1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
|
/* ------------------------------------------------------------------
* Copyright (C) 1998-2009 PacketVideo
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
* express or implied.
* See the License for the specific language governing permissions
* and limitations under the License.
* -------------------------------------------------------------------
*/
/*
Pathname: ./src/fwd_long_complex_rot.c
Funtions: fwd_long_complex_rot
------------------------------------------------------------------------------
REVISION HISTORY
Date: 10/18/2002
Description:
(1) Change the input arguments, no shifts information from
long_fft_rx4 is passed, only a single max is passed.
(2) Eliminate search for max, a fixed shift has replaced the
search for max with minimal loss of precision.
(3) Eliminated unused variables
Date: 10/28/2002
Description:
(1) Added comments per code review
(2) Eliminated hardly used condition on if-else (exp==0)
Description:
------------------------------------------------------------------------------
INPUT AND OUTPUT DEFINITIONS
Inputs:
Data_in = Input vector (sized for long windows
TWICE_FWD_LONG_CX_ROT_LENGTH), with time domain samples
type Int32 *
Data_out = Output vector with a post-rotation by exp(-j(2pi/N)(k+1/8)),
(sized for long windows TWICE_FWD_LONG_CX_ROT_LENGTH)
type Int32 *
max = Input, carries the maximum value of the input vector
"Data_in"
type Int32
Local Stores/Buffers/Pointers Needed:
None
Global Stores/Buffers/Pointers Needed:
None
Outputs:
exp = shift factor to reflect signal scaling
Pointers and Buffers Modified:
Results are return in "Data_out"
Local Stores Modified:
None
Global Stores Modified:
None
------------------------------------------------------------------------------
FUNCTION DESCRIPTION
fwd_long_complex_rot() performs the pre complex rotation for the MDCT
for the case of long windows. It also performs digit reverse ordering of
the first and second halves of the input vector "Data_in", as well as
reordering of the two half vectors (following radix-2 decomposition)
Word normalization is also done to ensure 16 by 16 bit multiplications.
------------------------------------------------------------------------------
REQUIREMENTS
fwd_long_complex_rot() should execute a pre-rotation by
exp(-j(2pi/N)(k+1/8)), digit reverse ordering and normalization
------------------------------------------------------------------------------
REFERENCES
------------------------------------------------------------------------------
RESOURCES USED
When the code is written for a specific target processor the
the resources used should be documented below.
STACK USAGE: [stack count for this module] + [variable to represent
stack usage for each subroutine called]
where: [stack usage variable] = stack usage for [subroutine
name] (see [filename].ext)
DATA MEMORY USED: x words
PROGRAM MEMORY USED: x words
CLOCK CYCLES: [cycle count equation for this module] + [variable
used to represent cycle count for each subroutine
called]
where: [cycle count variable] = cycle count for [subroutine
name] (see [filename].ext)
------------------------------------------------------------------------------
*/
/*----------------------------------------------------------------------------
; INCLUDES
----------------------------------------------------------------------------*/
#include "fwd_long_complex_rot.h"
#include "digit_reversal_tables.h"
#include "imdct_fxp.h"
#include "pv_normalize.h"
#include "fxp_mul32.h"
/*----------------------------------------------------------------------------
; MACROS
; Define module specific macros here
----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------
; DEFINES
; Include all pre-processor statements here. Include conditional
; compile variables also.
----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------
; LOCAL FUNCTION DEFINITIONS
; Function Prototype declaration
----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------
; LOCAL VARIABLE DEFINITIONS
; Variable declaration - defined here and used outside this module
----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------
; EXTERNAL FUNCTION REFERENCES
; Declare functions defined elsewhere and referenced in this module
----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------
; EXTERNAL VARIABLES REFERENCES
; Declare variables used in this module but defined elsewhere
----------------------------------------------------------------------------*/
Int fwd_long_complex_rot(
Int32 *Data_in,
Int32 *Data_out,
Int32 max)
{
Int i;
const Int32 *p_rotate;
Int32 temp_re;
Int32 temp_im;
Int32 *pData_in_ref1;
Int32 *pData_in_ref2;
Int32 exp_jw;
Int32 temp_re_32;
Int32 temp_im_32;
Int32 *pData_out_1;
Int32 *pData_out_2;
Int32 *pData_out_3;
Int32 *pData_out_4;
Int32 *pData_in_1;
Int32 *pData_in_2;
Int exp;
p_rotate = exp_rotation_N_2048;
pData_in_ref1 = Data_in;
pData_in_ref2 = &Data_in[TWICE_FWD_LONG_CX_ROT_LENGTH];
pData_out_1 = Data_out;
pData_out_2 = &Data_out[LONG_WINDOW_LENGTH_m_1];
pData_out_3 = &Data_out[LONG_WINDOW_LENGTH];
pData_out_4 = &Data_out[TWICE_LONG_WINDOW_LENGTH_m_1];
/*
* Data_out
* >>>> <<<<
* pData_out_3 pData_out_4
* | | | | |
* pData_out_1 pData_out_2
* >>>> <<<<
*/
exp = 16 - pv_normalize(max);
if (exp < 0)
{
exp = 0;
}
/*
* Apply A/2^(diff) + B
*/
pData_in_1 = pData_in_ref1;
pData_in_2 = pData_in_ref2;
for (i = FWD_LONG_CX_ROT_LENGTH; i != 0; i--)
{
/*
* cos_n + j*sin_n == exp(j(2pi/N)(k+1/8))
*/
exp_jw = *p_rotate++;
/*
* Use auxiliary variables to avoid double accesses to memory.
* Data in is scaled to use only lower 16 bits.
*/
temp_re = *(pData_in_1++) >> exp;
temp_im = *(pData_in_1++) >> exp;
/*
* Pre-rotation
*/
temp_re_32 = (cmplx_mul32_by_16(temp_re, temp_im, exp_jw));
temp_im_32 = (cmplx_mul32_by_16(temp_im, -temp_re, exp_jw));
*(pData_out_1++) = - temp_re_32;
*(pData_out_2--) = temp_im_32;
*(pData_out_3++) = - temp_im_32;
*(pData_out_4--) = temp_re_32;
/*
* Pointer increment to jump over imag (1 & 4) or real parts
* (2 & 3)
*/
pData_out_1++;
pData_out_2--;
pData_out_3++;
pData_out_4--;
/*
* Repeat procedure for odd index at the output
*/
exp_jw = *p_rotate++;
temp_re = *(pData_in_2++) >> exp;
temp_im = *(pData_in_2++) >> exp;
temp_re_32 = (cmplx_mul32_by_16(temp_re, temp_im, exp_jw));
temp_im_32 = (cmplx_mul32_by_16(temp_im, -temp_re, exp_jw));
*(pData_out_1++) = - temp_re_32;
*(pData_out_2--) = temp_im_32;
*(pData_out_3++) = - temp_im_32;
*(pData_out_4--) = temp_re_32;
pData_out_1++;
pData_out_2--;
pData_out_3++;
pData_out_4--;
}
return (exp + 1);
}
|