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 #pragma off (unreferenced)
  15 static char rcsid[] = "$Id: cdrom.c,v 1.1.1.1 2001-01-19 03:30:14 bradleyb Exp $";
  16 #pragma on (unreferenced)
  17
  18 #include <dos.h>
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <string.h>
  22
  23 #include "dpmi.h"
  24
  25 typedef struct {
  26         char unit;
  27         ushort dev_offset;
  28         ushort dev_segment;
  29 } dev_list;
  30
  31 typedef struct _Dev_Hdr {
  32         unsigned int dev_next;
  33         unsigned short dev_att;
  34         ushort dev_stat;
  35         ushort dev_int;
  36         char dev_name[8];
  37         short dev_resv;
  38         char dev_letr;
  39         char dev_units;
  40 } dev_header;
  41
  42 int find_descent_cd()
  43 {
  44         dpmi_real_regs rregs;
  45
  46         // Get dos memory for call...
  47         dev_list * buf;
  48         dev_header *device;
  49         int num_drives, i;
  50         unsigned cdrive, cur_drive, cdrom_drive;
  51
  52         memset(&rregs,0,sizeof(dpmi_real_regs));
  53         rregs.eax = 0x1500;
  54         rregs.ebx = 0;
  55         dpmi_real_int386x( 0x2f, &rregs );
  56         if ((rregs.ebx & 0xffff) == 0) {
  57                 return -1;                      // No cdrom
  58         }
  59         num_drives = rregs.ebx;
  60
  61         buf = (dev_list *)dpmi_get_temp_low_buffer( sizeof(dev_list)*26 );
  62         if (buf==NULL) {
  63                 return -2;                      // Error getting memory!
  64         }
  65
  66         memset(&rregs,0,sizeof(dpmi_real_regs));
  67         rregs.es = DPMI_real_segment(buf);
  68         rregs.ebx = DPMI_real_offset(buf);
  69         rregs.eax = 0x1501;
  70         dpmi_real_int386x( 0x2f, &rregs );
  71         cdrom_drive = 0;
  72         _dos_getdrive(&cdrive);
  73         for (i = 0; i < num_drives; i++) {
  74                 device = (dev_header *)((buf[i].dev_segment<<4)+ buf[i].dev_offset);
  75                 _dos_setdrive(device->dev_letr,&cur_drive);
  76                 _dos_getdrive(&cur_drive);
  77                 if (cur_drive == device->dev_letr) {
  78                         if (!chdir("\\descent")) {
  79                                 FILE * fp;
  80                                 fp = fopen( "saturn.hog", "rb" );
  81                                 if ( fp )       {
  82                                         cdrom_drive = device->dev_letr;
  83                                         fclose(fp);
  84                                         break;
  85                                 }
  86                         }
  87                 }
  88         }
  89         _dos_setdrive(cdrive,&cur_drive);
  90         return cdrom_drive;
  91 }
  92