mbed official / mbed-dsp

CMSIS DSP library

Dependents:   performance_timer Surfboard_ gps2rtty Capstone ... more

Legacy Warning

This is an mbed 2 library. To learn more about mbed OS 5, visit the docs.

cmsis_dsp/FilteringFunctions/arm_biquad_cascade_df1_init_f32.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_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 *
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 0.0.5 2010/04/26
emilmont 1:fdd22bb7aa52 33 * incorporated review comments and updated with latest CMSIS layer
emilmont 1:fdd22bb7aa52 34 *
emilmont 1:fdd22bb7aa52 35 * Version 0.0.3 2010/03/10
emilmont 1:fdd22bb7aa52 36 * Initial version
emilmont 1:fdd22bb7aa52 37 * ---------------------------------------------------------------------------*/
emilmont 1:fdd22bb7aa52 38
emilmont 1:fdd22bb7aa52 39 #include "arm_math.h"
emilmont 1:fdd22bb7aa52 40
emilmont 1:fdd22bb7aa52 41 /**
emilmont 1:fdd22bb7aa52 42 * @ingroup groupFilters
emilmont 1:fdd22bb7aa52 43 */
emilmont 1:fdd22bb7aa52 44
emilmont 1:fdd22bb7aa52 45 /**
emilmont 1:fdd22bb7aa52 46 * @addtogroup BiquadCascadeDF1
emilmont 1:fdd22bb7aa52 47 * @{
emilmont 1:fdd22bb7aa52 48 */
emilmont 1:fdd22bb7aa52 49
emilmont 1:fdd22bb7aa52 50 /**
emilmont 1:fdd22bb7aa52 51 * @details
emilmont 1:fdd22bb7aa52 52 * @brief Initialization function for the floating-point Biquad cascade filter.
emilmont 1:fdd22bb7aa52 53 * @param[in,out] *S points to an instance of the floating-point Biquad cascade structure.
emilmont 1:fdd22bb7aa52 54 * @param[in] numStages number of 2nd order stages in the filter.
emilmont 1:fdd22bb7aa52 55 * @param[in] *pCoeffs points to the filter coefficients array.
emilmont 1:fdd22bb7aa52 56 * @param[in] *pState points to the state array.
emilmont 1:fdd22bb7aa52 57 * @return none
emilmont 1:fdd22bb7aa52 58 *
emilmont 1:fdd22bb7aa52 59 *
emilmont 1:fdd22bb7aa52 60 * <b>Coefficient and State Ordering:</b>
emilmont 1:fdd22bb7aa52 61 *
emilmont 1:fdd22bb7aa52 62 * \par
emilmont 1:fdd22bb7aa52 63 * The coefficients are stored in the array <code>pCoeffs</code> in the following order:
emilmont 1:fdd22bb7aa52 64 * <pre>
emilmont 1:fdd22bb7aa52 65 * {b10, b11, b12, a11, a12, b20, b21, b22, a21, a22, ...}
emilmont 1:fdd22bb7aa52 66 * </pre>
emilmont 1:fdd22bb7aa52 67 *
emilmont 1:fdd22bb7aa52 68 * \par
emilmont 1:fdd22bb7aa52 69 * where <code>b1x</code> and <code>a1x</code> are the coefficients for the first stage,
emilmont 1:fdd22bb7aa52 70 * <code>b2x</code> and <code>a2x</code> are the coefficients for the second stage,
emilmont 1:fdd22bb7aa52 71 * and so on. The <code>pCoeffs</code> array contains a total of <code>5*numStages</code> values.
emilmont 1:fdd22bb7aa52 72 *
emilmont 1:fdd22bb7aa52 73 * \par
emilmont 1:fdd22bb7aa52 74 * The <code>pState</code> is a pointer to state array.
emilmont 1:fdd22bb7aa52 75 * 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 76 * The state variables are arranged in the <code>pState</code> array as:
emilmont 1:fdd22bb7aa52 77 * <pre>
emilmont 1:fdd22bb7aa52 78 * {x[n-1], x[n-2], y[n-1], y[n-2]}
emilmont 1:fdd22bb7aa52 79 * </pre>
emilmont 1:fdd22bb7aa52 80 * The 4 state variables for stage 1 are first, then the 4 state variables for stage 2, and so on.
emilmont 1:fdd22bb7aa52 81 * The state array has a total length of <code>4*numStages</code> values.
emilmont 1:fdd22bb7aa52 82 * The state variables are updated after each block of data is processed; the coefficients are untouched.
emilmont 1:fdd22bb7aa52 83 *
emilmont 1:fdd22bb7aa52 84 */
emilmont 1:fdd22bb7aa52 85
emilmont 1:fdd22bb7aa52 86 void arm_biquad_cascade_df1_init_f32(
emilmont 1:fdd22bb7aa52 87 arm_biquad_casd_df1_inst_f32 * S,
emilmont 1:fdd22bb7aa52 88 uint8_t numStages,
emilmont 1:fdd22bb7aa52 89 float32_t * pCoeffs,
emilmont 1:fdd22bb7aa52 90 float32_t * pState)
emilmont 1:fdd22bb7aa52 91 {
emilmont 1:fdd22bb7aa52 92 /* Assign filter stages */
emilmont 1:fdd22bb7aa52 93 S->numStages = numStages;
emilmont 1:fdd22bb7aa52 94
emilmont 1:fdd22bb7aa52 95 /* Assign coefficient pointer */
emilmont 1:fdd22bb7aa52 96 S->pCoeffs = pCoeffs;
emilmont 1:fdd22bb7aa52 97
emilmont 1:fdd22bb7aa52 98 /* Clear state buffer and size is always 4 * numStages */
emilmont 1:fdd22bb7aa52 99 memset(pState, 0, (4u * (uint32_t) numStages) * sizeof(float32_t));
emilmont 1:fdd22bb7aa52 100
emilmont 1:fdd22bb7aa52 101 /* Assign state pointer */
emilmont 1:fdd22bb7aa52 102 S->pState = pState;
emilmont 1:fdd22bb7aa52 103 }
emilmont 1:fdd22bb7aa52 104
emilmont 1:fdd22bb7aa52 105 /**
emilmont 1:fdd22bb7aa52 106 * @} end of BiquadCascadeDF1 group
emilmont 1:fdd22bb7aa52 107 */