boot/freeldr/freeldr/arch/i386/int386.S

   1 /*
   2  *  FreeLoader
   3  *  Copyright (C) 1998-2002  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 along
  16  *  with this program; if not, write to the Free Software Foundation, Inc.,
  17  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18  */
  19
  20 #include <asm.inc>
  21 #include <arch/pc/x86common.h>
  22 #include <arch/pc/pcbios.h>
  23
  24 .code32
  25
  26 EXTERN SwitchToReal:PROC
  27 EXTERN ContinueAddress:DWORD
  28
  29 Int386_regsin:
  30     .long 0
  31 Int386_regsout:
  32     .long 0
  33
  34 /*
  35  * int Int386(int ivec, REGS* in, REGS* out);
  36  */
  37 PUBLIC _Int386
  38 _Int386:
  39
  40     /* Get the function parameters */
  41     mov eax, dword ptr [esp + 4]
  42     mov dword ptr ds:[BSS_IntVector], eax
  43     mov eax, dword ptr [esp + 8]
  44     mov dword ptr [Int386_regsin], eax
  45     mov eax, dword ptr [esp + 12]
  46     mov dword ptr [Int386_regsout], eax
  47
  48     /* Save all registers + segment registers */
  49     push ds
  50     push es
  51     push fs
  52     push gs
  53     pusha
  54
  55     /* Copy input registers */
  56     mov esi, dword ptr [Int386_regsin]
  57     mov edi, BSS_RegisterSet
  58     mov ecx, REGS_SIZE / 4
  59     rep movsd
  60
  61     /* Set the function ID */
  62     mov bx, FNID_Int386
  63
  64     /* Set continue address and switch to real mode */
  65     mov dword ptr [ContinueAddress], offset Int386_return
  66     jmp SwitchToReal
  67
  68 Int386_return:
  69
  70     /* Copy output registers */
  71     mov esi, BSS_RegisterSet
  72     mov edi, dword ptr [Int386_regsout]
  73     mov ecx, REGS_SIZE / 4
  74     rep movsd
  75
  76     /* Restore all registers + segment registers */
  77     popa
  78     pop gs
  79     pop fs
  80     pop es
  81     pop ds
  82     ret
  83
  84 END