[svn] / trunk / xvidcore / src / bitstream / cbp.c Repository:
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revision 468, Tue Sep 10 22:30:18 2002 UTC revision 912, Sun Mar 9 12:00:58 2003 UTC
# Line 1  Line 1 
 /*****************************************************************************  
  *  
  *  XVID MPEG-4 VIDEO CODEC  
  *  - cbp function (zero block flags) -  
  *  
  *  Copyright (C) 2001-2002 - Edouard Gomez <ed.gomez@wanadoo.fr>  
  *  
  *  This program is an implementation of a part of one or more MPEG-4  
  *  Video tools as specified in ISO/IEC 14496-2 standard.  Those intending  
  *  to use this software module in hardware or software products are  
  *  advised that its use may infringe existing patents or copyrights, and  
  *  any such use would be at such party's own risk.  The original  
  *  developer of this software module and his/her company, and subsequent  
  *  editors and their companies, will have no liability for use of this  
  *  software or modifications or derivatives thereof.  
  *  
  *  This program is free software ; you can redistribute it and/or modify  
  *  it under the terms of the GNU General Public License as published by  
  *  the Free Software Foundation ; either version 2 of the License, or  
  *  (at your option) any later version.  
  *  
  *  This program is distributed in the hope that it will be useful,  
  *  but WITHOUT ANY WARRANTY ; without even the implied warranty of  
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the  
  *  GNU General Public License for more details.  
  *  
  *  You should have received a copy of the GNU General Public License  
  *  along with this program ; if not, write to the Free Software  
  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA  
  *  
  * $Id: cbp.c,v 1.7 2002-09-10 22:30:18 edgomez Exp $  
  *  
  ****************************************************************************/  
   
1  #include "../portab.h"  #include "../portab.h"
2  #include "cbp.h"  #include "cbp.h"
3    
 /*****************************************************************************  
  * Global function pointer  
  ****************************************************************************/  
   
4  cbpFuncPtr calc_cbp;  cbpFuncPtr calc_cbp;
5    
 /*****************************************************************************  
  * Functions  
  ****************************************************************************/  
   
6  /*  /*
7   * Returns a field of bits that indicates non zero ac blocks   * Returns a field of bits that indicates non zero ac blocks
8   * for this macro block   * for this macro block
9   */   */
10    
11    /* naive C */
12  uint32_t  uint32_t
13  calc_cbp_c(const int16_t codes[6 * 64])  calc_cbp_plain(const int16_t codes[6 * 64])
14  {  {
15          uint32_t i, j;          int i, j;
16          uint32_t cbp = 0;          uint32_t cbp = 0;
17    
18          for (i = 0; i < 6; i++) {          for (i = 0; i < 6; i++) {
19                  for (j = 1; j < 61; j += 4) {                  for (j=1; j<64;j++) {
20                          if (codes[i * 64 + j] | codes[i * 64 + j + 1] |                          if (codes[64*i+j]) {
                                 codes[i * 64 + j + 2] | codes[i * 64 + j + 3]) {  
21                                  cbp |= 1 << (5 - i);                                  cbp |= 1 << (5 - i);
22                                  break;                                  break;
23                          }                          }
24                  }                  }
25            }
26            return cbp;
27    }
28    
29                  if (codes[i * 64 + j] | codes[i * 64 + j + 1] | codes[i * 64 + j + 2])  /* optimized C */
30                          cbp |= 1 << (5 - i);  uint32_t
31    calc_cbp_c(const int16_t codes[6 * 64])
32    {
33            unsigned int i=6;
34            uint32_t cbp = 0;
35    
36    /* uses fixed relation: 4*codes = 1*codes64 */
37    /* if prototype is changed (e.g. from int16_t to something like int32) this routine
38       has to be changed! */
39    
40            do  {
41                    uint64_t *codes64 = (uint64_t*)codes;   /* the compiler doesn't really make this */
42                    uint32_t *codes32 = (uint32_t*)codes;   /* variables, just "addressing modes" */
43    
44                    cbp += cbp;
45            if (codes[1] || codes32[1]) {
46                            cbp++;
47          }          }
48            else if (codes64[1] | codes64[2] | codes64[3]) {
49                            cbp++;
50                    }
51            else if (codes64[4] | codes64[5] | codes64[6] | codes64[7]) {
52                            cbp++;
53                    }
54            else if (codes64[8] | codes64[9] | codes64[10] | codes64[11]) {
55                            cbp++;
56                    }
57            else if (codes64[12] | codes64[13] | codes64[14] | codes64[15]) {
58                            cbp++;
59                    }
60                    codes += 64;
61                    i--;
62        } while (i != 0);
63    
64          return cbp;          return cbp;
65    }
66    
67    
68    
69    
70    /* older code maybe better on some plattforms? */
71    #if (0==1)
72            for (i = 5; i >= 0; i--) {
73                    if (codes[1] | codes[2] | codes[3])
74                            cbp |= 1 << i;
75                    else {
76                            for (j = 4; j <= 56; j+=4)      /* [60],[61],[62],[63] are last */
77                                    if (codes[j] | codes[j+1] | codes[j+2] | codes[j+3]) {
78                                    cbp |= 1 << i;
79                                    break;
80                            }
81  }  }
82                    codes += 64;
83            }
84    
85            return cbp;
86    #endif
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