include/bout.h

   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 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 2 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  20
  21 /* All i80960 development is done in a CROSS-DEVELOPMENT environment.  I.e.,
  22    object code is generated on, and executed under the direction of a symbolic
  23    debugger running on, a host system.  We do not want to be subject to the
  24    vagaries of which host it is or whether it supports COFF or a.out format,
  25    or anything else.  We DO want to:
  26
  27         o always generate the same format object files, regardless of host.
  28
  29         o have an 'a.out' header that we can modify for our own purposes
  30           (the 80960 is typically an embedded processor and may require
  31           enhanced linker support that the normal a.out.h header can't
  32           accommodate).
  33
  34   As for byte-ordering, the following rules apply:
  35
  36         o Text and data that is actually downloaded to the target is always
  37           in i80960 (little-endian) order.
  38
  39         o All other numbers (in the header, symbols, relocation directives)
  40           are in host byte-order:  object files CANNOT be lifted from a
  41           little-end host and used on a big-endian (or vice versa) without
  42           modification.
  43   ==> THIS IS NO LONGER TRUE USING BFD.  WE CAN GENERATE ANY BYTE ORDER
  44       FOR THE HEADER, AND READ ANY BYTE ORDER.  PREFERENCE WOULD BE TO
  45       USE LITTLE-ENDIAN BYTE ORDER THROUGHOUT, REGARDLESS OF HOST.  <==
  46
  47         o The downloader ('comm960') takes care to generate a pseudo-header
  48           with correct (i80960) byte-ordering before shipping text and data
  49           off to the NINDY monitor in the target systems.  Symbols and
  50           relocation info are never sent to the target.  */
  51
  52 #define BMAGIC  0415
  53 /* We don't accept the following (see N_BADMAG macro).
  54    They're just here so GNU code will compile.  */
  55 #define OMAGIC  0407            /* old impure format */
  56 #define NMAGIC  0410            /* read-only text */
  57 #define ZMAGIC  0413            /* demand load format */
  58
  59 /* FILE HEADER
  60         All 'lengths' are given as a number of bytes.
  61         All 'alignments' are for relinkable files only;  an alignment of
  62                 'n' indicates the corresponding segment must begin at an
  63                 address that is a multiple of (2**n).  */
  64 struct external_exec
  65   {
  66     /* Standard stuff */
  67     unsigned char e_info[4];    /* Identifies this as a b.out file */
  68     unsigned char e_text[4];    /* Length of text */
  69     unsigned char e_data[4];    /* Length of data */
  70     unsigned char e_bss[4];     /* Length of uninitialized data area */
  71     unsigned char e_syms[4];    /* Length of symbol table */
  72     unsigned char e_entry[4];   /* Runtime start address */
  73     unsigned char e_trsize[4];  /* Length of text relocation info */
  74     unsigned char e_drsize[4];  /* Length of data relocation info */
  75
  76     /* Added for i960 */
  77     unsigned char e_tload[4];   /* Text runtime load address */
  78     unsigned char e_dload[4];   /* Data runtime load address */
  79     unsigned char e_talign[1];  /* Alignment of text segment */
  80     unsigned char e_dalign[1];  /* Alignment of data segment */
  81     unsigned char e_balign[1];  /* Alignment of bss segment */
  82     unsigned char e_relaxable[1];/* Assembled with enough info to allow linker to relax */
  83   };
  84
  85 #define EXEC_BYTES_SIZE (sizeof (struct external_exec))
  86
  87 /* These macros use the a_xxx field names, since they operate on the exec
  88    structure after it's been byte-swapped and realigned on the host machine.  */
  89 #define N_BADMAG(x)     (((x).a_info)!=BMAGIC)
  90 #define N_TXTOFF(x)     EXEC_BYTES_SIZE
  91 #define N_DATOFF(x)     ( N_TXTOFF(x) + (x).a_text )
  92 #define N_TROFF(x)      ( N_DATOFF(x) + (x).a_data )
  93 #define N_TRELOFF       N_TROFF
  94 #define N_DROFF(x)      ( N_TROFF(x) + (x).a_trsize )
  95 #define N_DRELOFF       N_DROFF
  96 #define N_SYMOFF(x)     ( N_DROFF(x) + (x).a_drsize )
  97 #define N_STROFF(x)     ( N_SYMOFF(x) + (x).a_syms )
  98 #define N_DATADDR(x)    ( (x).a_dload )
  99
 100 /* Address of text segment in memory after it is loaded.  */
 101 #if !defined (N_TXTADDR)
 102 #define N_TXTADDR(x) 0
 103 #endif
 104
 105 /* A single entry in the symbol table.  */
 106 struct nlist
 107   {
 108     union
 109       {
 110         char*          n_name;
 111         struct nlist * n_next;
 112         long           n_strx;  /* Index into string table      */
 113       } n_un;
 114
 115     unsigned char n_type;       /* See below                            */
 116     char          n_other;      /* Used in i80960 support -- see below  */
 117     short         n_desc;
 118     unsigned long n_value;
 119   };
 120
 121
 122 /* Legal values of n_type.  */
 123 #define N_UNDF  0       /* Undefined symbol     */
 124 #define N_ABS   2       /* Absolute symbol      */
 125 #define N_TEXT  4       /* Text symbol          */
 126 #define N_DATA  6       /* Data symbol          */
 127 #define N_BSS   8       /* BSS symbol           */
 128 #define N_FN    31      /* Filename symbol      */
 129
 130 #define N_EXT   1       /* External symbol (OR'd in with one of above)  */
 131 #define N_TYPE  036     /* Mask for all the type bits                   */
 132 #define N_STAB  0340    /* Mask for all bits used for SDB entries       */
 133
 134 /* MEANING OF 'n_other'
 135
 136   If non-zero, the 'n_other' fields indicates either a leaf procedure or
 137   a system procedure, as follows:
 138
 139         1 <= n_other <= 32 :
 140                 The symbol is the entry point to a system procedure.
 141                 'n_value' is the address of the entry, as for any other
 142                 procedure.  The system procedure number (which can be used in
 143                 a 'calls' instruction) is (n_other-1).  These entries come from
 144                 '.sysproc' directives.
 145
 146         n_other == N_CALLNAME
 147                 the symbol is the 'call' entry point to a leaf procedure.
 148                 The *next* symbol in the symbol table must be the corresponding
 149                 'bal' entry point to the procedure (see following).  These
 150                 entries come from '.leafproc' directives in which two different
 151                 symbols are specified (the first one is represented here).
 152
 153
 154         n_other == N_BALNAME
 155                 the symbol is the 'bal' entry point to a leaf procedure.
 156                 These entries result from '.leafproc' directives in which only
 157                 one symbol is specified, or in which the same symbol is
 158                 specified twice.
 159
 160   Note that an N_CALLNAME entry *must* have a corresponding N_BALNAME entry,
 161   but not every N_BALNAME entry must have an N_CALLNAME entry.  */
 162 #define N_CALLNAME      ((char)-1)
 163 #define N_BALNAME       ((char)-2)
 164 #define IS_CALLNAME(x)  (N_CALLNAME == (x))
 165 #define IS_BALNAME(x)   (N_BALNAME == (x))
 166 #define IS_OTHER(x)     ((x)>0 && (x) <=32)
 167
 168 #define b_out_relocation_info relocation_info
 169 struct relocation_info
 170   {
 171     int  r_address;     /* File address of item to be relocated.  */
 172     unsigned
 173 #define r_index r_symbolnum
 174     r_symbolnum:24,     /* Index of symbol on which relocation is based,
 175                            if r_extern is set.  Otherwise set to
 176                            either N_TEXT, N_DATA, or N_BSS to
 177                            indicate section on which relocation is
 178                            based.  */
 179       r_pcrel:1,        /* 1 => relocate PC-relative; else absolute
 180                            On i960, pc-relative implies 24-bit
 181                            address, absolute implies 32-bit.  */
 182       r_length:2,       /* Number of bytes to relocate:
 183                            0 => 1 byte
 184                            1 => 2 bytes -- used for 13 bit pcrel
 185                            2 => 4 bytes.  */
 186       r_extern:1,
 187       r_bsr:1,          /* Something for the GNU NS32K assembler.  */
 188       r_disp:1,         /* Something for the GNU NS32K assembler.  */
 189       r_callj:1,        /* 1 if relocation target is an i960 'callj'.  */
 190       r_relaxable:1;    /* 1 if enough info is left to relax the data.  */
 191 };