mirror of
https://github.com/autc04/Retro68.git
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248 lines
6.6 KiB
C
248 lines
6.6 KiB
C
/*
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Copyright 2015 Wolfgang Thaller.
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This file is part of Retro68.
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Retro68 is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Retro68 is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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Under Section 7 of GPL version 3, you are granted additional
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permissions described in the GCC Runtime Library Exception, version
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3.1, as published by the Free Software Foundation.
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You should have received a copy of the GNU General Public License and
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a copy of the GCC Runtime Library Exception along with this program;
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see the files COPYING and COPYING.RUNTIME respectively. If not, see
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<http://www.gnu.org/licenses/>.
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*/
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#include <stdint.h>
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#include <stdlib.h>
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#include <Processes.h>
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#include <Sound.h>
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#include <Memory.h>
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#include <OSUtils.h>
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#include "Retro68Runtime.h"
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struct flat_hdr {
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char magic[4];
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unsigned long rev; /* version */
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unsigned long entry; /* Offset of first executable instruction
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with text segment from beginning of file */
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unsigned long data_start; /* Offset of data segment from beginning of
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file */
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unsigned long data_end; /* Offset of end of data segment
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from beginning of file */
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unsigned long bss_end; /* Offset of end of bss segment from beginning
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of file */
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/* (It is assumed that data_end through bss_end forms the bss segment.) */
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unsigned long stack_size; /* Size of stack, in bytes */
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unsigned long reloc_start; /* Offset of relocation records from
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beginning of file */
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unsigned long reloc_count; /* Number of relocation records */
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unsigned long flags;
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unsigned long filler[6]; /* Reserved, set to zero */
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};
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typedef void (*voidFunction)(void);
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extern void __init_section(void);
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extern void __init_section_end(void);
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extern void __fini_section(void);
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extern void __fini_section_end(void);
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typedef struct Retro68RelocState
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{
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long headerVirtualAddress;
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Ptr bssPtr;
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Handle codeHandle;
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} Retro68RelocState;
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static Retro68RelocState relocState __attribute__ ((nocommon)) = {
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-sizeof(struct flat_hdr), NULL, NULL
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};
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#if 1
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#define assert(x) do { } while(0)
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#else
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#define assert(x) do { \
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if(!(x)) {\
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unsigned char str[6]; \
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int i; \
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int l = __LINE__; \
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for(i = 1; i < 6; i++) \
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str[i] = ' '; \
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str[0] = 5; \
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str[5] = '0'; \
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for(i = 5; l && i > 0; i--) \
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{ \
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str[i] = '0' + (l % 10); \
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l /= 10; \
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} \
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DebugStr(str); \
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} \
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} while(0)
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#endif
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void Retro68Relocate()
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{
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// Figure out the displacement
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// what is the difference between the addresses in our program code
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// and an address calculated by PC-relative access?
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long displacement;
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RETRO68_GET_DISPLACEMENT_STRIP(displacement);
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struct Retro68RelocState *rState = (Retro68RelocState*)
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((char*)&relocState + displacement);
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// rState now points to the global relocState variable
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if(displacement == 0)
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{
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if(rState->bssPtr)
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{
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// this is not the first time, no relocations needed.
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// should only happen for code resources
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// that are invoked more than once.
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// Lock the code to be sure.
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HLock(rState->codeHandle);
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return;
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}
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}
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// Locate the start of the FLT file header inside the code resource
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long headerOldVirtualAddress = rState->headerVirtualAddress;
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struct flat_hdr *header = (struct flat_hdr*) (headerOldVirtualAddress + displacement);
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uint8_t *base = (uint8_t*) (header+1);
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// Recover the handle to the code resource by looking at the
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// longword before the FLT header. The resource templates in Retro68.r store the offset
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// from the beginning of the code resource there.
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uint32_t headerOffsetInResource = ((uint32_t*)header)[-1];
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if(headerOffsetInResource < 4096)
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// Arbitrary magic number. We expect the offset to be small, just a few header bytes before it.
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// if it's out of range, assume the longword before the header is not the offset we're looking for.
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{
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Handle h = RecoverHandle((Ptr) header - headerOffsetInResource);
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if(MemError() == noErr && h)
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{
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// Make sure the code is locked. Only relevant for some code resources.
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HLock(h);
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rState->codeHandle = h;
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}
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}
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long bss_size = header->bss_end - header->data_end;
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long n = header->reloc_count;
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long *relocs = (long*)( (char*)header + header->reloc_start );
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long i;
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long data_end = header->data_end + headerOldVirtualAddress;
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uint32_t flt_size = (uint32_t) header->data_end;
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long bss_displacement = 0;
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// Allocate BSS section (uninitialized/zero-initialized global data)
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if(!rState->bssPtr)
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{
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THz zone = ApplicationZone();
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if(!zone || (char*)header < (char*)zone)
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rState->bssPtr = NewPtrSysClear(bss_size);
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else
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rState->bssPtr = NewPtrClear(bss_size);
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bss_displacement = (long)(rState->bssPtr) - data_end;
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}
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// Process relocation records
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for(i = 0; i < n; i++)
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{
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uint8_t *addrPtr = base + relocs[i];
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uint32_t addr;
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assert((Ptr)addrPtr >= (Ptr)header);
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assert((Ptr)addrPtr < (Ptr)header + flt_size);
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//addr = *(uint32_t*)addrPtr;
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addr = (((((addrPtr[0] << 8) | addrPtr[1]) << 8) | addrPtr[2]) << 8) | addrPtr[3];
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assert(addr + 0x40 >= headerOldVirtualAddress + 0x40);
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assert(addr + 0x40 < headerOldVirtualAddress + header->bss_end + 0x40);
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addr += (uint32_t)(addr - headerOldVirtualAddress) >= flt_size ?
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bss_displacement : displacement;
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assert((Ptr)addr >= (Ptr)header && (Ptr)addr < (Ptr)header + flt_size
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|| (Ptr)addr >= rState->bssPtr && (Ptr)addr < rState->bssPtr + bss_size);
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addrPtr[3] = addr;
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addrPtr[2] = (addr >>= 8);
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addrPtr[1] = (addr >>= 8);
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addrPtr[0] = (addr >>= 8);
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//*(uint32_t*)addrPtr = addr;
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}
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// We're basically done.
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// Now check whether we're on 68040 or later and need to flush the cache.
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SysEnvRec env;
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env.processor = 0;
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SysEnvirons(0, &env);
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if(env.processor >= env68040)
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{
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FlushCodeCache();
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}
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// accessing globals and calling functions is OK below here.
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rState->headerVirtualAddress += displacement;
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}
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void Retro68CallConstructors()
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{
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char *p = (char*)&__init_section;
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char *e = (char*)&__init_section_end;
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p += 2;
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while( p < e )
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{
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(*(voidFunction)(*(long*)p))();
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p += 6;
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}
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}
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void Retro68CallDestructors()
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{
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char *p = (char*)&__fini_section;
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char *e = (char*)&__fini_section_end;
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p += 2;
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while( p < e )
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{
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(*(voidFunction)(*(long*)p))();
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p += 6;
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}
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}
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void Retro68FreeGlobals()
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{
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if(relocState.bssPtr != (Ptr) -1)
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{
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DisposePtr(relocState.bssPtr);
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relocState.bssPtr = (Ptr) -1;
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}
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}
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