freeldr/freeldr/asmcode.h

   1 /*
   2  *  FreeLoader
   3  *  Copyright (C) 1999, 2000  Brian Palmer  <brianp@sginet.com>
   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; either version 2 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program; if not, write to the Free Software
  17  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18  */
  19
  20
  21 /* Defines needed for switching between real and protected mode */
  22 #define NULL_DESC       0x00    /* NULL descriptor */
  23 #define PMODE_CS        0x08    /* PMode code selector, base 0 limit 4g */
  24 #define PMODE_DS        0x10    /* PMode data selector, base 0 limit 4g */
  25 #define RMODE_CS        0x18    /* RMode code selector, base 0 limit 64k */
  26 #define RMODE_DS        0x20    /* RMode data selector, base 0 limit 64k */
  27
  28 #define KERNEL_BASE     0xC0000000
  29 //#define       USER_CS         0x08
  30 //#define       USER_DS         0x10
  31 //#define       KERNEL_CS       0x20
  32 //#define       KERNEL_DS       0x28
  33 #define KERNEL_CS       0x08
  34 #define KERNEL_DS       0x10
  35
  36 #define CR0_PE_SET      0x00000001      /* OR this value with CR0 to enable pmode */
  37 #define CR0_PE_CLR      0xFFFFFFFE      /* AND this value with CR0 to disable pmode */
  38
  39 #define NR_TASKS        128             /* Space reserved in the GDT for TSS descriptors */
  40
  41 #define STACK16ADDR     0x7000  /* The 16-bit stack top will be at 0000:7000 */
  42 #define STACK32ADDR     0x60000 /* The 32-bit stack top will be at 6000:0000, or 0x60000 */
  43
  44 #define FILESYSADDR     0x80000 /* The filesystem data address will be at 8000:0000, or 0x80000 */
  45
  46 #define FATCLUSTERBUF   0x60000 /* The fat filesystem's cluster buffer */
  47
  48 #define SCREENBUFFER    0x68000 /* The screen contents will be saved here */
  49 #define FREELDRINIADDR  0x6C000 /* The freeldr.ini load address will be at 6000:C000, or 0x6C000 */
  50
  51 #define SCRATCHSEG      0x7000  /* The 512-byte fixed scratch area will be at 7000:0000, or 0x70000 */
  52 #define SCRATCHOFF      0x0000  /* The 512-byte fixed scratch area will be at 7000:0000, or 0x70000 */
  53 #define SCRATCHAREA     0x70000 /* The 512-byte fixed scratch area will be at 7000:0000, or 0x70000 */
  54
  55 /* Makes "x" a global variable or label */
  56 #define EXTERN(x)       .global x; x:
  57
  58
  59
  60
  61 #ifndef ASM
  62
  63 void    enable_a20(void);
  64
  65 #endif /* ! ASM */