/* * 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 */