/*-----------------------------------------------------------------------------
* Copyright (C) 2010 ARM Limited. All rights reserved.
*
* $Date: 29. November 2010
* $Revision: V1.0.3
*
* Project: CMSIS DSP Library
* Title: arm_fir_interpolate_init_q15.c
*
* Description: Q15 FIR interpolator initialization function
*
* 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_Interpolate
* @{
*/
/**
* @brief Initialization function for the Q15 FIR interpolator.
* @param[in,out] *S points to an instance of the Q15 FIR interpolator structure.
* @param[in] L upsample factor.
* @param[in] numTaps number of filter coefficients in the filter.
* @param[in] *pCoeffs points to the filter coefficient buffer.
* @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
* the filter length numTaps
is not a multiple of the interpolation factor L
.
*
* Description:
* \par
* pCoeffs
points to the array of filter coefficients stored in time reversed order:
*
* {b[numTaps-1], b[numTaps-2], b[numTaps-2], ..., b[1], b[0]} ** The length of the filter
numTaps
must be a multiple of the interpolation factor L
.
* \par
* pState
points to the array of state variables.
* pState
is of length (numTaps/L)+blockSize-1
words
* where blockSize
is the number of input samples processed by each call to arm_fir_interpolate_q15()
.
*/
arm_status arm_fir_interpolate_init_q15(
arm_fir_interpolate_instance_q15 * S,
uint8_t L,
uint16_t numTaps,
q15_t * pCoeffs,
q15_t * pState,
uint32_t blockSize)
{
arm_status status;
/* The filter length must be a multiple of the interpolation factor */
if((numTaps % L) != 0u)
{
/* Set status as ARM_MATH_LENGTH_ERROR */
status = ARM_MATH_LENGTH_ERROR;
}
else
{
/* Assign coefficient pointer */
S->pCoeffs = pCoeffs;
/* Assign Interpolation factor */
S->L = L;
/* Assign polyPhaseLength */
S->phaseLength = numTaps / L;
/* Clear state buffer and size of buffer is always phaseLength + blockSize - 1 */
memset(pState, 0,
(blockSize + ((uint32_t) S->phaseLength - 1u)) * sizeof(q15_t));
/* Assign state pointer */
S->pState = pState;
status = ARM_MATH_SUCCESS;
}
return (status);
}
/**
* @} end of FIR_Interpolate group
*/