CMSIS DSP library
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Diff: cmsis_dsp/FilteringFunctions/arm_biquad_cascade_df1_32x64_init_q31.c
- Revision:
- 1:fdd22bb7aa52
- Child:
- 2:da51fb522205
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/cmsis_dsp/FilteringFunctions/arm_biquad_cascade_df1_32x64_init_q31.c Wed Nov 28 12:30:09 2012 +0000 @@ -0,0 +1,105 @@ +/* ---------------------------------------------------------------------- +* Copyright (C) 2010 ARM Limited. All rights reserved. +* +* $Date: 15. February 2012 +* $Revision: V1.1.0 +* +* Project: CMSIS DSP Library +* Title: arm_biquad_cascade_df1_32x64_init_q31.c +* +* Description: High precision Q31 Biquad cascade filter initialization function. +* +* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 +* +* Version 1.1.0 2012/02/15 +* Updated with more optimizations, bug fixes and minor API changes. +* +* Version 1.0.10 2011/7/15 +* Big Endian support added and Merged M0 and M3/M4 Source code. +* +* Version 1.0.3 2010/11/29 +* Re-organized the CMSIS folders and updated documentation. +* +* Version 1.0.2 2010/11/11 +* Documentation updated. +* +* Version 1.0.1 2010/10/05 +* Production release and review comments incorporated. +* +* Version 1.0.0 2010/09/20 +* Production release and review comments incorporated. +* +* Version 0.0.7 2010/06/10 +* Misra-C changes done +* -------------------------------------------------------------------- */ + +#include "arm_math.h" + +/** + * @ingroup groupFilters + */ + +/** + * @addtogroup BiquadCascadeDF1_32x64 + * @{ + */ + +/** + * @details + * + * @param[in,out] *S points to an instance of the high precision Q31 Biquad cascade filter structure. + * @param[in] numStages number of 2nd order stages in the filter. + * @param[in] *pCoeffs points to the filter coefficients. + * @param[in] *pState points to the state buffer. + * @param[in] postShift Shift to be applied after the accumulator. Varies according to the coefficients format. + * @return none + * + * <b>Coefficient and State Ordering:</b> + * + * \par + * The coefficients are stored in the array <code>pCoeffs</code> in the following order: + * <pre> + * {b10, b11, b12, a11, a12, b20, b21, b22, a21, a22, ...} + * </pre> + * where <code>b1x</code> and <code>a1x</code> are the coefficients for the first stage, + * <code>b2x</code> and <code>a2x</code> are the coefficients for the second stage, + * and so on. The <code>pCoeffs</code> array contains a total of <code>5*numStages</code> values. + * + * \par + * The <code>pState</code> points to state variables array and size of each state variable is 1.63 format. + * Each Biquad stage has 4 state variables <code>x[n-1], x[n-2], y[n-1],</code> and <code>y[n-2]</code>. + * The state variables are arranged in the state array as: + * <pre> + * {x[n-1], x[n-2], y[n-1], y[n-2]} + * </pre> + * The 4 state variables for stage 1 are first, then the 4 state variables for stage 2, and so on. + * The state array has a total length of <code>4*numStages</code> values. + * The state variables are updated after each block of data is processed; the coefficients are untouched. + */ + +void arm_biquad_cas_df1_32x64_init_q31( + arm_biquad_cas_df1_32x64_ins_q31 * S, + uint8_t numStages, + q31_t * pCoeffs, + q63_t * pState, + uint8_t postShift) +{ + /* Assign filter stages */ + S->numStages = numStages; + + /* Assign postShift to be applied to the output */ + S->postShift = postShift; + + /* Assign coefficient pointer */ + S->pCoeffs = pCoeffs; + + /* Clear state buffer and size is always 4 * numStages */ + memset(pState, 0, (4u * (uint32_t) numStages) * sizeof(q63_t)); + + /* Assign state pointer */ + S->pState = pState; +} + +/** + * @} end of BiquadCascadeDF1_32x64 group + */