usr/include/a.out.h

/*
 * Format of an a.out header
 */

struct  exec {  /* a.out header */
        int             a_magic;        /* magic number */
        unsigned        a_text;         /* size of text segment */
        unsigned        a_data;         /* size of initialized data */
        unsigned        a_bss;          /* size of uninitialized data */
        unsigned        a_syms;         /* size of symbol table */
        unsigned        a_entry;        /* entry point */
        unsigned        a_trsize;       /* size of text relocation */
        unsigned        a_drsize;       /* size of data relocation */
};

#define A_MAGIC1        0407            /* normal */
#define A_MAGIC2        0410            /* read-only text */
#define A_MAGIC3        0411            /* separated I&D (not on VAX) */
#define A_MAGIC4        0405            /* overlay */
#define A_MAGIC5        0413            /* demand page read-only text */

struct relocation_info {
          long  r_address;      /* relative to current segment */
          long  r_symbolnum:24,
                                /* if extern then symbol table */
                                /* ordinal (0, 1, 2, ...) else */
                                /* segment number (same as symbol types) */
                r_pcrel:1,      /* if so, segment offset has already */
                                /* been subtracted */
                r_length:2,     /* 0=byte, 1=word, 2=long */
                r_extern:1,     /* does not include value */
                                /* of symbol referenced */
                r_offset:1,     /* already includes origin */
                                /* of this segment (?) */
                r_pad:3;        /* nothing, yet */
};
struct  nlist { /* symbol table entry */
        char    n_name[8];      /* symbol name */
        char    n_type;         /* type flag */
        char    n_other;
        short   n_desc;
        unsigned n_value;       /* value */
};

        /* values for type flag */
#define N_UNDF  0               /* undefined */
#define N_ABS   02              /* absolute */
#define N_TEXT  04              /* text */
#define N_DATA  06              /* data */
#define N_BSS   08
#define N_TYPE  037
#define N_FN    037             /* file name symbol */

#define N_GSYM  0040            /* global sym: name,,type,0 */
#define N_FNAME 0042            /* procedure name (f77 kludge): name,,,0 */
#define N_FUN   0044            /* procedure: name,,linenumber,address */
#define N_STSYM 0046            /* static symbol: name,,type,address */
#define N_LCSYM 0048            /* .lcomm symbol: name,,type,address */
#define N_RSYM  0100            /* register sym: name,,register,offset */
#define N_SLINE 0104            /* src line: ,,linenumber,address */
#define N_SSYM  0140            /* structure elt: name,,type,struct_offset */
#define N_SO    0144            /* source file name: name,,,address */
#define N_LSYM  0200            /* local sym: name,,type,offset */
#define N_SOL   0204            /* #line source filename: name,,,address */
#define N_PSYM  0240            /* parameter: name,,type,offset */
#define N_ENTRY 0244            /* alternate entry: name,,linenumber,address */
#define N_LBRAC 0300            /* left bracket: ,,nesting level,address */
#define N_RBRAC 0340            /* right bracket: ,,nesting level,address */
#define N_BCOMM 0342            /* begin common: name,,, */
#define N_ECOMM 0344            /* end common: name,,, */
#define N_ECOML 0348            /* end common (local name): ,,,address */
#define N_LENG  0376            /* second stab entry with length information */

#define N_EXT   01              /* external bit, or'ed in */

#define FORMAT  "%08x"

#define STABTYPES       0340