workbench/devs/diskimage/dms/u_medium.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  *     Main decompression functions used in MEDIUM mode
   6  *
   7  */
   8
   9 #include "xdms.h"
  10
  11 #define MBITMASK 0x3fff
  12
  13 UWORD Unpack_MEDIUM (struct xdms_data *xdms, UBYTE *in, UBYTE *out, UWORD origsize) {
  14         UWORD medium_text_loc = xdms->medium_text_loc;
  15         UBYTE *text = xdms->text;
  16         UWORD i, j, c;
  17         UBYTE u, *outend;
  18
  19         INITBITBUF(in);
  20
  21         outend = out+origsize;
  22         while (out < outend) {
  23                 if (GETBITS(1)!=0) {
  24                         DROPBITS(1);
  25                         *out++ = text[medium_text_loc++ & MBITMASK] = (UBYTE)GETBITS(8);
  26                         DROPBITS(8);
  27                 } else {
  28                         DROPBITS(1);
  29                         c = GETBITS(8);  DROPBITS(8);
  30                         j = (UWORD)(d_code[c]+3);
  31                         u = d_len[c];
  32                         c = (UWORD)(((c << u) | GETBITS(u)) & 0xff);  DROPBITS(u);
  33                         u = d_len[c];
  34                         c = (UWORD)((d_code[c] << 8) | (((c << u) | GETBITS(u)) & 0xff));  DROPBITS(u);
  35                         i = (UWORD)(medium_text_loc - c - 1);
  36
  37                         while(j--) *out++ = text[medium_text_loc++ & MBITMASK] = text[i++ & MBITMASK];
  38
  39                 }
  40         }
  41         xdms->medium_text_loc = (UWORD)((medium_text_loc+66) & MBITMASK);
  42
  43         return 0;
  44 }