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| 2 | mjames | 1 | /* ---------------------------------------------------------------------- |
| 2 | * Copyright (C) 2010-2014 ARM Limited. All rights reserved. |
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| 3 | * |
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| 4 | * $Date: 19. March 2015 |
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| 5 | * $Revision: V.1.4.5 |
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| 6 | * |
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| 7 | * Project: CMSIS DSP Library |
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| 8 | * Title: arm_rfft_init_q15.c |
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| 9 | * |
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| 10 | * Description: RFFT & RIFFT Q15 initialisation function |
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| 11 | * |
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| 12 | * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 |
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| 13 | * |
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| 14 | * Redistribution and use in source and binary forms, with or without |
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| 15 | * modification, are permitted provided that the following conditions |
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| 16 | * are met: |
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| 17 | * - Redistributions of source code must retain the above copyright |
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| 18 | * notice, this list of conditions and the following disclaimer. |
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| 19 | * - Redistributions in binary form must reproduce the above copyright |
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| 20 | * notice, this list of conditions and the following disclaimer in |
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| 21 | * the documentation and/or other materials provided with the |
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| 22 | * distribution. |
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| 23 | * - Neither the name of ARM LIMITED nor the names of its contributors |
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| 24 | * may be used to endorse or promote products derived from this |
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| 25 | * software without specific prior written permission. |
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| 26 | * |
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| 27 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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| 28 | * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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| 29 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
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| 30 | * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
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| 31 | * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
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| 32 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
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| 33 | * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
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| 34 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
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| 35 | * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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| 36 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN |
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| 37 | * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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| 38 | * POSSIBILITY OF SUCH DAMAGE. |
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| 39 | * -------------------------------------------------------------------- */ |
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| 40 | |||
| 41 | |||
| 42 | #include "arm_math.h" |
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| 43 | #include "arm_common_tables.h" |
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| 44 | #include "arm_const_structs.h" |
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| 45 | |||
| 46 | /** |
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| 47 | * @ingroup groupTransforms |
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| 48 | */ |
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| 49 | |||
| 50 | /** |
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| 51 | * @addtogroup RealFFT |
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| 52 | * @{ |
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| 53 | */ |
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| 54 | |||
| 55 | |||
| 56 | |||
| 57 | /** |
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| 58 | * \par |
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| 59 | * Generation fixed-point realCoefAQ15 array in Q15 format: |
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| 60 | * \par |
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| 61 | * n = 4096 |
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| 62 | * <pre>for (i = 0; i < n; i++) |
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| 63 | * { |
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| 64 | * pATable[2 * i] = 0.5 * (1.0 - sin (2 * PI / (double) (2 * n) * (double) i)); |
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| 65 | * pATable[2 * i + 1] = 0.5 * (-1.0 * cos (2 * PI / (double) (2 * n) * (double) i)); |
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| 66 | * } </pre> |
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| 67 | * \par |
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| 68 | * Convert to fixed point Q15 format |
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| 69 | * round(pATable[i] * pow(2, 15)) |
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| 70 | *//** |
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| 71 | * \par |
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| 72 | * Generation of real_CoefB array: |
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| 73 | * \par |
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| 74 | * n = 4096 |
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| 75 | * <pre>for (i = 0; i < n; i++) |
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| 76 | * { |
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| 77 | * pBTable[2 * i] = 0.5 * (1.0 + sin (2 * PI / (double) (2 * n) * (double) i)); |
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| 78 | * pBTable[2 * i + 1] = 0.5 * (1.0 * cos (2 * PI / (double) (2 * n) * (double) i)); |
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| 79 | * } </pre> |
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| 80 | * \par |
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| 81 | * Convert to fixed point Q15 format |
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| 82 | * round(pBTable[i] * pow(2, 15)) |
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| 83 | * |
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| 84 | *//** |
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| 85 | * @brief Initialization function for the Q15 RFFT/RIFFT. |
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| 86 | * @param[in, out] *S points to an instance of the Q15 RFFT/RIFFT structure. |
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| 87 | * @param[in] fftLenReal length of the FFT. |
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| 88 | * @param[in] ifftFlagR flag that selects forward (ifftFlagR=0) or inverse (ifftFlagR=1) transform. |
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| 89 | * @param[in] bitReverseFlag flag that enables (bitReverseFlag=1) or disables (bitReverseFlag=0) bit reversal of output. |
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| 90 | * @return The function returns ARM_MATH_SUCCESS if initialization is successful or ARM_MATH_ARGUMENT_ERROR if <code>fftLenReal</code> is not a supported value. |
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| 91 | * |
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| 92 | * \par Description: |
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| 93 | * \par |
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| 94 | * The parameter <code>fftLenReal</code> Specifies length of RFFT/RIFFT Process. Supported FFT Lengths are 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192. |
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| 95 | * \par |
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| 96 | * The parameter <code>ifftFlagR</code> controls whether a forward or inverse transform is computed. |
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| 97 | * Set(=1) ifftFlagR to calculate RIFFT, otherwise RFFT is calculated. |
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| 98 | * \par |
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| 99 | * The parameter <code>bitReverseFlag</code> controls whether output is in normal order or bit reversed order. |
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| 100 | * Set(=1) bitReverseFlag for output to be in normal order otherwise output is in bit reversed order. |
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| 101 | * \par |
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| 102 | * This function also initializes Twiddle factor table. |
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| 103 | */ |
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| 104 | arm_status arm_rfft_init_q15( |
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| 105 | arm_rfft_instance_q15 * S, |
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| 106 | uint32_t fftLenReal, |
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| 107 | uint32_t ifftFlagR, |
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| 108 | uint32_t bitReverseFlag) |
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| 109 | { |
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| 110 | /* Initialise the default arm status */ |
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| 111 | arm_status status = ARM_MATH_SUCCESS; |
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| 112 | |||
| 113 | /* Initialize the Real FFT length */ |
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| 114 | S->fftLenReal = (uint16_t) fftLenReal; |
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| 115 | |||
| 116 | /* Initialize the Twiddle coefficientA pointer */ |
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| 117 | S->pTwiddleAReal = (q15_t *) realCoefAQ15; |
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| 118 | |||
| 119 | /* Initialize the Twiddle coefficientB pointer */ |
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| 120 | S->pTwiddleBReal = (q15_t *) realCoefBQ15; |
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| 121 | |||
| 122 | /* Initialize the Flag for selection of RFFT or RIFFT */ |
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| 123 | S->ifftFlagR = (uint8_t) ifftFlagR; |
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| 124 | |||
| 125 | /* Initialize the Flag for calculation Bit reversal or not */ |
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| 126 | S->bitReverseFlagR = (uint8_t) bitReverseFlag; |
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| 127 | |||
| 128 | /* Initialization of coef modifier depending on the FFT length */ |
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| 129 | switch (S->fftLenReal) |
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| 130 | { |
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| 131 | case 8192u: |
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| 132 | S->twidCoefRModifier = 1u; |
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| 133 | S->pCfft = &arm_cfft_sR_q15_len4096; |
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| 134 | break; |
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| 135 | case 4096u: |
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| 136 | S->twidCoefRModifier = 2u; |
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| 137 | S->pCfft = &arm_cfft_sR_q15_len2048; |
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| 138 | break; |
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| 139 | case 2048u: |
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| 140 | S->twidCoefRModifier = 4u; |
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| 141 | S->pCfft = &arm_cfft_sR_q15_len1024; |
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| 142 | break; |
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| 143 | case 1024u: |
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| 144 | S->twidCoefRModifier = 8u; |
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| 145 | S->pCfft = &arm_cfft_sR_q15_len512; |
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| 146 | break; |
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| 147 | case 512u: |
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| 148 | S->twidCoefRModifier = 16u; |
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| 149 | S->pCfft = &arm_cfft_sR_q15_len256; |
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| 150 | break; |
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| 151 | case 256u: |
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| 152 | S->twidCoefRModifier = 32u; |
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| 153 | S->pCfft = &arm_cfft_sR_q15_len128; |
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| 154 | break; |
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| 155 | case 128u: |
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| 156 | S->twidCoefRModifier = 64u; |
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| 157 | S->pCfft = &arm_cfft_sR_q15_len64; |
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| 158 | break; |
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| 159 | case 64u: |
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| 160 | S->twidCoefRModifier = 128u; |
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| 161 | S->pCfft = &arm_cfft_sR_q15_len32; |
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| 162 | break; |
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| 163 | case 32u: |
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| 164 | S->twidCoefRModifier = 256u; |
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| 165 | S->pCfft = &arm_cfft_sR_q15_len16; |
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| 166 | break; |
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| 167 | default: |
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| 168 | /* Reporting argument error if rfftSize is not valid value */ |
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| 169 | status = ARM_MATH_ARGUMENT_ERROR; |
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| 170 | break; |
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| 171 | } |
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| 172 | |||
| 173 | /* return the status of RFFT Init function */ |
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| 174 | return (status); |
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| 175 | } |
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| 176 | |||
| 177 | /** |
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| 178 | * @} end of RealFFT group |
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| 179 | */ |
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| 180 | |||
| 181 |