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/*
* exec.h
*
* This file is part of the Oxford Oberon-2 compiler
* Copyright (c) 2006--2016 J. M. Spivey
* All rights reserved
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
The binary file output by the linker and input by the run-time
interpreter consists of several segments followed by a trailer that
describes the layout of the segments. The segments may be preceded
by a block of arbitrary data, but they must appear in the following order:
CODE, DATA, RELOC, SYMTAB
By using a trailer rather than a header, we allow for a binary file
also to be a valid file in another format that uses a header -- like
the executable format of most operating systems including various
Unixes and MS--DOS. In that format, our code is just junk beyond the
end of the file, and it is usually ignored. So we can make
self-contained executables by concatenating the interpreter with the
code for a program. This idea was stolen from CAML Light.
*/
/* Codes for the segments: they must appear in the object file
in this order */
#define NSEGS 4
#define S_CODE 0 /* Bytecode */
#define S_DATA 1 /* Initialized data */
#define S_BSS 2 /* Below stack storage */
#define S_STACK 3 /* Stack */
typedef uchar word4[4];
typedef struct {
word4 magic; /* Magic number 'OBCX' */
word4 sig; /* Signature */
word4 primsig; /* Checksum of primitives */
word4 start; /* Offset of data start from end of file */
word4 entry; /* Entry point */
word4 gcmap; /* Global pointer map */
word4 libdir; /* Location of dynamic libraries */
word4 segment[NSEGS]; /* Segment sizes */
word4 nprocs, nmods, nsyms; /* No. of procs, modules, symbols */
} trailer;
/* Layout of relocation data */
#define WORD_SIZE 4
#define CODES_PER_BYTE 4
#define BITS_PER_CODE 2
#define CODE_MASK ((1 << BITS_PER_CODE) - 1)
#define reloc_bits(buf, i) (buf[(i)/CODES_PER_BYTE] >> \
((i) % CODES_PER_BYTE * BITS_PER_CODE) & CODE_MASK)
#define IBIT 0x80000000
/* Relocation codes */
#define R_NONE 0
#define R_WORD 1
#define R_ADDR 2
#define R_SUBR 3
/* Symbol tags */
#define X_NONE 0
#define X_MODULE 1
#define X_PROC 2
#define X_DATA 3
#define X_LINE 4
#define X_SYM 5
/* Fixed primitives */
#define INTERP 0 /* Index of interpreter as primitive */
#define DLTRAP 1 /* Index of dynlink trap */
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