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bitstream.c
Package: vcShiPinHuiYiKaiFaJiShuYuShiLi04.rar　[view]
Upload User: hbbaokai
Upload Date: 2009-07-13
Package Size: 328k
Code Size: 1k
Category:

VOIP program

Development Platform:

Visual C++

bitstream.c：Code Content
  1. #include "bitstream.h"
  2. static unsigned int mask[33] =
  3. {
  4.   0x00000000, 0x00000001, 0x00000003, 0x00000007,
  5.   0x0000000f, 0x0000001f, 0x0000003f, 0x0000007f,
  6.   0x000000ff, 0x000001ff, 0x000003ff, 0x000007ff,
  7.   0x00000fff, 0x00001fff, 0x00003fff, 0x00007fff,
  8.   0x0000ffff, 0x0001ffff, 0x0003ffff, 0x0007ffff,
  9.   0x000fffff, 0x001fffff, 0x003fffff, 0x007fffff,
  10.   0x00ffffff, 0x01ffffff, 0x03ffffff, 0x07ffffff,
  11.   0x0fffffff, 0x1fffffff, 0x3fffffff, 0x7fffffff,
  12.   0xffffffff
  13. };
  14. static unsigned char *byteptr;
  15. static int bytecnt; 
  16. static unsigned char outbfr;
  17. static int outcnt;
  18. void Bitstream_Init(void *buffer)
  19. {
  20. byteptr = (unsigned char *)buffer;
  21. bytecnt = 0;
  22. outbfr = 0;
  23. outcnt = 8;
  24. }
  25. void Bitstream_PutBits(int n, unsigned int val)
  26. {
  27. int diff;
  28. while ((diff = n - outcnt) >= 0) { 
  29. outbfr |= (unsigned char)(val >> diff);
  31. n = diff;
  32. val &= mask[n];
  33. *(byteptr ++) = outbfr;
  34. bytecnt++;
  35. outbfr = 0;
  36. outcnt = 8;
  37. }
  38. if (n > 0) { 
  39. outbfr |= (unsigned char)(val << (-diff));
  40. outcnt -= n;
  41. }
  42. }
  43. int Bitstream_Close()
  44. {
  45. while (outcnt != 8) Bitstream_PutBits(1, 1);
  46. return bytecnt;
  47. }
  48. int Bitstream_NextStartCode()
  49. {
  50. int count = outcnt;
  51. Bitstream_PutBits(1,0);
  52. while (outcnt != 8) Bitstream_PutBits(1, 1);
  53. return (count);
  54. }
  55. int Bitstream_GetLength()
  56. {
  57. return bytecnt;
  58. }