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Add and use SuperToUser macro to handle super->user mode switch
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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" | ||
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#ifndef _ATARI_SUPER_h | ||
#define _ATARI_SUPER_h | ||
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#include "SDL_stdinc.h" | ||
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#ifndef SuperToUser | ||
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/* | ||
* 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" \ | ||
); \ | ||
}) | ||
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#endif /* SuperToUser */ | ||
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#endif /* _ATARI_SUPER_h */ |
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