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/* ----------------------------------------------------------------------
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* Copyright (C) 2010 ARM Limited. All rights reserved.
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*
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* $Date: 15. July 2011
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* $Revision: V1.0.10
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*
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* Project: CMSIS DSP Library
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* Title: arm_fir_init_q15.c
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*
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* Description: Q15 FIR filter initialization function.
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*
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* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
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*
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* Version 1.0.10 2011/7/15
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* Big Endian support added and Merged M0 and M3/M4 Source code.
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*
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* Version 1.0.3 2010/11/29
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* Re-organized the CMSIS folders and updated documentation.
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*
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* Version 1.0.2 2010/11/11
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* Documentation updated.
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*
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* Version 1.0.1 2010/10/05
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* Production release and review comments incorporated.
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*
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* Version 1.0.0 2010/09/20
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* Production release and review comments incorporated.
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*
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* Version 0.0.5 2010/04/26
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* incorporated review comments and updated with latest CMSIS layer
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*
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* Version 0.0.3 2010/03/10
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* Initial version
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* ------------------------------------------------------------------- */
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#include "arm_math.h"
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/**
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* @ingroup groupFilters
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*/
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/**
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* @addtogroup FIR
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* @{
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*/
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/**
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* @param[in,out] *S points to an instance of the Q15 FIR filter structure.
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* @param[in] numTaps Number of filter coefficients in the filter. Must be even and greater than or equal to 4.
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* @param[in] *pCoeffs points to the filter coefficients buffer.
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* @param[in] *pState points to the state buffer.
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* @param[in] blockSize is number of samples processed per call.
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* @return The function returns ARM_MATH_SUCCESS if initialization is successful or ARM_MATH_ARGUMENT_ERROR if
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* <code>numTaps</code> is not greater than or equal to 4 and even.
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*
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* <b>Description:</b>
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* \par
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* <code>pCoeffs</code> points to the array of filter coefficients stored in time reversed order:
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* <pre>
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* {b[numTaps-1], b[numTaps-2], b[N-2], ..., b[1], b[0]}
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* </pre>
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* Note that <code>numTaps</code> must be even and greater than or equal to 4.
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* To implement an odd length filter simply increase <code>numTaps</code> by 1 and set the last coefficient to zero.
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* For example, to implement a filter with <code>numTaps=3</code> and coefficients
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* <pre>
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* {0.3, -0.8, 0.3}
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* </pre>
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* set <code>numTaps=4</code> and use the coefficients:
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* <pre>
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* {0.3, -0.8, 0.3, 0}.
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* </pre>
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* Similarly, to implement a two point filter
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* <pre>
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* {0.3, -0.3}
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* </pre>
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* set <code>numTaps=4</code> and use the coefficients:
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* <pre>
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* {0.3, -0.3, 0, 0}.
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* </pre>
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* \par
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* <code>pState</code> points to the array of state variables.
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* <code>pState</code> is of length <code>numTaps+blockSize-1</code>, where <code>blockSize</code> is the number of input samples processed by each call to <code>arm_fir_q15()</code>.
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*/
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arm_status arm_fir_init_q15(
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arm_fir_instance_q15 * S,
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uint16_t numTaps,
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q15_t * pCoeffs,
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q15_t * pState,
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uint32_t blockSize)
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{
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arm_status status;
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#ifndef ARM_MATH_CM0
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/* Run the below code for Cortex-M4 and Cortex-M3 */
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/* The Number of filter coefficients in the filter must be even and at least 4 */
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if((numTaps < 4u) || (numTaps & 0x1u))
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{
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status = ARM_MATH_ARGUMENT_ERROR;
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}
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else
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{
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/* Assign filter taps */
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S->numTaps = numTaps;
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/* Assign coefficient pointer */
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S->pCoeffs = pCoeffs;
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/* Clear the state buffer. The size is always (blockSize + numTaps - 1) */
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memset(pState, 0, (numTaps + (blockSize - 1u)) * sizeof(q15_t));
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/* Assign state pointer */
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S->pState = pState;
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status = ARM_MATH_SUCCESS;
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}
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return (status);
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#else
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/* Run the below code for Cortex-M0 */
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/* Assign filter taps */
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S->numTaps = numTaps;
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/* Assign coefficient pointer */
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S->pCoeffs = pCoeffs;
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/* Clear the state buffer. The size is always (blockSize + numTaps - 1) */
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memset(pState, 0, (numTaps + (blockSize - 1u)) * sizeof(q15_t));
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/* Assign state pointer */
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S->pState = pState;
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status = ARM_MATH_SUCCESS;
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return (status);
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#endif /* #ifndef ARM_MATH_CM0 */
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}
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/**
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* @} end of FIR group
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*/
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