1 /* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_dct4_init_q15.c
4 * Description: Initialization function of DCT-4 & IDCT4 Q15
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 @ingroup groupTransforms
34 */
35
36 /**
37 @addtogroup DCT4_IDCT4
38 @{
39 */
40
41 /**
42 @brief Initialization function for the Q15 DCT4/IDCT4.
43 @param[in,out] S points to an instance of Q15 DCT4/IDCT4 structure
44 @param[in] S_RFFT points to an instance of Q15 RFFT/RIFFT structure
45 @param[in] S_CFFT points to an instance of Q15 CFFT/CIFFT structure
46 @param[in] N length of the DCT4
47 @param[in] Nby2 half of the length of the DCT4
48 @param[in] normalize normalizing factor
49 @return execution status
50 - \ref ARM_MATH_SUCCESS : Operation successful
51 - \ref ARM_MATH_ARGUMENT_ERROR : <code>N</code> is not a supported transform length
52
53 @par Normalizing factor
54 The normalizing factor is <code>sqrt(2/N)</code>, which depends on the size of transform <code>N</code>.
55 Normalizing factors in 1.15 format are mentioned in the table below for different DCT sizes:
56
57 \image html dct4NormalizingQ15Table.gif
58 */
59
arm_dct4_init_q15(arm_dct4_instance_q15 * S,arm_rfft_instance_q15 * S_RFFT,arm_cfft_radix4_instance_q15 * S_CFFT,uint16_t N,uint16_t Nby2,q15_t normalize)60 arm_status arm_dct4_init_q15(
61 arm_dct4_instance_q15 * S,
62 arm_rfft_instance_q15 * S_RFFT,
63 arm_cfft_radix4_instance_q15 * S_CFFT,
64 uint16_t N,
65 uint16_t Nby2,
66 q15_t normalize)
67 {
68 /* Initialise the default arm status */
69 arm_status status = ARM_MATH_SUCCESS;
70
71 /* Initialize the DCT4 length */
72 S->N = N;
73
74 /* Initialize the half of DCT4 length */
75 S->Nby2 = Nby2;
76
77 /* Initialize the DCT4 Normalizing factor */
78 S->normalize = normalize;
79
80 /* Initialize Real FFT Instance */
81 S->pRfft = S_RFFT;
82
83 /* Initialize Complex FFT Instance */
84 S->pCfft = S_CFFT;
85
86 switch (N)
87 {
88 #if !defined(ARM_DSP_CONFIG_TABLES) || defined(ARM_ALL_FFT_TABLES) || defined(ARM_TABLE_DCT4_Q15_8192)
89 /* Initialize the table modifier values */
90 case 8192U:
91 S->pTwiddle = WeightsQ15_8192;
92 S->pCosFactor = cos_factorsQ15_8192;
93 break;
94 #endif
95
96 #if !defined(ARM_DSP_CONFIG_TABLES) || defined(ARM_ALL_FFT_TABLES) || defined(ARM_TABLE_DCT4_Q15_2048)
97 case 2048U:
98 S->pTwiddle = WeightsQ15_2048;
99 S->pCosFactor = cos_factorsQ15_2048;
100 break;
101 #endif
102
103 #if !defined(ARM_DSP_CONFIG_TABLES) || defined(ARM_ALL_FFT_TABLES) || defined(ARM_TABLE_DCT4_Q15_512)
104 case 512U:
105 S->pTwiddle = WeightsQ15_512;
106 S->pCosFactor = cos_factorsQ15_512;
107 break;
108 #endif
109
110 #if !defined(ARM_DSP_CONFIG_TABLES) || defined(ARM_ALL_FFT_TABLES) || defined(ARM_TABLE_DCT4_Q15_128)
111 case 128U:
112 S->pTwiddle = WeightsQ15_128;
113 S->pCosFactor = cos_factorsQ15_128;
114 break;
115 #endif
116
117 default:
118 status = ARM_MATH_ARGUMENT_ERROR;
119 }
120
121 /* Initialize the RFFT/RIFFT */
122 arm_rfft_init_q15(S->pRfft, S->N, 0U, 1U);
123
124 /* return the status of DCT4 Init function */
125 return (status);
126 }
127
128 /**
129 @} end of DCT4_IDCT4 group
130 */
131