CMSIS DSP library
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cmsis_dsp/FilteringFunctions/arm_fir_decimate_init_q15.c
- Committer:
- mbed_official
- Date:
- 2013-11-08
- Revision:
- 3:7a284390b0ce
- Parent:
- 2:da51fb522205
File content as of revision 3:7a284390b0ce:
/* ---------------------------------------------------------------------- * Copyright (C) 2010-2013 ARM Limited. All rights reserved. * * $Date: 17. January 2013 * $Revision: V1.4.1 * * Project: CMSIS DSP Library * Title: arm_fir_decimate_init_q15.c * * Description: Initialization function for the Q15 FIR Decimator. * * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * - Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * - Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * - Neither the name of ARM LIMITED nor the names of its contributors * may be used to endorse or promote products derived from this * software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. * ------------------------------------------------------------------- */ #include "arm_math.h" /** * @ingroup groupFilters */ /** * @addtogroup FIR_decimate * @{ */ /** * @brief Initialization function for the Q15 FIR decimator. * @param[in,out] *S points to an instance of the Q15 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 * <code>blockSize</code> is not a multiple of <code>M</code>. * * <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> * \par * <code>pState</code> points to the array of state variables. * <code>pState</code> is of length <code>numTaps+blockSize-1</code> words where <code>blockSize</code> is the number of input samples * to the call <code>arm_fir_decimate_q15()</code>. * <code>M</code> is the decimation factor. */ arm_status arm_fir_decimate_init_q15( arm_fir_decimate_instance_q15 * S, uint16_t numTaps, uint8_t M, q15_t * pCoeffs, q15_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 of buffer is always (blockSize + numTaps - 1) */ memset(pState, 0, (numTaps + (blockSize - 1u)) * sizeof(q15_t)); /* Assign state pointer */ S->pState = pState; /* Assign Decimation factor */ S->M = M; status = ARM_MATH_SUCCESS; } return (status); } /** * @} end of FIR_decimate group */