/**
 * @file x86.c
 * @brief Some x86 specific code / inline assembler.
 */

/*
All original materal Copyright (C) 2002-2007 UFO: Alien Invasion team.

15/06/06, Eddy Cullen (ScreamingWithNoSound):
	Reformatted to agreed style.
	Added doxygen file comment.
	Updated copyright notice.

Original file from Quake 2 v3.21: quake2-2.31/client/x86.c
Copyright (C) 1997-2001 Id Software, Inc.

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

*/

#include "client.h"

#if id386 && !__MINGW32__ && !__MINGW64__

static unsigned long bias;
static unsigned long *histogram;
static unsigned long start, range;

__declspec(naked)
void x86_TimerStart(void)
{
	__asm _emit 0fh
	__asm _emit 31h
	__asm mov start, eax
	__asm ret
}

__declspec(naked)
void x86_TimerStop(void)
{
	__asm push edi
	__asm mov edi, histogram
	__asm _emit 0fh
	__asm _emit 31h
	__asm sub eax, start
	__asm sub eax, bias
	__asm js discard
	__asm cmp eax, range
	__asm jge discard
	__asm lea edi,[edi + eax * 4]
	__asm inc dword ptr[edi]
discard:
	__asm pop edi
	__asm ret
}

#pragma warning( disable: 4035 )
static __declspec(naked)
unsigned long x86_TimerStopBias(void)
{
	__asm push edi
	__asm mov edi, histogram
	__asm _emit 0fh
	__asm _emit 31h
	__asm sub eax, start
	__asm pop edi
	__asm ret
}

#pragma warning( default:4035 )
void x86_TimerInit(unsigned long smallest, unsigned length)
{
	int i;
	unsigned long biastable[100];

	range = length;
	bias = 10000;

	for (i = 0; i < 100; i++) {
		x86_TimerStart();
		biastable[i] = x86_TimerStopBias();

		if (bias > biastable[i])
			bias = biastable[i];
	}

	bias += smallest;
	histogram = Mem_Alloc(range * sizeof(unsigned long));
}

unsigned long *x86_TimerGetHistogram(void)
{
	return histogram;
}

#endif