359 lines
13 KiB
C
359 lines
13 KiB
C
/*-
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*
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* This code is derived from software copyrighted by the Free Software
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* Foundation.
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*
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* @(#)symseg.h 8.1 (Berkeley) 6/6/93
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*/
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/* GDB symbol table format definitions.
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Copyright (C) 1987, 1988 Free Software Foundation, Inc.
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This file is part of GNU CC.
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GNU CC is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 1, or (at your option)
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any later version.
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GNU CC is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU CC; see the file COPYING. If not, write to
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the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
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/* Format of GDB symbol table data.
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There is one symbol segment for each source file or
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independant compilation. These segments are simply concatenated
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to form the GDB symbol table. A zero word where the beginning
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of a segment is expected indicates there are no more segments.
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Format of a symbol segment:
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The symbol segment begins with a word containing 1
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if it is in the format described here. Other formats may
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be designed, with other code numbers.
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The segment contains many objects which point at each other.
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The pointers are offsets in bytes from the beginning of the segment.
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Thus, each segment can be loaded into core and its pointers relocated
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to make valid in-core pointers.
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All the data objects in the segment can be found indirectly from
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one of them, the root object, of type `struct symbol_root'.
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It appears at the beginning of the segment.
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The total size of the segment, in bytes, appears as the `length'
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field of this object. This size includes the size of the
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root object.
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All the object data types are defined here to contain pointer types
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appropriate for in-core use on a relocated symbol segment.
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Casts to and from type int are required for working with
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unrelocated symbol segments such as are found in the file.
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The ldsymaddr word is filled in by the loader to contain
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the offset (in bytes) within the ld symbol table
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of the first nonglobal symbol from this compilation.
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This makes it possible to match those symbols
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(which contain line number information) reliably with
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the segment they go with.
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Core addresses within the program that appear in the symbol segment
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are not relocated by the loader. They are inserted by the assembler
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and apply to addresses as output by the assembler, so GDB must
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relocate them when it loads the symbol segment. It gets the information
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on how to relocate from the textrel, datarel, bssrel, databeg and bssbeg
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words of the root object.
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The words textrel, datarel and bssrel
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are filled in by ld with the amounts to relocate within-the-file
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text, data and bss addresses by; databeg and bssbeg can be
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used to tell which kind of relocation an address needs. */
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enum language {language_c};
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struct symbol_root
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{
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int format; /* Data format version */
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int length; /* # bytes in this symbol segment */
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int ldsymoff; /* Offset in ld symtab of this file's syms */
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int textrel; /* Relocation for text addresses */
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int datarel; /* Relocation for data addresses */
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int bssrel; /* Relocation for bss addresses */
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char *filename; /* Name of main source file compiled */
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char *filedir; /* Name of directory it was reached from */
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struct blockvector *blockvector; /* Vector of all symbol-naming blocks */
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struct typevector *typevector; /* Vector of all data types */
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enum language language; /* Code identifying the language used */
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char *version; /* Version info. Not fully specified */
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char *compilation; /* Compilation info. Not fully specified */
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int databeg; /* Address within the file of data start */
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int bssbeg; /* Address within the file of bss start */
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struct sourcevector *sourcevector; /* Vector of line-number info */
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};
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/* All data types of symbols in the compiled program
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are represented by `struct type' objects.
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All of these objects are pointed to by the typevector.
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The type vector may have empty slots that contain zero. */
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struct typevector
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{
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int length; /* Number of types described */
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struct type *type[1];
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};
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/* Different kinds of data types are distinguished by the `code' field. */
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enum type_code
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{
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TYPE_CODE_UNDEF, /* Not used; catches errors */
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TYPE_CODE_PTR, /* Pointer type */
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TYPE_CODE_ARRAY, /* Array type, lower bound zero */
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TYPE_CODE_STRUCT, /* C struct or Pascal record */
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TYPE_CODE_UNION, /* C union or Pascal variant part */
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TYPE_CODE_ENUM, /* Enumeration type */
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TYPE_CODE_FUNC, /* Function type */
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TYPE_CODE_INT, /* Integer type */
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TYPE_CODE_FLT, /* Floating type */
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TYPE_CODE_VOID, /* Void type (values zero length) */
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TYPE_CODE_SET, /* Pascal sets */
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TYPE_CODE_RANGE, /* Range (integers within spec'd bounds) */
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TYPE_CODE_PASCAL_ARRAY, /* Array with explicit type of index */
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};
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/* This appears in a type's flags word for an unsigned integer type. */
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#define TYPE_FLAG_UNSIGNED 1
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/* Other flag bits are used with GDB. */
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struct type
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{
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/* Code for kind of type */
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enum type_code code;
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/* Name of this type, or zero if none.
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This is used for printing only.
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Type names specified as input are defined by symbols. */
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char *name;
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/* Length in bytes of storage for a value of this type */
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int length;
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/* For a pointer type, describes the type of object pointed to.
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For an array type, describes the type of the elements.
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For a function type, describes the type of the value.
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Unused otherwise. */
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struct type *target_type;
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/* Type that is a pointer to this type.
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Zero if no such pointer-to type is known yet.
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The debugger may add the address of such a type
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if it has to construct one later. */
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struct type *pointer_type;
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/* Type that is a function returning this type.
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Zero if no such function type is known here.
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The debugger may add the address of such a type
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if it has to construct one later. */
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struct type *function_type;
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/* Flags about this type. */
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short flags;
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/* Number of fields described for this type */
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short nfields;
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/* For structure and union types, a description of each field.
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For set and pascal array types, there is one "field",
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whose type is the domain type of the set or array.
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For range types, there are two "fields",
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the minimum and maximum values (both inclusive).
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For enum types, each possible value is described by one "field".
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For range types, there are two "fields", that record constant values
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(inclusive) for the minimum and maximum.
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Using a pointer to a separate array of fields
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allows all types to have the same size, which is useful
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because we can allocate the space for a type before
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we know what to put in it. */
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struct field
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{
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/* Position of this field, counting in bits from start of
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containing structure. For a function type, this is the
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position in the argument list of this argument.
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For a range bound or enum value, this is the value itself. */
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int bitpos;
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/* Size of this field, in bits, or zero if not packed.
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For an unpacked field, the field's type's length
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says how many bytes the field occupies. */
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int bitsize;
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/* In a struct or enum type, type of this field.
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In a function type, type of this argument.
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In an array type, the domain-type of the array. */
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struct type *type;
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/* Name of field, value or argument.
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Zero for range bounds and array domains. */
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char *name;
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} *fields;
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};
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/* All of the name-scope contours of the program
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are represented by `struct block' objects.
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All of these objects are pointed to by the blockvector.
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Each block represents one name scope.
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Each lexical context has its own block.
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The first two blocks in the blockvector are special.
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The first one contains all the symbols defined in this compilation
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whose scope is the entire program linked together.
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The second one contains all the symbols whose scope is the
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entire compilation excluding other separate compilations.
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In C, these correspond to global symbols and static symbols.
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Each block records a range of core addresses for the code that
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is in the scope of the block. The first two special blocks
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give, for the range of code, the entire range of code produced
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by the compilation that the symbol segment belongs to.
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The blocks appear in the blockvector
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in order of increasing starting-address,
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and, within that, in order of decreasing ending-address.
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This implies that within the body of one function
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the blocks appear in the order of a depth-first tree walk. */
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struct blockvector
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{
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/* Number of blocks in the list. */
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int nblocks;
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/* The blocks themselves. */
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struct block *block[1];
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};
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struct block
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{
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/* Addresses in the executable code that are in this block.
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Note: in an unrelocated symbol segment in a file,
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these are always zero. They can be filled in from the
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N_LBRAC and N_RBRAC symbols in the loader symbol table. */
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int startaddr, endaddr;
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/* The symbol that names this block,
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if the block is the body of a function;
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otherwise, zero.
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Note: In an unrelocated symbol segment in an object file,
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this field may be zero even when the block has a name.
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That is because the block is output before the name
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(since the name resides in a higher block).
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Since the symbol does point to the block (as its value),
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it is possible to find the block and set its name properly. */
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struct symbol *function;
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/* The `struct block' for the containing block, or 0 if none. */
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/* Note that in an unrelocated symbol segment in an object file
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this pointer may be zero when the correct value should be
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the second special block (for symbols whose scope is one compilation).
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This is because the compiler ouptuts the special blocks at the
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very end, after the other blocks. */
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struct block *superblock;
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/* Number of local symbols. */
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int nsyms;
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/* The symbols. */
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struct symbol *sym[1];
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};
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/* Represent one symbol name; a variable, constant, function or typedef. */
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/* Different name spaces for symbols. Looking up a symbol specifies
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a namespace and ignores symbol definitions in other name spaces.
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VAR_NAMESPACE is the usual namespace.
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In C, this contains variables, function names, typedef names
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and enum type values.
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STRUCT_NAMESPACE is used in C to hold struct, union and enum type names.
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Thus, if `struct foo' is used in a C program,
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it produces a symbol named `foo' in the STRUCT_NAMESPACE.
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LABEL_NAMESPACE may be used for names of labels (for gotos);
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currently it is not used and labels are not recorded at all. */
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/* For a non-global symbol allocated statically,
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the correct core address cannot be determined by the compiler.
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The compiler puts an index number into the symbol's value field.
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This index number can be matched with the "desc" field of
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an entry in the loader symbol table. */
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enum namespace
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{
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UNDEF_NAMESPACE, VAR_NAMESPACE, STRUCT_NAMESPACE, LABEL_NAMESPACE,
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};
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/* An address-class says where to find the value of the symbol in core. */
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enum address_class
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{
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LOC_UNDEF, /* Not used; catches errors */
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LOC_CONST, /* Value is constant int */
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LOC_STATIC, /* Value is at fixed address */
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LOC_REGISTER, /* Value is in register */
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LOC_ARG, /* Value is at spec'd position in arglist */
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LOC_LOCAL, /* Value is at spec'd pos in stack frame */
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LOC_TYPEDEF, /* Value not used; definition in SYMBOL_TYPE
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Symbols in the namespace STRUCT_NAMESPACE
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all have this class. */
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LOC_LABEL, /* Value is address in the code */
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LOC_BLOCK, /* Value is address of a `struct block'.
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Function names have this class. */
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LOC_EXTERNAL, /* Value is at address not in this compilation.
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This is used for .comm symbols
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and for extern symbols within functions.
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Inside GDB, this is changed to LOC_STATIC once the
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real address is obtained from a loader symbol. */
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LOC_CONST_BYTES /* Value is a constant byte-sequence. */
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};
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struct symbol
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{
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/* Symbol name */
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char *name;
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/* Name space code. */
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enum namespace namespace;
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/* Address class */
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enum address_class class;
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/* Data type of value */
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struct type *type;
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/* constant value, or address if static, or register number,
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or offset in arguments, or offset in stack frame. */
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union
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{
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long value;
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struct block *block; /* for LOC_BLOCK */
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char *bytes; /* for LOC_CONST_BYTES */
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}
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value;
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};
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/* Source-file information.
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This describes the relation between source files and line numbers
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and addresses in the program text. */
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struct sourcevector
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{
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int length; /* Number of source files described */
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struct source *source[1]; /* Descriptions of the files */
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};
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/* Line number and address of one line. */
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struct line
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{
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int linenum;
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int address;
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};
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/* All the information on one source file. */
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struct source
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{
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char *name; /* Name of file */
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int nlines; /* Number of lines that follow */
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struct line lines[1]; /* Information on each line */
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};
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