| lzw压缩算法的c语言实现 |
|
|
|
|
| 来源： 作者： 添加日期：2006-7-17 6:53:04 点击次数： |
|
buffer->index = 0;
buffer->top = (WORD)ret;
return (WORD)ret;
}
//------------------------------------------------------------------------------
WORD empty_buffer( PLZW_DATA lzw, PBUFFER_DATA buffer)// Output buffer to file
{
DWORD ret;
if(buffer->end_flag) // The flag mark the end of decode
{
if( buffer->by_left )
{
buffer->lp_buffer[ buffer->index++ ] = (BYTE)( buffer->dw_buffer >> 32-buffer->by_left )<<(8-buffer->by_left);
}
}
WriteFile(lzw->h_dest, buffer->lp_buffer,buffer->index,&ret,NULL);
buffer->index = 0;
buffer->top = ret;
return (WORD)ret;
}
//------------------------------------------------------------------------------
#endif
(3) hash.h 定义了压缩时所用的码表操作函数，为了快速查找使用了hash算法，还有处理hash冲突的函数
#ifndef __HASH_H__
#define __HASH_H__
//------------------------------------------------------------------------------
#include <stdio.h>
#include <stdlib.h>
#include <windows.h>
//------------------------------------------------------------------------------
#define DIV TABLE_LEN
#define HASHSTEP 13 // It should bigger than 0.
//------------------------------------------------------------------------------
WORD get_hash_index( PLZW_DATA lzw )
{
DWORD tmp;
WORD result;
DWORD prefix;
DWORD suffix;
prefix = lzw->prefix;
suffix = lzw->suffix;
tmp = prefix<<8 | suffix;
result = tmp % DIV;
return result;
}
//------------------------------------------------------------------------------
WORD re_hash_index( WORD hash ) // If hash conflict occured we must recalculate
{ // hash index .
WORD result;
result = hash + HASHSTEP;
result = result % DIV;
return result;
}
//------------------------------------------------------------------------------
BOOL in_table( PLZW_DATA lzw ) // To find whether current code is already in table.
{
BOOL result;
WORD hash;
hash = get_hash_index( lzw );
if( lzw->lp_code[ hash ] == 0xFFFF )
{
result = FALSE; |
|
| |
