[cvs] / xvidcore / src / bitstream / bitstream.h Repository:
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revision 1.15, Tue Nov 26 23:44:10 2002 UTC revision 1.16.2.2, Mon Jul 28 12:39:32 2003 UTC
# Line 57  Line 57 
57  #ifndef _BITSTREAM_H_  #ifndef _BITSTREAM_H_
58  #define _BITSTREAM_H_  #define _BITSTREAM_H_
59    
60    #include <stdio.h>
61    
62  #include "../portab.h"  #include "../portab.h"
63  #include "../decoder.h"  #include "../decoder.h"
64  #include "../encoder.h"  #include "../encoder.h"
# Line 165  Line 167 
167                            uint32_t length)                            uint32_t length)
168  {  {
169          uint32_t tmp;          uint32_t tmp;
170            size_t bitpos;
171            ptr_t adjbitstream = (ptr_t)bitstream;
172    
173          bs->start = bs->tail = (uint32_t *) bitstream;          /*
174             * Start the stream on a uint32_t boundary, by rounding down to the
175             * previous uint32_t and skipping the intervening bytes.
176             */
177            bitpos = ((sizeof(uint32_t)-1) & (size_t)bitstream);
178            adjbitstream = adjbitstream - bitpos;
179            bs->start = bs->tail = (uint32_t *) adjbitstream;
180    
181          tmp = *(uint32_t *) bitstream;          tmp = *bs->start;
182  #ifndef ARCH_IS_BIG_ENDIAN  #ifndef ARCH_IS_BIG_ENDIAN
183          BSWAP(tmp);          BSWAP(tmp);
184  #endif  #endif
185          bs->bufa = tmp;          bs->bufa = tmp;
186    
187          tmp = *((uint32_t *) bitstream + 1);          tmp = *(bs->start + 1);
188  #ifndef ARCH_IS_BIG_ENDIAN  #ifndef ARCH_IS_BIG_ENDIAN
189          BSWAP(tmp);          BSWAP(tmp);
190  #endif  #endif
191          bs->bufb = tmp;          bs->bufb = tmp;
192    
193          bs->buf = 0;          bs->buf = 0;
194          bs->pos = 0;          bs->pos = bs->initpos = bitpos*8;
195          bs->length = length;          bs->length = length;
196  }  }
197    
# Line 208  Line 218 
218          bs->bufb = tmp;          bs->bufb = tmp;
219    
220          bs->buf = 0;          bs->buf = 0;
221          bs->pos = 0;          bs->pos = bs->initpos;
222  }  }
223    
224    
# Line 301  Line 311 
311  static uint32_t __inline  static uint32_t __inline
312  BitstreamPos(const Bitstream * const bs)  BitstreamPos(const Bitstream * const bs)
313  {  {
314          return 8 * ((ptr_t)bs->tail - (ptr_t)bs->start) + bs->pos;          return((uint32_t)(8*((ptr_t)bs->tail - (ptr_t)bs->start) + bs->pos - bs->initpos));
315  }  }
316    
317    
# Line 312  Line 322 
322  static uint32_t __inline  static uint32_t __inline
323  BitstreamLength(Bitstream * const bs)  BitstreamLength(Bitstream * const bs)
324  {  {
325          uint32_t len = (ptr_t) bs->tail - (ptr_t) bs->start;          uint32_t len = (uint32_t)((ptr_t)bs->tail - (ptr_t)bs->start);
326    
327          if (bs->pos) {          if (bs->pos) {
328                  uint32_t b = bs->buf;                  uint32_t b = bs->buf;
# Line 325  Line 335 
335                  len += (bs->pos + 7) / 8;                  len += (bs->pos + 7) / 8;
336          }          }
337    
338            /* initpos is always on a byte boundary */
339            if (bs->initpos)
340                    len -= bs->initpos/8;
341    
342          return len;          return len;
343  }  }
344    
# Line 349  Line 363 
363          }          }
364  }  }
365    
   
 /* pad bitstream to the next byte boundary */  
   
 static void __inline  
 BitstreamPad(Bitstream * const bs)  
 {  
         uint32_t remainder = bs->pos % 8;  
   
         if (remainder) {  
                 BitstreamForward(bs, 8 - remainder);  
         }  
 }  
   
   
366  /* read n bits from bitstream */  /* read n bits from bitstream */
367    
368  static uint32_t __inline  static uint32_t __inline
# Line 425  Line 425 
425          }          }
426  }  }
427    
428    static const int stuffing_codes[8] =
429    {
430                    /* nbits     stuffing code */
431            0,              /* 1          0 */
432            1,              /* 2          01 */
433            3,              /* 3          011 */
434            7,              /* 4          0111 */
435            0xf,    /* 5          01111 */
436            0x1f,   /* 6          011111 */
437            0x3f,   /* 7          0111111 */
438            0x7f,   /* 8          01111111 */
439    };
440    
441    /* pad bitstream to the next byte boundary */
442    
443    static void __inline
444    BitstreamPad(Bitstream * const bs)
445    {
446            int bits = 8 - (bs->pos % 8);
447            if (bits < 8)
448                    BitstreamPutBits(bs, stuffing_codes[bits - 1], bits);
449    }
450    
451    /*
452     * pad bitstream to the next byte boundary
453     * alway pad: even if currently at the byte boundary
454     */
455    
456    static void __inline
457    BitstreamPadAlways(Bitstream * const bs)
458    {
459            int bits = 8 - (bs->pos % 8);
460            BitstreamPutBits(bs, stuffing_codes[bits - 1], bits);
461    }
462    
463  #endif /* _BITSTREAM_H_ */  #endif /* _BITSTREAM_H_ */
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