Retro68/libretro/Retro68Runtime.h

/*
	Copyright 2017 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/>.
*/

#include <stdint.h>
#include <Types.h>

#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 doesn’t 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();
void Retro68InitMultisegApp();
void Retro68ApplyRelocations(uint8_t *base, uint32_t size, void *relocations, uint32_t displacements[]);

#define RETRO68_RELOCATE() RETRO68_CALL_UNRELOCATED(Retro68Relocate,())



/*
   struct object is an internal data structure in libgcc.
   Comments in unwind-dw2-fde.h imply that it will not
   increase in size.
 */
struct object { long space[8]; };

extern void __register_frame_info (const void *, struct object *)
				  __attribute__ ((weak));
extern void *__deregister_frame_info (const void *)
				     __attribute__ ((weak));

typedef struct Retro68RelocState
{
	Ptr bssPtr;
	Handle codeHandle;
        char hasStripAddr;
        char needFlushCache;
} Retro68RelocState;

extern Retro68RelocState relocState;