source: trunk/demos/spectrum/3rdparty/fftreal/FFTRealPassInverse.hpp@ 1168

Last change on this file since 1168 was 769, checked in by Dmitry A. Kuminov, 15 years ago

trunk: Merged in qt 4.6.3 sources from branches/vendor/nokia/qt.
File size: 6.2 KB
Line 
1/*****************************************************************************
2
3 FFTRealPassInverse.hpp
4 Copyright (c) 2005 Laurent de Soras
5
6--- Legal stuff ---
7
8This library is free software; you can redistribute it and/or
9modify it under the terms of the GNU Lesser General Public
10License as published by the Free Software Foundation; either
11version 2.1 of the License, or (at your option) any later version.
12
13This library is distributed in the hope that it will be useful,
14but WITHOUT ANY WARRANTY; without even the implied warranty of
15MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16Lesser General Public License for more details.
17
18You should have received a copy of the GNU Lesser General Public
19License along with this library; if not, write to the Free Software
20Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21
22*Tab=3***********************************************************************/
23
24
25
26#if defined (FFTRealPassInverse_CURRENT_CODEHEADER)
27 #error Recursive inclusion of FFTRealPassInverse code header.
28#endif
29#define FFTRealPassInverse_CURRENT_CODEHEADER
30
31#if ! defined (FFTRealPassInverse_CODEHEADER_INCLUDED)
32#define FFTRealPassInverse_CODEHEADER_INCLUDED
33
34
35
36/*\\\ INCLUDE FILES \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/
37
38#include "FFTRealUseTrigo.h"
39
40
41
42/*\\\ PUBLIC \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/
43
44
45
46template <int PASS>
47void FFTRealPassInverse <PASS>::process (long len, DataType dest_ptr [], DataType src_ptr [], const DataType f_ptr [], const DataType cos_ptr [], long cos_len, const long br_ptr [], OscType osc_list [])
48{
49 process_internal (
50 len,
51 dest_ptr,
52 f_ptr,
53 cos_ptr,
54 cos_len,
55 br_ptr,
56 osc_list
57 );
58 FFTRealPassInverse <PASS - 1>::process_rec (
59 len,
60 src_ptr,
61 dest_ptr,
62 cos_ptr,
63 cos_len,
64 br_ptr,
65 osc_list
66 );
67}
68
69
70
71template <int PASS>
72void FFTRealPassInverse <PASS>::process_rec (long len, DataType dest_ptr [], DataType src_ptr [], const DataType cos_ptr [], long cos_len, const long br_ptr [], OscType osc_list [])
73{
74 process_internal (
75 len,
76 dest_ptr,
77 src_ptr,
78 cos_ptr,
79 cos_len,
80 br_ptr,
81 osc_list
82 );
83 FFTRealPassInverse <PASS - 1>::process_rec (
84 len,
85 src_ptr,
86 dest_ptr,
87 cos_ptr,
88 cos_len,
89 br_ptr,
90 osc_list
91 );
92}
93
94template <>
95void FFTRealPassInverse <0>::process_rec (long len, DataType dest_ptr [], DataType src_ptr [], const DataType cos_ptr [], long cos_len, const long br_ptr [], OscType osc_list [])
96{
97 // Stops recursion
98}
99
100
101
102template <int PASS>
103void FFTRealPassInverse <PASS>::process_internal (long len, DataType dest_ptr [], const DataType src_ptr [], const DataType cos_ptr [], long cos_len, const long br_ptr [], OscType osc_list [])
104{
105 const long dist = 1L << (PASS - 1);
106 const long c1_r = 0;
107 const long c1_i = dist;
108 const long c2_r = dist * 2;
109 const long c2_i = dist * 3;
110 const long cend = dist * 4;
111 const long table_step = cos_len >> (PASS - 1);
112
113 enum { TRIGO_OSC = PASS - FFTRealFixLenParam::TRIGO_BD_LIMIT };
114 enum { TRIGO_DIRECT = (TRIGO_OSC >= 0) ? 1 : 0 };
115
116 long coef_index = 0;
117 do
118 {
119 const DataType * const sf = src_ptr + coef_index;
120 DataType * const df = dest_ptr + coef_index;
121
122 // Extreme coefficients are always real
123 df [c1_r] = sf [c1_r] + sf [c2_r];
124 df [c2_r] = sf [c1_r] - sf [c2_r];
125 df [c1_i] = sf [c1_i] * 2;
126 df [c2_i] = sf [c2_i] * 2;
127
128 FFTRealUseTrigo <TRIGO_DIRECT>::prepare (osc_list [TRIGO_OSC]);
129
130 // Others are conjugate complex numbers
131 for (long i = 1; i < dist; ++ i)
132 {
133 df [c1_r + i] = sf [c1_r + i] + sf [c2_r - i];
134 df [c1_i + i] = sf [c2_r + i] - sf [cend - i];
135
136 DataType c;
137 DataType s;
138 FFTRealUseTrigo <TRIGO_DIRECT>::iterate (
139 osc_list [TRIGO_OSC],
140 c,
141 s,
142 cos_ptr,
143 i * table_step,
144 (dist - i) * table_step
145 );
146
147 const DataType vr = sf [c1_r + i] - sf [c2_r - i];
148 const DataType vi = sf [c2_r + i] + sf [cend - i];
149
150 df [c2_r + i] = vr * c + vi * s;
151 df [c2_i + i] = vi * c - vr * s;
152 }
153
154 coef_index += cend;
155 }
156 while (coef_index < len);
157}
158
159template <>
160void FFTRealPassInverse <2>::process_internal (long len, DataType dest_ptr [], const DataType src_ptr [], const DataType cos_ptr [], long cos_len, const long br_ptr [], OscType osc_list [])
161{
162 // Antepenultimate pass
163 const DataType sqrt2_2 = DataType (SQRT2 * 0.5);
164
165 long coef_index = 0;
166 do
167 {
168 dest_ptr [coef_index ] = src_ptr [coef_index] + src_ptr [coef_index + 4];
169 dest_ptr [coef_index + 4] = src_ptr [coef_index] - src_ptr [coef_index + 4];
170 dest_ptr [coef_index + 2] = src_ptr [coef_index + 2] * 2;
171 dest_ptr [coef_index + 6] = src_ptr [coef_index + 6] * 2;
172
173 dest_ptr [coef_index + 1] = src_ptr [coef_index + 1] + src_ptr [coef_index + 3];
174 dest_ptr [coef_index + 3] = src_ptr [coef_index + 5] - src_ptr [coef_index + 7];
175
176 const DataType vr = src_ptr [coef_index + 1] - src_ptr [coef_index + 3];
177 const DataType vi = src_ptr [coef_index + 5] + src_ptr [coef_index + 7];
178
179 dest_ptr [coef_index + 5] = (vr + vi) * sqrt2_2;
180 dest_ptr [coef_index + 7] = (vi - vr) * sqrt2_2;
181
182 coef_index += 8;
183 }
184 while (coef_index < len);
185}
186
187template <>
188void FFTRealPassInverse <1>::process_internal (long len, DataType dest_ptr [], const DataType src_ptr [], const DataType cos_ptr [], long cos_len, const long br_ptr [], OscType osc_list [])
189{
190 // Penultimate and last pass at once
191 const long qlen = len >> 2;
192
193 long coef_index = 0;
194 do
195 {
196 const long ri_0 = br_ptr [coef_index >> 2];
197
198 const DataType b_0 = src_ptr [coef_index ] + src_ptr [coef_index + 2];
199 const DataType b_2 = src_ptr [coef_index ] - src_ptr [coef_index + 2];
200 const DataType b_1 = src_ptr [coef_index + 1] * 2;
201 const DataType b_3 = src_ptr [coef_index + 3] * 2;
202
203 dest_ptr [ri_0 ] = b_0 + b_1;
204 dest_ptr [ri_0 + 2 * qlen] = b_0 - b_1;
205 dest_ptr [ri_0 + 1 * qlen] = b_2 + b_3;
206 dest_ptr [ri_0 + 3 * qlen] = b_2 - b_3;
207
208 coef_index += 4;
209 }
210 while (coef_index < len);
211}
212
213
214
215/*\\\ PROTECTED \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/
216
217
218
219/*\\\ PRIVATE \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/
220
221
222
223#endif // FFTRealPassInverse_CODEHEADER_INCLUDED
224
225#undef FFTRealPassInverse_CURRENT_CODEHEADER
226
227
228
229/*\\\ EOF \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/
Note: See TracBrowser for help on using the repository browser.