1/* Yet Another Try at encapsulating bsd object files in coff.
2   Copyright 1988, 1989, 1991 Free Software Foundation, Inc.
3   Written by Pace Willisson 12/9/88
4
5   This file is obsolete.  It needs to be converted to just define a bunch
6   of stuff that BFD can use to do coff-encapsulated files.  --gnu@cygnus.com
7
8This program is free software; you can redistribute it and/or modify
9it under the terms of the GNU General Public License as published by
10the Free Software Foundation; either version 2 of the License, or
11(at your option) any later version.
12
13This program is distributed in the hope that it will be useful,
14but WITHOUT ANY WARRANTY; without even the implied warranty of
15MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16GNU General Public License for more details.
17
18You should have received a copy of the GNU General Public License
19along with this program; if not, write to the Free Software
20Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.  */
21
22/*
23 * We only use the coff headers to tell the kernel
24 * how to exec the file.  Therefore, the only fields that need to
25 * be filled in are the scnptr and vaddr for the text and data
26 * sections, and the vaddr for the bss.  As far as coff is concerned,
27 * there is no symbol table, relocation, or line numbers.
28 *
29 * A normal bsd header (struct exec) is placed after the coff headers,
30 * and before the real text.  I defined a the new fields 'a_machtype'
31 * and a_flags.  If a_machtype is M_386, and a_flags & A_ENCAP is
32 * true, then the bsd header is preceeded by a coff header.  Macros
33 * like N_TXTOFF and N_TXTADDR use this field to find the bsd header.
34 *
35 * The only problem is to track down the bsd exec header.  The
36 * macros HEADER_OFFSET, etc do this.
37 */
38
39#define N_FLAGS_COFF_ENCAPSULATE 0x20 /* coff header precedes bsd header */
40
41/* Describe the COFF header used for encapsulation.  */
42
43struct coffheader
44{
45  /* filehdr */
46  unsigned short f_magic;
47  unsigned short f_nscns;
48  long f_timdat;
49  long f_symptr;
50  long f_nsyms;
51  unsigned short f_opthdr;
52  unsigned short f_flags;
53  /* aouthdr */
54  short magic;
55  short vstamp;
56  long tsize;
57  long dsize;
58  long bsize;
59  long entry;
60  long text_start;
61  long data_start;
62  struct coffscn
63    {
64      char s_name[8];
65      long s_paddr;
66      long s_vaddr;
67      long s_size;
68      long s_scnptr;
69      long s_relptr;
70      long s_lnnoptr;
71      unsigned short s_nreloc;
72      unsigned short s_nlnno;
73      long s_flags;
74    } scns[3];
75};
76
77/* Describe some of the parameters of the encapsulation,
78   including how to find the encapsulated BSD header.  */
79
80/* FIXME, this is dumb.  The same tools can't handle a.outs for different
81   architectures, just because COFF_MAGIC is different; so you need a
82   separate GNU nm for every architecture!!?  Unfortunately, it needs to
83   be this way, since the COFF_MAGIC value is determined by the kernel
84   we're trying to fool here.  */
85
86#define COFF_MAGIC_I386 0514 /* I386MAGIC */
87#define COFF_MAGIC_M68K 0520 /* MC68MAGIC */
88
89#ifdef COFF_MAGIC
90short __header_offset_temp;
91#define HEADER_OFFSET(f) \
92	(__header_offset_temp = 0, \
93	 fread ((char *)&__header_offset_temp, sizeof (short), 1, (f)), \
94	 fseek ((f), -sizeof (short), 1), \
95	 __header_offset_temp==COFF_MAGIC ? sizeof(struct coffheader) : 0)
96#else
97#define HEADER_OFFSET(f) 0
98#endif
99
100#define HEADER_SEEK(f) (fseek ((f), HEADER_OFFSET((f)), 1))
101
102/* Describe the characteristics of the BSD header
103   that appears inside the encapsulation.  */
104
105/* Encapsulated coff files that are linked ZMAGIC have a text segment
106   offset just past the header (and a matching TXTADDR), excluding
107   the headers from the text segment proper but keeping the physical
108   layout and the virtual memory layout page-aligned.
109
110   Non-encapsulated a.out files that are linked ZMAGIC have a text
111   segment that starts at 0 and an N_TXTADR similarly offset to 0.
112   They too are page-aligned with each other, but they include the
113   a.out header as part of the text.
114
115   The _N_HDROFF gets sizeof struct exec added to it, so we have
116   to compensate here.  See <a.out.gnu.h>.  */
117
118#undef _N_HDROFF
119#undef N_TXTADDR
120#undef N_DATADDR
121
122#define _N_HDROFF(x) ((N_FLAGS(x) & N_FLAGS_COFF_ENCAPSULATE) ? \
123		      sizeof (struct coffheader) : 0)
124
125/* Address of text segment in memory after it is loaded.  */
126#define N_TXTADDR(x) \
127	((N_FLAGS(x) & N_FLAGS_COFF_ENCAPSULATE) ? \
128	 sizeof (struct coffheader) + sizeof (struct exec) : 0)
129#define SEGMENT_SIZE 0x400000
130
131#define N_DATADDR(x) \
132	((N_FLAGS(x) & N_FLAGS_COFF_ENCAPSULATE) ? \
133	 (SEGMENT_SIZE + ((N_TXTADDR(x)+(x).a_text-1) & ~(SEGMENT_SIZE-1))) : \
134	 (N_TXTADDR(x)+(x).a_text))
135