0 = *px++;
emilmont 1:fdd22bb7aa52 651
emilmont 1:fdd22bb7aa52 652 /* Perform the multiply-accumulate */
emilmont 1:fdd22bb7aa52 653 sum0 += (q31_t) x0 *c0;
emilmont 1:fdd22bb7aa52 654
emilmont 1:fdd22bb7aa52 655 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 656 tapCnt--;
emilmont 1:fdd22bb7aa52 657 }
emilmont 1:fdd22bb7aa52 658
emilmont 1:fdd22bb7aa52 659 /* Advance the state pointer by the decimation factor
emilmont 1:fdd22bb7aa52 660 * to process the next group of decimation factor number samples */
emilmont 1:fdd22bb7aa52 661 pState = pState + S->M;
emilmont 1:fdd22bb7aa52 662
emilmont 1:fdd22bb7aa52 663 /*Store filter output , smlad will return the values in 2.14 format */
emilmont 1:fdd22bb7aa52 664 /* so downsacle by 15 to get output in 1.15 */
emilmont 1:fdd22bb7aa52 665 *pDst++ = (q15_t) (__SSAT((sum0 >> 15), 16));
emilmont 1:fdd22bb7aa52 666
emilmont 1:fdd22bb7aa52 667 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 668 blkCnt--;
emilmont 1:fdd22bb7aa52 669 }
emilmont 1:fdd22bb7aa52 670
emilmont 1:fdd22bb7aa52 671 /* Processing is complete.
emilmont 1:fdd22bb7aa52 672 ** Now copy the last numTaps - 1 samples to the start of the state buffer.
emilmont 1:fdd22bb7aa52 673 ** This prepares the state buffer for the next function call. */
emilmont 1:fdd22bb7aa52 674
emilmont 1:fdd22bb7aa52 675 /* Points to the start of the state buffer */
emilmont 1:fdd22bb7aa52 676 pStateCurnt = S->pState;
emilmont 1:fdd22bb7aa52 677
emilmont 1:fdd22bb7aa52 678 i = numTaps - 1u;
emilmont 1:fdd22bb7aa52 679
emilmont 1:fdd22bb7aa52 680 /* copy data */
emilmont 1:fdd22bb7aa52 681 while(i > 0u)
emilmont 1:fdd22bb7aa52 682 {
emilmont 1:fdd22bb7aa52 683 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 684
emilmont 1:fdd22bb7aa52 685 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 686 i--;
emilmont 1:fdd22bb7aa52 687 }
emilmont 1:fdd22bb7aa52 688
emilmont 1:fdd22bb7aa52 689
emilmont 1:fdd22bb7aa52 690 }
mbed_official 3:7a284390b0ce 691 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
emilmont 1:fdd22bb7aa52 692
emilmont 1:fdd22bb7aa52 693
emilmont 1:fdd22bb7aa52 694 /**
emilmont 1:fdd22bb7aa52 695 * @} end of FIR_decimate group
emilmont 1:fdd22bb7aa52 696 */