1 /*****************************************************************************
2 *
3 * XVID MPEG-4 VIDEO CODEC
4 * - CBP related function -
5 *
6 * Copyright(C) 2002-2003 Edouard Gomez <ed.gomez@free.fr>
7 * 2003 Christoph Lampert <gruel@web.de>
8 *
9 * This program is free software ; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation ; either version 2 of the License, or
12 * (at your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY ; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program ; if not, write to the Free Software
21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
22 *
23 * $Id: cbp.c 1985 2011-05-18 09:02:35Z Isibaar $
24 *
25 ****************************************************************************/
26
27 #include "../portab.h"
28 #include "cbp.h"
29
30 cbpFuncPtr calc_cbp;
31
32 /*
33 * Returns a field of bits that indicates non zero ac blocks
34 * for this macro block
35 */
36
37 /* naive C */
38 uint32_t
calc_cbp_plain(const int16_t codes[6* 64])39 calc_cbp_plain(const int16_t codes[6 * 64])
40 {
41 int i, j;
42 uint32_t cbp = 0;
43
44 for (i = 0; i < 6; i++) {
45 for (j=1; j<64;j++) {
46 if (codes[64*i+j]) {
47 cbp |= 1 << (5-i);
48 break;
49 }
50 }
51 }
52 return cbp;
53 }
54
55 /* optimized C */
56 uint32_t
calc_cbp_c(const int16_t codes[6* 64])57 calc_cbp_c(const int16_t codes[6 * 64])
58 {
59 unsigned int i=6;
60 uint32_t cbp = 0;
61
62 /* uses fixed relation: 4*codes = 1*codes64 */
63 /* if prototype is changed (e.g. from int16_t to something like int32) this routine
64 has to be changed! */
65
66 do {
67 uint64_t *codes64 = (uint64_t*)codes; /* the compiler doesn't really make this */
68 uint32_t *codes32 = (uint32_t*)codes; /* variables, just "addressing modes" */
69
70 cbp += cbp;
71 if (codes[1] || codes32[1]) {
72 cbp++;
73 }
74 else if (codes64[1] | codes64[2] | codes64[3]) {
75 cbp++;
76 }
77 else if (codes64[4] | codes64[5] | codes64[6] | codes64[7]) {
78 cbp++;
79 }
80 else if (codes64[8] | codes64[9] | codes64[10] | codes64[11]) {
81 cbp++;
82 }
83 else if (codes64[12] | codes64[13] | codes64[14] | codes64[15]) {
84 cbp++;
85 }
86 codes += 64;
87 i--;
88 } while (i != 0);
89
90 return cbp;
91 }
92
93
94
95
96 /* older code maybe better on some plattforms? */
97 #if 0
98 for (i = 5; i >= 0; i--) {
99 if (codes[1] | codes[2] | codes[3])
100 cbp |= 1 << i;
101 else {
102 for (j = 4; j <= 56; j+=4) /* [60],[61],[62],[63] are last */
103 if (codes[j] | codes[j+1] | codes[j+2] | codes[j+3]) {
104 cbp |= 1 << i;
105 break;
106 }
107 }
108 codes += 64;
109 }
110
111 return cbp;
112 #endif
113