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
|
/*
* Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
* Copyright (C) 2008 - INRIA - Allan SIMON
*
* This file must be used under the terms of the CeCILL.
* This source file is licensed as described in the file COPYING, which
* you should have received as part of this distribution. The terms
* are also available at
* http://www.cecill.info/licences/Licence_CeCILL_V2-en.txt
*
*/
#include "fft_internal.h"
/*
** radix 4 iteration subroutine
*/
void r4tx( int nthpo, doubleComplex* c0, doubleComplex* c1, doubleComplex* c2, doubleComplex* c3)
{
int kk;
doubleComplex temp1 , temp2 , temp3 , temp4 ;
for(kk=0;kk<nthpo;kk+=4)
{
/* real and imag parts alternate */
temp1 = zadds ( c0[kk] , c2[kk] ) ;
temp2 = zdiffs( c0[kk] , c2[kk] ) ;
temp3 = zadds ( c1[kk] , c3[kk] ) ;
temp4 = zdiffs( c1[kk] , c3[kk] ) ;
/*
r1 = cr0[kk] + cr2[kk];
r2 = cr0[kk] - cr2[kk];
r3 = cr1[kk] + cr3[kk];
r4 = cr1[kk] - cr3[kk];
i1 = ci0[kk] + ci2[kk];
i2 = ci0[kk] - ci2[kk];
i3 = ci1[kk] + ci3[kk];
i4 = ci1[kk] - ci3[kk];
*/
c0[kk] = zadds ( temp1 , temp3 );
c1[kk] = zdiffs( temp1 , temp3 );
/*
cr0[kk] = r1 + r3;
ci0[kk] = i1 + i3;
cr1[kk] = r1 - r3;
ci1[kk] = i1 - i3;
*/
c2[kk] = DoubleComplex ( zreals ( temp2 ) - zimags( temp4 ) , zimags ( temp2 ) + zreals( temp4 ) );
c3[kk] = DoubleComplex ( zreals ( temp2 ) + zimags( temp4 ) , zimags ( temp2 ) - zreals( temp4 ) );
/*
cr2[kk] = r2 - i4;
ci2[kk] = i2 + r4;
cr3[kk] = r2 + i4;
ci3[kk] = i2 - r4;
*/
}
}
|
