msdos/int11.c

   1 /*
   2  * BIOS interrupt 11h handler
   3  */
   4
   5 #include <stdlib.h>
   6 #include "miscemu.h"
   7 #include "msdos.h"
   8 #include "drive.h"
   9 #include "debugtools.h"
  10
  11 /**********************************************************************
  12  *          INT_Int11Handler
  13  *
  14  * Handler for int 11h (get equipment list).
  15  */
  16 void WINAPI INT_Int11Handler( CONTEXT86 *context )
  17 {
  18     int diskdrives = 0;
  19     int parallelports = 0;
  20     int serialports = 0;
  21     int x;
  22
  23 /* borrowed from Ralph Brown's interrupt lists
  24
  25                     bits 15-14: number of parallel devices
  26                     bit     13: [Conv] Internal modem
  27                     bit     12: reserved
  28                     bits 11- 9: number of serial devices
  29                     bit      8: reserved
  30                     bits  7- 6: number of diskette drives minus one
  31                     bits  5- 4: Initial video mode:
  32                                     00b = EGA,VGA,PGA
  33                                     01b = 40 x 25 color
  34                                     10b = 80 x 25 color
  35                                     11b = 80 x 25 mono
  36                     bit      3: reserved
  37                     bit      2: [PS] =1 if pointing device
  38                                 [non-PS] reserved
  39                     bit      1: =1 if math co-processor
  40                     bit      0: =1 if diskette available for boot
  41 */
  42 /*  Currently the only of these bits correctly set are:
  43                 bits 15-14              } Added by William Owen Smith,
  44                 bits 11-9               } wos@dcs.warwick.ac.uk
  45                 bits 7-6
  46                 bit  2                  (always set)
  47 */
  48
  49     if (DRIVE_IsValid(0)) diskdrives++;
  50     if (DRIVE_IsValid(1)) diskdrives++;
  51     if (diskdrives) diskdrives--;
  52
  53     for (x=0; x!=MAX_PORTS; x++)
  54     {
  55         if (COM[x].devicename)
  56             serialports++;
  57         if (LPT[x].devicename)
  58             parallelports++;
  59     }
  60     if (serialports > 7)                /* 3 bits -- maximum value = 7 */
  61         serialports=7;
  62     if (parallelports > 3)              /* 2 bits -- maximum value = 3 */
  63         parallelports=3;
  64
  65     AX_reg(context) = (diskdrives << 6) | (serialports << 9) |
  66                       (parallelports << 14) | 0x02;
  67 }