1 /* rdfload.c RDOFF Object File loader library
3 * The Netwide Assembler is copyright (C) 1996 Simon Tatham and
4 * Julian Hall. All rights reserved. The software is
5 * redistributable under the licence given in the file "Licence"
6 * distributed in the NASM archive.
8 * Permission to use this file in your own projects is granted, as long
9 * as acknowledgement is given in an appropriate manner to its authors,
10 * with instructions of how to obtain a copy via ftp.
14 * TODO: this has been modified from previous version only in very
15 * simplistic ways. Needs to be improved drastically, especially:
16 * - support for more than the 2 standard segments
17 * - support for segment relocations (hard to do in ANSI C)
30 rdfmodule * rdfload(const char *filename)
37 f = malloc(sizeof(rdfmodule));
40 rdf_errno = 6; /* out of memory */
44 f->symtab = symtabNew();
53 if ( rdfopen( &(f->f), filename ) ) {
58 /* read in text and data segments, and header */
60 f->t = malloc (f->f.seg[0].length);
61 f->d = malloc (f->f.seg[1].length); /* BSS seg allocated later */
62 hdr = malloc (f->f.header_len);
64 if (! f->t || ! f->d || !hdr) {
73 if ( rdfloadseg (&f->f,RDOFF_HEADER,hdr) ||
74 rdfloadseg (&f->f,RDOFF_CODE,f->t) ||
75 rdfloadseg (&f->f,RDOFF_DATA,f->d) )
87 /* Allocate BSS segment; step through header and count BSS records */
89 while ( ( r = rdfgetheaderrec (&f->f) ) )
92 bsslength += r->b.amount;
95 f->b = malloc ( bsslength );
96 if (bsslength && (!f->b))
106 rdfheaderrewind (&f->f);
108 f->textrel = (long)f->t;
109 f->datarel = (long)f->d;
110 f->bssrel = (long)f->b;
115 int rdf_relocate(rdfmodule * m)
123 rdfheaderrewind ( & m->f );
124 collection_init(&imports);
126 while ( (r = rdfgetheaderrec ( & m->f ) ) )
130 case 1: /* Relocation record */
132 /* calculate relocation factor */
134 if (r->r.refseg == 0) rel = m->textrel;
135 else if (r->r.refseg == 1) rel = m->datarel;
136 else if (r->r.refseg == 2) rel = m->bssrel;
138 /* We currently do not support load-time linkage.
139 This should be added some time soon... */
141 return 1; /* return error code */
143 if ((r->r.segment & 63) == 0) seg = m->t;
144 else if ((r->r.segment & 63) == 1) seg = m->d;
146 continue; /* relocation not in a loaded segment */
148 /* it doesn't matter in this case that the code is non-portable,
149 as the entire concept of executing a module like this is
151 switch(r->r.length) {
153 seg[r->r.offset] += (char) rel;
156 *(int16 *)(seg + r->r.offset) += (int16) rel;
159 *(long *)(seg + r->r.offset) += rel;
164 case 3: /* export record - add to symtab */
165 e.segment = r->e.segment;
166 e.offset = r->e.offset +
167 (e.segment == 0 ? m->textrel : /* 0 -> code */
168 e.segment == 1 ? m->datarel : /* 1 -> data */
169 m->bssrel) ; /* 2 -> bss */
171 e.name = malloc(strlen(r->e.label) + 1);
175 strcpy(e.name,r->e.label);
176 symtabInsert(m->symtab,&e);
179 case 6: /* segment relocation */
180 fprintf(stderr, "%s: segment relocation not supported by this "
181 "loader\n", m->f.name);