- Main Page
- Modules
- Data Structures
- Files
- Examples

- File List
- Globals

# arm_biquad_cascade_df2T_f32.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_biquad_cascade_df2T_f32.c
    00009 *
    00010 * Description:  Processing function for the floating-point transposed
    00011 *               direct form II Biquad cascade filter.
    00012 *
    00013 * Target Processor: Cortex-M4/Cortex-M3
    00014 *
    00015 * Version 1.0.3 2010/11/29
    00016 *    Re-organized the CMSIS folders and updated documentation.
    00017 *
    00018 * Version 1.0.2 2010/11/11
    00019 *    Documentation updated.
    00020 *
    00021 * Version 1.0.1 2010/10/05
    00022 *    Production release and review comments incorporated.
    00023 *
    00024 * Version 1.0.0 2010/09/20
    00025 *    Production release and review comments incorporated
    00026 *
    00027 * Version 0.0.7  2010/06/10
    00028 *    Misra-C changes done
    00029 * -------------------------------------------------------------------- */
    00030
    00031 #include "arm_math.h"
    00032
    00140 void arm_biquad_cascade_df2T_f32(
    00141   const arm_biquad_cascade_df2T_instance_f32 * S,
    00142   float32_t * pSrc,
    00143   float32_t * pDst,
    00144   uint32_t blockSize)
    00145 {
    00146
    00147   float32_t *pIn = pSrc;                         /*  source pointer            */
    00148   float32_t *pOut = pDst;                        /*  destination pointer       */
    00149   float32_t *pState = S->pState;                 /*  State pointer            */
    00150   float32_t *pCoeffs = S->pCoeffs;               /*  coefficient pointer       */
    00151   float32_t acc0;                                /*  Simulates the accumulator */
    00152   float32_t b0, b1, b2, a1, a2;                  /*  Filter coefficients       */
    00153   float32_t Xn;                                  /*  temporary input           */
    00154   float32_t d1, d2;                              /*  state variables          */
    00155   uint32_t sample, stage = S->numStages;         /*  loop counters             */
    00156
    00157
    00158   do
    00159   {
    00160     /* Reading the coefficients */
    00161     b0 = *pCoeffs++;
    00162     b1 = *pCoeffs++;
    00163     b2 = *pCoeffs++;
    00164     a1 = *pCoeffs++;
    00165     a2 = *pCoeffs++;
    00166
    00167     /*Reading the state values */
    00168     d1 = pState[0];
    00169     d2 = pState[1];
    00170
    00171     /* Apply loop unrolling and compute 4 output values simultaneously. */
    00172     sample = blockSize >> 2u;
    00173
    00174     /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
    00175      ** a second loop below computes the remaining 1 to 3 samples. */
    00176     while(sample > 0u)
    00177     {
    00178       /* Read the first input */
    00179       Xn = *pIn++;
    00180
    00181       /* y[n] = b0 * x[n] + d1 */
    00182       acc0 = (b0 * Xn) + d1;
    00183
    00184       /* Store the result in the accumulator in the destination buffer. */
    00185       *pOut++ = acc0;
    00186
    00187       /* Every time after the output is computed state should be updated. */
    00188       /* d1 = b1 * x[n] + a1 * y[n] + d2 */
    00189       d1 = ((b1 * Xn) + (a1 * acc0)) + d2;
    00190
    00191       /* d2 = b2 * x[n] + a2 * y[n] */
    00192       d2 = (b2 * Xn) + (a2 * acc0);
    00193
    00194       /* Read the second input */
    00195       Xn = *pIn++;
    00196
    00197       /* y[n] = b0 * x[n] + d1 */
    00198       acc0 = (b0 * Xn) + d1;
    00199
    00200       /* Store the result in the accumulator in the destination buffer. */
    00201       *pOut++ = acc0;
    00202
    00203       /* Every time after the output is computed state should be updated. */
    00204       /* d1 = b1 * x[n] + a1 * y[n] + d2 */
    00205       d1 = ((b1 * Xn) + (a1 * acc0)) + d2;
    00206
    00207       /* d2 = b2 * x[n] + a2 * y[n] */
    00208       d2 = (b2 * Xn) + (a2 * acc0);
    00209
    00210       /* Read the third input */
    00211       Xn = *pIn++;
    00212
    00213       /* y[n] = b0 * x[n] + d1 */
    00214       acc0 = (b0 * Xn) + d1;
    00215
    00216       /* Store the result in the accumulator in the destination buffer. */
    00217       *pOut++ = acc0;
    00218
    00219       /* Every time after the output is computed state should be updated. */
    00220       /* d1 = b1 * x[n] + a1 * y[n] + d2 */
    00221       d1 = ((b1 * Xn) + (a1 * acc0)) + d2;
    00222
    00223       /* d2 = b2 * x[n] + a2 * y[n] */
    00224       d2 = (b2 * Xn) + (a2 * acc0);
    00225
    00226       /* Read the fourth input */
    00227       Xn = *pIn++;
    00228
    00229       /* y[n] = b0 * x[n] + d1 */
    00230       acc0 = (b0 * Xn) + d1;
    00231
    00232       /* Store the result in the accumulator in the destination buffer. */
    00233       *pOut++ = acc0;
    00234
    00235       /* Every time after the output is computed state should be updated. */
    00236       /* d1 = b1 * x[n] + a1 * y[n] + d2 */
    00237       d1 = (b1 * Xn) + (a1 * acc0) + d2;
    00238
    00239       /* d2 = b2 * x[n] + a2 * y[n] */
    00240       d2 = (b2 * Xn) + (a2 * acc0);
    00241
    00242       /* decrement the loop counter */
    00243       sample--;
    00244
    00245     }
    00246
    00247     /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
    00248      ** No loop unrolling is used. */
    00249     sample = blockSize & 0x3u;
    00250
    00251     while(sample > 0u)
    00252     {
    00253       /* Read the input */
    00254       Xn = *pIn++;
    00255
    00256       /* y[n] = b0 * x[n] + d1 */
    00257       acc0 = (b0 * Xn) + d1;
    00258
    00259       /* Store the result in the accumulator in the destination buffer. */
    00260       *pOut++ = acc0;
    00261
    00262       /* Every time after the output is computed state should be updated. */
    00263       /* d1 = b1 * x[n] + a1 * y[n] + d2 */
    00264       d1 = ((b1 * Xn) + (a1 * acc0)) + d2;
    00265
    00266       /* d2 = b2 * x[n] + a2 * y[n] */
    00267       d2 = (b2 * Xn) + (a2 * acc0);
    00268
    00269       /* decrement the loop counter */
    00270       sample--;
    00271     }
    00272
    00273     /* Store the updated state variables back into the state array */
    00274     *pState++ = d1;
    00275     *pState++ = d2;
    00276
    00277     /* The current stage input is given as the output to the next stage */
    00278     pIn = pDst;
    00279
    00280     /*Reset the output working pointer */
    00281     pOut = pDst;
    00282
    00283     /* decrement the loop counter */
    00284     stage--;
    00285
    00286   } while(stage > 0u);
    00287
    00288
    00289 }
    00290
    00291

All Data Structures Files Functions Variables Typedefs Enumerations Enumerator Defines