SRB2/src/vid_copy.s
2020-02-19 14:08:45 -08:00

61 lines
1.8 KiB
ArmAsm

// SONIC ROBO BLAST 2
//-----------------------------------------------------------------------------
// Copyright (C) 1998-2000 by DooM Legacy Team.
// Copyright (C) 1999-2020 by Sonic Team Junior.
//
// This program is free software distributed under the
// terms of the GNU General Public License, version 2.
// See the 'LICENSE' file for more details.
//-----------------------------------------------------------------------------
/// \file vid_copy.s
/// \brief code for updating the linear frame buffer screen.
#include "asm_defs.inc" // structures, must match the C structures!
// DJGPPv2 is as fast as this one, but then someone may compile with a less
// good version of DJGPP than mine, so this little asm will do the trick!
#define srcptr 4+16
#define destptr 8+16
#define width 12+16
#define height 16+16
#define srcrowbytes 20+16
#define destrowbytes 24+16
// VID_BlitLinearScreen( src, dest, width, height, srcwidth, destwidth );
// width is given as BYTES
#ifdef __i386__
.globl C(VID_BlitLinearScreen_ASM)
C(VID_BlitLinearScreen_ASM):
pushl %ebp // preserve caller's stack frame
pushl %edi
pushl %esi // preserve register variables
pushl %ebx
cld
movl srcptr(%esp),%esi
movl destptr(%esp),%edi
movl width(%esp),%ebx
movl srcrowbytes(%esp),%eax
subl %ebx,%eax
movl destrowbytes(%esp),%edx
subl %ebx,%edx
shrl $2,%ebx
movl height(%esp),%ebp
LLRowLoop:
movl %ebx,%ecx
rep/movsl (%esi),(%edi)
addl %eax,%esi
addl %edx,%edi
decl %ebp
jnz LLRowLoop
popl %ebx // restore register variables
popl %esi
popl %edi
popl %ebp // restore the caller's stack frame
ret
#endif