1 /* ----------------------------------------------------------------------
2  * Project:      CMSIS DSP Library
3  * Title:        arm_cfft_radix2_init_q31.c
4  * Description:  Radix-2 Decimation in Frequency Fixed-point CFFT & CIFFT Initialization 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   @addtogroup ComplexFFTDeprecated
34   @{
35  */
36 
37 /**
38   @brief         Initialization function for the Q31 CFFT/CIFFT.
39   @deprecated    Do not use this function. It has been superseded by \ref arm_cfft_q31 and will be removed in the future.
40   @param[in,out] S              points to an instance of the Q31 CFFT/CIFFT structure
41   @param[in]     fftLen         length of the FFT
42   @param[in]     ifftFlag       flag that selects transform direction
43                    - value = 0: forward transform
44                    - value = 1: inverse transform
45   @param[in]     bitReverseFlag flag that enables / disables bit reversal of output
46                    - value = 0: disables bit reversal of output
47                    - value = 1: enables bit reversal of output
48   @return        execution status
49                    - \ref ARM_MATH_SUCCESS        : Operation successful
50                    - \ref ARM_MATH_ARGUMENT_ERROR : <code>fftLen</code> is not a supported length
51 
52   @par           Details
53                    The parameter <code>ifftFlag</code> controls whether a forward or inverse transform is computed.
54                    Set(=1) ifftFlag for calculation of CIFFT otherwise CFFT is calculated
55   @par
56                    The parameter <code>bitReverseFlag</code> controls whether output is in normal order or bit reversed order.
57                    Set(=1) bitReverseFlag for output to be in normal order otherwise output is in bit reversed order.
58   @par
59                    The parameter <code>fftLen</code> Specifies length of CFFT/CIFFT process. Supported FFT Lengths are 16, 64, 256, 1024.
60   @par
61                    This Function also initializes Twiddle factor table pointer and Bit reversal table pointer.
62 */
63 
arm_cfft_radix2_init_q31(arm_cfft_radix2_instance_q31 * S,uint16_t fftLen,uint8_t ifftFlag,uint8_t bitReverseFlag)64 arm_status arm_cfft_radix2_init_q31(
65   arm_cfft_radix2_instance_q31 * S,
66   uint16_t fftLen,
67   uint8_t ifftFlag,
68   uint8_t bitReverseFlag)
69 {
70   /*  Initialise the default arm status */
71   arm_status status = ARM_MATH_ARGUMENT_ERROR;
72 
73   /*  Initialise the default arm status */
74   status = ARM_MATH_SUCCESS;
75 
76   /*  Initialise the FFT length */
77   S->fftLen = fftLen;
78 
79   /*  Initialise the Twiddle coefficient pointer */
80   S->pTwiddle = (q31_t *) twiddleCoef_4096_q31;
81 
82   /*  Initialise the Flag for selection of CFFT or CIFFT */
83   S->ifftFlag = ifftFlag;
84 
85   /*  Initialise the Flag for calculation Bit reversal or not */
86   S->bitReverseFlag = bitReverseFlag;
87 
88   /*  Initializations of Instance structure depending on the FFT length */
89   switch (S->fftLen)
90   {
91     /*  Initializations of structure parameters for 4096 point FFT */
92   case 4096U:
93     /*  Initialise the twiddle coef modifier value */
94     S->twidCoefModifier = 1U;
95     /*  Initialise the bit reversal table modifier */
96     S->bitRevFactor = 1U;
97     /*  Initialise the bit reversal table pointer */
98     S->pBitRevTable = (uint16_t *) armBitRevTable;
99     break;
100 
101     /*  Initializations of structure parameters for 2048 point FFT */
102   case 2048U:
103     /*  Initialise the twiddle coef modifier value */
104     S->twidCoefModifier = 2U;
105     /*  Initialise the bit reversal table modifier */
106     S->bitRevFactor = 2U;
107     /*  Initialise the bit reversal table pointer */
108     S->pBitRevTable = (uint16_t *) & armBitRevTable[1];
109     break;
110 
111     /*  Initializations of structure parameters for 1024 point FFT */
112   case 1024U:
113     /*  Initialise the twiddle coef modifier value */
114     S->twidCoefModifier = 4U;
115     /*  Initialise the bit reversal table modifier */
116     S->bitRevFactor = 4U;
117     /*  Initialise the bit reversal table pointer */
118     S->pBitRevTable = (uint16_t *) & armBitRevTable[3];
119     break;
120 
121     /*  Initializations of structure parameters for 512 point FFT */
122   case 512U:
123     /*  Initialise the twiddle coef modifier value */
124     S->twidCoefModifier = 8U;
125     /*  Initialise the bit reversal table modifier */
126     S->bitRevFactor = 8U;
127     /*  Initialise the bit reversal table pointer */
128     S->pBitRevTable = (uint16_t *) & armBitRevTable[7];
129     break;
130 
131   case 256U:
132     /*  Initializations of structure parameters for 256 point FFT */
133     S->twidCoefModifier = 16U;
134     S->bitRevFactor = 16U;
135     S->pBitRevTable = (uint16_t *) & armBitRevTable[15];
136     break;
137 
138   case 128U:
139     /*  Initializations of structure parameters for 128 point FFT */
140     S->twidCoefModifier = 32U;
141     S->bitRevFactor = 32U;
142     S->pBitRevTable = (uint16_t *) & armBitRevTable[31];
143     break;
144 
145   case 64U:
146     /*  Initializations of structure parameters for 64 point FFT */
147     S->twidCoefModifier = 64U;
148     S->bitRevFactor = 64U;
149     S->pBitRevTable = (uint16_t *) & armBitRevTable[63];
150     break;
151 
152   case 32U:
153     /*  Initializations of structure parameters for 32 point FFT */
154     S->twidCoefModifier = 128U;
155     S->bitRevFactor = 128U;
156     S->pBitRevTable = (uint16_t *) & armBitRevTable[127];
157     break;
158 
159   case 16U:
160     /*  Initializations of structure parameters for 16 point FFT */
161     S->twidCoefModifier = 256U;
162     S->bitRevFactor = 256U;
163     S->pBitRevTable = (uint16_t *) & armBitRevTable[255];
164     break;
165 
166 
167   default:
168     /*  Reporting argument error if fftSize is not valid value */
169     status = ARM_MATH_ARGUMENT_ERROR;
170     break;
171   }
172 
173   return (status);
174 }
175 
176 /**
177   @} end of ComplexFFTDeprecated group
178  */
179