workbench/devs/diskimage/dms/u_rle.c

   1 /*
   2  *     xDMS  v1.3  -  Portable DMS archive unpacker  -  Public Domain
   3  *     Written by     Andre Rodrigues de la Rocha  <adlroc@usa.net>
   4  *
   5  *     Run Length Encoding decompression function used in most
   6  *     modes after decompression by other algorithm
   7  *
   8  */
   9
  10 #include "xdms.h"
  11
  12 UWORD Unpack_RLE (struct xdms_data *xdms, UBYTE *in, UBYTE *out, UWORD origsize) {
  13         UWORD n;
  14         UBYTE a,b, *outend;
  15
  16         outend = out+origsize;
  17         while (out<outend){
  18                 if ((a = *in++) != 0x90)
  19                         *out++ = a;
  20                 else if (!(b = *in++))
  21                         *out++ = a;
  22                 else {
  23                         a = *in++;
  24                         if (b == 0xff) {
  25                                 n = *in++;
  26                                 n = (UWORD)((n<<8) + *in++);
  27                         } else
  28                                 n = b;
  29                         if (out+n > outend) return 1;
  30                         memset(out,a,(size_t) n);
  31                         out += n;
  32                 }
  33         }
  34         return 0;
  35 }