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+/* ----------------------------------------------------------------------
+* 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_q31.c
+*
+* Description: Initialization function for Q31 FIR Decimation filter.
+*
+* 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 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
+ * <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 passed to <code>arm_fir_decimate_q31()</code>.
+ * <code>M</code> 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
+ */