| /* ---------------------------------------------------------------------- |
| * Copyright (C) 2010-2014 ARM Limited. All rights reserved. |
| * |
| * $Date: 19. March 2015 |
| * $Revision: V.1.4.5 |
| * |
| * 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 |
| */ |