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
36Input
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
40Returns
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
99const 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
122void 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