| Èçäàòåëüñêèé äîì ÎÎÎ "Ãåéì Ëýíä" | ÑÏÅÖÂÛÏÓÑÊ ÆÓÐÍÀËÀ ÕÀÊÅÐ #62, ßÍÂÀÐÜ 2006 ã. |
Àëãîðèòìû ñæàòèÿ
GPcH (admin@dotfix.net)
Ñïåöâûïóñê: Õàêåð, íîìåð #062, ñòð. 062-062-5
www.ibsensoftware.com — ñàéò àâòîðîâ aplib. çäåñü ìîæíî ñêà×àòü áèáëèîòåêó èëè ñîðöû äåïàêåðà. òàêæå èìååòñß âîçìîæíîñòü êóïèòü aplib äëß êîììåð×åñêîé ýêñïëóàòàöèè, ïðàâäà, çà $29.
http://en.wikipedia.org — ïðîñòàß ýíöèêëîïåäèß, íåñìîòðß íà ýòî èìåííî â íåé î×åíü ïîäðîáíî ðàññìîòðåíû ìíîãèå àëãîðèòìû ñæàòèß, ðàññêàçàíî îá àâòîðàõ, äàíû àðõèïîëåçíûå ïåðåêðåñòíûå ññûëêè íà îïèñàíèå ðàçëè×íûõ òåõíîëîãèé, èñïîëüçóåìûõ ïðè ïîñòðîåíèè òîãî èëè èíîãî àëãîðèòìà.
êñòàòè, âîò ññûëêà íà îïèñàíèå àëãîðèòìîâ:
http://en.wikipedia.org/wiki/category:lossless_compression_algorithms.
ñàéòû ïîïóëßðíûõ àðõèâàòîðîâ:
www.powerarchiver.com — äîâîëüíî ìîùíûé ïàêåð. ñæèìàåò â ôîðìàòå 7zip. ïëàòíûé — ñòîèò îêîëî $20.
www.izarc.org — íàêîíåö-òî! åäèíñòâåííûé ïóòåâûé ïàêåð, êîòîðûé ìîæíî ïîëó×èòü àáñîëþòíî áåñïëàòíî. ïëþñ èìååòñß ïîääåðæêà òàêèõ ôîðìàòîâ, êàê 7-zip, a, ace, arc, arj, b64, bh, bin, bz2, bza, c2d, cab, cdi, cpio, deb, enc, gca, gz, gza, ha, img, iso, jar, lha, lib, lzh, mdf, mbf, mim, nrg, pak, pdi, pk3, rar, rpm, tar, taz, tbz, tgz, tz, uue, war, xxe, yz1, z, zip, zoo. âïå×àòëßåò?
Ðàñïàêîâùèê aplib íà Ñ: êàê âñå ïðîñòî
unsigned int aP_depack(unsigned char *source, unsigned char *destination)
{
unsigned int offs, len, R0, LWM;
int done; int i; aP_d_input = source;
aP_d_output = destination; LWM = 0;
aP_d_tagpos = 0; *aP_d_output = *aP_d_input;
aP_d_output++; aP_d_input++; done = 0;
while (!done)
{ if (aP_d_getbit()) { if (aP_d_getbit()) {
if (aP_d_getbit())
{
offs = 0;
for (i = 4; i; i--) offs = (offs << 1) + aP_d_getbit();
if (offs)
{
*aP_d_output = *(aP_d_output - offs);
aP_d_output++;
} else {
*aP_d_output = 0x00;
aP_d_output++;
}
LWM = 0;
} else {
offs = *aP_d_input;
aP_d_input++;
len = 2 + (offs & 0x0001);
offs >>= 1;
if (offs)
{
for (; len; len--)
{
*aP_d_output = *(aP_d_output - offs);
aP_d_output++;
}
} else done = 1;
R0 = offs;
LWM = 1;
}
} else {
offs = aP_d_getgamma();
if ((LWM == 0) && (offs == 2))
{
offs = R0;
len = aP_d_getgamma();
for (; len; len--)
{
*aP_d_output = *(aP_d_output - offs);
aP_d_output++;
}
} else {
if (LWM == 0) offs -= 3; else offs -= 2;
offs <<= 8;
offs += *aP_d_input;
aP_d_input++;
len = aP_d_getgamma();
if (offs >= 32000) len++;
if (offs >= 1280) len++;
if (offs < 128) len += 2;
for (; len; len--)
{
*aP_d_output = *(aP_d_output - offs);
aP_d_output++;
}
R0 = offs;
}
LWM = 1;
}
} else { *aP_d_output = *aP_d_input;
aP_d_output++; aP_d_input++;
LWM = 0; } }
return (aP_d_output - destination);
}
Îäíà èç ðåàëèçàöèé ìåòîäà Õàôôìàíà îò VVS Soft Group. Ïîëíûé èñõîäíèê — íà CD
procedure PakOneByte;
{ --- ñæàòèå è ïåðåñûëêà â âûõîäíîé áóôåð îäíîãî áàéòà --- }
Var Mask : word;
Tail : boolean;
begin
CRC:=CRC XOR InBuf[InCounter];
Mask:=CodeTable[InBuf[InCounter]]^.BiteChain SHR CounterBite;
OutWord:=OutWord OR Mask;