reactos/ntoskrnl/ke/i386/fpu.c

   1 /*
   2  *  ReactOS kernel
   3  *  Copyright (C) 1998, 1999, 2000, 2001 ReactOS Team
   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  * PROJECT:         ReactOS kernel
  21  * FILE:            ntoskrnl/ke/i386/fpu.c
  22  * PURPOSE:         Handles the FPU
  23  * PROGRAMMER:      David Welch (welch@mcmail.com)
  24  * UPDATE HISTORY:
  25  *                  Created 22/05/98
  26  */
  27
  28 /* INCLUDES *****************************************************************/
  29
  30 #include <ddk/ntddk.h>
  31 #include <internal/ke.h>
  32 #include <internal/mm.h>
  33 #include <internal/ps.h>
  34
  35 #define NDEBUG
  36 #include <internal/debug.h>
  37
  38 /* GLOBALS *******************************************************************/
  39
  40 static ULONG HardwareMathSupport;
  41
  42 /* FUNCTIONS *****************************************************************/
  43
  44 VOID
  45 KiCheckFPU(VOID)
  46 {
  47    unsigned short int status;
  48    int cr0;
  49
  50    HardwareMathSupport = 0;
  51
  52    __asm__("clts\n\t");
  53    __asm__("fninit\n\t");
  54    __asm__("fstsw %0\n\t" : "=a" (status));
  55    if (status != 0)
  56      {
  57         __asm__("movl %%cr0, %0\n\t" : "=a" (cr0));
  58         cr0 = cr0 | 0x4;
  59         __asm__("movl %0, %%cr0\n\t" :
  60                 : "a" (cr0));
  61         DbgPrint("No FPU detected\n");
  62         return;
  63      }
  64    /* FIXME: Do fsetpm */
  65    HardwareMathSupport = 1;
  66 }