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)
31 rdfmodule * rdfload(const char *filename)
38 f = malloc(sizeof(rdfmodule));
41 rdf_errno = 6; /* out of memory */
45 f->symtab = symtabNew();
54 if ( rdfopen( &(f->f), filename ) ) {
59 /* read in text and data segments, and header */
61 f->t = malloc (f->f.seg[0].length);
62 f->d = malloc (f->f.seg[1].length); /* BSS seg allocated later */
63 hdr = malloc (f->f.header_len);
65 if (! f->t || ! f->d || !hdr) {
74 if ( rdfloadseg (&f->f,RDOFF_HEADER,hdr) ||
75 rdfloadseg (&f->f,RDOFF_CODE,f->t) ||
76 rdfloadseg (&f->f,RDOFF_DATA,f->d) )
88 /* Allocate BSS segment; step through header and count BSS records */
90 while ( ( r = rdfgetheaderrec (&f->f) ) )
93 bsslength += r->b.amount;
96 f->b = malloc ( bsslength );
97 if (bsslength && (!f->b))
107 rdfheaderrewind (&f->f);
109 f->textrel = (long)f->t;
110 f->datarel = (long)f->d;
111 f->bssrel = (long)f->b;
116 int rdf_relocate(rdfmodule * m)
124 rdfheaderrewind ( & m->f );
125 collection_init(&imports);
127 while ( (r = rdfgetheaderrec ( & m->f ) ) )
131 case 1: /* Relocation record */
133 /* calculate relocation factor */
135 if (r->r.refseg == 0) rel = m->textrel;
136 else if (r->r.refseg == 1) rel = m->datarel;
137 else if (r->r.refseg == 2) rel = m->bssrel;
139 /* We currently do not support load-time linkage.
140 This should be added some time soon... */
142 return 1; /* return error code */
144 if ((r->r.segment & 63) == 0) seg = m->t;
145 else if ((r->r.segment & 63) == 1) seg = m->d;
147 continue; /* relocation not in a loaded segment */
149 /* it doesn't matter in this case that the code is non-portable,
150 as the entire concept of executing a module like this is
152 switch(r->r.length) {
154 seg[r->r.offset] += (char) rel;
157 *(int16 *)(seg + r->r.offset) += (int16) rel;
160 *(long *)(seg + r->r.offset) += rel;
165 case 3: /* export record - add to symtab */
166 e.segment = r->e.segment;
167 e.offset = r->e.offset +
168 (e.segment == 0 ? m->textrel : /* 0 -> code */
169 e.segment == 1 ? m->datarel : /* 1 -> data */
170 m->bssrel) ; /* 2 -> bss */
172 e.name = malloc(strlen(r->e.label) + 1);
176 strcpy(e.name,r->e.label);
177 symtabInsert(m->symtab,&e);
180 case 6: /* segment relocation */
181 fprintf(stderr, "%s: segment relocation not supported by this "
182 "loader\n", m->f.name);