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Retro68
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Retro68/libretro/MultiSegApp.c

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#include <OSUtils.h>
#include <Traps.h>
#include <Resources.h>
#include <Memory.h>
#include <Processes.h>
#include <stdint.h>
#include "PoorMansDebugging.h"
#include "Retro68Runtime.h"
static UniversalProcPtr OriginalLoadSeg;
static UniversalProcPtr OriginalUnloadSeg;
static UniversalProcPtr OriginalExitToShell;
static UniversalProcPtr OriginalLaunch;
static UniversalProcPtr OriginalChain;
extern pascal void PatchedLoadSeg(void);
typedef union JTEntry
{
struct {
uint16_t offset;
uint16_t push;
int16_t id;
uint16_t loadseg;
} near;
struct {
int16_t id;
uint16_t loadseg;
uint32_t offset;
} far;
struct {
int16_t id;
uint16_t jmp;
void* addr;
} jmp;
} JTEntry;
typedef struct CODEHeader
{
int16_t magic0;
int16_t magic1;
uint32_t nearEntryOffset;
uint32_t nNearEntries;
uint32_t farEntryOffset;
uint32_t nFarEntries;
uint32_t a5relocOffset;
uint8_t *currentA5;
uint32_t relocOffset;
uint8_t *loadAddress;
uint32_t reserved;
} CODEHeader;
#define StripAddressCompat(p) (relocState.hasStripAddr ? StripAddress(p) : StripAddress24(p))
pascal void* Retro68LoadSegment(uint8_t *p)
{
union JTEntry *jtEntry = (JTEntry*) (p - 4);
short id = jtEntry->far.id;
uint32_t offset = jtEntry->far.offset;
/*{
char buf[256];
sprintf(buf+1, "Loading seg %d.;g", id);
buf[0] = strlen(buf+1);
DebugStr((unsigned char*) buf);
}*/
// TODO: UseResFile?
Handle CODE = GetResource('CODE', id);
assert(CODE);
HLock(CODE);
uint8_t *base = StripAddressCompat((uint8_t *)*CODE);
CODEHeader *header = (CODEHeader*) base;
uint32_t codeSize = GetHandleSize(CODE);
uint8_t * a5 = (uint8_t*) StripAddressCompat((void*)SetCurrentA5());
if(header->loadAddress != base || header->currentA5 != a5)
{
long displacements[4] = {
base - header->loadAddress, // code
a5 - header->currentA5,
a5 - header->currentA5,
a5 - header->currentA5
};
header->loadAddress = base;
header->currentA5 = a5;
Handle RELA = NULL;
RELA = GetResource('RELA', id);
assert(RELA);
Retro68ApplyRelocations(base + 40, codeSize - 40, *RELA, displacements);
HPurge(RELA);
}
/* Update JT Entries */
// FIXME: hardcoded JT offset, there is a LM global for this somewhere:
jtEntry = (JTEntry*) (a5 + 32 + header->farEntryOffset);
int n = header->nFarEntries;
while(n--)
{
void * addr = base + jtEntry->far.offset;
//jtEntry->jmp.id = jtEntry->far.id;
jtEntry->jmp.jmp = 0x4EF9;
jtEntry->jmp.addr = addr;
++jtEntry;
}
if(relocState.hasFlushCodeCache)
FlushCodeCache();
/* Load Exception Information */
if (__register_frame_info)
{
int32_t offset = ((int32_t*) (base + codeSize))[-1];
void *eh_frame_info = base + codeSize - 4 + offset;
struct object *object = (struct object*) (base + codeSize - 36);
__register_frame_info(eh_frame_info, object);
}
return base + offset;
}
static pascal void PatchedUnloadSeg(Ptr ptr)
{
union JTEntry *jtEntry = (JTEntry*) (ptr - 2);
if(jtEntry->jmp.jmp != 0x4EF9)
return; // not loaded or invalid pointer.
int id = jtEntry->jmp.id;
Handle CODE = GetResource('CODE', id);
uint8_t *base = StripAddressCompat((uint8_t *)*CODE);
CODEHeader *header = (CODEHeader*) base;
uint32_t codeSize = GetHandleSize(CODE);
// TODO: check header->magic, pass on to original UnloadSeg?
/* Load Exception Information */
if (__register_frame_info)
{
int32_t offset = ((int32_t*) (base + codeSize))[-1];
void *eh_frame_info = base + codeSize - 4 + offset;
__deregister_frame_info(eh_frame_info);
}
uint8_t * a5 = (uint8_t*) StripAddressCompat((void*)SetCurrentA5());
// FIXME: hardcoded JT offset, there is a LM global for this somewhere:
jtEntry = (JTEntry*) (a5 + 32 + header->farEntryOffset);
int n = header->nFarEntries;
while(n--)
{
if(jtEntry->jmp.jmp == 0x4EF9 && jtEntry->jmp.id == id)
{
uint32_t offset = (uint8_t*) jtEntry->jmp.addr - base;
jtEntry->far.loadseg = _LoadSeg;
jtEntry->far.offset = offset;
}
++jtEntry;
}
if(relocState.hasFlushCodeCache)
FlushCodeCache();
HUnlock(CODE);
HPurge(CODE);
}
static void InstallPatches(void);
static void UninstallPatches(void);
static pascal void PatchedExitToShell(void)
{
UninstallPatches();
ExitToShell();
}
#pragma parameter __D0 Launch(__A0)
OSErr Launch(void *param) = { 0xA9F2 };
#pragma parameter __D0 Chain(__A0)
OSErr Chain(void *param) = { 0xA9F2 };
#pragma parameter __D0 PatchedLaunch(__A0)
static OSErr PatchedLaunch(void *p)
{
UninstallPatches();
OSErr err = Launch(p);
InstallPatches();
return err;
}
#pragma parameter __D0 PatchedChain(__A0)
static OSErr PatchedChain(void *p)
{
UninstallPatches();
OSErr err = Chain(p);
InstallPatches();
return err;
}
static void InstallPatches(void)
{
SetToolTrapAddress((UniversalProcPtr)&PatchedLoadSeg, _LoadSeg);
SetToolTrapAddress((UniversalProcPtr)&PatchedUnloadSeg, _UnLoadSeg);
SetToolTrapAddress((UniversalProcPtr)&PatchedExitToShell, _ExitToShell);
SetToolTrapAddress((UniversalProcPtr)&PatchedLaunch, _Launch);
SetToolTrapAddress((UniversalProcPtr)&PatchedChain, _Chain);
}
static void UninstallPatches(void)
{
SetToolTrapAddress((UniversalProcPtr)OriginalLoadSeg, _LoadSeg);
SetToolTrapAddress((UniversalProcPtr)OriginalUnloadSeg, _UnLoadSeg);
SetToolTrapAddress((UniversalProcPtr)OriginalExitToShell, _ExitToShell);
SetToolTrapAddress((UniversalProcPtr)OriginalLaunch, _Launch);
SetToolTrapAddress((UniversalProcPtr)OriginalChain, _Chain);
}
// section boundaries
extern uint8_t _stext, _etext, _sdata, _edata, _sbss[], _ebss;
void Retro68InitMultisegApp(void)
{
uint8_t * a5 = (uint8_t*) StripAddressCompat((void*)SetCurrentA5());
// CODE Segment 1 is already loaded - we are in it.
// Update the jump table addresses.
JTEntry *jtEntry = (JTEntry*) (a5 + 32 + 16); // TODO: hardcoded offsets
while(jtEntry->far.id == 1)
{
void * addr = &_stext - 4 + jtEntry->far.offset;
//jtEntry->jmp.id = jtEntry->far.id;
jtEntry->jmp.jmp = 0x4EF9;
jtEntry->jmp.addr = addr;
++jtEntry;
}
if(relocState.hasFlushCodeCache)
FlushCodeCache();
// Zero-initialize bss
for(uint32_t *p = (uint32_t*) &_sbss;
p < (uint32_t*) &_ebss; ++p)
*p = 0;
// Set up patched LoadSeg
// NOTE: OriginalLoadSeg is the first global variable we can use
OriginalLoadSeg = GetToolTrapAddress(_LoadSeg);
OriginalUnloadSeg = GetToolTrapAddress(_UnLoadSeg);
OriginalExitToShell = GetToolTrapAddress(_ExitToShell);
OriginalLaunch = GetToolTrapAddress(_Launch);
OriginalChain = GetToolTrapAddress(_Chain);
InstallPatches();
// Load and relocate statically initialized DATA
Handle DATA = GetResource('DATA', 0);
BlockMoveData(*DATA, &_sdata, &_edata - &_sdata);
ReleaseResource(DATA);
long displacements[4] = {
0,
a5 - (uint8_t*)NULL,
a5 - (uint8_t*)NULL,
a5 - (uint8_t*)NULL
};
Handle RELA = NULL;
RELA = GetResource('RELA', 0);
assert(RELA);
Retro68ApplyRelocations(&_sdata, &_edata - &_sdata, *RELA, displacements);
ReleaseResource(RELA);
}
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