sample/mdiskchk.c

   1 /* -*- c -*- ------------------------------------------------------------- *
   2  *
   3  *   Copyright 2003-2008 H. Peter Anvin - All Rights Reserved
   4  *
   5  *   This program is free software; you can redistribute it and/or modify
   6  *   it under the terms of the GNU General Public License as published by
   7  *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
   8  *   Boston MA 02111-1307, USA; either version 2 of the License, or
   9  *   (at your option) any later version; incorporated herein by reference.
  10  *
  11  * ----------------------------------------------------------------------- */
  12
  13 /*
  14  * mdiskchk.c
  15  *
  16  * DOS program to check for the existence of a memdisk.
  17  *
  18  * This program can be compiled for DOS with the OpenWatcom compiler
  19  * (http://www.openwatcom.org/):
  20  *
  21  * wcl -3 -osx -mt mdiskchk.c
  22  */
  23
  24 #include <stdio.h>
  25 #include <string.h>
  26 #include <i86.h>                /* For MK_FP() */
  27
  28 typedef unsigned long  uint32_t;
  29 typedef unsigned short uint16_t;
  30 typedef unsigned char  uint8_t;
  31
  32 struct memdiskinfo {
  33   uint16_t bytes;               /* Bytes from memdisk */
  34   uint16_t version;             /* Memdisk version */
  35   uint32_t base;                /* Base of disk in high memory */
  36   uint32_t size;                /* Size of disk in sectors */
  37   char far * cmdline;           /* Command line */
  38   void far * oldint13;          /* Old INT 13h */
  39   void far * oldint15;          /* Old INT 15h */
  40   uint16_t olddosmem;
  41   uint8_t  bootloaderid;
  42
  43   uint8_t _pad;
  44
  45   /* We add our own fields at the end */
  46   int cylinders;
  47   int heads;
  48   int sectors;
  49 };
  50
  51 struct memdiskinfo * query_memdisk(int drive)
  52 {
  53   static struct memdiskinfo mm;
  54   uint32_t _eax, _ebx, _ecx, _edx;
  55   uint16_t _es, _di;
  56   unsigned char _dl = drive;
  57   uint16_t bytes;
  58
  59   __asm {
  60     .386 ;
  61     mov eax, 454d0800h ;
  62     mov ecx, 444d0000h ;
  63     mov edx, 53490000h ;
  64     mov dl, _dl ;
  65     mov ebx, 3f4b0000h ;
  66     int 13h ;
  67     mov _eax, eax ;
  68     mov _ecx, ecx ;
  69     mov _edx, edx ;
  70     mov _ebx, ebx ;
  71     mov _es, es ;
  72     mov _di, di ;
  73   }
  74
  75   if ( _eax >> 16 != 0x4d21 ||
  76        _ecx >> 16 != 0x4d45 ||
  77        _edx >> 16 != 0x4944 ||
  78        _ebx >> 16 != 0x4b53 )
  79     return NULL;
  80
  81   memset(&mm, 0, sizeof mm);
  82
  83   bytes = *(uint16_t far *)MK_FP(_es, _di);
  84
  85   /* 27 is the most we know how to handle */
  86   if ( bytes > 27 )
  87     bytes = 27;
  88
  89   _fmemcpy((void far *)&mm, (void far *)MK_FP(_es,_di), bytes);
  90
  91   mm.cylinders = ((_ecx >> 8) & 0xff) + ((_ecx & 0xc0) << 2) + 1;
  92   mm.heads     = ((_edx >> 8) & 0xff) + 1;
  93   mm.sectors   = (_ecx & 0x3f);
  94
  95   return &mm;
  96 }
  97
  98 const char *bootloadername(uint8_t id)
  99 {
 100   static const struct {
 101     uint8_t id, mask;
 102     const char *name;
 103   } *lp, list[] =
 104     {
 105       { 0x10, 0xf0, "LILO" },
 106       { 0x20, 0xf0, "LOADLIN" },
 107       { 0x31, 0xff, "SYSLINUX" },
 108       { 0x32, 0xff, "PXELINUX" },
 109       { 0x33, 0xff, "ISOLINUX" },
 110       { 0x34, 0xff, "EXTLINUX" },
 111       { 0x30, 0xf0, "SYSLINUX family" },
 112       { 0x40, 0xf0, "Etherboot" },
 113       { 0x50, 0xf0, "ELILO" },
 114       { 0x70, 0xf0, "GrUB" },
 115       { 0x80, 0xf0, "U-Boot" },
 116       { 0x00, 0x00, "unknown" }
 117     };
 118
 119   for ( lp = list ; ; lp++ ) {
 120     if ( ((id ^ lp->id) & lp->mask) == 0 )
 121       return lp->name;
 122   }
 123 }
 124
 125 int main(int argc, char *argv[])
 126 {
 127   int d;
 128   int found = 0;
 129   struct memdiskinfo *m;
 130
 131   for ( d = 0 ; d <= 0xff ; d++ ) {
 132     if ( (m = query_memdisk(d)) != NULL ) {
 133       printf("Drive %02X is MEMDISK %u.%02u:\n"
 134              "\tAddress = 0x%08lx, len = %lu sectors, chs = %u/%u/%u,\n"
 135              "\tloader = 0x%02x (%s),\n"
 136              "\tcmdline = %Fs\n",
 137              d, m->version >> 8, m->version & 0xff,
 138              m->base, m->size, m->cylinders, m->heads, m->sectors,
 139              m->bootloaderid, bootloadername(m->bootloaderid),
 140              m->cmdline);
 141       found++;
 142     }
 143   }
 144
 145   return found;
 146 }