1 //*@@@+++@@@@******************************************************************
2 //
3 // Copyright � Microsoft Corp.
4 // All rights reserved.
5 //
6 // Redistribution and use in source and binary forms, with or without
7 // modification, are permitted provided that the following conditions are met:
8 //
9 // � Redistributions of source code must retain the above copyright notice,
10 // this list of conditions and the following disclaimer.
11 // � Redistributions in binary form must reproduce the above copyright notice,
12 // this list of conditions and the following disclaimer in the documentation
13 // and/or other materials provided with the distribution.
14 //
15 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
16 // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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21 // SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
22 // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
23 // CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
24 // ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
25 // POSSIBILITY OF SUCH DAMAGE.
26 //
27 //*@@@---@@@@******************************************************************
28
29 #include "strTransform.h"
30
31 /** need to swap b and c **/
32 /** rounding behavior: [0 0 0 0] <-> [+ - - -]
33 [+ + + +] <-> [+3/4 - - -]
34 [- - - -] <-> [- - - -] **/
strDCT2x2dn(PixelI * pa,PixelI * pb,PixelI * pc,PixelI * pd)35 Void strDCT2x2dn(PixelI *pa, PixelI *pb, PixelI *pc, PixelI *pd)
36 {
37 PixelI a, b, c, d, C, t;
38 a = *pa;
39 b = *pb;
40 C = *pc;
41 d = *pd;
42
43 a += d;
44 b -= C;
45 t = ((a - b) >> 1);
46 c = t - d;
47 d = t - C;
48 a -= d;
49 b += c;
50
51 *pa = a;
52 *pb = b;
53 *pc = c;
54 *pd = d;
55 }
56
strDCT2x2up(PixelI * pa,PixelI * pb,PixelI * pc,PixelI * pd)57 Void strDCT2x2up(PixelI *pa, PixelI *pb, PixelI *pc, PixelI *pd)
58 {
59 PixelI a, b, c, d, C, t;
60 a = *pa;
61 b = *pb;
62 C = *pc;
63 d = *pd;
64
65 a += d;
66 b -= C;
67 t = ((a - b + 1) >> 1);
68 c = t - d;
69 d = t - C;
70 a -= d;
71 b += c;
72
73 *pa = a;
74 *pb = b;
75 *pc = c;
76 *pd = d;
77 }
78
FOURBUTTERFLY_HARDCODED1(PixelI * p)79 Void FOURBUTTERFLY_HARDCODED1(PixelI *p)
80 {
81 strDCT2x2dn(&p[0], &p[4], &p[8], &p[12]);
82 strDCT2x2dn(&p[1], &p[5], &p[9], &p[13]);
83 strDCT2x2dn(&p[2], &p[6], &p[10], &p[14]);
84 strDCT2x2dn(&p[3], &p[7], &p[11], &p[15]);
85 }
86