Architectures
=============

BFD's idea of an architecture is implimented in archures.c. BFD keeps one atom in a BFD describing the architecture of the data attached to the BFD;  a pointer to a bfd_arch_info_type. Pointers to structures can be requested independently of a bfd so that an architecture's information can be interrogated without access to an open bfd. The arch information is provided by each architecture package. The set of default architectures is selected by the #define SELECT_ARCHITECTURES.  This is normally set up in the config\/h\- file of your choice.  If the name is not defined, then all the architectures supported are included. When BFD starts up, all the architectures are called with an initialize method.  It is up to the architecture back end to insert as many items into the list of arches as it wants to, generally this would be one for each machine and one for the default case (an item with a machine field of 0).

bfd_architecture
----------------

Description

This enum gives the object file's CPU architecture, in a global sense. E.g. what processor family does it belong to? There is another field, which indicates what processor within the family is in use.  The machine gives a number which distingushes different versions of the architecture, containing for example 2 and 3 for Intel i960 KA and i960 KB, and 68020 and 68030 for Motorola 68020 and 68030.

     enum bfd_architecture
     {
       bfd_arch_unknown,    /* File arch not known */
       bfd_arch_obscure,    /* Arch known, not one of these */
       bfd_arch_m68k,       /* Motorola 68xxx */
       bfd_arch_vax,        /* DEC Vax */
       bfd_arch_i960,       /* Intel 960 */
          /* The order of the following is important.
            lower number indicates a machine type that
            only accepts a subset of the instructions
            available to machines with higher numbers.
            The exception is the "ca", which is
            incompatible with all other machines except
            "core". */

     #define bfd_mach_i960_core      1
     #define bfd_mach_i960_ka_sa     2
     #define bfd_mach_i960_kb_sb     3
     #define bfd_mach_i960_mc        4
     #define bfd_mach_i960_xa        5
     #define bfd_mach_i960_ca        6

       bfd_arch_a29k,       /* AMD 29000 */
       bfd_arch_sparc,      /* SPARC */
       bfd_arch_mips,       /* MIPS Rxxxx */
       bfd_arch_i386,       /* Intel 386 */
       bfd_arch_ns32k,      /* National Semiconductor 32xxx */
       bfd_arch_tahoe,      /* CCI/Harris Tahoe */
       bfd_arch_i860,       /* Intel 860 */
       bfd_arch_romp,       /* IBM ROMP PC/RT */
       bfd_arch_alliant,    /* Alliant */
       bfd_arch_convex,     /* Convex */
       bfd_arch_m88k,       /* Motorola 88xxx */
       bfd_arch_pyramid,    /* Pyramid Technology */
       bfd_arch_h8300,      /* Hitachi H8/300 */
       bfd_arch_rs6000,     /* IBM RS/6000 */
       bfd_arch_last
       };

bfd_arch_info
-------------

Description

This structure contains information on architectures for use within BFD.

     typedef int bfd_reloc_code_type;

     typedef struct bfd_arch_info
     {
       int bits_per_word;
       int bits_per_address;
       int bits_per_byte;
       enum bfd_architecture arch;
       long mach;
       char *arch_name;
       CONST  char *printable_name;
       /* true if this is the default machine for the architecture */
      unsigned int section_align_power;
       boolean the_default;
       CONST struct bfd_arch_info * EXFUN((*compatible),
     	(CONST struct bfd_arch_info *a,
     	 CONST struct bfd_arch_info *b));

       boolean EXFUN((*scan),(CONST struct bfd_arch_info *,CONST char *));
       unsigned int EXFUN((*disassemble),(bfd_vma addr, CONST char *data,
     				     PTR stream));
       CONST struct reloc_howto_struct *EXFUN((*reloc_type_lookup),
         (CONST struct bfd_arch_info *,
         bfd_reloc_code_type  code));

       struct bfd_arch_info *next;

     } bfd_arch_info_type;

bfd_printable_name
..................

Synopsis

     CONST char *bfd_printable_name(bfd *abfd);

Description

Return a printable string representing the architecture and machine from the pointer to the arch info structure

bfd_scan_arch
.............

Synopsis

     bfd_arch_info_type *bfd_scan_arch(CONST char *);

Description

This routine is provided with a string and tries to work out if bfd supports any cpu which could be described with the name provided.  The routine returns a pointer to an arch_info structure if a machine is found, otherwise NULL.

bfd_arch_get_compatible
.......................

Synopsis

     CONST bfd_arch_info_type *bfd_arch_get_compatible(
         CONST bfd *abfd,
         CONST bfd *bbfd);

Description

This routine is used to determine whether two BFDs' architectures and achine types are compatible.  It calculates the lowest common denominator between the two architectures and machine types implied by the BFDs and returns a pointer to an arch_info structure describing the compatible machine.

bfd_default_arch_struct
.......................

Description

The bfd_default_arch_struct is an item of bfd_arch_info_type which has been initialized to a fairly generic state.  A BFD starts life by pointing to this structure, until the correct back end has determined the real architecture of the file.

     extern bfd_arch_info_type bfd_default_arch_struct;

bfd_set_arch_info
.................

Synopsis

     void bfd_set_arch_info(bfd *, bfd_arch_info_type *);

bfd_default_set_arch_mach
.........................

Synopsis

     boolean bfd_default_set_arch_mach(bfd *abfd,
         enum bfd_architecture arch,
         unsigned long mach);

Description

Set the architecture and machine type in a bfd. This finds the correct pointer to structure and inserts it into the arch_info pointer.

bfd_get_arch
............

Synopsis

     enum bfd_architecture bfd_get_arch(bfd *abfd);

Description

Returns the enumerated type which describes the supplied bfd's architecture

bfd_get_mach
............

Synopsis

     unsigned long bfd_get_mach(bfd *abfd);

Description

Returns the long type which describes the supplied bfd's machine

bfd_arch_bits_per_byte
......................

Synopsis

     unsigned int bfd_arch_bits_per_byte(bfd *abfd);

Description

Returns the number of bits in one of the architectures bytes

bfd_arch_bits_per_address
.........................

Synopsis

     unsigned int bfd_arch_bits_per_address(bfd *abfd);

Description

Returns the number of bits in one of the architectures addresses

bfd_arch_init
.............

Synopsis

     void  bfd_arch_init(void);

Description

This routine initializes the architecture dispatch table by calling all installed architecture packages and getting them to poke around.

bfd_arch_linkin
...............

Synopsis

     void bfd_arch_linkin(bfd_arch_info_type *);

Description

Link the provided arch info structure into the list

bfd_default_compatible
......................

Synopsis

     CONST bfd_arch_info_type *bfd_default_compatible
        (CONST bfd_arch_info_type *a,
         CONST bfd_arch_info_type *b);

Description

The default function for testing for compatibility.

bfd_default_scan
................

Synopsis

     boolean bfd_default_scan(CONST struct bfd_arch_info *, CONST char *);

Description

The default function for working out whether this is an architecture hit and a machine hit.

bfd_get_arch_info
.................

Synopsis

     bfd_arch_info_type * bfd_get_arch_info(bfd *);

bfd_lookup_arch
...............

Synopsis

     bfd_arch_info_type *bfd_lookup_arch
        (enum bfd_architecture
         arch,
         long machine);

Description

Look for the architecure info struct which matches the arguments given. A machine of 0 will match the machine/architecture structure which marks itself as the default.

bfd_printable_arch_mach
.......................

Synopsis

     CONST char * bfd_printable_arch_mach
        (enum bfd_architecture arch, unsigned long machine);

Description

Return a printable string representing the architecture and machine type. NB. The use of this routine is depreciated.