arm_biquad_cascade_df1_init_q15.c
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CLexer
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r41 | /*----------------------------------------------------------------------------- | ||
| * Copyright (C) 2010 ARM Limited. All rights reserved. | ||||
| * | ||||
| * $Date: 15. July 2011 | ||||
| * $Revision: V1.0.10 | ||||
| * | ||||
| * Project: CMSIS DSP Library | ||||
| * Title: arm_biquad_cascade_df1_init_q15.c | ||||
| * | ||||
| * Description: Q15 Biquad cascade DirectFormI(DF1) filter initialization function. | ||||
| * | ||||
| * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 | ||||
| * | ||||
| * 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 0.0.5 2010/04/26 | ||||
| * incorporated review comments and updated with latest CMSIS layer | ||||
| * | ||||
| * Version 0.0.3 2010/03/10 | ||||
| * Initial version | ||||
| * ---------------------------------------------------------------------------*/ | ||||
| #include "arm_math.h" | ||||
| /** | ||||
| * @ingroup groupFilters | ||||
| */ | ||||
| /** | ||||
| * @addtogroup BiquadCascadeDF1 | ||||
| * @{ | ||||
| */ | ||||
| /** | ||||
| * @details | ||||
| * | ||||
| * @param[in,out] *S points to an instance of the Q15 Biquad cascade 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 to the accumulator result. 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, 0, b11, b12, a11, a12, b20, 0, 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>6*numStages</code> values. | ||||
| * The zero coefficient between <code>b1</code> and <code>b2</code> facilities use of 16-bit SIMD instructions on the Cortex-M4. | ||||
| * | ||||
| * \par | ||||
| * The state variables are stored in the array <code>pState</code>. | ||||
| * 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 <code>pState</code> 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_cascade_df1_init_q15( | ||||
| arm_biquad_casd_df1_inst_q15 * S, | ||||
| uint8_t numStages, | ||||
| q15_t * pCoeffs, | ||||
| q15_t * pState, | ||||
| int8_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(q15_t)); | ||||
| /* Assign state pointer */ | ||||
| S->pState = pState; | ||||
| } | ||||
| /** | ||||
| * @} end of BiquadCascadeDF1 group | ||||
| */ | ||||