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Annotation of 43BSDTahoe/man/man5/stab.5, revision 1.1

1.1     ! root        1: .\" Copyright (c) 1980 Regents of the University of California.
        !             2: .\" All rights reserved.  The Berkeley software License Agreement
        !             3: .\" specifies the terms and conditions for redistribution.
        !             4: .\"
        !             5: .\"    @(#)stab.5      6.3 (Berkeley) 5/19/86
        !             6: .\"
        !             7: .TH STAB 5 "May 19, 1986"
        !             8: .UC 4
        !             9: .SH NAME
        !            10: stab \- symbol table types
        !            11: .SH SYNOPSIS
        !            12: .B "#include <stab.h>"
        !            13: .SH DESCRIPTION
        !            14: .I Stab.h
        !            15: defines some values of the n_type field of the symbol table of a.out files.
        !            16: These are the types for permanent symbols (i.e. not local labels, etc.)
        !            17: used by the old debugger
        !            18: .I sdb
        !            19: and the Berkeley Pascal compiler
        !            20: .IR pc (1).
        !            21: Symbol table entries can be produced by the
        !            22: .I .stabs
        !            23: assembler directive.
        !            24: This allows one to specify a double-quote delimited name, a symbol type,
        !            25: one char and one short of information about the symbol, and an unsigned
        !            26: long (usually an address).
        !            27: To avoid having to produce an explicit label for the address field,
        !            28: the
        !            29: .I .stabd
        !            30: directive can be used to implicitly address the current location.
        !            31: If no name is needed, symbol table entries can be generated using the
        !            32: .I .stabn
        !            33: directive.
        !            34: The loader promises to preserve the order of symbol table entries produced
        !            35: by
        !            36: .I .stab
        !            37: directives.
        !            38: As described in
        !            39: .IR a.out (5),
        !            40: an element of the symbol table
        !            41: consists of the following structure:
        !            42: .PP
        !            43: .nf
        !            44: /*
        !            45: .ti +\w'/'u
        !            46: * Format of a symbol table entry.
        !            47: .ti +\w'/'u
        !            48: */
        !            49: .ta \w'#define\ 'u +\w'unsigned 'u +\w'char\ \ 'u +\w'n_name;\ \ 'u
        !            50: struct nlist {
        !            51:        union {
        !            52:                char    *n_name;        /* for use when in-core */
        !            53:                long    n_strx;         /* index into file string table */
        !            54:        } n_un;
        !            55:        unsigned char   n_type;         /* type flag */
        !            56:        char            n_other;        /* unused */
        !            57:        short           n_desc;         /* see struct desc, below */
        !            58:        unsigned        n_value;        /* address or offset or line */
        !            59: };
        !            60: .fi
        !            61: .DT
        !            62: .PP
        !            63: The low bits of the n_type field are used to place a symbol into
        !            64: at most one segment, according to 
        !            65: the following masks, defined in
        !            66: .RI < a.out.h >.
        !            67: A symbol can be in none of these segments by having none of these segment
        !            68: bits set.
        !            69: .PP
        !            70: .nf
        !            71: /*
        !            72: .ti +\w'/'u
        !            73: * Simple values for n_type.
        !            74: .ti +\w'/'u
        !            75: */
        !            76: .ta \w'#define\ 'u +\w'N_FNAME\ 'u +\w'0x0\ \ \ 'u
        !            77: #define        N_UNDF  0x0     /* undefined */
        !            78: #define        N_ABS   0x2     /* absolute */
        !            79: #define        N_TEXT  0x4     /* text */
        !            80: #define        N_DATA  0x6     /* data */
        !            81: #define        N_BSS   0x8     /* bss */
        !            82: 
        !            83: #define        N_EXT   01      /* external bit, or'ed in */
        !            84: .DT
        !            85: .fi
        !            86: .PP
        !            87: The n_value field of a symbol is relocated by the linker,
        !            88: .IR ld (1)
        !            89: as an address within the appropriate segment.
        !            90: N_value fields of symbols not in any segment are unchanged by the linker.
        !            91: In addition, the linker will discard certain symbols, according to rules
        !            92: of its own, unless the n_type field has one of the following bits set:
        !            93: .PP
        !            94: .nf
        !            95: /*
        !            96: .ti +\w'/'u
        !            97: * Other permanent symbol table entries have some of the N_STAB bits set.
        !            98: .ti +\w'/'u
        !            99: * These are given in <stab.h>
        !           100: .ti +\w'/'u
        !           101: */
        !           102: .ta \w'#define\ 'u +\w'N_FNAME\ 'u +\w'0x0\ \ \ 'u
        !           103: #define        N_STAB          0xe0            /* if any of these bits set, don't discard */
        !           104: 
        !           105: .DT
        !           106: .fi
        !           107: .PP
        !           108: This allows up to 112 (7 \(** 16) symbol types, split between the various
        !           109: segments.
        !           110: Some of these have already been claimed.
        !           111: The old symbolic debugger,
        !           112: .IR sdb ,
        !           113: uses the following n_type values:
        !           114: .PP
        !           115: .nf
        !           116: .ta \w'#define\ 'u +\w'N_FNAME\ 'u +\w'0x0\ \ \ 'u
        !           117: #define        N_GSYM  0x20    /* global symbol: name,,0,type,0 */
        !           118: #define        N_FNAME 0x22    /* procedure name (f77 kludge): name,,0 */
        !           119: #define        N_FUN   0x24    /* procedure: name,,0,linenumber,address */
        !           120: #define        N_STSYM 0x26    /* static symbol: name,,0,type,address */
        !           121: #define        N_LCSYM 0x28    /* .lcomm symbol: name,,0,type,address */
        !           122: #define        N_RSYM  0x40    /* register sym: name,,0,type,register */
        !           123: #define        N_SLINE 0x44    /* src line: 0,,0,linenumber,address */
        !           124: #define        N_SSYM  0x60    /* structure elt: name,,0,type,struct_offset */
        !           125: #define        N_SO    0x64    /* source file name: name,,0,0,address */
        !           126: #define        N_LSYM  0x80    /* local sym: name,,0,type,offset */
        !           127: #define        N_SOL   0x84    /* #included file name: name,,0,0,address */
        !           128: #define        N_PSYM  0xa0    /* parameter: name,,0,type,offset */
        !           129: #define        N_ENTRY 0xa4    /* alternate entry: name,linenumber,address */
        !           130: #define        N_LBRAC 0xc0    /* left bracket: 0,,0,nesting level,address */
        !           131: #define        N_RBRAC 0xe0    /* right bracket: 0,,0,nesting level,address */
        !           132: #define        N_BCOMM 0xe2    /* begin common: name,, */
        !           133: #define        N_ECOMM 0xe4    /* end common: name,, */
        !           134: #define        N_ECOML 0xe8    /* end common (local name): ,,address */
        !           135: #define        N_LENG  0xfe    /* second stab entry with length information */
        !           136: .fi
        !           137: .PP
        !           138: where the comments give
        !           139: .I sdb
        !           140: conventional use for
        !           141: .IR .stab s
        !           142: and the n_name, n_other, n_desc, and n_value fields
        !           143: of the given n_type. 
        !           144: .I Sdb
        !           145: uses the n_desc field to hold a type specifier in the form used
        !           146: by the Portable C Compiler,
        !           147: .IR cc (1);
        !           148: see the header file \fIpcc.h\fP
        !           149: for details on the format of these type values.
        !           150: .PP
        !           151: The Berkeley Pascal compiler,
        !           152: .IR pc (1),
        !           153: uses the following n_type value:
        !           154: .PP
        !           155: .nf
        !           156: #define        N_PC    0x30    /* global pascal symbol: name,,0,subtype,line */
        !           157: .fi
        !           158: .PP
        !           159: and uses the following subtypes to do type checking across separately
        !           160: compiled files:
        !           161: .nf
        !           162:        1       source file name
        !           163:        2       included file name
        !           164:        3       global label
        !           165:        4       global constant
        !           166:        5       global type
        !           167:        6       global variable
        !           168:        7       global function
        !           169:        8       global procedure
        !           170:        9       external function
        !           171:        10      external procedure
        !           172:        11      library variable
        !           173:        12      library routine
        !           174: .fi
        !           175: .SH "SEE ALSO"
        !           176: as(1), ld(1), dbx(1), a.out(5)
        !           177: .SH BUGS
        !           178: .PP
        !           179: More basic types are needed.

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