source: trunk/libs/newlib/src/include/bout.h @ 468

Last change on this file since 468 was 444, checked in by satin@…, 6 years ago

add newlib,libalmos-mkh, restructure shared_syscalls.h and mini-libc

File size: 7.6 KB
RevLine 
[444]1/* This file is a modified version of 'a.out.h'.  It is to be used in all
2   GNU tools modified to support the i80960 (or tools that operate on
3   object files created by such tools).
4
5   Copyright 2001, 2010 Free Software Foundation, Inc.
6
7   This program is free software; you can redistribute it and/or modify
8   it under the terms of the GNU General Public License as published by
9   the Free Software Foundation; either version 3 of the License, or
10   (at your option) any later version.
11
12   This program is distributed in the hope that it will be useful,
13   but WITHOUT ANY WARRANTY; without even the implied warranty of
14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15   GNU General Public License for more details.
16
17   You should have received a copy of the GNU General Public License
18   along with this program; if not, write to the Free Software
19   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
20   MA 02110-1301, USA.  */
21 
22/* All i80960 development is done in a CROSS-DEVELOPMENT environment.  I.e.,
23   object code is generated on, and executed under the direction of a symbolic
24   debugger running on, a host system.  We do not want to be subject to the
25   vagaries of which host it is or whether it supports COFF or a.out format,
26   or anything else.  We DO want to:
27 
28        o always generate the same format object files, regardless of host.
29 
30        o have an 'a.out' header that we can modify for our own purposes
31          (the 80960 is typically an embedded processor and may require
32          enhanced linker support that the normal a.out.h header can't
33          accommodate).
34 
35  As for byte-ordering, the following rules apply:
36 
37        o Text and data that is actually downloaded to the target is always
38          in i80960 (little-endian) order.
39 
40        o All other numbers (in the header, symbols, relocation directives)
41          are in host byte-order:  object files CANNOT be lifted from a
42          little-end host and used on a big-endian (or vice versa) without
43          modification.
44  ==> THIS IS NO LONGER TRUE USING BFD.  WE CAN GENERATE ANY BYTE ORDER
45      FOR THE HEADER, AND READ ANY BYTE ORDER.  PREFERENCE WOULD BE TO
46      USE LITTLE-ENDIAN BYTE ORDER THROUGHOUT, REGARDLESS OF HOST.  <==
47 
48        o The downloader ('comm960') takes care to generate a pseudo-header
49          with correct (i80960) byte-ordering before shipping text and data
50          off to the NINDY monitor in the target systems.  Symbols and
51          relocation info are never sent to the target.  */
52
53#define BMAGIC  0415
54/* We don't accept the following (see N_BADMAG macro).
55   They're just here so GNU code will compile.  */
56#define OMAGIC  0407            /* old impure format */
57#define NMAGIC  0410            /* read-only text */
58#define ZMAGIC  0413            /* demand load format */
59
60/* FILE HEADER
61        All 'lengths' are given as a number of bytes.
62        All 'alignments' are for relinkable files only;  an alignment of
63                'n' indicates the corresponding segment must begin at an
64                address that is a multiple of (2**n).  */
65struct external_exec
66  {
67    /* Standard stuff */
68    unsigned char e_info[4];    /* Identifies this as a b.out file */
69    unsigned char e_text[4];    /* Length of text */
70    unsigned char e_data[4];    /* Length of data */
71    unsigned char e_bss[4];     /* Length of uninitialized data area */
72    unsigned char e_syms[4];    /* Length of symbol table */
73    unsigned char e_entry[4];   /* Runtime start address */
74    unsigned char e_trsize[4];  /* Length of text relocation info */
75    unsigned char e_drsize[4];  /* Length of data relocation info */
76
77    /* Added for i960 */
78    unsigned char e_tload[4];   /* Text runtime load address */
79    unsigned char e_dload[4];   /* Data runtime load address */
80    unsigned char e_talign[1];  /* Alignment of text segment */
81    unsigned char e_dalign[1];  /* Alignment of data segment */
82    unsigned char e_balign[1];  /* Alignment of bss segment */
83    unsigned char e_relaxable[1];/* Assembled with enough info to allow linker to relax */
84  };
85
86#define EXEC_BYTES_SIZE (sizeof (struct external_exec))
87
88/* These macros use the a_xxx field names, since they operate on the exec
89   structure after it's been byte-swapped and realigned on the host machine.  */
90#define N_BADMAG(x)     (((x).a_info)!=BMAGIC)
91#define N_TXTOFF(x)     EXEC_BYTES_SIZE
92#define N_DATOFF(x)     ( N_TXTOFF(x) + (x).a_text )
93#define N_TROFF(x)      ( N_DATOFF(x) + (x).a_data )
94#define N_TRELOFF       N_TROFF
95#define N_DROFF(x)      ( N_TROFF(x) + (x).a_trsize )
96#define N_DRELOFF       N_DROFF
97#define N_SYMOFF(x)     ( N_DROFF(x) + (x).a_drsize )
98#define N_STROFF(x)     ( N_SYMOFF(x) + (x).a_syms )
99#define N_DATADDR(x)    ( (x).a_dload )   
100
101/* Address of text segment in memory after it is loaded.  */
102#if !defined (N_TXTADDR)
103#define N_TXTADDR(x) 0
104#endif
105
106/* A single entry in the symbol table.  */
107struct nlist
108  {
109    union
110      {
111        char*          n_name;
112        struct nlist * n_next;
113        long           n_strx;  /* Index into string table      */
114      } n_un;
115
116    unsigned char n_type;       /* See below                            */
117    char          n_other;      /* Used in i80960 support -- see below  */
118    short         n_desc;
119    unsigned long n_value;
120  };
121
122
123/* Legal values of n_type.  */
124#define N_UNDF  0       /* Undefined symbol     */
125#define N_ABS   2       /* Absolute symbol      */
126#define N_TEXT  4       /* Text symbol          */
127#define N_DATA  6       /* Data symbol          */
128#define N_BSS   8       /* BSS symbol           */
129#define N_FN    31      /* Filename symbol      */
130
131#define N_EXT   1       /* External symbol (OR'd in with one of above)  */
132#define N_TYPE  036     /* Mask for all the type bits                   */
133#define N_STAB  0340    /* Mask for all bits used for SDB entries       */
134
135/* MEANING OF 'n_other'
136 
137  If non-zero, the 'n_other' fields indicates either a leaf procedure or
138  a system procedure, as follows:
139 
140        1 <= n_other <= 32 :
141                The symbol is the entry point to a system procedure.
142                'n_value' is the address of the entry, as for any other
143                procedure.  The system procedure number (which can be used in
144                a 'calls' instruction) is (n_other-1).  These entries come from
145                '.sysproc' directives.
146 
147        n_other == N_CALLNAME
148                the symbol is the 'call' entry point to a leaf procedure.
149                The *next* symbol in the symbol table must be the corresponding
150                'bal' entry point to the procedure (see following).  These
151                entries come from '.leafproc' directives in which two different
152                symbols are specified (the first one is represented here).
153       
154 
155        n_other == N_BALNAME
156                the symbol is the 'bal' entry point to a leaf procedure.
157                These entries result from '.leafproc' directives in which only
158                one symbol is specified, or in which the same symbol is
159                specified twice.
160 
161  Note that an N_CALLNAME entry *must* have a corresponding N_BALNAME entry,
162  but not every N_BALNAME entry must have an N_CALLNAME entry.  */
163#define N_CALLNAME      ((char)-1)
164#define N_BALNAME       ((char)-2)
165#define IS_CALLNAME(x)  (N_CALLNAME == (x))
166#define IS_BALNAME(x)   (N_BALNAME == (x))
167#define IS_OTHER(x)     ((x)>0 && (x) <=32)
168
169#define b_out_relocation_info relocation_info
170struct relocation_info
171  {
172    int  r_address;     /* File address of item to be relocated.  */
173    unsigned
174#define r_index r_symbolnum
175    r_symbolnum:24,     /* Index of symbol on which relocation is based,
176                           if r_extern is set.  Otherwise set to
177                           either N_TEXT, N_DATA, or N_BSS to
178                           indicate section on which relocation is
179                           based.  */
180      r_pcrel:1,        /* 1 => relocate PC-relative; else absolute
181                           On i960, pc-relative implies 24-bit
182                           address, absolute implies 32-bit.  */
183      r_length:2,       /* Number of bytes to relocate:
184                           0 => 1 byte
185                           1 => 2 bytes -- used for 13 bit pcrel
186                           2 => 4 bytes.  */
187      r_extern:1,
188      r_bsr:1,          /* Something for the GNU NS32K assembler.  */
189      r_disp:1,         /* Something for the GNU NS32K assembler.  */
190      r_callj:1,        /* 1 if relocation target is an i960 'callj'.  */
191      r_relaxable:1;    /* 1 if enough info is left to relax the data.  */
192};
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