[bug-pcl] bugs in PCL compression mode 9

[Henry Stiles]

Hello Derek

Thanks for the patch, could you post the pcl file that prompted the
change.  Thanks in advance.

Derek B. Noonburg writes:
 > There are a couple of problems with the uncompress_9 function in
 > GhostPCL 1.41.  I'm attaching a patch file.
 > 
 > I've only done minor testing (with output from a Windows driver for the
 > Brother 1850).  Also, it seems to match up with the code in the PCL3
 > driver in ghostscript (which compresses images using mode 9).
 > 
 > - Derek
 > *** rtrstcmp.c.orig	Mon Mar 14 17:16:12 2005
 > --- rtrstcmp.c	Mon Mar 14 17:16:52 2005
 > ***************
 > *** 194,201 ****
 >           if (comp) {
 >               offset = (val >> 5) & 0x3;
 >               more_offset = (offset == 0x3);
 > !             cnt = (val & 0x1f) + 1;
 > !             more_cnt = (cnt == 0x20);
 >           } else {
 >               offset = (val >> 3) & 0xf;
 >               more_offset = (offset == 0xf);
 > --- 194,201 ----
 >           if (comp) {
 >               offset = (val >> 5) & 0x3;
 >               more_offset = (offset == 0x3);
 > !             cnt = (val & 0x1f) + 2;
 > !             more_cnt = (cnt == 0x21);
 >           } else {
 >               offset = (val >> 3) & 0xf;
 >               more_offset = (offset == 0xf);
 > ***************
 > *** 213,244 ****
 >               uint    extra = *pin++;
 >   
 >               more_cnt = (extra == 0xff);
 > !             offset += extra;
 >           }
 >   
 >           if ((pb += offset) >= plim)
 >               break;
 >           if (comp) {
 > !             uint    j = i / 2;
 > ! 
 > !             while (j-- > 0) {
 > !                 uint    rep_cnt = *pin++;
 > !                 uint    rep_val = *pin++;
 > ! 
 > !                 if (rep_cnt > plim - pb)
 > !                     rep_cnt = plim - pb;
 > !                 while (rep_cnt-- > 0)
 > !                     *pb++ = rep_val;
 > !             }
 > !             i -= 2 * j;
 >               
 >           } else {
 >               if (cnt > i)
 >                   cnt = i;
 > -             i -= cnt;
 > -             pin += cnt;
 >               if (cnt > plim - pb)
 >                   cnt = plim - pb;
 >               while (cnt-- > 0)
 >                   *pb++ = *pin++;
 >           }
 > --- 213,240 ----
 >               uint    extra = *pin++;
 >   
 >               more_cnt = (extra == 0xff);
 > ! 	    cnt += extra;
 >           }
 >   
 >           if ((pb += offset) >= plim)
 >               break;
 >           if (comp) {
 > ! 	    uint rep_val = 0;
 > ! 	    if (i > 0) {
 > ! 	        rep_val = *pin++;
 > ! 		--i;
 > ! 	    }
 > !             if (cnt > plim - pb)
 > !                 cnt = plim - pb;
 > !             while (cnt-- > 0)
 > !                 *pb++ = rep_val;
 >               
 >           } else {
 >               if (cnt > i)
 >                   cnt = i;
 >               if (cnt > plim - pb)
 >                   cnt = plim - pb;
 > +             i -= cnt;
 >               while (cnt-- > 0)
 >                   *pb++ = *pin++;
 >           }
 > _______________________________________________
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 > bug-pcl at ghostscript.com
 > http://www.ghostscript.com/mailman/listinfo/bug-pcl

-- 
./Henry
Artifex Software