main/old/cdrom.c

   1 /*
   2 THE COMPUTER CODE CONTAINED HEREIN IS THE SOLE PROPERTY OF PARALLAX
   3 SOFTWARE CORPORATION ("PARALLAX").  PARALLAX, IN DISTRIBUTING THE CODE TO
   4 END-USERS, AND SUBJECT TO ALL OF THE TERMS AND CONDITIONS HEREIN, GRANTS A
   5 ROYALTY-FREE, PERPETUAL LICENSE TO SUCH END-USERS FOR USE BY SUCH END-USERS
   6 IN USING, DISPLAYING,  AND CREATING DERIVATIVE WORKS THEREOF, SO LONG AS
   7 SUCH USE, DISPLAY OR CREATION IS FOR NON-COMMERCIAL, ROYALTY OR REVENUE
   8 FREE PURPOSES.  IN NO EVENT SHALL THE END-USER USE THE COMPUTER CODE
   9 CONTAINED HEREIN FOR REVENUE-BEARING PURPOSES.  THE END-USER UNDERSTANDS
  10 AND AGREES TO THE TERMS HEREIN AND ACCEPTS THE SAME BY USE OF THIS FILE.
  11 COPYRIGHT 1993-1999 PARALLAX SOFTWARE CORPORATION.  ALL RIGHTS RESERVED.
  12 */
  13
  14 #include <dos.h>
  15 #include <stdio.h>
  16 #include <stdlib.h>
  17 #include <string.h>
  18
  19 #include "dpmi.h"
  20
  21 typedef struct {
  22         char unit;
  23         ushort dev_offset;
  24         ushort dev_segment;
  25 } dev_list;
  26
  27 typedef struct _Dev_Hdr {
  28         unsigned int dev_next;
  29         unsigned short dev_att;
  30         ushort dev_stat;
  31         ushort dev_int;
  32         char dev_name[8];
  33         short dev_resv;
  34         char dev_letr;
  35         char dev_units;
  36 } dev_header;
  37
  38 int find_descent_cd()
  39 {
  40         dpmi_real_regs rregs;
  41
  42         // Get dos memory for call...
  43         dev_list * buf;
  44         dev_header *device;
  45         int num_drives, i;
  46         unsigned cdrive, cur_drive, cdrom_drive;
  47
  48         memset(&rregs,0,sizeof(dpmi_real_regs));
  49         rregs.eax = 0x1500;
  50         rregs.ebx = 0;
  51         dpmi_real_int386x( 0x2f, &rregs );
  52         if ((rregs.ebx & 0xffff) == 0) {
  53                 return -1;                      // No cdrom
  54         }
  55         num_drives = rregs.ebx;
  56
  57         buf = (dev_list *)dpmi_get_temp_low_buffer( sizeof(dev_list)*26 );
  58         if (buf==NULL) {
  59                 return -2;                      // Error getting memory!
  60         }
  61
  62         memset(&rregs,0,sizeof(dpmi_real_regs));
  63         rregs.es = DPMI_real_segment(buf);
  64         rregs.ebx = DPMI_real_offset(buf);
  65         rregs.eax = 0x1501;
  66         dpmi_real_int386x( 0x2f, &rregs );
  67         cdrom_drive = 0;
  68         _dos_getdrive(&cdrive);
  69         for (i = 0; i < num_drives; i++) {
  70                 device = (dev_header *)((buf[i].dev_segment<<4)+ buf[i].dev_offset);
  71                 _dos_setdrive(device->dev_letr,&cur_drive);
  72                 _dos_getdrive(&cur_drive);
  73                 if (cur_drive == device->dev_letr) {
  74                         if (!chdir("\\descent")) {
  75                                 FILE * fp;
  76                                 fp = fopen( "saturn.hog", "rb" );
  77                                 if ( fp )       {
  78                                         cdrom_drive = device->dev_letr;
  79                                         fclose(fp);
  80                                         break;
  81                                 }
  82                         }
  83                 }
  84         }
  85         _dos_setdrive(cdrive,&cur_drive);
  86         return cdrom_drive;
  87 }
  88