1 /*
    2 Copyright (C) 1997-2001 Id Software, Inc.
    3 
    4 This program is free software; you can redistribute it and/or
    5 modify it under the terms of the GNU General Public License
    6 as published by the Free Software Foundation; either version 2
    7 of the License, or (at your option) any later version.
    8 
    9 This program is distributed in the hope that it will be useful,
   10 but WITHOUT ANY WARRANTY; without even the implied warranty of
   11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  
   12 
   13 See the 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
   18 
   19 */
   20 #include <stdlib.h>
   21 #include "client.h"
   22 
   23 #if id386
   24 
   25 static unsigned long bias;
   26 static unsigned long *histogram;
   27 static unsigned long start, range;
   28 static unsigned long bias;
   29 
   30 __declspec( naked ) void x86_TimerStart( void )
   31 {
   32         __asm _emit 0fh
   33         __asm _emit 31h
   34         __asm mov  start, eax
   35         __asm ret
   36 }
   37 
   38 __declspec( naked ) void x86_TimerStop( void )
   39 {
   40         __asm push edi
   41         __asm mov edi, histogram
   42         __asm _emit 0fh
   43         __asm _emit 31h
   44         __asm sub eax, start
   45         __asm sub eax, bias
   46         __asm js discard
   47         __asm cmp eax, range
   48         __asm jge  discard
   49         __asm lea edi, [edi + eax*4]
   50         __asm inc dword ptr [edi]
   51 discard:
   52         __asm pop edi
   53         __asm ret
   54 }
   55 
   56 #pragma warning( disable: 4035 )
   57 static __declspec( naked ) unsigned long x86_TimerStopBias( void )
   58 {
   59         __asm push edi
   60         __asm mov edi, histogram
   61         __asm _emit 0fh
   62         __asm _emit 31h
   63         __asm sub eax, start
   64         __asm pop edi
   65         __asm ret
   66 }
   67 #pragma warning( default:4035 )
   68 
   69 void x86_TimerInit( unsigned long smallest, unsigned length )
   70 {
   71         int i;
   72         unsigned long biastable[100];
   73 
   74         range = length;
   75         bias = 10000;
   76 
   77         for ( i = 0; i < 100; i++ )
   78         {
   79                 x86_TimerStart();
   80                 biastable[i] = x86_TimerStopBias();
   81 
   82                 if ( bias > biastable[i] )
   83                         bias = biastable[i];
   84         }
   85 
   86         bias += smallest;
   87         histogram = Z_Malloc( range * sizeof( unsigned long ) );
   88 }
   89 
   90 unsigned long *x86_TimerGetHistogram( void )
   91 {
   92         return histogram;
   93 }
   94 
   95 #endif
   96