reactos/ntoskrnl/ke/i386/bios.c

   1 /* $Id$
   2  *
   3  * COPYRIGHT:       See COPYING in the top level directory
   4  * PROJECT:         ReactOS kernel
   5  * FILE:            ntoskrnl/ke/i386/bios.c
   6  * PURPOSE:         Support for calling the BIOS in v86 mode
   7  *
   8  * PROGRAMMERS:     David Welch (welch@cwcom.net)
   9  */
  10
  11 /* INCLUDES *****************************************************************/
  12
  13 #include <ntoskrnl.h>
  14 #define NDEBUG
  15 #include <internal/debug.h>
  16
  17 /* GLOBALS *******************************************************************/
  18
  19 #define TRAMPOLINE_BASE    (0x10000)
  20
  21 extern VOID Ki386RetToV86Mode(PKV86M_REGISTERS InRegs,
  22                               PKV86M_REGISTERS OutRegs);
  23
  24 /* FUNCTIONS *****************************************************************/
  25
  26 NTSTATUS STDCALL
  27 Ke386CallBios(UCHAR Int, PKV86M_REGISTERS Regs)
  28 {
  29   PUCHAR Ip;
  30   KV86M_REGISTERS ORegs;
  31   NTSTATUS Status;
  32
  33   /*
  34    * Set up a trampoline for executing the BIOS interrupt
  35    */
  36   Ip = (PUCHAR)TRAMPOLINE_BASE;
  37   Ip[0] = 0xCD;              /* int XX */
  38   Ip[1] = Int;
  39   Ip[2] = 0x63;              /* arpl ax, ax */
  40   Ip[3] = 0xC0;
  41   Ip[4] = 0x90;              /* nop */
  42   Ip[5] = 0x90;              /* nop */
  43
  44   /*
  45    * Munge the registers
  46    */
  47   Regs->Eip = 0;
  48   Regs->Cs = TRAMPOLINE_BASE / 16;
  49   Regs->Esp = 0xFFFF;
  50   Regs->Ss = TRAMPOLINE_BASE / 16;
  51   Regs->Eflags = (1 << 1) | (1 << 17) | (1 << 9);     /* VM, IF */
  52   Regs->RecoveryAddress = TRAMPOLINE_BASE + 2;
  53   Regs->RecoveryInstruction[0] = 0x63;       /* arpl ax, ax */
  54   Regs->RecoveryInstruction[1] = 0xC0;
  55   Regs->RecoveryInstruction[2] = 0x90;       /* nop */
  56   Regs->RecoveryInstruction[3] = 0x90;       /* nop */
  57   Regs->Flags = KV86M_EMULATE_CLI_STI | KV86M_ALLOW_IO_PORT_ACCESS;
  58   Regs->Vif = 1;
  59   Regs->PStatus = &Status;
  60
  61   /*
  62    * Execute the BIOS interrupt
  63    */
  64   Ki386RetToV86Mode(Regs, &ORegs);
  65
  66   /*
  67    * Copy the return values back to the caller
  68    */
  69   memcpy(Regs, &ORegs, sizeof(KV86M_REGISTERS));
  70
  71   return(Status);
  72 }
  73
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