?? lempel-ziv 壓縮算法.txt
字號(hào):
// 本程序采用 Lempel-Ziv 壓縮算法, 云風(fēng)沒(méi)有對(duì)這個(gè)算法做深入研究
// 代碼是根據(jù) Markus Franz Xaver Johannes Oberhumer 的 LZO 改寫(xiě)
// 而成, 所以算法上的問(wèn)題請(qǐng)不要問(wèn)我, 如果你對(duì)這個(gè)壓縮算法有興趣,
// 請(qǐng)拜訪 LZO 的主頁(yè)
// http://wildsau.idv.uni-linz.ac.at/mfx/lzo.html
// LZO 屬于 GNU 軟件, 在此聲明, 本文件中的代碼使用權(quán)利不同于風(fēng)魂游
// 戲程序庫(kù)中的其他部分, 請(qǐng)遵守 GNU 協(xié)議使用.
//#include <stdio.h>
//#include <string.h>
#include <stdlib.h>
#define byte unsigned char
int _stdcall compress(void *src, unsigned src_len, void *dst);
int _stdcall decompress(void *src, unsigned src_len, void *dst);
static unsigned _do_compress (byte *in, unsigned in_len, byte *out, unsigned *out_len)
{
static long wrkmem [16384L];
register byte *ip;
byte *op;
byte *in_end = in + in_len;
byte *ip_end = in + in_len - 13;
byte *ii;
byte **dict = (byte **)wrkmem;
op = out;
ip = in;
ii = ip;
ip += 4;
for(;;)
{
register byte *m_pos;
unsigned m_off;
unsigned m_len;
unsigned dindex;
dindex = ((0x21*(((((((unsigned)(ip[3])<<6)^ip[2])<<5)^ip[1])<<5)^ip[0]))>>5) & 0x3fff;
m_pos = dict [dindex];
if(((unsigned)m_pos < (unsigned)in) ||
(m_off = (unsigned)((unsigned)ip-(unsigned)m_pos) ) <= 0 ||
m_off > 0xbfff)
goto literal;
if(m_off <= 0x0800 || m_pos[3] == ip[3])
goto try_match;
dindex = (dindex & 0x7ff ) ^ 0x201f;
m_pos = dict[dindex];
if((unsigned)(m_pos) < (unsigned)(in) ||
(m_off = (unsigned)( (int)((unsigned)ip-(unsigned)m_pos))) <= 0 ||
m_off > 0xbfff)
goto literal;
if (m_off <= 0x0800 || m_pos[3] == ip[3])
goto try_match;
goto literal;
try_match:
if(*(unsigned short*)m_pos == *(unsigned short*)ip && m_pos[2]==ip[2])
goto match;
literal:
dict[dindex] = ip;
++ip;
if (ip >= ip_end)
break;
continue;
match:
dict[dindex] = ip;
if(ip - ii > 0)
{
register unsigned t = ip - ii;
if (t <= 3)
op[-2] |= (byte)t;
else if(t <= 18)
*op++ = (byte)(t - 3);
else
{
register unsigned tt = t - 18;
*op++ = 0;
while(tt > 255)
{
tt -= 255;
*op++ = 0;
}
*op++ = (byte)tt;
}
do *op++ = *ii++; while (--t > 0);
}
ip += 3;
if(m_pos[3] != *ip++ || m_pos[4] != *ip++ || m_pos[5] != *ip++ ||
m_pos[6] != *ip++ || m_pos[7] != *ip++ || m_pos[8] != *ip++ )
{
--ip;
m_len = ip - ii;
if(m_off <= 0x0800 )
{
--m_off;
*op++ = (byte)(((m_len - 1) << 5) | ((m_off & 7) << 2));
*op++ = (byte)(m_off >> 3);
}
else
if (m_off <= 0x4000 )
{
-- m_off;
*op++ = (byte)(32 | (m_len - 2));
goto m3_m4_offset;
}
else
{
m_off -= 0x4000;
*op++ = (byte)(16 | ((m_off & 0x4000) >> 11) | (m_len - 2));
goto m3_m4_offset;
}
}
else
{
{
byte *end = in_end;
byte *m = m_pos + 9;
while (ip < end && *m == *ip)
m++, ip++;
m_len = (ip - ii);
}
if(m_off <= 0x4000)
{
--m_off;
if (m_len <= 33)
*op++ = (byte)(32 | (m_len - 2));
else
{
m_len -= 33;
*op++=32;
goto m3_m4_len;
}
}
else
{
m_off -= 0x4000;
if(m_len <= 9)
*op++ = (byte)(16|((m_off & 0x4000) >> 11) | (m_len - 2));
else
{
m_len -= 9;
*op++ = (byte)(16 | ((m_off & 0x4000) >> 11));
m3_m4_len:
while (m_len > 255)
{
m_len -= 255;
*op++ = 0;
}
*op++ = (byte)m_len;
}
}
m3_m4_offset:
*op++ = (byte)((m_off & 63) << 2);
*op++ = (byte)(m_off >> 6);
}
ii = ip;
if (ip >= ip_end)
break;
}
*out_len = op - out;
return (unsigned) (in_end - ii);
}
int _stdcall compress(void *in, unsigned in_len,
void *out)
{
byte *op = out;
unsigned t,out_len;
if (in_len <= 13)
t = in_len;
else
{
t = _do_compress (in,in_len,op,&out_len);
op += out_len;
}
if (t > 0)
{
if (op == (byte*)out && t <= 238)
*op++ = (byte) ( 17 + t );
else
if (t <= 3)
op[-2] |= (byte)t ;
else
if (t <= 18)
*op++ = (byte)(t-3);
else
{
unsigned tt = t - 18;
*op++ = 0;
while (tt > 255)
{
tt -= 255;
*op++ = 0;
}
*op++ = (byte)tt;
}
do *op++ = *ii++; while (--t > 0);
}
*op++ = 17;
*op++ = 0;
*op++ = 0;
return (op - (byte*)out);
}
int _stdcall decompress (void *in, unsigned in_len,
void *out)
{
register byte *op;
register byte *ip;
register unsigned t;
register byte *m_pos;
byte *ip_end = (byte*)in + in_len;
op = out;
ip = in;
if(*ip > 17)
{
t = *ip++ - 17;
if (t < 4)
goto match_next;
do *op++ = *ip++; while (--t > 0);
goto first_literal_run;
}
for(;;)
{
t = *ip++;
if (t >= 16) goto match;
if (t == 0)
{
while (*ip == 0)
{
t += 255;
ip++;
}
t += 15 + *ip++;
}
* (unsigned *) op = * ( unsigned *) ip;
op += 4; ip += 4;
if (--t > 0)
{
if (t >= 4)
{
do
{
* (unsigned * ) op = * ( unsigned * ) ip;
op += 4; ip += 4; t -= 4;
} while (t >= 4);
if (t > 0) do *op++ = *ip++; while (--t > 0);
}
else
do *op++ = *ip++; while (--t > 0);
}
first_literal_run:
t = *ip++;
if (t >= 16)
goto match;
m_pos = op - 0x0801;
m_pos -= t >> 2;
m_pos -= *ip++ << 2;
*op++ = *m_pos++; *op++ = *m_pos++; *op++ = *m_pos;
goto match_done;
for(;;)
{
match:
if (t >= 64)
{
m_pos = op - 1;
m_pos -= (t >> 2) & 7;
m_pos -= *ip++ << 3;
t = (t >> 5) - 1;
goto copy_match;
}
else
if (t >= 32)
{
t &= 31;
if (t == 0)
{
while (*ip == 0)
{
t += 255;
ip++;
}
t += 31 + *ip++;
}
m_pos = op - 1;
m_pos -= (* ( unsigned short * ) ip) >> 2;
ip += 2;
}
else
if (t >= 16)
{
m_pos = op;
m_pos -= (t & 8) << 11;
t &= 7;
if (t == 0)
{
while (*ip == 0)
{
t += 255;
ip++;
}
t += 7 + *ip++;
}
m_pos -= (* ( unsigned short *) ip) >> 2;
ip += 2;
if (m_pos == op)
goto eof_found;
m_pos -= 0x4000;
}
else
{
m_pos = op - 1;
m_pos -= t >> 2;
m_pos -= *ip++ << 2;
*op++ = *m_pos++; *op++ = *m_pos;
goto match_done;
}
if (t >= 6 && (op - m_pos) >= 4)
{
* (unsigned *) op = * ( unsigned *) m_pos;
op += 4; m_pos += 4; t -= 2;
do
{
* (unsigned *) op = * ( unsigned *) m_pos;
op += 4; m_pos += 4; t -= 4;
}while (t >= 4);
if (t > 0)
do *op++ = *m_pos++; while (--t > 0);
}
else
{
copy_match:
*op++ = *m_pos++; *op++ = *m_pos++;
do *op++ = *m_pos++; while (--t > 0);
}
match_done:
t = ip[-2] & 3;
if (t == 0) break;
match_next:
do *op++ = *ip++; while (--t > 0);
t = *ip++;
}
}
eof_found:
if (ip != ip_end) return -1;
return (op - (byte*)out);
}
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