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markom |
/* Copyright 1992 Free Software Foundation, Inc.
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*
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* This file is a modified version of 'a.out.h'. It is to be used in all
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* all GNU tools modified to support the i80960 (or tools that operate on
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* object files created by such tools).
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*
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* All i80960 development is done in a CROSS-DEVELOPMENT environment. I.e.,
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* object code is generated on, and executed under the direction of a symbolic
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* debugger running on, a host system. We do not want to be subject to the
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* vagaries of which host it is or whether it supports COFF or a.out format,
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* or anything else. We DO want to:
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*
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* o always generate the same format object files, regardless of host.
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*
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* o have an 'a.out' header that we can modify for our own purposes
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* (the 80960 is typically an embedded processor and may require
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* enhanced linker support that the normal a.out.h header can't
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* accommodate).
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*
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* As for byte-ordering, the following rules apply:
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*
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* o Text and data that is actually downloaded to the target is always
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* in i80960 (little-endian) order.
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*
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* o All other numbers (in the header, symbols, relocation directives)
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* are in host byte-order: object files CANNOT be lifted from a
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* little-end host and used on a big-endian (or vice versa) without
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* modification.
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*
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* o The downloader ('comm960') takes care to generate a pseudo-header
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* with correct (i80960) byte-ordering before shipping text and data
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* off to the NINDY monitor in the target systems. Symbols and
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* relocation info are never sent to the target.
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*/
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#define BMAGIC 0415
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/* We don't accept the following (see N_BADMAG macro).
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* They're just here so GNU code will compile.
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*/
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#define OMAGIC 0407 /* old impure format */
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#define NMAGIC 0410 /* read-only text */
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#define ZMAGIC 0413 /* demand load format */
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/* FILE HEADER
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* All 'lengths' are given as a number of bytes.
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* All 'alignments' are for relinkable files only; an alignment of
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* 'n' indicates the corresponding segment must begin at an
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* address that is a multiple of (2**n).
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*/
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struct exec {
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/* Standard stuff */
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unsigned long a_magic; /* Identifies this as a b.out file */
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unsigned long a_text; /* Length of text */
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unsigned long a_data; /* Length of data */
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unsigned long a_bss; /* Length of runtime uninitialized data area */
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unsigned long a_syms; /* Length of symbol table */
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unsigned long a_entry; /* Runtime start address */
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unsigned long a_trsize; /* Length of text relocation info */
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unsigned long a_drsize; /* Length of data relocation info */
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/* Added for i960 */
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unsigned long a_tload; /* Text runtime load address */
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unsigned long a_dload; /* Data runtime load address */
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unsigned char a_talign; /* Alignment of text segment */
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unsigned char a_dalign; /* Alignment of data segment */
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unsigned char a_balign; /* Alignment of bss segment */
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unsigned char unused; /* (Just to make struct size a multiple of 4) */
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};
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#define N_BADMAG(x) (((x).a_magic)!=BMAGIC)
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#define N_TXTOFF(x) ( sizeof(struct exec) )
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#define N_DATOFF(x) ( N_TXTOFF(x) + (x).a_text )
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#define N_TROFF(x) ( N_DATOFF(x) + (x).a_data )
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#define N_DROFF(x) ( N_TROFF(x) + (x).a_trsize )
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#define N_SYMOFF(x) ( N_DROFF(x) + (x).a_drsize )
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#define N_STROFF(x) ( N_SYMOFF(x) + (x).a_syms )
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/* A single entry in the symbol table
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*/
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struct nlist {
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union {
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char *n_name;
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struct nlist *n_next;
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long n_strx; /* Index into string table */
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} n_un;
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unsigned char n_type; /* See below */
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char n_other; /* Used in i80960 support -- see below */
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short n_desc;
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unsigned long n_value;
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};
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/* Legal values of n_type
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*/
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#define N_UNDF 0 /* Undefined symbol */
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#define N_ABS 2 /* Absolute symbol */
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#define N_TEXT 4 /* Text symbol */
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#define N_DATA 6 /* Data symbol */
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#define N_BSS 8 /* BSS symbol */
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#define N_FN 31 /* Filename symbol */
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#define N_EXT 1 /* External symbol (OR'd in with one of above) */
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#define N_TYPE 036 /* Mask for all the type bits */
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#define N_STAB 0340 /* Mask for all bits used for SDB entries */
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/* MEANING OF 'n_other'
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*
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* If non-zero, the 'n_other' fields indicates either a leaf procedure or
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* a system procedure, as follows:
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*
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* 1 <= n_other <= 32 :
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* The symbol is the entry point to a system procedure.
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* 'n_value' is the address of the entry, as for any other
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* procedure. The system procedure number (which can be used in
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* a 'calls' instruction) is (n_other-1). These entries come from
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* '.sysproc' directives.
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*
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* n_other == N_CALLNAME
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* the symbol is the 'call' entry point to a leaf procedure.
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* The *next* symbol in the symbol table must be the corresponding
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* 'bal' entry point to the procedure (see following). These
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* entries come from '.leafproc' directives in which two different
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* symbols are specified (the first one is represented here).
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*
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*
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* n_other == N_BALNAME
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* the symbol is the 'bal' entry point to a leaf procedure.
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* These entries result from '.leafproc' directives in which only
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* one symbol is specified, or in which the same symbol is
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* specified twice.
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*
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* Note that an N_CALLNAME entry *must* have a corresponding N_BALNAME entry,
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* but not every N_BALNAME entry must have an N_CALLNAME entry.
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*/
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#define N_CALLNAME -1
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#define N_BALNAME -2
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struct relocation_info {
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int r_address; /* File address of item to be relocated */
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unsigned
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r_symbolnum:24,/* Index of symbol on which relocation is based*/
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r_pcrel:1, /* 1 => relocate PC-relative; else absolute
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* On i960, pc-relative implies 24-bit
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* address, absolute implies 32-bit.
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*/
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r_length:2, /* Number of bytes to relocate:
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* 0 => 1 byte
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* 1 => 2 bytes
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* 2 => 4 bytes -- only value used for i960
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*/
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r_extern:1,
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r_bsr:1, /* Something for the GNU NS32K assembler */
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r_disp:1, /* Something for the GNU NS32K assembler */
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r_callj:1, /* 1 if relocation target is an i960 'callj' */
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nuthin:1; /* Unused */
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};
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