CMSIS DSP Software Library: arm_lms_norm_q31.c Source File
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arm_lms_norm_q31.c
Go to the documentation of this file.00001 /* ----------------------------------------------------------------------
00002 * Copyright (C) 2010 ARM Limited. All rights reserved.
00003 *
00004 * $Date: 29. November 2010
00005 * $Revision: V1.0.3
00006 *
00007 * Project: CMSIS DSP Library
00008 * Title: arm_lms_norm_q31.c
00009 *
00010 * Description: Processing function for the Q31 NLMS filter.
00011 *
00012 * Target Processor: Cortex-M4/Cortex-M3
00013 *
00014 * Version 1.0.3 2010/11/29
00015 * Re-organized the CMSIS folders and updated documentation.
00016 *
00017 * Version 1.0.2 2010/11/11
00018 * Documentation updated.
00019 *
00020 * Version 1.0.1 2010/10/05
00021 * Production release and review comments incorporated.
00022 *
00023 * Version 1.0.0 2010/09/20
00024 * Production release and review comments incorporated
00025 *
00026 * Version 0.0.7 2010/06/10
00027 * Misra-C changes done
00028 * -------------------------------------------------------------------- */
00029
00030 #include "arm_math.h"
00031
00066 void arm_lms_norm_q31(
00067 arm_lms_norm_instance_q31 * S,
00068 q31_t * pSrc,
00069 q31_t * pRef,
00070 q31_t * pOut,
00071 q31_t * pErr,
00072 uint32_t blockSize)
00073 {
00074 q31_t *pState = S->pState; /* State pointer */
00075 q31_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
00076 q31_t *pStateCurnt; /* Points to the current sample of the state */
00077 q31_t *px, *pb; /* Temporary pointers for state and coefficient buffers */
00078 q31_t mu = S->mu; /* Adaptive factor */
00079 uint32_t numTaps = S->numTaps; /* Number of filter coefficients in the filter */
00080 uint32_t tapCnt, blkCnt; /* Loop counters */
00081 q63_t energy; /* Energy of the input */
00082 q63_t acc; /* Accumulator */
00083 q31_t e = 0, d = 0; /* error, reference data sample */
00084 q31_t w = 0, in; /* weight factor and state */
00085 q31_t x0; /* temporary variable to hold input sample */
00086 uint32_t shift = 32u - ((uint32_t) S->postShift + 1u); /* Shift to be applied to the output */
00087 q31_t errorXmu, oneByEnergy; /* Temporary variables to store error and mu product and reciprocal of energy */
00088 q31_t postShift; /* Post shift to be applied to weight after reciprocal calculation */
00089 q31_t coef; /* Temporary variable for coef */
00090
00091 energy = S->energy;
00092 x0 = S->x0;
00093
00094 /* S->pState points to buffer which contains previous frame (numTaps - 1) samples */
00095 /* pStateCurnt points to the location where the new input data should be written */
00096 pStateCurnt = &(S->pState[(numTaps - 1u)]);
00097
00098 blkCnt = blockSize;
00099
00100 while(blkCnt > 0u)
00101 {
00102
00103 /* Copy the new input sample into the state buffer */
00104 *pStateCurnt++ = *pSrc;
00105
00106 /* Initialize pState pointer */
00107 px = pState;
00108
00109 /* Initialize coeff pointer */
00110 pb = (pCoeffs);
00111
00112 /* Read the sample from input buffer */
00113 in = *pSrc++;
00114
00115 /* Update the energy calculation */
00116 energy = (q31_t) ((((q63_t) energy << 32) -
00117 (((q63_t) x0 * x0) << 1)) >> 32);
00118 energy = (q31_t) (((((q63_t) in * in) << 1) + (energy << 32)) >> 32);
00119
00120 /* Set the accumulator to zero */
00121 acc = 0;
00122
00123 /* Loop unrolling. Process 4 taps at a time. */
00124 tapCnt = numTaps >> 2;
00125
00126 while(tapCnt > 0u)
00127 {
00128 /* Perform the multiply-accumulate */
00129 acc += ((q63_t) (*px++)) * (*pb++);
00130 acc += ((q63_t) (*px++)) * (*pb++);
00131 acc += ((q63_t) (*px++)) * (*pb++);
00132 acc += ((q63_t) (*px++)) * (*pb++);
00133
00134 /* Decrement the loop counter */
00135 tapCnt--;
00136 }
00137
00138 /* If the filter length is not a multiple of 4, compute the remaining filter taps */
00139 tapCnt = numTaps % 0x4u;
00140
00141 while(tapCnt > 0u)
00142 {
00143 /* Perform the multiply-accumulate */
00144 acc += ((q63_t) (*px++)) * (*pb++);
00145
00146 /* Decrement the loop counter */
00147 tapCnt--;
00148 }
00149
00150 /* Converting the result to 1.31 format */
00151 acc = (q31_t) (acc >> shift);
00152
00153 /* Store the result from accumulator into the destination buffer. */
00154 *pOut++ = (q31_t) acc;
00155
00156 /* Compute and store error */
00157 d = *pRef++;
00158 e = d - (q31_t) acc;
00159 *pErr++ = e;
00160
00161 /* Calculates the reciprocal of energy */
00162 postShift = arm_recip_q31(energy + DELTA_Q31,
00163 &oneByEnergy, &S->recipTable[0]);
00164
00165 /* Calculation of product of (e * mu) */
00166 errorXmu = (q31_t) (((q63_t) e * mu) >> 31);
00167
00168 /* Weighting factor for the normalized version */
00169 w = clip_q63_to_q31(((q63_t) errorXmu * oneByEnergy) >> (31 - postShift));
00170
00171 /* Initialize pState pointer */
00172 px = pState;
00173
00174 /* Initialize coeff pointer */
00175 pb = (pCoeffs);
00176
00177 /* Loop unrolling. Process 4 taps at a time. */
00178 tapCnt = numTaps >> 2;
00179
00180 /* Update filter coefficients */
00181 while(tapCnt > 0u)
00182 {
00183 /* Perform the multiply-accumulate */
00184
00185 /* coef is in 2.30 format */
00186 coef = (q31_t) (((q63_t) w * (*px++)) >> (32));
00187 /* get coef in 1.31 format by left shifting */
00188 *pb = clip_q63_to_q31((q63_t) *pb + (coef << 1u));
00189 /* update coefficient buffer to next coefficient */
00190 pb++;
00191
00192 coef = (q31_t) (((q63_t) w * (*px++)) >> (32));
00193 *pb = clip_q63_to_q31((q63_t) *pb + (coef << 1u));
00194 pb++;
00195
00196 coef = (q31_t) (((q63_t) w * (*px++)) >> (32));
00197 *pb = clip_q63_to_q31((q63_t) *pb + (coef << 1u));
00198 pb++;
00199
00200 coef = (q31_t) (((q63_t) w * (*px++)) >> (32));
00201 *pb = clip_q63_to_q31((q63_t) *pb + (coef << 1u));
00202 pb++;
00203
00204 /* Decrement the loop counter */
00205 tapCnt--;
00206 }
00207
00208 /* If the filter length is not a multiple of 4, compute the remaining filter taps */
00209 tapCnt = numTaps % 0x4u;
00210
00211 while(tapCnt > 0u)
00212 {
00213 /* Perform the multiply-accumulate */
00214 coef = (q31_t) (((q63_t) w * (*px++)) >> (32));
00215 *pb = clip_q63_to_q31((q63_t) *pb + (coef << 1u));
00216 pb++;
00217
00218 /* Decrement the loop counter */
00219 tapCnt--;
00220 }
00221
00222 /* Read the sample from state buffer */
00223 x0 = *pState;
00224
00225 /* Advance state pointer by 1 for the next sample */
00226 pState = pState + 1;
00227
00228 /* Decrement the loop counter */
00229 blkCnt--;
00230 }
00231
00232 /* Save energy and x0 values for the next frame */
00233 S->energy = (q31_t) energy;
00234 S->x0 = x0;
00235
00236 /* Processing is complete. Now copy the last numTaps - 1 samples to the
00237 satrt of the state buffer. This prepares the state buffer for the
00238 next function call. */
00239
00240 /* Points to the start of the pState buffer */
00241 pStateCurnt = S->pState;
00242
00243 /* Loop unrolling for (numTaps - 1u) samples copy */
00244 tapCnt = (numTaps - 1u) >> 2u;
00245
00246 /* copy data */
00247 while(tapCnt > 0u)
00248 {
00249 *pStateCurnt++ = *pState++;
00250 *pStateCurnt++ = *pState++;
00251 *pStateCurnt++ = *pState++;
00252 *pStateCurnt++ = *pState++;
00253
00254 /* Decrement the loop counter */
00255 tapCnt--;
00256 }
00257
00258 /* Calculate remaining number of copies */
00259 tapCnt = (numTaps - 1u) % 0x4u;
00260
00261 /* Copy the remaining q31_t data */
00262 while(tapCnt > 0u)
00263 {
00264 *pStateCurnt++ = *pState++;
00265
00266 /* Decrement the loop counter */
00267 tapCnt--;
00268 }
00269
00270 }
00271
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