NASM 0.91

13 files changed, 1744 insertions, 0 deletions

diff --git a/rdoff/Makefile b/rdoff/Makefile
new file mode 100644
index 0000000..2e55dde
--- /dev/null
+++ b/rdoff/Makefile
@@ -0,0 +1,43 @@
+# Makefile for RDOFF object file utils; part of the Netwide Assembler
+#
+# The Netwide Assembler is copyright (C) 1996 Simon Tatham and
+# Julian Hall. All rights reserved. The software is
+# redistributable under the licence given in the file "Licence"
+# distributed in the NASM archive.
+#
+# This Makefile is designed for use under Unix (probably fairly
+# portably).
+
+CC = gcc
+CCFLAGS = -c -O -g -Wall -ansi -pedantic -I..
+LINK = gcc
+LINKFLAGS = -o
+DLINKFLAGS = -o
+LIBRARIES =
+STRIP = strip
+LDRDFLIBS = rdoff.o ../nasmlib.o symtab.o collectn.o
+RDXLIBS = rdoff.o rdfload.o symtab.o collectn.o
+
+.c.o:
+	$(CC) $(CCFLAGS) $*.c
+
+all : rdfdump ldrdf rdx
+
+rdfdump : rdfdump.o
+	$(LINK) $(LINKFLAGS) rdfdump rdfdump.o
+ldrdf : ldrdf.o $(LDRDFLIBS)
+	$(LINK) $(LINKFLAGS) ldrdf ldrdf.o $(LDRDFLIBS)
+rdx : rdx.o  $(RDXLIBS)
+	$(LINK) $(LINKFLAGS) rdx rdx.o $(RDXLIBS)
+
+rdfdump.o : rdfdump.c
+rdoff.o : rdoff.c rdoff.h
+ldrdf.o : ldrdf.c rdoff.h ../nasmlib.h symtab.h collectn.h
+symtab.o : symtab.c symtab.h
+collectn.o : collectn.c collectn.h
+rdx.o : rdx.c rdoff.h rdfload.h symtab.h
+rdfload.o : rdfload.c rdfload.h rdoff.h collectn.h symtab.h
+
+clean :
+	rm -f *.o *~ rdfdump ldrdf rdx
+	make -C test clean
diff --git a/rdoff/collectn.c b/rdoff/collectn.c
new file mode 100644
index 0000000..c265c95
--- /dev/null
+++ b/rdoff/collectn.c
@@ -0,0 +1,40 @@
+/* collectn.c	Implements variable length pointer arrays [collections]
+ *
+ * This file is public domain.
+ */
+
+#include "collectn.h"
+#include <stdlib.h>
+
+void collection_init(Collection * c)
+{
+  int i;
+
+  for (i = 0; i < 32; i++) c->p[i] = NULL;
+  c->next = NULL;
+}
+
+void ** colln(Collection * c, int index)
+{
+  while (index >= 32) {
+    index -= 32;
+    if (c->next == NULL) {
+      c->next = malloc(sizeof(Collection));
+      collection_init(c->next);
+    }
+    c = c->next;
+  }
+  return &(c->p[index]);
+}
+
+void collection_reset(Collection *c)
+{
+  int i;
+  if (c->next) {
+    collection_reset(c->next);
+    free(c->next);
+  }
+
+  c->next = NULL;
+  for (i = 0; i < 32; i++) c->p[i] = NULL;
+}
diff --git a/rdoff/collectn.h b/rdoff/collectn.h
new file mode 100644
index 0000000..b3f2d52
--- /dev/null
+++ b/rdoff/collectn.h
@@ -0,0 +1,22 @@
+/* collectn.h	Header file for 'collection' abstract data type
+ *
+ * This file is public domain, and does not come under the NASM license.
+ * It, along with 'collectn.c' implements what is basically a variable
+ * length array (of pointers)
+ */
+
+#ifndef _COLLECTN_H
+#define _COLLECTN_H
+
+typedef struct tagCollection {
+  void	*p[32];		/* array of pointers to objects */
+
+  struct tagCollection *next;
+} Collection;
+
+void	collection_init(Collection * c);
+void ** colln(Collection * c, int index);
+void	collection_reset(Collection * c);
+
+#endif
+
diff --git a/rdoff/ldrdf.c b/rdoff/ldrdf.c
new file mode 100644
index 0000000..ce86b7e
--- /dev/null
+++ b/rdoff/ldrdf.c
@@ -0,0 +1,540 @@
+/* ldrdf.c	RDOFF Object File linker/loader main program
+ *
+ * The Netwide Assembler is copyright (C) 1996 Simon Tatham and
+ * Julian Hall. All rights reserved. The software is
+ * redistributable under the licence given in the file "Licence"
+ * distributed in the NASM archive.
+ */
+
+/* TODO: Make the system skip a module (other than the first) if none
+ * of the other specified modules contain a reference to it.
+ * May require the system to make an extra pass of the modules to be
+ * loaded eliminating those that aren't required.
+ *
+ * Support libaries (.a files - requires a 'ranlib' type utility)
+ *
+ * -s option to strip resolved symbols from exports.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "nasm.h"
+#include "rdoff.h"
+#include "nasmlib.h"
+#include "symtab.h"
+#include "collectn.h"
+
+#define LDRDF_VERSION "0.11"
+
+/* global variables - those to set options: */
+
+int 	verbose = 0;	/* reflects setting of command line switch */
+int	align = 16;
+int	errors = 0;	/* set by functions to cause halt after current
+			   stage of processing */
+
+/* the linked list of modules that must be loaded & linked */
+
+struct modulenode {
+    rdffile	f;	/* the file */
+    long	coderel;	/* module's code relocation factor */
+    long	datarel;	/* module's data relocation factor */
+    long	bssrel;		/* module's bss data reloc. factor */
+    void *	header;		/* header location, if loaded */
+    char *	name;		/* filename */
+    struct modulenode *next;
+};
+
+struct modulenode *modules = NULL,*lastmodule = NULL;
+
+void *symtab;	/* The symbol table */
+
+rdf_headerbuf * newheader ;	/* New header to be written to output */
+
+/* loadmodule - find the characteristics of a module and add it to the
+ *		list of those being linked together			*/
+
+void loadmodule(char *filename)
+{
+  struct modulenode *prev;
+  if (! modules) {
+    modules = malloc(sizeof(struct modulenode));
+    lastmodule = modules;
+    prev = NULL;
+  }
+  else {
+    lastmodule->next = malloc(sizeof(struct modulenode));
+    prev = lastmodule;
+    lastmodule = lastmodule->next;
+  }
+
+  if (! lastmodule) {
+    fputs("ldrdf: not enough memory\n",stderr);
+    exit(1);
+  }
+
+  if (rdfopen(&lastmodule->f,filename)) {
+    rdfperror("ldrdf",filename);
+    exit(1);
+  }
+
+  lastmodule->header = NULL;	/* header hasn't been loaded */
+  lastmodule->name = filename;
+  lastmodule->next = NULL;
+
+  if (prev) {
+    lastmodule->coderel = prev->coderel + prev->f.code_len;
+    if (lastmodule->coderel % align != 0)
+      lastmodule->coderel += align - (lastmodule->coderel % align);
+    lastmodule->datarel = prev->datarel + prev->f.data_len;
+    if (lastmodule->datarel % align != 0)
+      lastmodule->datarel += align - (lastmodule->datarel % align);
+  }
+  else {
+    lastmodule->coderel = 0;
+    lastmodule->datarel = 0;
+  }
+
+  if (verbose)
+    printf("%s code = %08lx (+%04lx), data = %08lx (+%04lx)\n",filename,
+	   lastmodule->coderel,lastmodule->f.code_len,
+	   lastmodule->datarel,lastmodule->f.data_len);
+
+}
+
+/* load_segments()	allocates memory for & loads the code & data segs
+ *			from the RDF modules
+ */
+
+char *text,*data;
+long textlength,datalength,bsslength;
+
+void load_segments(void)
+{
+  struct modulenode *mod;
+
+  if (!modules) {
+    fprintf(stderr,"ldrdf: nothing to do\n");
+    exit(0);
+  }
+  if (!lastmodule) {
+    fprintf(stderr,"ldrdf: panic: module list exists, but lastmodule=NULL\n");
+    exit(3);
+  }
+
+  if (verbose)
+    printf("loading modules into memory\n");
+
+  /* The following stops 16 bit DOS from crashing whilst attempting to
+     work using segments > 64K */
+  if (sizeof(int) == 2) { /* expect a 'code has no effect' warning on 32 bit
+			    platforms... */
+    if (lastmodule->coderel + lastmodule->f.code_len > 65535 ||
+	lastmodule->datarel + lastmodule->f.data_len > 65535) {
+      fprintf(stderr,"ldrdf: segment length has exceeded 64K; use a 32 bit "
+	      "version.\nldrdf: code size = %05lx, data size = %05lx\n",
+	      lastmodule->coderel + lastmodule->f.code_len,
+	      lastmodule->datarel + lastmodule->f.data_len);
+      exit(1);
+    }
+  }
+
+  text = malloc(textlength = lastmodule->coderel + lastmodule->f.code_len);
+  data = malloc(datalength = lastmodule->datarel + lastmodule->f.data_len);
+
+  if (!text || !data) {
+    fprintf(stderr,"ldrdf: out of memory\n");
+    exit(1);
+  }
+
+  mod = modules;
+  while (mod) {		/* load the segments for each module */
+    mod->header = malloc(mod->f.header_len);
+    if (!mod->header) {
+      fprintf(stderr,"ldrdf: out of memory\n");
+      exit(1);
+    }
+    if (rdfloadseg(&mod->f,RDOFF_HEADER,mod->header) ||
+	rdfloadseg(&mod->f,RDOFF_CODE,&text[mod->coderel]) ||
+	rdfloadseg(&mod->f,RDOFF_DATA,&data[mod->datarel])) {
+      rdfperror("ldrdf",mod->name);
+      exit(1);
+    }
+    rdfclose(&mod->f);	/* close file; segments remain */
+    mod = mod->next;
+  }
+}
+
+/* build_symbols()	step through each module's header, and locate
+ *			exported symbols, placing them in a global table
+ */
+
+void build_symbols()
+{
+  struct modulenode *mod;
+  rdfheaderrec *r;
+  symtabEnt e;
+  long bssloc,cbBss;
+
+  if (verbose) printf("building global symbol table:\n");
+  newheader = rdfnewheader();
+
+  symtab = symtabNew();
+  bssloc = 0;			/* keep track of location of BSS symbols */
+
+  for (mod = modules; mod; mod = mod->next)
+  {
+      mod->bssrel = bssloc;
+      cbBss = 0;
+      rdfheaderrewind(&mod->f);
+      while ((r = rdfgetheaderrec(&mod->f)))
+      {
+
+	  if (r->type == 5)		/* Allocate BSS */
+	      cbBss += r->b.amount;
+
+	  if (r->type != 3) continue;	/* ignore all but export recs */
+
+	  e.segment = r->e.segment;
+	  e.offset = r->e.offset +
+	               (e.segment == 0 ? mod->coderel : /* 0 -> code */
+			e.segment == 1 ? mod->datarel : /* 1 -> data */
+			                 mod->bssrel) ; /* 2 -> bss  */
+	  e.flags = 0;
+	  e.name = malloc(strlen(r->e.label) + 1);
+	  if (! e.name)
+	  {
+	      fprintf(stderr,"ldrdf: out of memory\n");
+	      exit(1);
+	  }
+	  strcpy(e.name,r->e.label);
+	  symtabInsert(symtab,&e);
+      }
+      bssloc += cbBss;
+  }
+  if (verbose)
+  {
+      symtabDump(symtab,stdout);
+      printf("BSS length = %ld bytes\n\n",bssloc);
+  }
+  bsslength = bssloc;
+}
+
+/* link_segments()	step through relocation records in each module's
+ *			header, fixing up references.
+ */
+
+void link_segments(void)
+{
+  struct modulenode	*mod;
+  Collection		imports;
+  symtabEnt		*s;
+  long 			rel,relto = 0; /* placate gcc */
+  char 			*seg;
+  rdfheaderrec		*r;
+  int			bRelative;
+
+  if (verbose) printf("linking segments\n");
+
+  collection_init(&imports);
+
+  for (mod = modules; mod; mod = mod->next) {
+    if (verbose >= 2) printf("* processing %s\n",mod->name);
+    rdfheaderrewind(&mod->f);
+    while((r = rdfgetheaderrec(&mod->f))) {
+	switch(r->type) {
+	case 1:		/* relocation record */
+	    if (r->r.segment >= 64) {     	/* Relative relocation; */
+		bRelative = 1;		/* need to find location relative */
+		r->r.segment -= 64;		/* to start of this segment */
+		relto = r->r.segment == 0 ? mod->coderel : mod->datarel;
+	    }
+	    else
+		bRelative = 0;		/* non-relative - need to relocate
+					 * at load time			*/
+
+	    /* calculate absolute offset of reference, not rel to beginning of
+	       segment */
+	    r->r.offset += r->r.segment == 0 ? mod->coderel : mod->datarel;
+
+	    /* calculate the relocation factor to apply to the operand -
+	       the base address of one of this modules segments if referred
+	       segment is 0 - 2, or the address of an imported symbol
+	       otherwise. */
+
+	    if (r->r.refseg == 0) rel = mod->coderel;
+	    else if (r->r.refseg == 1) rel = mod->datarel;
+	    else if (r->r.refseg == 2) rel = mod->bssrel;
+	    else {		/* cross module link - find reference */
+		s = *colln(&imports,r->r.refseg - 2);
+		if (!s) {
+		    fprintf(stderr,"ldrdf: link to undefined segment %04x in"
+			    " %s:%d\n", r->r.refseg,mod->name,r->r.segment);
+		    errors = 1;
+		    break;
+		}
+		rel = s->offset;
+
+		r->r.refseg = s->segment;	/* change referred segment,
+						   so that new header is
+						   correct */
+	    }
+
+	    if (bRelative)	/* Relative - subtract current segment start */
+		rel -= relto;
+	    else
+	    {			/* Add new relocation header */
+		rdfaddheader(newheader,r);
+	    }
+
+	    /* Work out which segment we're making changes to ... */
+	    if (r->r.segment == 0) seg = text;
+	    else if (r->r.segment == 1) seg = data;
+	    else {
+		fprintf(stderr,"ldrdf: relocation in unknown segment %d in "
+			"%s\n", r->r.segment,mod->name);
+		errors = 1;
+		break;
+	    }
+
+	    /* Add the relocation factor to the datum specified: */
+
+	    if (verbose >= 3)
+		printf("  - relocating %d:%08lx by %08lx\n",r->r.segment,
+		       r->r.offset,rel);
+
+	    /**** The following code is non-portable. Rewrite it... ****/
+	    switch(r->r.length) {
+	    case 1:
+		seg[r->r.offset] += (char) rel;
+		break;
+	    case 2:
+		*(int16 *)(seg + r->r.offset) += (int16) rel;
+		break;
+	    case 4:
+		*(long *)(seg + r->r.offset) += rel;
+		break;
+	    }
+	    break;
+
+	case 2:		/* import record */
+	    s = symtabFind(symtab, r->i.label);
+	    if (s == NULL) {
+		/* Need to add support for dynamic linkage */
+		fprintf(stderr,"ldrdf: undefined symbol %s in module %s\n",
+			r->i.label,mod->name);
+		errors = 1;
+	    }
+	    else
+	    {
+		*colln(&imports,r->i.segment - 2) = s;
+		if (verbose >= 2)
+		    printf("imported %s as %04x\n", r->i.label, r->i.segment);
+	    }
+	    break;
+
+	case 3:		/* export; dump to output new version */
+	    s = symtabFind(symtab, r->e.label);
+	    if (! s) continue;	/* eh? probably doesn't matter... */
+
+	    r->e.offset = s->offset;
+	    rdfaddheader(newheader,r);
+	    break;
+
+	case 4:		/* DLL record */
+	    rdfaddheader(newheader,r);		/* copy straight to output */
+	    break;
+	}
+    }
+    collection_reset(&imports);
+  }
+}
+
+/* write_output()	write linked program out to a file */
+
+void write_output(char *filename)
+{
+    FILE		* fp;
+    rdfheaderrec	r;
+
+    fp = fopen(filename,"wb");
+    if (! fp)
+    {
+	fprintf(stderr,"ldrdf: could not open '%s' for writing\n",filename);
+	exit(1);
+    }
+
+
+    /* add BSS length count to header... */
+    if (bsslength)
+    {
+	r.type = 5;
+	r.b.amount = bsslength;
+	rdfaddheader(newheader,&r);
+    }
+
+    /* Write header */
+    rdfwriteheader(fp,newheader);
+    rdfdoneheader(newheader);
+    newheader = NULL;
+
+    /* Write text */
+    if (fwrite(&textlength,1,4,fp) != 4
+	|| fwrite(text,1,textlength,fp) !=textlength)
+    {
+	fprintf(stderr,"ldrdf: error writing %s\n",filename);
+	exit(1);
+    }
+
+    /* Write data */
+    if (fwrite(&datalength,1,4,fp) != 4 ||
+	fwrite(data,1,datalength,fp) != datalength)
+    {
+	fprintf (stderr,"ldrdf: error writing %s\n", filename);
+	exit(1);
+    }
+    fclose(fp);
+}
+
+
+/* main program: interpret command line, and pass parameters on to
+ * individual module loaders & the linker
+ *
+ * Command line format:
+ * ldrdf [-o outfile | -x] [-r xxxx] [-v] [--] infile [infile ...]
+ *
+ * Default action is to output a file named 'aout.rdx'. -x specifies
+ * that the linked object program should be executed, rather than
+ * written to a file. -r specifies that the object program should
+ * be prelocated at address 'xxxx'. This option cannot be used
+ * in conjunction with -x.
+ */
+
+const char *usagemsg = "usage:\n"
+" ldrdf [-o outfile | -x] [-a x] [-v] [-p x] [--] infile [infile ...]\n\n"
+" ldrdf -h	displays this message\n"
+" ldrdf -r	displays version information\n\n"
+"   -o selects output filename (default is aout.rdx)\n"
+"   -x causes ldrdx to link & execute rather than write to file\n"
+"   -a x causes object program to be statically relocated to address 'x'\n"
+"   -v turns on verbose mode\n"
+"   -p x causes segments to be aligned (padded) to x byte boundaries\n"
+"      (default is 16 bytes)\n";
+
+void usage(void)
+{
+  fputs(usagemsg,stderr);
+}
+
+int main(int argc,char **argv)
+{
+  char	*ofilename = "aout.rdx";
+  long	relocateaddr = -1;	/* -1 if no relocation is to occur */
+  int	execute = 0;		/* 1 to execute after linking, 0 otherwise */
+  int	procsw = 1;		/* set to 0 by '--' */
+  int	tmp;
+
+  if (argc == 1) {
+    usage();
+    exit(1);
+  }
+
+  /* process command line switches, and add modules specified to linked list
+     of modules, keeping track of total memory required to load them */
+
+  while(argv++,--argc) {
+    if (procsw && !strcmp(*argv,"-h")) {	/* Help command */
+      usage(); exit(1);
+    }
+    else if (procsw && !strcmp(*argv,"-r")) {
+      printf("ldrdf version %s (%s) (%s)\n",LDRDF_VERSION,_RDOFF_H,
+	     sizeof(int) == 2 ? "16 bit" : "32 bit");
+      exit(1);
+    }
+    else if (procsw && !strcmp(*argv,"-o")) {
+      ofilename = *++argv;
+      --argc;
+      if (execute) {
+	fprintf(stderr,"ldrdf: -o and -x switches incompatible\n");
+	exit(1);
+      }
+      if (verbose > 1) printf("output filename set to '%s'\n",ofilename);
+    }
+    else if (procsw && !strcmp(*argv,"-x")) {
+      execute++;
+      if (verbose > 1) printf("will execute linked object\n");
+    }
+    else if (procsw && !strcmp(*argv,"-a")) {
+      relocateaddr = readnum(*++argv,&tmp);
+      --argc;
+      if (tmp) {
+	fprintf(stderr,"ldrdf: error in parameter to '-a' switch: '%s'\n",
+		*argv);
+	exit(1);
+      }
+      if (execute) {
+	fprintf(stderr,"ldrdf: -a and -x switches incompatible\n");
+	exit(1);
+      }
+      if (verbose) printf("will relocate to %08lx\n",relocateaddr);
+    }
+    else if (procsw && !strcmp(*argv,"-v")) {
+      verbose++;
+      if (verbose == 1) printf("verbose mode selected\n");
+    }
+    else if (procsw && !strcmp(*argv,"-p")) {
+      align = readnum(*++argv,&tmp);
+      --argc;
+      if (tmp) {
+	fprintf(stderr,"ldrdf: error in parameter to '-p' switch: '%s'\n",
+		*argv);
+	exit(1);
+      }
+      if (align != 1 && align != 2 && align != 4 && align != 8 && align != 16
+	  && align != 32 && align != 256) {
+	fprintf(stderr,"ldrdf: %d is an invalid alignment factor - must be"
+		"1,2,4,8,16 or 256\n",align);
+	exit(1);
+      }
+      if (verbose > 1) printf("alignment %d selected\n",align);
+    }
+    else if (procsw && !strcmp(*argv,"--")) {
+      procsw = 0;
+    }
+    else {					/* is a filename */
+      if (verbose > 1) printf("processing module %s\n",*argv);
+      loadmodule(*argv);
+    }
+  }
+
+  /* we should be scanning for unresolved references, and removing
+     unreferenced modules from the list of modules here, so that
+     we know about the final size once libraries have been linked in */
+
+  load_segments();	/* having calculated size of reqd segments, load
+			   each rdoff module's segments into memory */
+
+  build_symbols();	/* build a global symbol table...
+			   perhaps this should be done before load_segs? */
+
+  link_segments();	/* step through each module's header, and resolve
+			   references to the global symbol table.
+			   This also does local address fixups. */
+
+  if (errors) {
+    fprintf(stderr,"ldrdf: there were errors - aborted\n");
+    exit(errors);
+  }
+  if (execute) {
+    fprintf(stderr,"ldrdf: module execution not yet supported\n");
+    exit(1);
+  }
+  if (relocateaddr != -1) {
+    fprintf(stderr,"ldrdf: static relocation not yet supported\n");
+    exit(1);
+  }
+
+  write_output(ofilename);
+  return 0;
+}
diff --git a/rdoff/rdf.doc b/rdoff/rdf.doc
new file mode 100644
index 0000000..300c2bc
--- /dev/null
+++ b/rdoff/rdf.doc
@@ -0,0 +1,99 @@
+RDOFF: Relocatable Dynamically-linked Object File Format
+========================================================
+
+RDOFF was designed initially to test the object-file production
+interface to NASM. It soon became apparent that it could be enhanced
+for use in serious applications due to its simplicity; code to load
+and execute an RDOFF object module is very simple. It also contains
+enhancements to allow it to be linked with a dynamic link library at
+either run- or load- time, depending on how complex you wish to make
+your loader.
+
+The RDOFF format (version 1.1, as produced by NASM v0.91) is defined
+as follows:
+
+The first six bytes of the file contain the string 'RDOFF1'. Other
+versions of the format may contain other last characters other than
+'1' - all little endian versions of the file will always contain an
+ASCII character with value greater than 32. If RDOFF is used on a
+big-endian machine at some point in the future, the version will be
+encoded in decimal rather than ASCII, so will be below 32.
+
+All multi-byte fields follwing this are encoded in either little- or
+big-endian format depending on the system described by this version
+information. Object files should be encoded in the endianness of
+their target machine; files of incorrect endianness will be rejected
+by the loader - this means that loaders do not need to convert
+endianness, as RDOFF has been designed with simplicity of loading at
+the forefront of the design requirements.
+
+The next 4 byte field is the length of the header in bytes. The
+header consists of a sequence of variable length records. Each
+record's type is identified by the first byte of the record. Record
+types 1-4 are currently supported. Record type 5 will be added in
+the near future, when I implement BSS segments. Record type 6 may be
+to do with debugging, when I get debugging implemented.
+
+Type 1: Relocation
+==================
+
+Offset  Length  Description
+0       1       Type (contains 1)
+1       1       Segment that contains reference (0 = text, 1 = data)
+                Add 64 to this number to indicate a relative linkage
+                to an external symbol (see notes)
+2       4       Offset of reference
+6       1       Length of reference (1,2 or 4 bytes)
+7       2       Segment to which reference is made (0 = text, 1 =
+                data, 2 = BSS [when implemented]) others are external
+                symbols.
+
+Total length = 9 bytes
+
+Type 2: Symbol Import
+=====================
+
+0       1       Type (2)
+1       2       Segment number that will be used in references to this
+                symbol.
+3       ?       Null terminated string containing label (up to 32
+                chars) to match against exports in linkage.
+
+Type 3: Symbol Export
+=====================
+
+0       1       Type (3)
+1       1       Segment containing object to be exported (0/1/2)
+2       4       Offset within segment
+6       ?       Null terminate string containing label to export (32
+                char maximum length)
+
+Type 4: Dynamic Link Library
+============================
+
+0       1       Type (4)
+1       ?       Library name (up to 128 chars)
+
+Type 5: Reserve BSS
+===================
+
+0       1       Type (5)
+1       4       Amount of BSS space to reserve in bytes
+
+Total length: 5 bytes
+
+-----------------------------------------------------------------------------
+
+Following the header is the text (code) segment. This is preceded by
+a 4-byte integer, which is its length in bytes. This is followed by
+the length of the data segment (also 4 bytes), and finally the data
+segment.
+
+Notes
+=====
+
+Relative linking: The number stored at the address is offset
+required from the imported symbol, with the address of the end of
+the instruction subtracted from it. This means that the linker can
+simply add the address of the label relative to the beginning of the
+current segment to it.
diff --git a/rdoff/rdfdump.c b/rdoff/rdfdump.c
new file mode 100644
index 0000000..4d4f4df
--- /dev/null
+++ b/rdoff/rdfdump.c
@@ -0,0 +1,156 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+FILE *infile;
+
+long translatelong(long in) {		/* translate from little endian to
+					   local representation */
+  long r;
+  unsigned char *i;
+
+  i = (unsigned char *)&in;
+  r = i[3];
+  r = (r << 8) + i[2];
+  r = (r << 8) + i[1];
+  r = (r << 8) + *i;
+
+  return r;
+}
+
+int translateshort(short in) {
+  int r;
+  unsigned char *i;
+
+  i = (unsigned char *)&in;
+  r = (i[1] << 8) + *i;
+
+  return r;
+}
+void print_header(long length) {
+  unsigned char buf[129],t,s,l;
+  long o;
+  short rs;
+
+  while (length > 0) {
+    fread(&t,1,1,infile);
+    switch(t) {
+    case 1:		/* relocation record */
+      fread(&s,1,1,infile);
+      fread(&o,4,1,infile);
+      fread(&l,1,1,infile);
+      fread(&rs,2,1,infile);
+      printf("  relocation: location (%04x:%08lx), length %d, "
+	     "referred seg %04x\n",(int)s,translatelong(o),(int)l,
+	     translateshort(rs));
+      length -= 9;
+      break;
+    case 2:             /* import record */
+      fread(&rs,2,1,infile);
+      l = 0;
+      do {
+	fread(&buf[l],1,1,infile);
+      } while (buf[l++]);
+      printf("  import: segment %04x = %s\n",translateshort(rs),buf);
+      length -= l + 3;
+      break;
+    case 3:             /* export record */
+      fread(&s,1,1,infile);
+      fread(&o,4,1,infile);
+      l = 0;
+      do {
+	fread(&buf[l],1,1,infile);
+      } while (buf[l++]);
+      printf("  export: (%04x:%08lx) = %s\n",(int)s,translatelong(o),buf);
+      length -= l + 6;
+      break;
+    case 4:		/* DLL record */
+      l = 0;
+      do {
+	fread(&buf[l],1,1,infile);
+      } while (buf[l++]);
+      printf("  dll: %s\n",buf);
+      length -= l + 1;
+      break;
+    case 5:		/* BSS reservation */
+      fread(&l,4,1,infile);
+      printf("  bss reservation: %08lx bytes\n",translatelong(l));
+      length -= 5;
+      break;
+    default:
+      printf("  unrecognised record (type %d)\n",(int)t);
+      length --;
+    }
+  }
+}
+
+int main(int argc,char **argv) {
+  char id[7];
+  long l;
+  int verbose = 0;
+
+  puts("RDOFF Dump utility v1.1 (C) Copyright 1996 Julian R Hall");
+
+  if (argc < 2) {
+    fputs("Usage: rdfdump [-v] <filename>\n",stderr);
+    exit(1);
+  }
+
+  if (! strcmp (argv[1], "-v") )
+  {
+    verbose = 1;
+    if (argc < 3)
+    {
+      fputs("required parameter missing\n",stderr);
+      exit(1);
+    }
+    argv++;
+  }
+
+  infile = fopen(argv[1],"rb");
+  if (! infile) {
+    fprintf(stderr,"rdfdump: Could not open %s",argv[1]);
+    exit(1);
+  }
+
+  fread(id,6,1,infile);
+  if (strncmp(id,"RDOFF",5)) {
+    fputs("rdfdump: File does not contain valid RDOFF header\n",stderr);
+    exit(1);
+  }
+
+  printf("File %s: RDOFF version %c\n\n",argv[1],id[5]);
+  if (id[5] < '1' || id[5] > '1') {
+    fprintf(stderr,"rdfdump: unknown RDOFF version '%c'\n",id[5]);
+    exit(1);
+  }
+
+  fread(&l,4,1,infile);
+  l = translatelong(l);
+  printf("Header (%ld bytes):\n",l);
+  print_header(l);
+
+  fread(&l,4,1,infile);
+  l = translatelong(l);
+  printf("\nText segment length = %ld bytes\n",l);
+  while(l--) {
+    fread(id,1,1,infile);
+    if (verbose) printf("  %02x",(int) (unsigned char)id[0]);
+  }
+  if (verbose) printf("\n\n");
+
+  fread(&l,4,1,infile);
+  l = translatelong(l);
+  printf("Data segment length = %ld bytes\n",l);
+
+  if (verbose)
+  {
+    while (l--) {
+      fread(id,1,1,infile);
+      printf("  %02x",(int) (unsigned char) id[0]);
+    }
+    printf("\n");
+  }
+  fclose(infile);
+  return 0;
+}
diff --git a/rdoff/rdfload.c b/rdoff/rdfload.c
new file mode 100644
index 0000000..ad340b3
--- /dev/null
+++ b/rdoff/rdfload.c
@@ -0,0 +1,173 @@
+/* rdfload.c	RDOFF Object File loader library
+ *
+ * The Netwide Assembler is copyright (C) 1996 Simon Tatham and
+ * Julian Hall. All rights reserved. The software is
+ * redistributable under the licence given in the file "Licence"
+ * distributed in the NASM archive.
+ *
+ * Permission to use this file in your own projects is granted, as long
+ * as acknowledgement is given in an appropriate manner to its authors,
+ * with instructions of how to obtain a copy via ftp.
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "rdfload.h"
+#include "symtab.h"
+#include "rdoff.h"
+#include "collectn.h"
+
+extern int rdf_errno;
+
+rdfmodule * rdfload(const char *filename)
+{
+    rdfmodule 	* f = malloc(sizeof(rdfmodule));
+    long 	bsslength = 0;
+    char	* hdr;
+    rdfheaderrec *r;
+
+    if (f == NULL)
+    {
+	rdf_errno = 6;		/* out of memory */
+	return NULL;
+    }
+
+    f->symtab = symtabNew();
+    if (!f->symtab)
+    {
+	free(f);
+	rdf_errno = 6;
+	return NULL;
+    }
+
+    /* open the file */
+    if ( rdfopen( &(f->f), filename ) ) {
+	free(f);
+	return NULL;
+    }
+
+    /* read in text and data segments, and header */
+
+    f->t = malloc (f->f.code_len);
+    f->d = malloc (f->f.data_len); /* BSS seg allocated later */
+    hdr = malloc (f->f.header_len);
+
+    if (! f->t || ! f->d || !hdr) {
+	rdf_errno = 6;
+	rdfclose(&f->f);
+	if (f->t) free(f->t);
+	if (f->d) free(f->d);
+	free(f);
+	return NULL;
+    }
+
+    if ( rdfloadseg (&f->f,RDOFF_HEADER,hdr) ||
+	 rdfloadseg (&f->f,RDOFF_CODE,f->t) ||
+	 rdfloadseg (&f->f,RDOFF_DATA,f->d) )
+    {
+	rdfclose(&f->f);
+	free(f->t);
+	free(f->d);
+	free(f);
+	free(hdr);
+	return NULL;
+    }
+
+    rdfclose(&f->f);
+
+    /* Allocate BSS segment; step through header and count BSS records */
+
+    while ( ( r = rdfgetheaderrec (&f->f) ) )
+    {
+	if (r->type == 5)
+	    bsslength += r->b.amount;
+    }
+
+    f->b = malloc ( bsslength );
+    if (! f->b )
+    {
+	free(f->t);
+	free(f->d);
+	free(f);
+	free(hdr);
+	rdf_errno = 6;
+	return NULL;
+    }
+
+    rdfheaderrewind (&f->f);
+
+    f->textrel = (long)f->t;
+    f->datarel = (long)f->d;
+    f->bssrel  = (long)f->b;
+
+    return f;
+}
+
+int rdf_relocate(rdfmodule * m)
+{
+    rdfheaderrec	* r;
+    Collection		imports;
+    symtabEnt		e;
+    long		rel;
+    unsigned char	* seg;
+
+    rdfheaderrewind ( & m->f );
+    collection_init(&imports);
+
+    while ( (r = rdfgetheaderrec ( & m->f ) ) )
+    {
+	switch (r->type)
+	{
+	case 1:		/* Relocation record */
+
+	    /* calculate relocation factor */
+
+	    if (r->r.refseg == 0) rel = m->textrel;
+	    else if (r->r.refseg == 1) rel = m->datarel;
+	    else if (r->r.refseg == 2) rel = m->bssrel;
+	    else
+		/* We currently do not support load-time linkage.
+		   This should be added some time soon... */
+
+		return 1;	/* return error code */
+
+	    if ((r->r.segment & 63) == 0) seg = m->t;
+	    else if ((r->r.segment & 63) == 1) seg = m->d;
+	    else
+		return 1;
+
+	    /* it doesn't matter in this case that the code is non-portable,
+	       as the entire concept of executing a module like this is
+	       non-portable */
+	    switch(r->r.length) {
+	    case 1:
+		seg[r->r.offset] += (char) rel;
+		break;
+	    case 2:
+		*(int16 *)(seg + r->r.offset) += (int16) rel;
+		break;
+	    case 4:
+		*(long *)(seg + r->r.offset) += rel;
+		break;
+	    }
+	    break;
+
+	case 3:			/* export record - add to symtab */
+	    e.segment = r->e.segment;
+	    e.offset = r->e.offset +
+	               (e.segment == 0 ? m->textrel : /* 0 -> code */
+			e.segment == 1 ? m->datarel : /* 1 -> data */
+			                 m->bssrel) ; /* 2 -> bss  */
+	    e.flags = 0;
+	    e.name = malloc(strlen(r->e.label) + 1);
+	    if (! e.name)
+		return 1;
+
+	    strcpy(e.name,r->e.label);
+	    symtabInsert(m->symtab,&e);
+	    break;
+	}
+    }
+    return 0;
+}
diff --git a/rdoff/rdfload.h b/rdoff/rdfload.h
new file mode 100644
index 0000000..5e264b9
--- /dev/null
+++ b/rdoff/rdfload.h
@@ -0,0 +1,29 @@
+/* rdfload.h	RDOFF Object File loader library header file
+ *
+ * The Netwide Assembler is copyright (C) 1996 Simon Tatham and
+ * Julian Hall. All rights reserved. The software is
+ * redistributable under the licence given in the file "Licence"
+ * distributed in the NASM archive.
+ *
+ * See the file 'rdfload.c' for special license information for this
+ * file.
+ */
+
+#ifndef _RDFLOAD_H
+#define _RDFLOAD_H
+
+#include "rdoff.h"
+
+typedef struct RDFModuleStruct {
+  rdffile	f;	/* file structure */
+  unsigned char * t, * d, * b; /* text, data, and bss segments */
+  long		textrel;
+  long		datarel;
+  long		bssrel;
+  void *	symtab;
+} rdfmodule;
+
+rdfmodule * rdfload(const char * filename);
+int rdf_relocate(rdfmodule * m);
+
+#endif
diff --git a/rdoff/rdoff.c b/rdoff/rdoff.c
new file mode 100644
index 0000000..9a969ad
--- /dev/null
+++ b/rdoff/rdoff.c
@@ -0,0 +1,367 @@
+/* rdoff.c   	library of routines for manipulating rdoff files
+ *
+ * The Netwide Assembler is copyright (C) 1996 Simon Tatham and
+ * Julian Hall. All rights reserved. The software is
+ * redistributable under the licence given in the file "Licence"
+ * distributed in the NASM archive.
+ */
+
+/* TODO:	The functions in this module assume they are running
+ *		on a little-endian machine. This should be fixed to
+ *		make it portable.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "rdoff.h"
+
+/* ========================================================================
+ * Code for memory buffers (for delayed writing of header until we know
+ * how long it is).
+ * ======================================================================== */
+
+
+memorybuffer * newmembuf(){
+  memorybuffer * t;
+
+  t = malloc(sizeof(memorybuffer));
+
+  t->length = 0;
+  t->next = NULL;
+  return t;
+}
+
+void membufwrite(memorybuffer *b, void *data, int bytes) {
+  int16 w;
+  long l;
+
+  if (b->next) {        /* memory buffer full - use next buffer */
+    membufwrite(b->next,data,bytes);
+    return;
+  }
+  if ((bytes < 0 && b->length - bytes > BUF_BLOCK_LEN)
+      || (bytes > 0 && b->length + bytes > BUF_BLOCK_LEN)) {
+
+    /* buffer full and no next allocated... allocate and initialise next
+     * buffer */
+
+    b->next = newmembuf();
+    membufwrite(b->next,data,bytes);
+  }
+
+  switch(bytes) {
+  case -4:              /* convert to little-endian */
+    l = * (long *) data ;
+    b->buffer[b->length++] = l & 0xFF;
+    l >>= 8 ;
+    b->buffer[b->length++] = l & 0xFF;
+    l >>= 8 ;
+    b->buffer[b->length++] = l & 0xFF;
+    l >>= 8 ;
+    b->buffer[b->length++] = l & 0xFF;
+    break;
+
+  case -2:
+    w = * (int16 *) data ;
+    b->buffer[b->length++] = w & 0xFF;
+    w >>= 8 ;
+    b->buffer[b->length++] = w & 0xFF;
+    break;
+
+  default:
+    while(bytes--) {
+      b->buffer[b->length++] = *(* (unsigned char **) &data);
+
+      (* (unsigned char **) &data)++ ;
+    }
+    break;
+  }
+}
+
+void membufdump(memorybuffer *b,FILE *fp)
+{
+  if (!b) return;
+
+  fwrite (b->buffer, 1, b->length, fp);
+
+  membufdump(b->next,fp);
+}
+
+int membuflength(memorybuffer *b)
+{
+  if (!b) return 0;
+  return b->length + membuflength(b->next);
+}
+
+void freemembuf(memorybuffer *b)
+{
+  if (!b) return;
+  freemembuf(b->next);
+  free(b);
+}
+
+/* =========================================================================
+   General purpose routines and variables used by the library functions
+   ========================================================================= */
+
+long translatelong(long in) {           /* translate from little endian to
+                                           local representation */
+  long r;
+  unsigned char *i;
+
+  i = (unsigned char *)&in;
+  r = i[3];
+  r = (r << 8) + i[2];
+  r = (r << 8) + i[1];
+  r = (r << 8) + *i;
+
+  return r;
+}
+
+const char *RDOFFId = "RDOFF1"; /* written to the start of RDOFF files */
+
+const char *rdf_errors[7] = {
+  "no error occurred","could not open file","invalid file format",
+  "error reading file","unknown error","header not read",
+  "out of memory"};
+
+int rdf_errno = 0;
+
+/* ========================================================================
+   The library functions
+   ======================================================================== */
+
+int rdfopen(rdffile *f, const char *name)
+{
+  char buf[8];
+
+  if (translatelong(0x01020304) != 0x01020304)
+  {					/* fix this to be portable! */
+    fputs("*** this program requires a little endian machine\n",stderr);
+    fprintf(stderr,"01020304h = %08lxh\n",translatelong(0x01020304));
+    exit(3);
+  }
+
+
+  f->fp = fopen(name,"rb");
+  if (!f->fp) return rdf_errno = 1;		/* error 1: file open error */
+
+  fread(buf,6,1,f->fp);		/* read header */
+  buf[6] = 0;
+
+  if (strcmp(buf,RDOFFId)) {
+    fclose(f->fp);
+    return rdf_errno = 2; 	/* error 2: invalid file format */
+  }
+
+  if (fread(&f->header_len,1,4,f->fp) != 4) {
+    fclose(f->fp);
+    return rdf_errno = 3;	/* error 3: file read error */
+  }
+
+  if (fseek(f->fp,f->header_len,SEEK_CUR)) {
+    fclose(f->fp);
+    return rdf_errno = 2;	/* seek past end of file...? */
+  }
+
+  if (fread(&f->code_len,1,4,f->fp) != 4) {
+    fclose(f->fp);
+    return rdf_errno = 3;
+  }
+
+  f->code_ofs = ftell(f->fp);
+  if (fseek(f->fp,f->code_len,SEEK_CUR)) {
+    fclose(f->fp);
+    return rdf_errno = 2;
+  }
+
+  if (fread(&f->data_len,1,4,f->fp) != 4) {
+    fclose(f->fp);
+    return rdf_errno = 3;
+  }
+
+  f->data_ofs = ftell(f->fp);
+  rewind(f->fp);
+  f->header_loc = NULL;
+  return 0;
+}
+
+int rdfclose(rdffile *f)
+{
+    fclose(f->fp);
+    return 0;
+}
+
+void rdfperror(const char *app,const char *name)
+{
+  fprintf(stderr,"%s:%s: %s\n",app,name,rdf_errors[rdf_errno]);
+}
+
+int rdfloadseg(rdffile *f,int segment,void *buffer)
+{
+  long fpos;
+  long slen;
+
+  switch(segment) {
+  case RDOFF_HEADER:
+    fpos = 10;
+    slen = f->header_len;
+    f->header_loc = (char *)buffer;
+    f->header_fp = 0;
+    break;
+  case RDOFF_CODE:
+    fpos = f->code_ofs;
+    slen = f->code_len;
+    break;
+  case RDOFF_DATA:
+    fpos = f->data_ofs;
+    slen = f->data_len;
+    break;
+  default:
+    fpos = 0;
+    slen = 0;
+  }
+
+  if (fseek(f->fp,fpos,SEEK_SET))
+    return rdf_errno = 4;
+
+  if (fread(buffer,1,slen,f->fp) != slen)
+    return rdf_errno = 3;
+
+  return 0;
+}
+
+/* Macros for reading integers from header in memory */
+
+#define RI8(v) v = f->header_loc[f->header_fp++]
+#define RI16(v) { v = (f->header_loc[f->header_fp] + \
+		       (f->header_loc[f->header_fp+1] << 8)); \
+		  f->header_fp += 2; }
+
+#define RI32(v) { v = (f->header_loc[f->header_fp] + \
+		       (f->header_loc[f->header_fp+1] << 8) + \
+		       (f->header_loc[f->header_fp+2] << 16) + \
+		       (f->header_loc[f->header_fp+3] << 24)); \
+		  f->header_fp += 4; }
+
+#define RS(str,max) { for(i=0;i<max;i++){\
+  RI8(str[i]); if (!str[i]) break;} str[i]=0; }
+
+rdfheaderrec *rdfgetheaderrec(rdffile *f)
+{
+  static rdfheaderrec r;
+  int i;
+
+  if (!f->header_loc) {
+    rdf_errno = 5;
+    return NULL;
+  }
+
+  if (f->header_fp >= f->header_len) return 0;
+
+  RI8(r.type);
+  switch(r.type) {
+  case 1:	/* Relocation record */
+    RI8(r.r.segment);
+    RI32(r.r.offset);
+    RI8(r.r.length);
+    RI16(r.r.refseg);
+    break;
+
+  case 2:	/* Imported symbol record */
+    RI16(r.i.segment);
+    RS(r.i.label,32);
+    break;
+
+  case 3:	/* Exported symbol record */
+    RI8(r.e.segment);
+    RI32(r.e.offset);
+    RS(r.e.label,32);
+    break;
+
+  case 4:	/* DLL record */
+    RS(r.d.libname,127);
+    break;
+
+  case 5:	/* BSS reservation record */
+    RI32(r.b.amount);
+    break;
+
+  default:
+    rdf_errno = 2; /* invalid file */
+    return NULL;
+  }
+  return &r;
+}
+
+void rdfheaderrewind(rdffile *f)
+{
+  f->header_fp = 0;
+}
+
+
+rdf_headerbuf * rdfnewheader(void)
+{
+    return newmembuf();
+}
+
+int rdfaddheader(rdf_headerbuf * h, rdfheaderrec * r)
+{
+    switch (r->type)
+    {
+    case 1:
+	membufwrite(h,&r->type,1);
+	membufwrite(h,&r->r.segment,1);
+	membufwrite(h,&r->r.offset,-4);
+	membufwrite(h,&r->r.length,1);
+	membufwrite(h,&r->r.refseg,-2);    /* 9 bytes written */
+	break;
+
+    case 2:				/* import */
+	membufwrite(h,&r->type,1);
+	membufwrite(h,&r->i.segment,-2);
+	membufwrite(h,&r->i.label,strlen(r->i.label) + 1);
+	break ;
+
+    case 3:				/* export */
+	membufwrite(h,&r->type,1);
+	membufwrite(h,&r->e.segment,1);
+	membufwrite(h,&r->e.offset,-4);
+	membufwrite(h,&r->e.label,strlen(r->e.label) + 1);
+	break ;
+
+    case 4:				/* DLL */
+	membufwrite(h,&r->type,1);
+	membufwrite(h,&r->d.libname,strlen(r->d.libname) + 1);
+	break ;
+
+    case 5:				/* BSS */
+	membufwrite(h,&r->type,1);
+	membufwrite(h,&r->b.amount,-4);
+	break ;
+
+    default:
+	return (rdf_errno = 2);
+    }
+    return 0;
+}
+
+int rdfwriteheader(FILE * fp, rdf_headerbuf * h)
+{
+    long		l;
+
+    fwrite (RDOFFId, 1, strlen(RDOFFId), fp) ;
+
+    l = translatelong ( membuflength (h) );
+    fwrite (&l, 4, 1, fp);
+
+    membufdump(h, fp);
+
+    return 0;		/* no error handling in here... CHANGE THIS! */
+}
+
+void rdfdoneheader(rdf_headerbuf * h)
+{
+    freemembuf(h);
+}
diff --git a/rdoff/rdoff.h b/rdoff/rdoff.h
new file mode 100644
index 0000000..b022400
--- /dev/null
+++ b/rdoff/rdoff.h
@@ -0,0 +1,112 @@
+/* rdoff.h	RDOFF Object File manipulation routines header file
+ *
+ * The Netwide Assembler is copyright (C) 1996 Simon Tatham and
+ * Julian Hall. All rights reserved. The software is
+ * redistributable under the licence given in the file "Licence"
+ * distributed in the NASM archive.
+ */
+
+#ifndef _RDOFF_H
+#define _RDOFF_H "RDOFF1 support routines v0.1"
+
+typedef short int16;    /* not sure if this will be required to be altered
+                           at all... best to typedef it just in case */
+
+/* the records that can be found in the RDOFF header */
+
+struct RelocRec {
+  char  type;           /* must be 1 */
+  char  segment;        /* only 0 for code, or 1 for data supported,
+			   but add 64 for relative refs (ie do not require
+			   reloc @ loadtime, only linkage) */
+  long  offset;         /* from start of segment in which reference is loc'd */
+  char  length;         /* 1 2 or 4 bytes */
+  int16 refseg;         /* segment to which reference refers to */
+};
+
+struct ImportRec {
+  char  type;           /* must be 2 */
+  int16 segment;        /* segment number allocated to the label for reloc
+                           records - label is assumed to be at offset zero
+                           in this segment, so linker must fix up with offset
+                           of segment and of offset within segment */
+  char  label[33];      /* zero terminated... should be written to file until
+                           the zero, but not after it - max len = 32 chars */
+};
+
+struct ExportRec {
+  char  type;           /* must be 3 */
+  char  segment;        /* segment referred to (0/1) */
+  long  offset;         /* offset within segment */
+  char  label[33];      /* zero terminated as above. max len = 32 chars */
+};
+
+struct DLLRec {
+  char  type;           /* must be 4 */
+  char  libname[128];   /* name of library to link with at load time */
+};
+
+struct BSSRec {
+  char type;		/* must be 5 */
+  long amount;		/* number of bytes BSS to reserve */
+};
+
+typedef union RDFHeaderRec {
+  char type;			/* invariant throughout all below */
+  struct RelocRec r;		/* type == 1 */
+  struct ImportRec i;		/* type == 2 */
+  struct ExportRec e;		/* type == 3 */
+  struct DLLRec d;		/* type == 4 */
+  struct BSSRec b;		/* type == 5 */
+} rdfheaderrec;
+
+typedef struct RDFFileInfo {
+  FILE *fp;		/* file descriptor; must be open to use this struct */
+  int rdoff_ver;	/* should be 1; any higher => not guaranteed to work */
+  long header_len;
+  long code_len;
+  long data_len;
+  long code_ofs;
+  long data_ofs;
+  char *header_loc;	/* keep location of header */
+  long header_fp;	/* current location within header for reading */
+} rdffile;
+
+#define BUF_BLOCK_LEN 4088              /* selected to match page size (4096)
+                                         * on 80x86 machines for efficiency */
+typedef struct memorybuffer {
+  int length;
+  char buffer[BUF_BLOCK_LEN];
+  struct memorybuffer *next;
+} memorybuffer;
+
+typedef memorybuffer rdf_headerbuf;
+
+/* segments used by RDOFF, understood by rdoffloadseg */
+#define RDOFF_CODE 0
+#define RDOFF_DATA 1
+#define RDOFF_HEADER -1
+/* mask for 'segment' in relocation records to find if relative relocation */
+#define RDOFF_RELATIVEMASK 64
+/* mask to find actual segment value in relocation records */
+#define RDOFF_SEGMENTMASK 63
+
+/* RDOFF file manipulation functions */
+int rdfopen(rdffile *f,const char *name);
+int rdfclose(rdffile *f);
+int rdfloadseg(rdffile *f,int segment,void *buffer);
+rdfheaderrec *rdfgetheaderrec(rdffile *f);   /* returns static storage */
+void rdfheaderrewind(rdffile *f);	     /* back to start of header */
+void rdfperror(const char *app,const char *name);
+
+/* functions to write a new RDOFF header to a file -
+   use rdfnewheader to allocate a header, rdfaddheader to add records to it,
+   rdfwriteheader to write 'RDOFF1', length of header, and the header itself
+   to a file, and then rdfdoneheader to dispose of the header */
+
+rdf_headerbuf *rdfnewheader(void);
+int rdfaddheader(rdf_headerbuf *h,rdfheaderrec *r);
+int rdfwriteheader(FILE *fp,rdf_headerbuf *h);
+void rdfdoneheader(rdf_headerbuf *h);
+
+#endif		/* _RDOFF_H */
diff --git a/rdoff/rdx.c b/rdoff/rdx.c
new file mode 100644
index 0000000..28ffc42
--- /dev/null
+++ b/rdoff/rdx.c
@@ -0,0 +1,61 @@
+/* rdx.c	RDOFF Object File loader program
+ *
+ * The Netwide Assembler is copyright (C) 1996 Simon Tatham and
+ * Julian Hall. All rights reserved. The software is
+ * redistributable under the licence given in the file "Licence"
+ * distributed in the NASM archive.
+ */
+
+/* note: most of the actual work of this program is done by the modules
+   "rdfload.c", which loads and relocates the object file, and by "rdoff.c",
+   which contains general purpose routines to manipulate RDOFF object
+   files. You can use these files in your own program to load RDOFF objects
+   and execute the code in them in a similar way to what is shown here. */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "rdfload.h"
+#include "rdoff.h"
+#include "symtab.h"
+
+typedef int (*main_fn) (int,char**);	/* Main function prototype */
+
+int main(int argc, char **argv)
+{
+    rdfmodule 	* m;
+    main_fn	code;
+    symtabEnt	* s;
+
+    if (argc < 2)
+    {
+	puts("usage: rdf <rdoff-executable> [params]\n");
+	exit(255);
+    }
+
+    m = rdfload(argv[1]);
+
+    if (! m)
+    {
+	rdfperror("rdf",argv[1]);
+	exit(255);
+    }
+
+    rdf_relocate(m);	/* in this instance, the default relocation
+			   values will work fine, but they may need changing
+			   in other cases... */
+
+    s = symtabFind(m->symtab, "_main");
+    if (! s)
+    {
+	fprintf(stderr,"rdx: could not find symbol '_main' in '%s'\n",argv[1]);
+	exit(255);
+    }
+
+    code = (main_fn) s->offset;
+
+    argv++, argc--;	/* remove 'rdx' from command line */
+
+    return code(argc,argv);	/* execute */
+}
+
diff --git a/rdoff/symtab.c b/rdoff/symtab.c
new file mode 100644
index 0000000..c0ff3e5
--- /dev/null
+++ b/rdoff/symtab.c
@@ -0,0 +1,80 @@
+/* symtab.c	Routines to maintain and manipulate a symbol table
+ *
+ * The Netwide Assembler is copyright (C) 1996 Simon Tatham and
+ * Julian Hall. All rights reserved. The software is
+ * redistributable under the licence given in the file "Licence"
+ * distributed in the NASM archive.
+ */
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "symtab.h"
+
+/* TODO: Implement a hash table, not this stupid implementation which
+   is too slow to be of practical use */
+
+/* Private data types */
+
+typedef struct tagSymtab {
+  symtabEnt		ent;
+  struct tagSymtab	* next;
+} symtabList;
+
+typedef symtabList *	_symtab;
+
+void *symtabNew(void)
+{
+  void *p = malloc(sizeof(_symtab));
+  if (p == NULL) {
+    fprintf(stderr,"symtab: out of memory\n");
+    exit(3);
+  }
+  *(_symtab *)p = NULL;
+
+  return p;
+}
+
+void symtabDone(void *symtab)
+{
+  /* DO SOMETHING HERE! */
+}
+
+void symtabInsert(void *symtab,symtabEnt *ent)
+{
+  symtabList	*l = malloc(sizeof(symtabList));
+
+  if (l == NULL) {
+    fprintf(stderr,"symtab: out of memory\n");
+    exit(3);
+  }
+
+  l->ent = *ent;
+  l->next = *(_symtab *)symtab;
+  *(_symtab *)symtab = l;
+}
+
+symtabEnt *symtabFind(void *symtab,char *name)
+{
+  symtabList	*l = *(_symtab *)symtab;
+
+  while (l) {
+    if (!strcmp(l->ent.name,name)) {
+      return &(l->ent);
+    }
+    l = l->next;
+  }
+  return NULL;
+}
+
+void symtabDump(void *symtab,FILE *of)
+{
+  symtabList	*l = *(_symtab *)symtab;
+
+  while(l) {
+    fprintf(of,"%32s %s:%08lx (%ld)\n",l->ent.name,
+	    l->ent.segment ? "data" : "code" ,
+	    l->ent.offset, l->ent.flags);
+    l = l->next;
+  }
+}
+
diff --git a/rdoff/symtab.h b/rdoff/symtab.h
new file mode 100644
index 0000000..5780d44
--- /dev/null
+++ b/rdoff/symtab.h
@@ -0,0 +1,22 @@
+/* symtab.h	Header file for symbol table manipulation routines
+ *
+ * The Netwide Assembler is copyright (C) 1996 Simon Tatham and
+ * Julian Hall. All rights reserved. The software is
+ * redistributable under the licence given in the file "Licence"
+ * distributed in the NASM archive.
+ */
+
+typedef struct {
+  char 	*name;
+  long	segment;
+  long	offset;
+  long	flags;
+} symtabEnt;
+
+void *symtabNew(void);
+void symtabDone(void *symtab);
+void symtabInsert(void *symtab,symtabEnt *ent);
+symtabEnt *symtabFind(void *symtab,char *name);
+void symtabDump(void *symtab,FILE *of);
+
+