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【C】 RLE编码
作者:李海俊 / 发布于2011/10/9/ 634
<div>?/*---rle.c---------------------------------------------------------
* Decode & Encode a file for RLE.
*
* Entry: RLEEncode(IN unsigned char *infile,// input file buffer
* IN unsigned long inlen, // input length
* IN unsigned char *outfile, // output file buffer
* IN&OUT unsigned long *outlen, // output length
* IN unsigned char sentinel1, // default sentinel
* IN unsigned char sentinel2 // changed sentinel
* );
*
* RLEEncode() returns:
* -1: output buffer too small
* 0: success
* 
* Entry: RLEDecode(IN unsigned char *infile, // input file buffer
* IN unsigned long inlen, // input length
* IN unsigned char *outfile, // output file length
* IN&OUT unsigned long *outlen // output length
* );
*
* RLEDecode() returns:
* 0: success
* 1: outlen too small, and return outlen was needed;
*
*---------------------------------------------------------------*/
#include <windows.h>
#include <stdio.h></div>
<div>int RLEEncode( unsigned char *infile, unsigned long inlen, 
 unsigned char *outfile, unsigned long *outlen,
 unsigned char sentinel1, unsigned char sentinel2)
{
 unsigned char sentinel,
 prev_char;
 unsigned long i,
 j;
 unsigned short count;
 
 sentinel = sentinel1;</div>
<div> i = 0;
 j = 0;
 count = 1; 
 
 outfile[ j++ ] = 'R';
 outfile[ j++ ] = 'L';
 outfile[ j++ ] = 'E';
 outfile[ j++ ] = sentinel1;
 outfile[ j++ ] = sentinel2;
 
 *(unsigned long *)&outfile[ j ] = inlen;
 j += sizeof( unsigned long );</div>
<div> while ( i <= inlen )
 {
 if ( j > *outlen )
 {
 return -1;
 }
count = 1;
 prev_char = infile[ i++ ];
 if ( prev_char == sentinel )
 {
 outfile[ j++ ] = sentinel;
 outfile[ j++ ] = 0x00;
 if ( sentinel == sentinel1 )
 {
 outfile[ j++ ] = sentinel2;
 sentinel = sentinel2;
 }
 else
 {
 outfile[ j++ ] = sentinel1;
 sentinel = sentinel1;
 }
 } 
 while ( prev_char == infile[ i ] )
 {
 i++;
 count++;
 if ( i > inlen ) 
 {
 break;
 }
 if ( count == 255 )
 {
 break;
 }
 }
 switch ( count )
 {
 case 1:
 outfile[ j++ ] = prev_char;
 break;
 case 2:
 outfile[ j++ ] = prev_char;
 outfile[ j++ ] = prev_char;
 break;
 default:
 outfile[ j++ ] = sentinel;
 outfile[ j++ ] = count;
 outfile[ j++ ] = prev_char;
 break;
 } 
 }
 *outlen = j;
 return 0;
}
<div>int RLEDecode( unsigned char *infile, unsigned long inlen, 
 unsigned char *outfile, unsigned long *outlen )
{
 unsigned long i,
 j,
 len;
 unsigned char default_sentinel,
 change_sentinel,
 prev_char;
 unsigned short count;
 
 i = 0;
 j = 0;
 if ( infile[ i++ ] == 'R' &&\
 infile[i++] == 'L' && \
 infile[i++] == 'E')
 {
 default_sentinel = infile[ i++ ];
 change_sentinel = infile[ i++ ];
 len = *( unsigned long * )&infile[ i ];
 i += sizeof ( unsigned long );
 if ( *outlen < len )
 {
 *outlen = len;
 return 1;
 }
 }
 else
 {
 return 2;
 }
 
 while ( i < inlen )
 {
 prev_char = infile[ i++ ];
 count = 1;
 if ( prev_char == default_sentinel )
 {
 if ( infile[ i ] == 0x00 )
 { 
 i++;
 if ( change_sentinel == infile[ i ] )
 {
 change_sentinel = default_sentinel;
 default_sentinel = infile[ i++ ];
 continue;
 }
 else
 {
 // error
 }
 }
 else
 {
 count = infile[ i ];
 i++;
 prev_char = infile[ i++ ];
 }
 }
 do
 {
 outfile[ j++ ] = prev_char;
 }
 while ( --count );
 }
 return 0;
}
<div>int main ( int argc, char *argv[] )
{
char *szinfile = "C:\\1.bin";
char *szoutfile = "C:\\2.bin";
HANDLE hinfile,
 houtfile;
HANDLE hmapinfile;
unsigned char *lpinfile, 
 *lpoutfile;
unsigned long dwinfile_size = 0, 
 dwoutfile_size = 0, 
 dwwrite = 0, 
 save_size = 0;</div>
<div>hinfile = CreateFileA ( szinfile, GENERIC_READ, FILE_SHARE_READ,\
0, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0 );</div>
<div>dwinfile_size = GetFileSize ( hinfile, NULL );</div>
<div>hmapinfile = CreateFileMapping ( hinfile, NULL, PAGE_READONLY, \
0, 0, NULL );</div>
<div>lpinfile = ( unsigned char * ) MapViewOfFile ( hmapinfile, FILE_MAP_READ, 0, 0, 0 );</div>
<div>RLEDecode ( lpinfile, dwinfile_size, 0 ,&dwoutfile_size );
//save_size = dwoutfile_size = dwinfile_size * 2;</div>
<div>lpoutfile = ( unsigned char * ) VirtualAlloc ( NULL, dwoutfile_size, \
MEM_RESERVE | MEM_COMMIT, PAGE_READWRITE );</div>
<div>//RLEEncode ( lpinfile, dwinfile_size, lpoutfile, &dwoutfile_size, 'A', 'B' );
RLEDecode ( lpinfile, dwinfile_size, lpoutfile, &dwoutfile_size );</div>
<div>houtfile = CreateFileA ( szoutfile, GENERIC_WRITE, FILE_SHARE_READ, \
0, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, 0 );</div>
<div>WriteFile ( houtfile, lpoutfile, dwoutfile_size, &dwwrite, NULL );
VirtualFree ( lpoutfile, save_size, MEM_DECOMMIT );</div>
<div>CloseHandle ( houtfile );</div>
<div>UnmapViewOfFile ( lpinfile );
CloseHandle ( hmapinfile );
CloseHandle ( hinfile );
return 0;
}
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