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/*
SDL - Simple DirectMedia Layer
Copyright (C) 1997-2012 Sam Lantinga
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
Sam Lantinga
slouken@libsdl.org
*/
#include "SDL_config.h"
#ifndef _ATARI_SUPER_h
#define _ATARI_SUPER_h
#include "SDL_stdinc.h"
#ifndef SuperToUser
/*
* Safe binding to switch back from supervisor to user mode.
* On TOS or EmuTOS, if the stack pointer has changed between Super(0)
* and Super(oldssp), the resulting user stack pointer is wrong.
* This bug does not occur with FreeMiNT.
* So the safe way to return from supervisor to user mode is to backup
* the stack pointer then restore it after the trap.
* Sometimes, GCC optimizes the stack usage, so this matters.
*/
#define SuperToUser(ptr) \
(void)__extension__ \
({ \
register long retvalue __asm__("d0"); \
register long sp_backup; \
\
__asm__ volatile \
( \
"movl sp,%1\n\t" \
"movl %2,sp@-\n\t" \
"movw #0x20,sp@-\n\t" \
"trap #1\n\t" \
"movl %1,sp\n\t" \
: "=r"(retvalue), "=&r"(sp_backup) /* outputs */ \
: "g"((long)(ptr)) /* inputs */ \
: "d1", "d2", "a0", "a1", "a2" \
); \
})
#endif /* SuperToUser */
#endif /* _ATARI_SUPER_h */
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