/* ----------------------------------------------------------------------
* Copyright (C) 2010 ARM Limited. All rights reserved.
*
* $Date: 29. November 2010
* $Revision: V1.0.3
*
* Project: CMSIS DSP Library
* Title: arm_fir_decimate_init_q31.c
*
* Description: Initialization function for Q31 FIR Decimation filter.
*
* Target Processor: Cortex-M4/Cortex-M3
*
* 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 FIR_decimate
* @{
*/
/**
* @brief Initialization function for the Q31 FIR decimator.
* @param[in,out] *S points to an instance of the Q31 FIR decimator structure.
* @param[in] numTaps number of coefficients in the filter.
* @param[in] M decimation factor.
* @param[in] *pCoeffs points to the filter coefficients.
* @param[in] *pState points to the state buffer.
* @param[in] blockSize number of input samples to process per call.
* @return The function returns ARM_MATH_SUCCESS if initialization was successful or ARM_MATH_LENGTH_ERROR if
* blockSize
is not a multiple of M
.
*
* Description:
* \par
* pCoeffs
points to the array of filter coefficients stored in time reversed order:
*
* {b[numTaps-1], b[numTaps-2], b[N-2], ..., b[1], b[0]} ** \par *
pState
points to the array of state variables.
* pState
is of length numTaps+blockSize-1
words where blockSize
is the number of input samples passed to arm_fir_decimate_q31()
.
* M
is the decimation factor.
*/
arm_status arm_fir_decimate_init_q31(
arm_fir_decimate_instance_q31 * S,
uint16_t numTaps,
uint8_t M,
q31_t * pCoeffs,
q31_t * pState,
uint32_t blockSize)
{
arm_status status;
/* The size of the input block must be a multiple of the decimation factor */
if((blockSize % M) != 0u)
{
/* Set status as ARM_MATH_LENGTH_ERROR */
status = ARM_MATH_LENGTH_ERROR;
}
else
{
/* 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 - 1)) * sizeof(q31_t));
/* Assign state pointer */
S->pState = pState;
/* Assign Decimation factor */
S->M = M;
status = ARM_MATH_SUCCESS;
}
return (status);
}
/**
* @} end of FIR_decimate group
*/