Retro68/libretro/Retro68Runtime.h
Wolfgang Thaller 95b59e3315 Support for older systems (64K ROMs). See issue #22.
Thanks to @mdanh2002 for submitting the patch.
2017-04-11 20:44:47 +02:00

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/*
Copyright 2015 Wolfgang Thaller.
This file is part of Retro68.
Retro68 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 3 of the License, or
(at your option) any later version.
Retro68 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.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>.
*/
#define _RETRO68_GET_DISPLACEMENT(DISPLACEMENT, STRIP) \
do { \
char *virtualstart, *realstart; \
__asm__( "1:\n" \
"\tmove.l #1b, %0\n" \
"\tlea (1b:w,%%pc), %1" \
: "=r"(virtualstart) , "=a"(realstart) ); \
DISPLACEMENT = STRIP(realstart) - virtualstart; \
} while(0)
#define RETRO68_GET_DISPLACEMENT(DISPLACEMENT) \
_RETRO68_GET_DISPLACEMENT(DISPLACEMENT, )
// Calls to the StripAddress() trap are supposed to make sure addresses are 32-bit clean.
// But this trap doesnt exist on old ROMs and old system versions,
// so programs built with StripAddress will mysteriously crash.
// Those systems always run in 24-bit mode, so we can just take the lower 24
// bits of the 32 bit address.
// StripAddress24 must not be used on 32-bit systems, or the resulting crashes
// will be even more mysterious.
#define StripAddress24(x) ((char*) ((unsigned long)(x) & 0x00FFFFFF))
#define RETRO68_GET_DISPLACEMENT_STRIP24(DISPLACEMENT) \
_RETRO68_GET_DISPLACEMENT(DISPLACEMENT, StripAddress24)
// original StripAddress
#define RETRO68_GET_DISPLACEMENT_STRIP(DISPLACEMENT) \
_RETRO68_GET_DISPLACEMENT(DISPLACEMENT, StripAddress)
#define RETRO68_CALL_UNRELOCATED(FUN,ARGS) \
do { \
long displacement; \
RETRO68_GET_DISPLACEMENT(displacement); \
(*(typeof(&FUN)) ((char*)(&FUN) + displacement)) ARGS; \
} while(0)
void Retro68Relocate();
void Retro68CallConstructors();
void Retro68CallDestructors();
void Retro68FreeGlobals();
#define RETRO68_RELOCATE() RETRO68_CALL_UNRELOCATED(Retro68Relocate,())