1 /* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_rfft_init_f32.c
4 * Description: RFFT & RIFFT Floating point initialisation function
5 *
6 * $Date: 23 April 2021
7 * $Revision: V1.9.0
8 *
9 * Target Processor: Cortex-M and Cortex-A cores
10 * -------------------------------------------------------------------- */
11 /*
12 * Copyright (C) 2010-2021 ARM Limited or its affiliates. All rights reserved.
13 *
14 * SPDX-License-Identifier: Apache-2.0
15 *
16 * Licensed under the Apache License, Version 2.0 (the License); you may
17 * not use this file except in compliance with the License.
18 * You may obtain a copy of the License at
19 *
20 * www.apache.org/licenses/LICENSE-2.0
21 *
22 * Unless required by applicable law or agreed to in writing, software
23 * distributed under the License is distributed on an AS IS BASIS, WITHOUT
24 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
25 * See the License for the specific language governing permissions and
26 * limitations under the License.
27 */
28
29 #include "dsp/transform_functions.h"
30 #include "arm_common_tables.h"
31
32
33 /**
34 @ingroup RealFFT
35 */
36
37 /**
38 @addtogroup DeprecatedRealFFT
39 @{
40 */
41
42 /**
43 @brief Initialization function for the floating-point RFFT/RIFFT.
44 @deprecated Do not use this function. It has been superceded by \ref arm_rfft_fast_init_f32 and will be removed in the future.
45 @param[in,out] S points to an instance of the floating-point RFFT/RIFFT structure
46 @param[in,out] S_CFFT points to an instance of the floating-point CFFT/CIFFT structure
47 @param[in] fftLenReal length of the FFT.
48 @param[in] ifftFlagR flag that selects transform direction
49 - value = 0: forward transform
50 - value = 1: inverse transform
51 @param[in] bitReverseFlag flag that enables / disables bit reversal of output
52 - value = 0: disables bit reversal of output
53 - value = 1: enables bit reversal of output
54 @return execution status
55 - \ref ARM_MATH_SUCCESS : Operation successful
56 - \ref ARM_MATH_ARGUMENT_ERROR : <code>fftLenReal</code> is not a supported length
57
58 @par Description
59 The parameter <code>fftLenReal</code>specifies length of RFFT/RIFFT Process.
60 Supported FFT Lengths are 128, 512, 2048.
61 @par
62 The parameter <code>ifftFlagR</code> controls whether a forward or inverse transform is computed.
63 Set(=1) ifftFlagR to calculate RIFFT, otherwise RFFT is calculated.
64 @par
65 The parameter <code>bitReverseFlag</code> controls whether output is in normal order or bit reversed order.
66 Set(=1) bitReverseFlag for output to be in normal order otherwise output is in bit reversed order.
67 @par
68 This function also initializes Twiddle factor table.
69 */
70
arm_rfft_init_f32(arm_rfft_instance_f32 * S,arm_cfft_radix4_instance_f32 * S_CFFT,uint32_t fftLenReal,uint32_t ifftFlagR,uint32_t bitReverseFlag)71 arm_status arm_rfft_init_f32(
72 arm_rfft_instance_f32 * S,
73 arm_cfft_radix4_instance_f32 * S_CFFT,
74 uint32_t fftLenReal,
75 uint32_t ifftFlagR,
76 uint32_t bitReverseFlag)
77 {
78 /* Initialise the default arm status */
79 arm_status status = ARM_MATH_ARGUMENT_ERROR;
80
81
82 /* Initialise the default arm status */
83 status = ARM_MATH_SUCCESS;
84
85 /* Initialize the Real FFT length */
86 S->fftLenReal = (uint16_t) fftLenReal;
87
88 /* Initialize the Complex FFT length */
89 S->fftLenBy2 = (uint16_t) fftLenReal / 2U;
90
91 /* Initialize the Twiddle coefficientA pointer */
92 S->pTwiddleAReal = (float32_t *) realCoefA;
93
94 /* Initialize the Twiddle coefficientB pointer */
95 S->pTwiddleBReal = (float32_t *) realCoefB;
96
97 /* Initialize the Flag for selection of RFFT or RIFFT */
98 S->ifftFlagR = (uint8_t) ifftFlagR;
99
100 /* Initialize the Flag for calculation Bit reversal or not */
101 S->bitReverseFlagR = (uint8_t) bitReverseFlag;
102
103 /* Initializations of structure parameters depending on the FFT length */
104 switch (S->fftLenReal)
105 {
106 /* Init table modifier value */
107 case 8192U:
108 S->twidCoefRModifier = 1U;
109 break;
110 case 2048U:
111 S->twidCoefRModifier = 4U;
112 break;
113 case 512U:
114 S->twidCoefRModifier = 16U;
115 break;
116 case 128U:
117 S->twidCoefRModifier = 64U;
118 break;
119 default:
120 /* Reporting argument error if rfftSize is not valid value */
121 status = ARM_MATH_ARGUMENT_ERROR;
122 break;
123 }
124
125 /* Init Complex FFT Instance */
126 S->pCfft = S_CFFT;
127
128 if (S->ifftFlagR)
129 {
130 /* Initializes the CIFFT Module for fftLenreal/2 length */
131 arm_cfft_radix4_init_f32(S->pCfft, S->fftLenBy2, 1U, 0U);
132 }
133 else
134 {
135 /* Initializes the CFFT Module for fftLenreal/2 length */
136 arm_cfft_radix4_init_f32(S->pCfft, S->fftLenBy2, 0U, 0U);
137 }
138
139 /* return the status of RFFT Init function */
140 return (status);
141
142 }
143
144 /**
145 @} end of DeprecatedRealFFT group
146 */
147
