| lzw压缩算法的c语言实现 |
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| 来源： 作者： 添加日期：2006-7-17 6:53:04 点击次数： |
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lzw->cur_code_len = 9;
}
if(lzw->code >= 1<<CODE_LEN )
{
re_init_lzw(lzw);
}
}
//------------------------------------------------------------------------------
WORD get_next_code( PBUFFER_DATA buffer , PLZW_DATA lzw )
{
BYTE next;
WORD code;
while( buffer->by_left < lzw->cur_code_len )
{
if( buffer->index == BUFFERSIZE )
{
load_buffer( lzw->h_sour, buffer );
}
next = buffer->lp_buffer[ buffer->index++ ];
buffer->dw_buffer |= (DWORD)next << (24-buffer->by_left);
buffer->by_left += 8;
}
code = buffer->dw_buffer >> ( 32 - lzw->cur_code_len );
buffer->dw_buffer <<= lzw->cur_code_len;
buffer->by_left -= lzw->cur_code_len;
return code;
}
//------------------------------------------------------------------------------
VOID do_decode( PBUFFER_DATA in, PBUFFER_DATA out, PLZW_DATA lzw, PSTACK_DATA stack)
{
WORD code;
WORD tmp;
while( in->index != in->top )
{
code = get_next_code( in ,lzw );
if( code < 0x100 )
{
// code already in table
// then simply output the code
lzw->suffix = (BYTE)code;
}
else
{
if( code < lzw->code )
{
// code also in table
// then output code chain
tmp = lzw->lp_prefix[ code ];
while( tmp > 0x100 )
{
tmp = lzw->lp_prefix[ tmp ];
}
lzw->suffix = (BYTE)tmp;
}
else
{
// code == lzw->code
// code not in table
// add code into table
// and out put code
tmp = lzw->prefix;
while( tmp > 0x100 )
{
tmp = lzw->lp_prefix[ tmp ];
}
lzw->suffix = (BYTE)tmp;
}
}
insert_2_table( lzw );
out_code(code,out,lzw,stack);
lzw->prefix = code;
}
}
//------------------------------------------------------------------------------
VOID decode( HANDLE h_sour, HANDLE h_dest )
{
LZW_DATA lzw;
BUFFER_DATA in ;
BUFFER_DATA out;
STACK_DATA stack;
BOOL first_run;
first_run = TRUE;
lzw_create( &lzw ,h_sour,h_dest );
buffer_create( &in ); |
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