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Retro68
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Reorganize startup code (make some parts publicly available)

This commit is contained in:
Wolfgang Thaller 2015-07-17 21:07:03 +02:00
parent e4d2e8bd00
commit 1cc5202ccf
5 changed files with 192 additions and 89 deletions
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1
CMakeLists.txt
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@ -23,6 +23,7 @@ add_subdirectory(libretro)
# add library path so that GCC picks up the freshly-built libretro
link_directories(${CMAKE_CURRENT_BINARY_DIR}/libretro)
include_directories(${CMAKE_CURRENT_SOURCE_DIR}/libretro)
add_subdirectory(Console)
add_subdirectory(TestApps)

5
libretro/CMakeLists.txt
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@ -23,7 +23,10 @@
cmake_minimum_required(VERSION 2.8)
add_library(retrocrt start.c
add_library(retrocrt
Retro68Runtime.h
start.c
relocate.c
malloc.c
syscalls.c
glue.c

46
libretro/Retro68Runtime.h Normal file
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@ -0,0 +1,46 @@
/*
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) \
do { \
long virtualstart, realstart; \
__asm__( "1:\n" \
"\tmove.l #1b, %0\n" \
"\tlea (1b:w,%%pc), %1" \
: "=r"(virtualstart) , "=a"(realstart) ); \
DISPLACEMENT = realstart - virtualstart; \
} while(0)
#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();
#define RETRO68_RELOCATE() RETRO68_CALL_UNRELOCATED(Retro68Relocate,())

137
libretro/relocate.c Normal file
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@ -0,0 +1,137 @@
/*
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/>.
*/
#include <stdint.h>
#include <stdlib.h>
#include <Processes.h>
#include <Sound.h>
#include <Memory.h>
#include <OSUtils.h>
#include "Retro68Runtime.h"
struct flat_hdr {
char magic[4];
unsigned long rev; /* version */
unsigned long entry; /* Offset of first executable instruction
with text segment from beginning of file */
unsigned long data_start; /* Offset of data segment from beginning of
file */
unsigned long data_end; /* Offset of end of data segment
from beginning of file */
unsigned long bss_end; /* Offset of end of bss segment from beginning
of file */
/* (It is assumed that data_end through bss_end forms the bss segment.) */
unsigned long stack_size; /* Size of stack, in bytes */
unsigned long reloc_start; /* Offset of relocation records from
beginning of file */
unsigned long reloc_count; /* Number of relocation records */
unsigned long flags;
unsigned long filler[6]; /* Reserved, set to zero */
};
typedef void (*voidFunction)(void);
extern void __init_section(void);
extern void __init_section_end(void);
extern void __fini_section(void);
extern void __fini_section_end(void);
static long headerVirtualAddress = -0x40;
static Ptr savedBSS = (Ptr) -1;
#define ACCESS_DISPLACED(VAR) \
( * (typeof(&VAR)) ((char*)(&VAR) + displacement) )
void Retro68Relocate()
{
long displacement;
RETRO68_GET_DISPLACEMENT(displacement);
struct flat_hdr *header = (struct flat_hdr*) (ACCESS_DISPLACED(headerVirtualAddress) + displacement);
SysEnvRec env;
long bss_size;
env.processor = 0;
SysEnvirons(0, &env);
bss_size = header->bss_end - header->data_end;
long n = header->reloc_count;
long *relocs = (long*)( (char*)header + header->reloc_start );
long i;
long data_end = header->data_end - 0x40;
long bss_displacement = 0;
Ptr bss = ACCESS_DISPLACED(savedBSS);
if(bss == (Ptr)-1)
{
bss = NewPtrClear(bss_size);
bss_displacement = (long)bss - data_end;
}
for(i = 0; i < n; i++)
{
uint8_t *addrPtr = (uint8_t*)(relocs[i] + displacement);
long addr;
addr = (addrPtr[0] << 24) | (addrPtr[1] << 16) | (addrPtr[2] << 8) | addrPtr[3];
addr += addr >= data_end ? bss_displacement : displacement;
addrPtr[0] = addr >> 24;
addrPtr[1] = addr >> 16;
addrPtr[2] = addr >> 8;
addrPtr[3] = addr;
}
if(env.processor >= env68040)
{
FlushCodeCache();
}
// accessing globals and calling functions is OK below here.
headerVirtualAddress += displacement;
savedBSS = bss;
}
void Retro68CallConstructors()
{
char *p = (char*)&__init_section;
char *e = (char*)&__init_section_end;
p += 2;
while( p < e )
{
(*(voidFunction)(*(long*)p))();
p += 6;
}
}

92
libretro/start.c
View File

@ -25,101 +25,17 @@
#include <stdint.h>
#include <stdlib.h>
#include <SegLoad.h>
#include <Processes.h>
#include <Sound.h>
#include <Memory.h>
#include <OSUtils.h>
#include "Retro68Runtime.h"
int main(int argc, char* argv[]);
struct flat_hdr {
char magic[4];
unsigned long rev; /* version */
unsigned long entry; /* Offset of first executable instruction
with text segment from beginning of file */
unsigned long data_start; /* Offset of data segment from beginning of
file */
unsigned long data_end; /* Offset of end of data segment
from beginning of file */
unsigned long bss_end; /* Offset of end of bss segment from beginning
of file */
/* (It is assumed that data_end through bss_end forms the bss segment.) */
unsigned long stack_size; /* Size of stack, in bytes */
unsigned long reloc_start; /* Offset of relocation records from
beginning of file */
unsigned long reloc_count; /* Number of relocation records */
unsigned long flags;
unsigned long filler[6]; /* Reserved, set to zero */
};
typedef void (*voidFunction)(void);
extern void __init_section(void);
extern void __init_section_end(void);
extern void __fini_section(void);
extern void __fini_section_end(void);
void _start()
{
long virtualstart, realstart;
__asm__( "move.l #_start, %0" : "=r"(virtualstart) );
__asm__( "lea (_start:w,%%pc), %0" : "=a"(realstart) );
long displacement = realstart - virtualstart;
struct flat_hdr *header = (struct flat_hdr*) (displacement - 0x40);
SysEnvRec env;
long bss_size;
env.processor = 0;
SysEnvirons(0, &env);
RETRO68_RELOCATE();
Retro68CallConstructors();
bss_size = header->bss_end - header->data_end;
Ptr bss = NewPtrClear(bss_size);
long n = header->reloc_count;
long *relocs = (long*)( (char*)header + header->reloc_start );
long i;
long data_end = header->data_end - 0x40;
long bss_displacement = (long)bss - data_end;
for(i = 0; i < n; i++)
{
uint8_t *addrPtr = (uint8_t*)(relocs[i] + displacement);
long addr;
addr = (addrPtr[0] << 24) | (addrPtr[1] << 16) | (addrPtr[2] << 8) | addrPtr[3];
addr += addr >= data_end ? bss_displacement : displacement;
addrPtr[0] = addr >> 24;
addrPtr[1] = addr >> 16;
addrPtr[2] = addr >> 8;
addrPtr[3] = addr;
}
if(env.processor >= env68040)
{
FlushCodeCache();
}
{
char *p = (char*)&__init_section;
char *e = (char*)&__init_section_end;
p += 2;
while( p < e )
{
(*(voidFunction)(*(long*)p))();
p += 6;
}
}
int result;
{
char *argv[2] = { "./a.out", NULL };