1 /* ----------------------------------------------------------------------
2 * Copyright (C) 2010 ARM Limited. All rights reserved.
7 * Project: CMSIS DSP Library
8 * Title: arm_fir_decimate_init_q15.c
10 * Description: Initialization function for the Q15 FIR Decimator.
12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
14 * Version 1.0.10 2011/7/15
15 * Big Endian support added and Merged M0 and M3/M4 Source code.
17 * Version 1.0.3 2010/11/29
18 * Re-organized the CMSIS folders and updated documentation.
20 * Version 1.0.2 2010/11/11
21 * Documentation updated.
23 * Version 1.0.1 2010/10/05
24 * Production release and review comments incorporated.
26 * Version 1.0.0 2010/09/20
27 * Production release and review comments incorporated
29 * Version 0.0.7 2010/06/10
30 * Misra-C changes done
31 * ------------------------------------------------------------------- */
36 * @ingroup groupFilters
40 * @addtogroup FIR_decimate
45 * @brief Initialization function for the Q15 FIR decimator.
46 * @param[in,out] *S points to an instance of the Q15 FIR decimator structure.
47 * @param[in] numTaps number of coefficients in the filter.
48 * @param[in] M decimation factor.
49 * @param[in] *pCoeffs points to the filter coefficients.
50 * @param[in] *pState points to the state buffer.
51 * @param[in] blockSize number of input samples to process per call.
52 * @return The function returns ARM_MATH_SUCCESS if initialization was successful or ARM_MATH_LENGTH_ERROR if
53 * <code>blockSize</code> is not a multiple of <code>M</code>.
57 * <code>pCoeffs</code> points to the array of filter coefficients stored in time reversed order:
59 * {b[numTaps-1], b[numTaps-2], b[N-2], ..., b[1], b[0]}
62 * <code>pState</code> points to the array of state variables.
63 * <code>pState</code> is of length <code>numTaps+blockSize-1</code> words where <code>blockSize</code> is the number of input samples
64 * to the call <code>arm_fir_decimate_q15()</code>.
65 * <code>M</code> is the decimation factor.
68 arm_status arm_fir_decimate_init_q15(
69 arm_fir_decimate_instance_q15 * S,
79 /* The size of the input block must be a multiple of the decimation factor */
80 if((blockSize % M) != 0u)
82 /* Set status as ARM_MATH_LENGTH_ERROR */
83 status = ARM_MATH_LENGTH_ERROR;
87 /* Assign filter taps */
90 /* Assign coefficient pointer */
93 /* Clear the state buffer. The size of buffer is always (blockSize + numTaps - 1) */
94 memset(pState, 0, (numTaps + (blockSize - 1u)) * sizeof(q15_t));
96 /* Assign state pointer */
99 /* Assign Decimation factor */
102 status = ARM_MATH_SUCCESS;
110 * @} end of FIR_decimate group