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CMSIS DSP library

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cmsis_dsp/FilteringFunctions/arm_lms_q31.c@1:fdd22bb7aa52, 2012-11-28 (annotated)

Committer:
emilmont
Date:
Wed Nov 28 12:30:09 2012 +0000
Revision:
1:fdd22bb7aa52
Child:
2:da51fb522205
DSP library code

Who changed what in which revision?

UserRevisionLine numberNew contents of line
emilmont 1:fdd22bb7aa52 1 /* ----------------------------------------------------------------------
emilmont 1:fdd22bb7aa52 2 * Copyright (C) 2010 ARM Limited. All rights reserved.
emilmont 1:fdd22bb7aa52 3 *
emilmont 1:fdd22bb7aa52 4 * $Date: 15. February 2012
emilmont 1:fdd22bb7aa52 5 * $Revision: V1.1.0
emilmont 1:fdd22bb7aa52 6 *
emilmont 1:fdd22bb7aa52 7 * Project: CMSIS DSP Library
emilmont 1:fdd22bb7aa52 8 * Title: arm_lms_q31.c
emilmont 1:fdd22bb7aa52 9 *
emilmont 1:fdd22bb7aa52 10 * Description: Processing function for the Q31 LMS filter.
emilmont 1:fdd22bb7aa52 11 *
emilmont 1:fdd22bb7aa52 12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
emilmont 1:fdd22bb7aa52 13 *
emilmont 1:fdd22bb7aa52 14 * Version 1.1.0 2012/02/15
emilmont 1:fdd22bb7aa52 15 * Updated with more optimizations, bug fixes and minor API changes.
emilmont 1:fdd22bb7aa52 16 *
emilmont 1:fdd22bb7aa52 17 * Version 1.0.10 2011/7/15
emilmont 1:fdd22bb7aa52 18 * Big Endian support added and Merged M0 and M3/M4 Source code.
emilmont 1:fdd22bb7aa52 19 *
emilmont 1:fdd22bb7aa52 20 * Version 1.0.3 2010/11/29
emilmont 1:fdd22bb7aa52 21 * Re-organized the CMSIS folders and updated documentation.
emilmont 1:fdd22bb7aa52 22 *
emilmont 1:fdd22bb7aa52 23 * Version 1.0.2 2010/11/11
emilmont 1:fdd22bb7aa52 24 * Documentation updated.
emilmont 1:fdd22bb7aa52 25 *
emilmont 1:fdd22bb7aa52 26 * Version 1.0.1 2010/10/05
emilmont 1:fdd22bb7aa52 27 * Production release and review comments incorporated.
emilmont 1:fdd22bb7aa52 28 *
emilmont 1:fdd22bb7aa52 29 * Version 1.0.0 2010/09/20
emilmont 1:fdd22bb7aa52 30 * Production release and review comments incorporated
emilmont 1:fdd22bb7aa52 31 *
emilmont 1:fdd22bb7aa52 32 * Version 0.0.7 2010/06/10
emilmont 1:fdd22bb7aa52 33 * Misra-C changes done
emilmont 1:fdd22bb7aa52 34 * -------------------------------------------------------------------- */
emilmont 1:fdd22bb7aa52 35
emilmont 1:fdd22bb7aa52 36 #include "arm_math.h"
emilmont 1:fdd22bb7aa52 37 /**
emilmont 1:fdd22bb7aa52 38 * @ingroup groupFilters
emilmont 1:fdd22bb7aa52 39 */
emilmont 1:fdd22bb7aa52 40
emilmont 1:fdd22bb7aa52 41 /**
emilmont 1:fdd22bb7aa52 42 * @addtogroup LMS
emilmont 1:fdd22bb7aa52 43 * @{
emilmont 1:fdd22bb7aa52 44 */
emilmont 1:fdd22bb7aa52 45
emilmont 1:fdd22bb7aa52 46 /**
emilmont 1:fdd22bb7aa52 47 * @brief Processing function for Q31 LMS filter.
emilmont 1:fdd22bb7aa52 48 * @param[in] *S points to an instance of the Q15 LMS filter structure.
emilmont 1:fdd22bb7aa52 49 * @param[in] *pSrc points to the block of input data.
emilmont 1:fdd22bb7aa52 50 * @param[in] *pRef points to the block of reference data.
emilmont 1:fdd22bb7aa52 51 * @param[out] *pOut points to the block of output data.
emilmont 1:fdd22bb7aa52 52 * @param[out] *pErr points to the block of error data.
emilmont 1:fdd22bb7aa52 53 * @param[in] blockSize number of samples to process.
emilmont 1:fdd22bb7aa52 54 * @return none.
emilmont 1:fdd22bb7aa52 55 *
emilmont 1:fdd22bb7aa52 56 * \par Scaling and Overflow Behavior:
emilmont 1:fdd22bb7aa52 57 * The function is implemented using an internal 64-bit accumulator.
emilmont 1:fdd22bb7aa52 58 * The accumulator has a 2.62 format and maintains full precision of the intermediate
emilmont 1:fdd22bb7aa52 59 * multiplication results but provides only a single guard bit.
emilmont 1:fdd22bb7aa52 60 * Thus, if the accumulator result overflows it wraps around rather than clips.
emilmont 1:fdd22bb7aa52 61 * In order to avoid overflows completely the input signal must be scaled down by
emilmont 1:fdd22bb7aa52 62 * log2(numTaps) bits.
emilmont 1:fdd22bb7aa52 63 * The reference signal should not be scaled down.
emilmont 1:fdd22bb7aa52 64 * After all multiply-accumulates are performed, the 2.62 accumulator is shifted
emilmont 1:fdd22bb7aa52 65 * and saturated to 1.31 format to yield the final result.
emilmont 1:fdd22bb7aa52 66 * The output signal and error signal are in 1.31 format.
emilmont 1:fdd22bb7aa52 67 *
emilmont 1:fdd22bb7aa52 68 * \par
emilmont 1:fdd22bb7aa52 69 * In this filter, filter coefficients are updated for each sample and the updation of filter cofficients are saturted.
emilmont 1:fdd22bb7aa52 70 */
emilmont 1:fdd22bb7aa52 71
emilmont 1:fdd22bb7aa52 72 void arm_lms_q31(
emilmont 1:fdd22bb7aa52 73 const arm_lms_instance_q31 * S,
emilmont 1:fdd22bb7aa52 74 q31_t * pSrc,
emilmont 1:fdd22bb7aa52 75 q31_t * pRef,
emilmont 1:fdd22bb7aa52 76 q31_t * pOut,
emilmont 1:fdd22bb7aa52 77 q31_t * pErr,
emilmont 1:fdd22bb7aa52 78 uint32_t blockSize)
emilmont 1:fdd22bb7aa52 79 {
emilmont 1:fdd22bb7aa52 80 q31_t *pState = S->pState; /* State pointer */
emilmont 1:fdd22bb7aa52 81 uint32_t numTaps = S->numTaps; /* Number of filter coefficients in the filter */
emilmont 1:fdd22bb7aa52 82 q31_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
emilmont 1:fdd22bb7aa52 83 q31_t *pStateCurnt; /* Points to the current sample of the state */
emilmont 1:fdd22bb7aa52 84 q31_t mu = S->mu; /* Adaptive factor */
emilmont 1:fdd22bb7aa52 85 q31_t *px; /* Temporary pointer for state */
emilmont 1:fdd22bb7aa52 86 q31_t *pb; /* Temporary pointer for coefficient buffer */
emilmont 1:fdd22bb7aa52 87 uint32_t tapCnt, blkCnt; /* Loop counters */
emilmont 1:fdd22bb7aa52 88 q63_t acc; /* Accumulator */
emilmont 1:fdd22bb7aa52 89 q31_t e = 0; /* error of data sample */
emilmont 1:fdd22bb7aa52 90 q31_t alpha; /* Intermediate constant for taps update */
emilmont 1:fdd22bb7aa52 91 q31_t coef; /* Temporary variable for coef */
emilmont 1:fdd22bb7aa52 92 q31_t acc_l, acc_h; /* temporary input */
emilmont 1:fdd22bb7aa52 93 uint32_t uShift = ((uint32_t) S->postShift + 1u);
emilmont 1:fdd22bb7aa52 94 uint32_t lShift = 32u - uShift; /* Shift to be applied to the output */
emilmont 1:fdd22bb7aa52 95
emilmont 1:fdd22bb7aa52 96 /* S->pState points to buffer which contains previous frame (numTaps - 1) samples */
emilmont 1:fdd22bb7aa52 97 /* pStateCurnt points to the location where the new input data should be written */
emilmont 1:fdd22bb7aa52 98 pStateCurnt = &(S->pState[(numTaps - 1u)]);
emilmont 1:fdd22bb7aa52 99
emilmont 1:fdd22bb7aa52 100 /* Initializing blkCnt with blockSize */
emilmont 1:fdd22bb7aa52 101 blkCnt = blockSize;
emilmont 1:fdd22bb7aa52 102
emilmont 1:fdd22bb7aa52 103
emilmont 1:fdd22bb7aa52 104 #ifndef ARM_MATH_CM0
emilmont 1:fdd22bb7aa52 105
emilmont 1:fdd22bb7aa52 106 /* Run the below code for Cortex-M4 and Cortex-M3 */
emilmont 1:fdd22bb7aa52 107
emilmont 1:fdd22bb7aa52 108 while(blkCnt > 0u)
emilmont 1:fdd22bb7aa52 109 {
emilmont 1:fdd22bb7aa52 110 /* Copy the new input sample into the state buffer */
emilmont 1:fdd22bb7aa52 111 *pStateCurnt++ = *pSrc++;
emilmont 1:fdd22bb7aa52 112
emilmont 1:fdd22bb7aa52 113 /* Initialize state pointer */
emilmont 1:fdd22bb7aa52 114 px = pState;
emilmont 1:fdd22bb7aa52 115
emilmont 1:fdd22bb7aa52 116 /* Initialize coefficient pointer */
emilmont 1:fdd22bb7aa52 117 pb = pCoeffs;
emilmont 1:fdd22bb7aa52 118
emilmont 1:fdd22bb7aa52 119 /* Set the accumulator to zero */
emilmont 1:fdd22bb7aa52 120 acc = 0;
emilmont 1:fdd22bb7aa52 121
emilmont 1:fdd22bb7aa52 122 /* Loop unrolling. Process 4 taps at a time. */
emilmont 1:fdd22bb7aa52 123 tapCnt = numTaps >> 2;
emilmont 1:fdd22bb7aa52 124
emilmont 1:fdd22bb7aa52 125 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 126 {
emilmont 1:fdd22bb7aa52 127 /* Perform the multiply-accumulate */
emilmont 1:fdd22bb7aa52 128 /* acc += b[N] * x[n-N] */
emilmont 1:fdd22bb7aa52 129 acc += ((q63_t) (*px++)) * (*pb++);
emilmont 1:fdd22bb7aa52 130
emilmont 1:fdd22bb7aa52 131 /* acc += b[N-1] * x[n-N-1] */
emilmont 1:fdd22bb7aa52 132 acc += ((q63_t) (*px++)) * (*pb++);
emilmont 1:fdd22bb7aa52 133
emilmont 1:fdd22bb7aa52 134 /* acc += b[N-2] * x[n-N-2] */
emilmont 1:fdd22bb7aa52 135 acc += ((q63_t) (*px++)) * (*pb++);
emilmont 1:fdd22bb7aa52 136
emilmont 1:fdd22bb7aa52 137 /* acc += b[N-3] * x[n-N-3] */
emilmont 1:fdd22bb7aa52 138 acc += ((q63_t) (*px++)) * (*pb++);
emilmont 1:fdd22bb7aa52 139
emilmont 1:fdd22bb7aa52 140 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 141 tapCnt--;
emilmont 1:fdd22bb7aa52 142 }
emilmont 1:fdd22bb7aa52 143
emilmont 1:fdd22bb7aa52 144 /* If the filter length is not a multiple of 4, compute the remaining filter taps */
emilmont 1:fdd22bb7aa52 145 tapCnt = numTaps % 0x4u;
emilmont 1:fdd22bb7aa52 146
emilmont 1:fdd22bb7aa52 147 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 148 {
emilmont 1:fdd22bb7aa52 149 /* Perform the multiply-accumulate */
emilmont 1:fdd22bb7aa52 150 acc += ((q63_t) (*px++)) * (*pb++);
emilmont 1:fdd22bb7aa52 151
emilmont 1:fdd22bb7aa52 152 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 153 tapCnt--;
emilmont 1:fdd22bb7aa52 154 }
emilmont 1:fdd22bb7aa52 155
emilmont 1:fdd22bb7aa52 156 /* Converting the result to 1.31 format */
emilmont 1:fdd22bb7aa52 157 /* Calc lower part of acc */
emilmont 1:fdd22bb7aa52 158 acc_l = acc & 0xffffffff;
emilmont 1:fdd22bb7aa52 159
emilmont 1:fdd22bb7aa52 160 /* Calc upper part of acc */
emilmont 1:fdd22bb7aa52 161 acc_h = (acc >> 32) & 0xffffffff;
emilmont 1:fdd22bb7aa52 162
emilmont 1:fdd22bb7aa52 163 acc = (uint32_t) acc_l >> lShift | acc_h << uShift;
emilmont 1:fdd22bb7aa52 164
emilmont 1:fdd22bb7aa52 165 /* Store the result from accumulator into the destination buffer. */
emilmont 1:fdd22bb7aa52 166 *pOut++ = (q31_t) acc;
emilmont 1:fdd22bb7aa52 167
emilmont 1:fdd22bb7aa52 168 /* Compute and store error */
emilmont 1:fdd22bb7aa52 169 e = *pRef++ - (q31_t) acc;
emilmont 1:fdd22bb7aa52 170
emilmont 1:fdd22bb7aa52 171 *pErr++ = (q31_t) e;
emilmont 1:fdd22bb7aa52 172
emilmont 1:fdd22bb7aa52 173 /* Compute alpha i.e. intermediate constant for taps update */
emilmont 1:fdd22bb7aa52 174 alpha = (q31_t) (((q63_t) e * mu) >> 31);
emilmont 1:fdd22bb7aa52 175
emilmont 1:fdd22bb7aa52 176 /* Initialize state pointer */
emilmont 1:fdd22bb7aa52 177 /* Advance state pointer by 1 for the next sample */
emilmont 1:fdd22bb7aa52 178 px = pState++;
emilmont 1:fdd22bb7aa52 179
emilmont 1:fdd22bb7aa52 180 /* Initialize coefficient pointer */
emilmont 1:fdd22bb7aa52 181 pb = pCoeffs;
emilmont 1:fdd22bb7aa52 182
emilmont 1:fdd22bb7aa52 183 /* Loop unrolling. Process 4 taps at a time. */
emilmont 1:fdd22bb7aa52 184 tapCnt = numTaps >> 2;
emilmont 1:fdd22bb7aa52 185
emilmont 1:fdd22bb7aa52 186 /* Update filter coefficients */
emilmont 1:fdd22bb7aa52 187 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 188 {
emilmont 1:fdd22bb7aa52 189 /* coef is in 2.30 format */
emilmont 1:fdd22bb7aa52 190 coef = (q31_t) (((q63_t) alpha * (*px++)) >> (32));
emilmont 1:fdd22bb7aa52 191 /* get coef in 1.31 format by left shifting */
emilmont 1:fdd22bb7aa52 192 *pb = clip_q63_to_q31((q63_t) * pb + (coef << 1u));
emilmont 1:fdd22bb7aa52 193 /* update coefficient buffer to next coefficient */
emilmont 1:fdd22bb7aa52 194 pb++;
emilmont 1:fdd22bb7aa52 195
emilmont 1:fdd22bb7aa52 196 coef = (q31_t) (((q63_t) alpha * (*px++)) >> (32));
emilmont 1:fdd22bb7aa52 197 *pb = clip_q63_to_q31((q63_t) * pb + (coef << 1u));
emilmont 1:fdd22bb7aa52 198 pb++;
emilmont 1:fdd22bb7aa52 199
emilmont 1:fdd22bb7aa52 200 coef = (q31_t) (((q63_t) alpha * (*px++)) >> (32));
emilmont 1:fdd22bb7aa52 201 *pb = clip_q63_to_q31((q63_t) * pb + (coef << 1u));
emilmont 1:fdd22bb7aa52 202 pb++;
emilmont 1:fdd22bb7aa52 203
emilmont 1:fdd22bb7aa52 204 coef = (q31_t) (((q63_t) alpha * (*px++)) >> (32));
emilmont 1:fdd22bb7aa52 205 *pb = clip_q63_to_q31((q63_t) * pb + (coef << 1u));
emilmont 1:fdd22bb7aa52 206 pb++;
emilmont 1:fdd22bb7aa52 207
emilmont 1:fdd22bb7aa52 208 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 209 tapCnt--;
emilmont 1:fdd22bb7aa52 210 }
emilmont 1:fdd22bb7aa52 211
emilmont 1:fdd22bb7aa52 212 /* If the filter length is not a multiple of 4, compute the remaining filter taps */
emilmont 1:fdd22bb7aa52 213 tapCnt = numTaps % 0x4u;
emilmont 1:fdd22bb7aa52 214
emilmont 1:fdd22bb7aa52 215 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 216 {
emilmont 1:fdd22bb7aa52 217 /* Perform the multiply-accumulate */
emilmont 1:fdd22bb7aa52 218 coef = (q31_t) (((q63_t) alpha * (*px++)) >> (32));
emilmont 1:fdd22bb7aa52 219 *pb = clip_q63_to_q31((q63_t) * pb + (coef << 1u));
emilmont 1:fdd22bb7aa52 220 pb++;
emilmont 1:fdd22bb7aa52 221
emilmont 1:fdd22bb7aa52 222 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 223 tapCnt--;
emilmont 1:fdd22bb7aa52 224 }
emilmont 1:fdd22bb7aa52 225
emilmont 1:fdd22bb7aa52 226 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 227 blkCnt--;
emilmont 1:fdd22bb7aa52 228 }
emilmont 1:fdd22bb7aa52 229
emilmont 1:fdd22bb7aa52 230 /* Processing is complete. Now copy the last numTaps - 1 samples to the
emilmont 1:fdd22bb7aa52 231 satrt of the state buffer. This prepares the state buffer for the
emilmont 1:fdd22bb7aa52 232 next function call. */
emilmont 1:fdd22bb7aa52 233
emilmont 1:fdd22bb7aa52 234 /* Points to the start of the pState buffer */
emilmont 1:fdd22bb7aa52 235 pStateCurnt = S->pState;
emilmont 1:fdd22bb7aa52 236
emilmont 1:fdd22bb7aa52 237 /* Loop unrolling for (numTaps - 1u) samples copy */
emilmont 1:fdd22bb7aa52 238 tapCnt = (numTaps - 1u) >> 2u;
emilmont 1:fdd22bb7aa52 239
emilmont 1:fdd22bb7aa52 240 /* copy data */
emilmont 1:fdd22bb7aa52 241 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 242 {
emilmont 1:fdd22bb7aa52 243 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 244 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 245 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 246 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 247
emilmont 1:fdd22bb7aa52 248 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 249 tapCnt--;
emilmont 1:fdd22bb7aa52 250 }
emilmont 1:fdd22bb7aa52 251
emilmont 1:fdd22bb7aa52 252 /* Calculate remaining number of copies */
emilmont 1:fdd22bb7aa52 253 tapCnt = (numTaps - 1u) % 0x4u;
emilmont 1:fdd22bb7aa52 254
emilmont 1:fdd22bb7aa52 255 /* Copy the remaining q31_t data */
emilmont 1:fdd22bb7aa52 256 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 257 {
emilmont 1:fdd22bb7aa52 258 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 259
emilmont 1:fdd22bb7aa52 260 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 261 tapCnt--;
emilmont 1:fdd22bb7aa52 262 }
emilmont 1:fdd22bb7aa52 263
emilmont 1:fdd22bb7aa52 264 #else
emilmont 1:fdd22bb7aa52 265
emilmont 1:fdd22bb7aa52 266 /* Run the below code for Cortex-M0 */
emilmont 1:fdd22bb7aa52 267
emilmont 1:fdd22bb7aa52 268 while(blkCnt > 0u)
emilmont 1:fdd22bb7aa52 269 {
emilmont 1:fdd22bb7aa52 270 /* Copy the new input sample into the state buffer */
emilmont 1:fdd22bb7aa52 271 *pStateCurnt++ = *pSrc++;
emilmont 1:fdd22bb7aa52 272
emilmont 1:fdd22bb7aa52 273 /* Initialize pState pointer */
emilmont 1:fdd22bb7aa52 274 px = pState;
emilmont 1:fdd22bb7aa52 275
emilmont 1:fdd22bb7aa52 276 /* Initialize pCoeffs pointer */
emilmont 1:fdd22bb7aa52 277 pb = pCoeffs;
emilmont 1:fdd22bb7aa52 278
emilmont 1:fdd22bb7aa52 279 /* Set the accumulator to zero */
emilmont 1:fdd22bb7aa52 280 acc = 0;
emilmont 1:fdd22bb7aa52 281
emilmont 1:fdd22bb7aa52 282 /* Loop over numTaps number of values */
emilmont 1:fdd22bb7aa52 283 tapCnt = numTaps;
emilmont 1:fdd22bb7aa52 284
emilmont 1:fdd22bb7aa52 285 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 286 {
emilmont 1:fdd22bb7aa52 287 /* Perform the multiply-accumulate */
emilmont 1:fdd22bb7aa52 288 acc += ((q63_t) (*px++)) * (*pb++);
emilmont 1:fdd22bb7aa52 289
emilmont 1:fdd22bb7aa52 290 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 291 tapCnt--;
emilmont 1:fdd22bb7aa52 292 }
emilmont 1:fdd22bb7aa52 293
emilmont 1:fdd22bb7aa52 294 /* Converting the result to 1.31 format */
emilmont 1:fdd22bb7aa52 295 /* Store the result from accumulator into the destination buffer. */
emilmont 1:fdd22bb7aa52 296 /* Calc lower part of acc */
emilmont 1:fdd22bb7aa52 297 acc_l = acc & 0xffffffff;
emilmont 1:fdd22bb7aa52 298
emilmont 1:fdd22bb7aa52 299 /* Calc upper part of acc */
emilmont 1:fdd22bb7aa52 300 acc_h = (acc >> 32) & 0xffffffff;
emilmont 1:fdd22bb7aa52 301
emilmont 1:fdd22bb7aa52 302 acc = (uint32_t) acc_l >> lShift | acc_h << uShift;
emilmont 1:fdd22bb7aa52 303
emilmont 1:fdd22bb7aa52 304 *pOut++ = (q31_t) acc;
emilmont 1:fdd22bb7aa52 305
emilmont 1:fdd22bb7aa52 306 /* Compute and store error */
emilmont 1:fdd22bb7aa52 307 e = *pRef++ - (q31_t) acc;
emilmont 1:fdd22bb7aa52 308
emilmont 1:fdd22bb7aa52 309 *pErr++ = (q31_t) e;
emilmont 1:fdd22bb7aa52 310
emilmont 1:fdd22bb7aa52 311 /* Weighting factor for the LMS version */
emilmont 1:fdd22bb7aa52 312 alpha = (q31_t) (((q63_t) e * mu) >> 31);
emilmont 1:fdd22bb7aa52 313
emilmont 1:fdd22bb7aa52 314 /* Initialize pState pointer */
emilmont 1:fdd22bb7aa52 315 /* Advance state pointer by 1 for the next sample */
emilmont 1:fdd22bb7aa52 316 px = pState++;
emilmont 1:fdd22bb7aa52 317
emilmont 1:fdd22bb7aa52 318 /* Initialize pCoeffs pointer */
emilmont 1:fdd22bb7aa52 319 pb = pCoeffs;
emilmont 1:fdd22bb7aa52 320
emilmont 1:fdd22bb7aa52 321 /* Loop over numTaps number of values */
emilmont 1:fdd22bb7aa52 322 tapCnt = numTaps;
emilmont 1:fdd22bb7aa52 323
emilmont 1:fdd22bb7aa52 324 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 325 {
emilmont 1:fdd22bb7aa52 326 /* Perform the multiply-accumulate */
emilmont 1:fdd22bb7aa52 327 coef = (q31_t) (((q63_t) alpha * (*px++)) >> (32));
emilmont 1:fdd22bb7aa52 328 *pb += (coef << 1u);
emilmont 1:fdd22bb7aa52 329 pb++;
emilmont 1:fdd22bb7aa52 330
emilmont 1:fdd22bb7aa52 331 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 332 tapCnt--;
emilmont 1:fdd22bb7aa52 333 }
emilmont 1:fdd22bb7aa52 334
emilmont 1:fdd22bb7aa52 335 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 336 blkCnt--;
emilmont 1:fdd22bb7aa52 337 }
emilmont 1:fdd22bb7aa52 338
emilmont 1:fdd22bb7aa52 339 /* Processing is complete. Now copy the last numTaps - 1 samples to the
emilmont 1:fdd22bb7aa52 340 start of the state buffer. This prepares the state buffer for the
emilmont 1:fdd22bb7aa52 341 next function call. */
emilmont 1:fdd22bb7aa52 342
emilmont 1:fdd22bb7aa52 343 /* Points to the start of the pState buffer */
emilmont 1:fdd22bb7aa52 344 pStateCurnt = S->pState;
emilmont 1:fdd22bb7aa52 345
emilmont 1:fdd22bb7aa52 346 /* Copy (numTaps - 1u) samples */
emilmont 1:fdd22bb7aa52 347 tapCnt = (numTaps - 1u);
emilmont 1:fdd22bb7aa52 348
emilmont 1:fdd22bb7aa52 349 /* Copy the data */
emilmont 1:fdd22bb7aa52 350 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 351 {
emilmont 1:fdd22bb7aa52 352 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 353
emilmont 1:fdd22bb7aa52 354 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 355 tapCnt--;
emilmont 1:fdd22bb7aa52 356 }
emilmont 1:fdd22bb7aa52 357
emilmont 1:fdd22bb7aa52 358 #endif /* #ifndef ARM_MATH_CM0 */
emilmont 1:fdd22bb7aa52 359
emilmont 1:fdd22bb7aa52 360 }
emilmont 1:fdd22bb7aa52 361
emilmont 1:fdd22bb7aa52 362 /**
emilmont 1:fdd22bb7aa52 363 * @} end of LMS group
emilmont 1:fdd22bb7aa52 364 */