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From: karl@mstar.UUCP
Newsgroups: comp.sources.misc
Subject: Very small ZCAT program for decompressing *.Z files
Message-ID: <8705141214.AA19848@mstar.UUCP>
Date: Thu, 14-May-87 11:14:37 EDT
Article-I.D.: mstar.8705141214.AA19848
Posted: Thu May 14 11:14:37 1987
Date-Received: Tue, 19-May-87 04:41:34 EDT
References: <3655@mirror.TMC.COM>
Sender: allbery@ncoast.UUCP
Reply-To: karl@mstar.UUCP (Karl Fox)
Organization: Morning Star Technologies, Columbus, Ohio
Lines: 57
Approved: allbery@ncoast.UUCP
Status: R


Sorry if this is too short -- I didn't know where else to put it.

This 'zcat' program works much like the standard public domain zcat
(which is usually linked to compress and uncompress), except that it
is only a filter -- no command line arguments are used.  We use it
frequently when shipping compressed software to customers over UUCP,
many of whom are not UNIX wizards and don't routinely get good stuff
like compress.c from usenet.

I was going to submit it to the Obfuscated C contest until I saw the
requirement about entries being original work.  This program is derived
directly from the public domain compress.c.  It requires that your
machine be able to support 16-bit decompression, which uses very large
arrays for hashing.

If somebody wanted to make a SHAR that could compress and uuencode
files, then include a small program (like this, but with uudecode,
too?) that could transform it back, I would kiss their feet.

#!/bin/sh
#
#    This is a SHAR archive.  To extract, remove everything
#    above the #!/bin/sh line and type "sh filename"
#
if `test ! -s ./zcat.c`
then
    echo "Writing ./zcat.c"
    sed 's/^X//' > ./zcat.c << '\End\of\File\ ./zcat.c'
X#include <stdio.h>
X#define d define
X#d G getchar()
X#d I if
X#d H(n) ((C*)h)[n]
X#d C char
X#d U unsigned long
X#d u unsigned short
X#d R register C*
X#d B(n) (1<<(n))
X#d V(a,b) (a&(B(b)-1))
X#d E {fprintf(stderr,"Bad COMPRESS file format\n");exit(1);}
Xint i,q,b,n,k=16,e=128,j=0,O=0,S=0;u t[69001];long o,v,c,m,M=B(16),f=0;U h[
X69001];C D[16];long g(){R p=D;I(j>0||O>=S||f>m){I(f>m)m= ++n==k?M:B(n)-1;I(j>0)
Xm=B(n=9)-1,j=0;S=fread(D,1,n,stdin);I(S<=0)return-1;O=0;S=(S<<3)-n+1;}q=O;b=n;p
X+=q>>3;q&=7;c=V(*p++>>q,8-q);q=8-q;b-=q;I(b>=8)c|=(*p++&255)<<q,q+=8,b-=8;c|=V(
X*p,b)<<q;O+=n;return c;}main(){I(G!=31||G!=157)E;k=G;e=k&128;k&=31;M=B(k);I(k>
X16)E;z();exit(0);}z(){long w;R s;m=B(n=9)-1;for(w=255;w>=0;w--)t[w]=0,H(w)=(C)w
X;f=e?257:256;i=o=g();I(o==-1)return;putchar((C)i);s=(C*)&H(B(16));while((w=g())
X>-1){I(w==256&&e){for(w=255;w>=0;w--)t[w]=0;j=1;f=256;I((w=g())==-1)break;}v=w;
XI(w>=f)*s++=i,w=o;while((U)w>=(U)256)*s++=H(w),w=t[w];*s++=i=H(w);do putchar(*
X--s);while(s>&H(B(16)));I((w=f)<M)t[w]=(u)o,H(w)=i,f=w+1;o=v;}}
\End\of\File\ ./zcat.c
else
    echo "Not overwriting ./zcat.c"
fi
echo "Finished archive 1 of 1"
exit
-- 
Karl Fox, Morning Star Technologies, Inc.    ...!{cbatt,cbosgd}!mstar!karl