diff keiko/exec.h @ 0:bfdcc3820b32

Basis
author Mike Spivey <mike@cs.ox.ac.uk>
date Thu, 05 Oct 2017 08:04:15 +0100
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/keiko/exec.h	Thu Oct 05 08:04:15 2017 +0100
@@ -0,0 +1,96 @@
+/*
+ * 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_WORD 16
+#define BITS_PER_CODE 2
+#define CODE_MASK ((1 << BITS_PER_CODE) - 1)
+
+#define reloc_bits(buf, i) (buf[(i)/CODES_PER_WORD] >> \
+        ((i) % CODES_PER_WORD * BITS_PER_CODE) & CODE_MASK)
+
+/* Relocation codes */
+#define R_WORD 0
+#define R_DATA 1
+#define R_CODE 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 */