quakeforge-old/common/d_scana.s

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/*
d_scana.s
x86 assembly-language turbulent texture mapping code
Copyright (C) 1996-1997 Id Software, Inc.
Copyright (C) 1999,2000 contributors of the QuakeForge project
Please see the file "AUTHORS" for a list of contributors
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
$Id$
*/
#include <asm_i386.h>
#include <quakeasm.h>
#include <asm_draw.h>
#include <d_ifacea.h>
#if 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