1 /* ------------------------------------------------------------------
2 * Copyright (C) 1998-2009 PacketVideo
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
13 * express or implied.
14 * See the License for the specific language governing permissions
15 * and limitations under the License.
16 * -------------------------------------------------------------------
17 */
18 /*
19 ------------------------------------------------------------------------------
20
21 PacketVideo Corp.
22 MP3 Decoder Library
23 Filename: mdct_18.cpp
24
25 Date: 09/21/2007
26
27 ------------------------------------------------------------------------------
28 REVISION HISTORY
29
30
31 Description:
32
33 ------------------------------------------------------------------------------
34 INPUT AND OUTPUT DEFINITIONS
35
36 Input
37 int32 vec[], input vector of length 6
38 int32 *history input for overlap and add, vector updated with
39 next overlap and add values
40 Returns
41 none mdct computation in-place
42
43
44 ------------------------------------------------------------------------------
45 FUNCTION DESCRIPTION
46
47 Returns the mdct of length 6 of the input vector, as well as the overlap
48 vector for next iteration ( on history[])
49
50 ------------------------------------------------------------------------------
51 REQUIREMENTS
52
53
54 ------------------------------------------------------------------------------
55 REFERENCES
56
57 ------------------------------------------------------------------------------
58 PSEUDO-CODE
59
60 ------------------------------------------------------------------------------
61 */
62
63
64 /*----------------------------------------------------------------------------
65 ; INCLUDES
66 ----------------------------------------------------------------------------*/
67
68 #include "pv_mp3dec_fxd_op.h"
69 #include "pvmp3_mdct_6.h"
70
71
72 /*----------------------------------------------------------------------------
73 ; MACROS
74 ; Define module specific macros here
75 ----------------------------------------------------------------------------*/
76
77
78 /*----------------------------------------------------------------------------
79 ; DEFINES
80 ; Include all pre-processor statements here. Include conditional
81 ; compile variables also.
82 ----------------------------------------------------------------------------*/
83 #define QFORMAT 29
84 #define Qfmt29(a) (int32)((a)*((int32)1<<QFORMAT) + ((a)>=0?0.5F:-0.5F))
85
86 /*----------------------------------------------------------------------------
87 ; LOCAL FUNCTION DEFINITIONS
88 ; Function Prototype declaration
89 ----------------------------------------------------------------------------*/
90
91 /*----------------------------------------------------------------------------
92 ; LOCAL STORE/BUFFER/POINTER DEFINITIONS
93 ; Variable declaration - defined here and used outside this module
94 ----------------------------------------------------------------------------*/
95 /*
96 * (1./(2*cos((pi/(2*N))*(2*i+1)))), N = 12, i = [0:N/2-1]
97 */
98
99 const int32 cosTerms_1_ov_cos_phi_N6[6] =
100 {
101
102 Qfmt29(0.50431448029008f), Qfmt29(0.54119610014620f),
103 Qfmt29(0.63023620700513f), Qfmt29(0.82133981585229f),
104 Qfmt29(1.30656296487638f), Qfmt29(3.83064878777019f)
105 };
106
107 /*----------------------------------------------------------------------------
108 ; EXTERNAL FUNCTION REFERENCES
109 ; Declare functions defined elsewhere and referenced in this module
110 ----------------------------------------------------------------------------*/
111
112 /*----------------------------------------------------------------------------
113 ; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES
114 ; Declare variables used in this module but defined elsewhere
115 ----------------------------------------------------------------------------*/
116
117 /*----------------------------------------------------------------------------
118 ; FUNCTION CODE
119 ----------------------------------------------------------------------------*/
120
121
pvmp3_mdct_6(int32 vec[],int32 * history)122 void pvmp3_mdct_6(int32 vec[], int32 *history)
123 {
124 int32 i;
125 int32 tmp;
126 int32 tmp1;
127 int32 tmp2;
128
129 int32 *pt_vec = vec;
130 int32 *pt_vec_o = vec;
131 const int32 *pt_cos = cosTerms_1_ov_cos_phi_N6;
132
133 for (i = 2; i != 0; i--)
134 {
135 tmp = *(pt_vec++);
136 tmp1 = *(pt_vec++);
137 tmp2 = *(pt_vec++);
138 *(pt_vec_o++) = fxp_mul32_Q29(tmp, *(pt_cos++));
139 *(pt_vec_o++) = fxp_mul32_Q29(tmp1, *(pt_cos++));
140 *(pt_vec_o++) = fxp_mul32_Q29(tmp2, *(pt_cos++));
141 }
142
143
144 pvmp3_dct_6(vec); // Even terms
145
146
147 tmp = -(vec[0] + vec[1]);
148 history[3] = tmp;
149 history[2] = tmp;
150 tmp = -(vec[1] + vec[2]);
151 vec[0] = vec[3] + vec[4];
152 vec[1] = vec[4] + vec[5];
153 history[4] = tmp;
154 history[1] = tmp;
155 tmp = -(vec[2] + vec[3]);
156 vec[4] = -vec[1];
157 history[5] = tmp;
158 history[0] = tmp;
159
160 vec[2] = vec[5];
161 vec[3] = -vec[5];
162 vec[5] = -vec[0];
163
164 }
165
166