mbed official / mbed-dsp

CMSIS DSP library

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cmsis_dsp/FilteringFunctions/arm_biquad_cascade_df1_init_f32.c@3:7a284390b0ce, 2013-11-08 (annotated)

Committer:
mbed_official
Date:
Fri Nov 08 13:45:10 2013 +0000
Revision:
3:7a284390b0ce
Parent:
2:da51fb522205 
Synchronized with git revision e69956aba2f68a2a26ac26b051f8d349deaa1ce8

Who changed what in which revision?

UserRevisionLine numberNew contents of line
emilmont 1:fdd22bb7aa52 1 /*-----------------------------------------------------------------------------
mbed_official 3:7a284390b0ce 2 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
emilmont 1:fdd22bb7aa52 3 *
mbed_official 3:7a284390b0ce 4 * $Date: 17. January 2013
mbed_official 3:7a284390b0ce 5 * $Revision: V1.4.1
emilmont 1:fdd22bb7aa52 6 *
emilmont 2:da51fb522205 7 * Project: CMSIS DSP Library
emilmont 1:fdd22bb7aa52 8 * Title: arm_biquad_cascade_df1_init_f32.c
emilmont 1:fdd22bb7aa52 9 *
emilmont 1:fdd22bb7aa52 10 * Description: floating-point Biquad cascade DirectFormI(DF1) filter initialization function.
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 BiquadCascadeDF1
emilmont 1:fdd22bb7aa52 49 * @{
emilmont 1:fdd22bb7aa52 50 */
emilmont 1:fdd22bb7aa52 51
emilmont 1:fdd22bb7aa52 52 /**
emilmont 1:fdd22bb7aa52 53 * @details
emilmont 1:fdd22bb7aa52 54 * @brief Initialization function for the floating-point Biquad cascade filter.
emilmont 1:fdd22bb7aa52 55 * @param[in,out] *S points to an instance of the floating-point Biquad cascade structure.
emilmont 1:fdd22bb7aa52 56 * @param[in] numStages number of 2nd order stages in the filter.
emilmont 1:fdd22bb7aa52 57 * @param[in] *pCoeffs points to the filter coefficients array.
emilmont 1:fdd22bb7aa52 58 * @param[in] *pState points to the state array.
emilmont 1:fdd22bb7aa52 59 * @return none
emilmont 1:fdd22bb7aa52 60 *
emilmont 1:fdd22bb7aa52 61 *
emilmont 1:fdd22bb7aa52 62 * <b>Coefficient and State Ordering:</b>
emilmont 1:fdd22bb7aa52 63 *
emilmont 1:fdd22bb7aa52 64 * \par
emilmont 1:fdd22bb7aa52 65 * The coefficients are stored in the array <code>pCoeffs</code> in the following order:
emilmont 1:fdd22bb7aa52 66 * <pre>
emilmont 1:fdd22bb7aa52 67 * {b10, b11, b12, a11, a12, b20, b21, b22, a21, a22, ...}
emilmont 1:fdd22bb7aa52 68 * </pre>
emilmont 1:fdd22bb7aa52 69 *
emilmont 1:fdd22bb7aa52 70 * \par
emilmont 1:fdd22bb7aa52 71 * where <code>b1x</code> and <code>a1x</code> are the coefficients for the first stage,
emilmont 1:fdd22bb7aa52 72 * <code>b2x</code> and <code>a2x</code> are the coefficients for the second stage,
emilmont 1:fdd22bb7aa52 73 * and so on. The <code>pCoeffs</code> array contains a total of <code>5*numStages</code> values.
emilmont 1:fdd22bb7aa52 74 *
emilmont 1:fdd22bb7aa52 75 * \par
emilmont 1:fdd22bb7aa52 76 * The <code>pState</code> is a pointer to state array.
emilmont 1:fdd22bb7aa52 77 * Each Biquad stage has 4 state variables <code>x[n-1], x[n-2], y[n-1],</code> and <code>y[n-2]</code>.
emilmont 1:fdd22bb7aa52 78 * The state variables are arranged in the <code>pState</code> array as:
emilmont 1:fdd22bb7aa52 79 * <pre>
emilmont 1:fdd22bb7aa52 80 * {x[n-1], x[n-2], y[n-1], y[n-2]}
emilmont 1:fdd22bb7aa52 81 * </pre>
emilmont 1:fdd22bb7aa52 82 * The 4 state variables for stage 1 are first, then the 4 state variables for stage 2, and so on.
emilmont 1:fdd22bb7aa52 83 * The state array has a total length of <code>4*numStages</code> values.
emilmont 1:fdd22bb7aa52 84 * The state variables are updated after each block of data is processed; the coefficients are untouched.
emilmont 1:fdd22bb7aa52 85 *
emilmont 1:fdd22bb7aa52 86 */
emilmont 1:fdd22bb7aa52 87
emilmont 1:fdd22bb7aa52 88 void arm_biquad_cascade_df1_init_f32(
emilmont 1:fdd22bb7aa52 89 arm_biquad_casd_df1_inst_f32 * S,
emilmont 1:fdd22bb7aa52 90 uint8_t numStages,
emilmont 1:fdd22bb7aa52 91 float32_t * pCoeffs,
emilmont 1:fdd22bb7aa52 92 float32_t * pState)
emilmont 1:fdd22bb7aa52 93 {
emilmont 1:fdd22bb7aa52 94 /* Assign filter stages */
emilmont 1:fdd22bb7aa52 95 S->numStages = numStages;
emilmont 1:fdd22bb7aa52 96
emilmont 1:fdd22bb7aa52 97 /* Assign coefficient pointer */
emilmont 1:fdd22bb7aa52 98 S->pCoeffs = pCoeffs;
emilmont 1:fdd22bb7aa52 99
emilmont 1:fdd22bb7aa52 100 /* Clear state buffer and size is always 4 * numStages */
emilmont 1:fdd22bb7aa52 101 memset(pState, 0, (4u * (uint32_t) numStages) * sizeof(float32_t));
emilmont 1:fdd22bb7aa52 102
emilmont 1:fdd22bb7aa52 103 /* Assign state pointer */
emilmont 1:fdd22bb7aa52 104 S->pState = pState;
emilmont 1:fdd22bb7aa52 105 }
emilmont 1:fdd22bb7aa52 106
emilmont 1:fdd22bb7aa52 107 /**
emilmont 1:fdd22bb7aa52 108 * @} end of BiquadCascadeDF1 group
emilmont 1:fdd22bb7aa52 109 */