1 /*-----------------------------------------------------------------------------
2 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
4 * $Date: 17. January 2013
7 * Project: CMSIS DSP Library
8 * Title: arm_fir_interpolate_init_q15.c
10 * Description: Q15 FIR interpolator initialization function
12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
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44 * @ingroup groupFilters
48 * @addtogroup FIR_Interpolate
53 * @brief Initialization function for the Q15 FIR interpolator.
54 * @param[in,out] *S points to an instance of the Q15 FIR interpolator structure.
55 * @param[in] L upsample factor.
56 * @param[in] numTaps number of filter coefficients in the filter.
57 * @param[in] *pCoeffs points to the filter coefficient buffer.
58 * @param[in] *pState points to the state buffer.
59 * @param[in] blockSize number of input samples to process per call.
60 * @return The function returns ARM_MATH_SUCCESS if initialization was successful or ARM_MATH_LENGTH_ERROR if
61 * the filter length <code>numTaps</code> is not a multiple of the interpolation factor <code>L</code>.
65 * <code>pCoeffs</code> points to the array of filter coefficients stored in time reversed order:
67 * {b[numTaps-1], b[numTaps-2], b[numTaps-2], ..., b[1], b[0]}
69 * The length of the filter <code>numTaps</code> must be a multiple of the interpolation factor <code>L</code>.
71 * <code>pState</code> points to the array of state variables.
72 * <code>pState</code> is of length <code>(numTaps/L)+blockSize-1</code> words
73 * where <code>blockSize</code> is the number of input samples processed by each call to <code>arm_fir_interpolate_q15()</code>.
76 arm_status
arm_fir_interpolate_init_q15(
77 arm_fir_interpolate_instance_q15
* S
,
86 /* The filter length must be a multiple of the interpolation factor */
87 if((numTaps
% L
) != 0u)
89 /* Set status as ARM_MATH_LENGTH_ERROR */
90 status
= ARM_MATH_LENGTH_ERROR
;
95 /* Assign coefficient pointer */
98 /* Assign Interpolation factor */
101 /* Assign polyPhaseLength */
102 S
->phaseLength
= numTaps
/ L
;
104 /* Clear state buffer and size of buffer is always phaseLength + blockSize - 1 */
106 (blockSize
+ ((uint32_t) S
->phaseLength
- 1u)) * sizeof(q15_t
));
108 /* Assign state pointer */
111 status
= ARM_MATH_SUCCESS
;
119 * @} end of FIR_Interpolate group