d_scana.s

/*
	d_scana.S

	(description)

	Copyright (C) 1996-1997  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:

		Free Software Foundation, Inc.
		59 Temple Place - Suite 330
		Boston, MA  02111-1307, USA

	$Id: d_scana.s,v 1.2 2005-07-05 20:01:04 disconn3ct Exp $
*/
// d_scana.s
// x86 assembly-language turbulent texture mapping code

#include "asm_i386.h"
#include "quakeasm.h"
#include "asm_draw.h"
#include "d_ifacea.h"

#ifdef id386

	.data

	.text

//----------------------------------------------------------------------
// turbulent texture mapping code
//----------------------------------------------------------------------

	.align 4
.globl C(D_DrawTurbulent8Span)
C(D_DrawTurbulent8Span):
	pushl	%ebp				// preserve caller's stack frame pointer
	pushl	%esi				// preserve register variables
	pushl	%edi
	pushl	%ebx

	movl	C(r_turb_s),%esi
	movl	C(r_turb_t),%ecx
	movl	C(r_turb_pdest),%edi
	movl	C(r_turb_spancount),%ebx

Llp:
	movl	%ecx,%eax
	movl	%esi,%edx
	sarl	$16,%eax
	movl	C(r_turb_turb),%ebp
	sarl	$16,%edx
	andl	$(CYCLE-1),%eax
	andl	$(CYCLE-1),%edx
	movl	(%ebp,%eax,4),%eax
	movl	(%ebp,%edx,4),%edx
	addl	%esi,%eax
	sarl	$16,%eax
	addl	%ecx,%edx
	sarl	$16,%edx
	andl	$(TURB_TEX_SIZE-1),%eax
	andl	$(TURB_TEX_SIZE-1),%edx
	shll	$6,%edx
	movl	C(r_turb_pbase),%ebp
	addl	%eax,%edx
	incl	%edi
	addl	C(r_turb_sstep),%esi
	addl	C(r_turb_tstep),%ecx
	movb	(%ebp,%edx,1),%dl
	decl	%ebx
	movb	%dl,-1(%edi)
	jnz		Llp

	movl	%edi,C(r_turb_pdest)

	popl	%ebx				// restore register variables
	popl	%edi
	popl	%esi
	popl	%ebp				// restore caller's stack frame pointer
	ret

#endif	// id386