CMSIS DSP library
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cmsis_dsp/FilteringFunctions/arm_fir_init_q15.c
- Committer:
- emilmont
- Date:
- 2012-11-28
- Revision:
- 1:fdd22bb7aa52
- Child:
- 2:da51fb522205
File content as of revision 1:fdd22bb7aa52:
/* ---------------------------------------------------------------------- * Copyright (C) 2010 ARM Limited. All rights reserved. * * $Date: 15. February 2012 * $Revision: V1.1.0 * * Project: CMSIS DSP Library * Title: arm_fir_init_q15.c * * Description: Q15 FIR 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 0.0.5 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 FIR * @{ */ /** * @param[in,out] *S points to an instance of the Q15 FIR filter structure. * @param[in] numTaps Number of filter coefficients in the filter. Must be even and greater than or equal to 4. * @param[in] *pCoeffs points to the filter coefficients buffer. * @param[in] *pState points to the state buffer. * @param[in] blockSize is number of samples processed per call. * @return The function returns ARM_MATH_SUCCESS if initialization is successful or ARM_MATH_ARGUMENT_ERROR if * <code>numTaps</code> is not greater than or equal to 4 and even. * * <b>Description:</b> * \par * <code>pCoeffs</code> points to the array of filter coefficients stored in time reversed order: * <pre> * {b[numTaps-1], b[numTaps-2], b[N-2], ..., b[1], b[0]} * </pre> * Note that <code>numTaps</code> must be even and greater than or equal to 4. * To implement an odd length filter simply increase <code>numTaps</code> by 1 and set the last coefficient to zero. * For example, to implement a filter with <code>numTaps=3</code> and coefficients * <pre> * {0.3, -0.8, 0.3} * </pre> * set <code>numTaps=4</code> and use the coefficients: * <pre> * {0.3, -0.8, 0.3, 0}. * </pre> * Similarly, to implement a two point filter * <pre> * {0.3, -0.3} * </pre> * set <code>numTaps=4</code> and use the coefficients: * <pre> * {0.3, -0.3, 0, 0}. * </pre> * \par * <code>pState</code> points to the array of state variables. * <code>pState</code> is of length <code>numTaps+blockSize</code>, when running on Cortex-M4 and Cortex-M3 and is of length <code>numTaps+blockSize-1</code>, when running on Cortex-M0 where <code>blockSize</code> is the number of input samples processed by each call to <code>arm_fir_q15()</code>. */ arm_status arm_fir_init_q15( arm_fir_instance_q15 * S, uint16_t numTaps, q15_t * pCoeffs, q15_t * pState, uint32_t blockSize) { arm_status status; #ifndef ARM_MATH_CM0 /* Run the below code for Cortex-M4 and Cortex-M3 */ /* The Number of filter coefficients in the filter must be even and at least 4 */ if(numTaps & 0x1u) { status = ARM_MATH_ARGUMENT_ERROR; } else { /* Assign filter taps */ S->numTaps = numTaps; /* Assign coefficient pointer */ S->pCoeffs = pCoeffs; /* Clear the state buffer. The size is always (blockSize + numTaps ) */ memset(pState, 0, (numTaps + (blockSize)) * sizeof(q15_t)); /* Assign state pointer */ S->pState = pState; status = ARM_MATH_SUCCESS; } return (status); #else /* Run the below code for Cortex-M0 */ /* Assign filter taps */ S->numTaps = numTaps; /* Assign coefficient pointer */ S->pCoeffs = pCoeffs; /* Clear the state buffer. The size is always (blockSize + numTaps - 1) */ memset(pState, 0, (numTaps + (blockSize - 1u)) * sizeof(q15_t)); /* Assign state pointer */ S->pState = pState; status = ARM_MATH_SUCCESS; return (status); #endif /* #ifndef ARM_MATH_CM0 */ } /** * @} end of FIR group */