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# arm_lms_norm_q15.c

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    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_q15.c
    00009 *
    00010 * Description:  Q15 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
    00065 void arm_lms_norm_q15(
    00066   arm_lms_norm_instance_q15 * S,
    00067   q15_t * pSrc,
    00068   q15_t * pRef,
    00069   q15_t * pOut,
    00070   q15_t * pErr,
    00071   uint32_t blockSize)
    00072 {
    00073   q15_t *pState = S->pState;                     /* State pointer */
    00074   q15_t *pCoeffs = S->pCoeffs;                   /* Coefficient pointer */
    00075   q15_t *pStateCurnt;                            /* Points to the current sample of the state */
    00076   q15_t *px, *pb;                                /* Temporary pointers for state and coefficient buffers */
    00077   q15_t mu = S->mu;                              /* Adaptive factor */
    00078   uint32_t numTaps = S->numTaps;                 /* Number of filter coefficients in the filter */
    00079   uint32_t tapCnt, blkCnt;                       /* Loop counters */
    00080   q31_t energy;                                  /* Energy of the input */
    00081   q63_t acc;                                     /* Accumulator */
    00082   q15_t e = 0, d = 0;                            /* error, reference data sample */
    00083   q15_t w = 0, in;                               /* weight factor and state */
    00084   q15_t x0;                                      /* temporary variable to hold input sample */
    00085   uint32_t shift = (uint32_t) S->postShift + 1u; /* Shift to be applied to the output */
    00086   q15_t errorXmu, oneByEnergy;                   /* Temporary variables to store error and mu product and reciprocal of energy */
    00087   q15_t postShift;                               /* Post shift to be applied to weight after reciprocal calculation */
    00088   q31_t coef;                                    /* Teporary variable for coefficient */
    00089
    00090   energy = S->energy;
    00091   x0 = S->x0;
    00092
    00093   /* S->pState points to buffer which contains previous frame (numTaps - 1) samples */
    00094   /* pStateCurnt points to the location where the new input data should be written */
    00095   pStateCurnt = &(S->pState[(numTaps - 1u)]);
    00096
    00097   blkCnt = blockSize;
    00098
    00099   while(blkCnt > 0u)
    00100   {
    00101     /* Copy the new input sample into the state buffer */
    00102     *pStateCurnt++ = *pSrc;
    00103
    00104     /* Initialize pState pointer */
    00105     px = pState;
    00106
    00107     /* Initialize coeff pointer */
    00108     pb = (pCoeffs);
    00109
    00110     /* Read the sample from input buffer */
    00111     in = *pSrc++;
    00112
    00113     /* Update the energy calculation */
    00114     energy -= (((q31_t) x0 * (x0)) >> 15);
    00115     energy += (((q31_t) in * (in)) >> 15);
    00116
    00117     /* Set the accumulator to zero */
    00118     acc = 0;
    00119
    00120     /* Loop unrolling.  Process 4 taps at a time. */
    00121     tapCnt = numTaps >> 2;
    00122
    00123     while(tapCnt > 0u)
    00124     {
    00125
    00126       /* Perform the multiply-accumulate */
    00127       acc = __SMLALD(*__SIMD32(px)++, (*__SIMD32(pb)++), acc);
    00128       acc = __SMLALD(*__SIMD32(px)++, (*__SIMD32(pb)++), acc);
    00129
    00130       /* Decrement the loop counter */
    00131       tapCnt--;
    00132     }
    00133
    00134     /* If the filter length is not a multiple of 4, compute the remaining filter taps */
    00135     tapCnt = numTaps % 0x4u;
    00136
    00137     while(tapCnt > 0u)
    00138     {
    00139       /* Perform the multiply-accumulate */
    00140       acc += (((q31_t) * px++ * (*pb++)));
    00141
    00142       /* Decrement the loop counter */
    00143       tapCnt--;
    00144     }
    00145
    00146     /* Converting the result to 1.15 format */
    00147     acc = __SSAT((acc >> (16u - shift)), 16u);
    00148
    00149     /* Store the result from accumulator into the destination buffer. */
    00150     *pOut++ = (q15_t) acc;
    00151
    00152     /* Compute and store error */
    00153     d = *pRef++;
    00154     e = d - (q15_t) acc;
    00155     *pErr++ = e;
    00156
    00157     /* Calculation of 1/energy */
    00158     postShift = arm_recip_q15((q15_t) energy + DELTA_Q15,
    00159                               &oneByEnergy, S->recipTable);
    00160
    00161     /* Calculation of e * mu value */
    00162     errorXmu = (q15_t) (((q31_t) e * mu) >> 15);
    00163
    00164     /* Calculation of (e * mu) * (1/energy) value */
    00165     acc = (((q31_t) errorXmu * oneByEnergy) >> (15 - postShift));
    00166
    00167     /* Weighting factor for the normalized version */
    00168     w = (q15_t) __SSAT((q31_t) acc, 16);
    00169
    00170     /* Initialize pState pointer */
    00171     px = pState;
    00172
    00173     /* Initialize coeff pointer */
    00174     pb = (pCoeffs);
    00175
    00176     /* Loop unrolling.  Process 4 taps at a time. */
    00177     tapCnt = numTaps >> 2;
    00178
    00179     /* Update filter coefficients */
    00180     while(tapCnt > 0u)
    00181     {
    00182       coef = *pb + (((q31_t) w * (*px++)) >> 15);
    00183       *pb++ = (q15_t) __SSAT((coef), 16);
    00184       coef = *pb + (((q31_t) w * (*px++)) >> 15);
    00185       *pb++ = (q15_t) __SSAT((coef), 16);
    00186       coef = *pb + (((q31_t) w * (*px++)) >> 15);
    00187       *pb++ = (q15_t) __SSAT((coef), 16);
    00188       coef = *pb + (((q31_t) w * (*px++)) >> 15);
    00189       *pb++ = (q15_t) __SSAT((coef), 16);
    00190
    00191       /* Decrement the loop counter */
    00192       tapCnt--;
    00193     }
    00194
    00195     /* If the filter length is not a multiple of 4, compute the remaining filter taps */
    00196     tapCnt = numTaps % 0x4u;
    00197
    00198     while(tapCnt > 0u)
    00199     {
    00200       /* Perform the multiply-accumulate */
    00201       coef = *pb + (((q31_t) w * (*px++)) >> 15);
    00202       *pb++ = (q15_t) __SSAT((coef), 16);
    00203
    00204       /* Decrement the loop counter */
    00205       tapCnt--;
    00206     }
    00207
    00208     /* Read the sample from state buffer */
    00209     x0 = *pState;
    00210
    00211     /* Advance state pointer by 1 for the next sample */
    00212     pState = pState + 1u;
    00213
    00214     /* Decrement the loop counter */
    00215     blkCnt--;
    00216   }
    00217
    00218   /* Save energy and x0 values for the next frame */
    00219   S->energy = (q15_t) energy;
    00220   S->x0 = x0;
    00221
    00222   /* Processing is complete. Now copy the last numTaps - 1 samples to the
    00223      satrt of the state buffer. This prepares the state buffer for the
    00224      next function call. */
    00225
    00226   /* Points to the start of the pState buffer */
    00227   pStateCurnt = S->pState;
    00228
    00229   /* Calculation of count for copying integer writes */
    00230   tapCnt = (numTaps - 1u) >> 2;
    00231
    00232   while(tapCnt > 0u)
    00233   {
    00234
    00235     *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;
    00236     *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;
    00237
    00238     tapCnt--;
    00239
    00240   }
    00241
    00242   /* Calculation of count for remaining q15_t data */
    00243   tapCnt = (numTaps - 1u) % 0x4u;
    00244
    00245   /* copy data */
    00246   while(tapCnt > 0u)
    00247   {
    00248     *pStateCurnt++ = *pState++;
    00249
    00250     /* Decrement the loop counter */
    00251     tapCnt--;
    00252   }
    00253
    00254
    00255 }
    00256
    00257

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