[bug-pcl] bugs in PCL compression mode 9

[Derek B. Noonburg]

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
-------------- next part --------------
*** 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++;
          }