reactos/ntoskrnl/ke/i386/fpu.c

   1 /* $Id: fpu.c,v 1.11 2003/11/06 20:40:25 gvg Exp $
   2  *
   3  *  ReactOS kernel
   4  *  Copyright (C) 1998, 1999, 2000, 2001 ReactOS Team
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation; either version 2 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, write to the Free Software
  18  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  */
  20 /*
  21  * PROJECT:         ReactOS kernel
  22  * FILE:            ntoskrnl/ke/i386/fpu.c
  23  * PURPOSE:         Handles the FPU
  24  * PROGRAMMER:      David Welch (welch@mcmail.com)
  25  * UPDATE HISTORY:
  26  *                  Created 22/05/98
  27  */
  28
  29 /* INCLUDES *****************************************************************/
  30
  31 #include <ddk/ntddk.h>
  32 #include <internal/ke.h>
  33 #include <internal/mm.h>
  34 #include <internal/ps.h>
  35
  36 #define NDEBUG
  37 #include <internal/debug.h>
  38
  39 /* GLOBALS *******************************************************************/
  40
  41 ULONG HardwareMathSupport;
  42
  43 /* FUNCTIONS *****************************************************************/
  44
  45 VOID INIT_FUNCTION
  46 KiCheckFPU(VOID)
  47 {
  48    unsigned short int status;
  49    int cr0;
  50
  51    HardwareMathSupport = 0;
  52
  53    __asm__("movl %%cr0, %0\n\t" : "=a" (cr0));
  54    /* Set NE and MP. */
  55    cr0 = cr0 | 0x22;
  56    /* Clear EM */
  57    cr0 = cr0 & (~0x4);
  58    __asm__("movl %0, %%cr0\n\t" : : "a" (cr0));
  59
  60    __asm__("clts\n\t");
  61    __asm__("fninit\n\t");
  62    __asm__("fstsw %0\n\t" : "=a" (status));
  63    if (status != 0)
  64      {
  65         __asm__("movl %%cr0, %0\n\t" : "=a" (cr0));
  66         /* Set the EM flag in CR0 so any FPU instructions cause a trap. */
  67         cr0 = cr0 | 0x4;
  68         __asm__("movl %0, %%cr0\n\t" :
  69                 : "a" (cr0));
  70         return;
  71      }
  72    /* fsetpm for i287, ignored by i387 */
  73    __asm__(".byte 0xDB, 0xE4\n\t");
  74    HardwareMathSupport = 1;
  75 }
  76
  77 /* This is a rather naive implementation of Ke(Save/Restore)FloatingPointState
  78    which will not work for WDM drivers. Please feel free to improve */
  79
  80 #define FPU_STATE_SIZE 108
  81
  82 NTSTATUS STDCALL
  83 KeSaveFloatingPointState(OUT PKFLOATING_SAVE Save)
  84 {
  85   char *FpState;
  86
  87   FpState = ExAllocatePool(PagedPool, FPU_STATE_SIZE);
  88   if (NULL == FpState)
  89     {
  90       return STATUS_INSUFFICIENT_RESOURCES;
  91     }
  92   *((PVOID *) Save) = FpState;
  93
  94   __asm__("fsave %0\n\t" : "=m" (*FpState));
  95
  96   return STATUS_SUCCESS;
  97 }
  98
  99 NTSTATUS STDCALL
 100 KeRestoreFloatingPointState(IN PKFLOATING_SAVE Save)
 101 {
 102   char *FpState = *((PVOID *) Save);
 103
 104   __asm__("frstor %0\n\t" : "=m" (*FpState));
 105   ExFreePool(FpState);
 106
 107   return STATUS_SUCCESS;
 108 }