
@example
DEFINITION MODULE SYSTEM ;

EXPORT QUALIFIED BITSPERBYTE, BYTESPERWORD,
                 ADDRESS, WORD, BYTE, CSIZE_T, CSSIZE_T, (* 
                 Target specific data types.  *)
                 ADR, TSIZE, ROTATE, SHIFT, THROW, TBITSIZE ;
                 (* SIZE is also exported if -fpim2 is used.  *)

CONST
@findex BITSPERBYTE (const)
  BITSPERBYTE   = __ATTRIBUTE__ __BUILTIN__ ((BITS_PER_UNIT)) ;
@findex BYTESPERWORD (const)
  BYTESPERWORD  = __ATTRIBUTE__ __BUILTIN__ ((UNITS_PER_WORD)) ;

(* Note that the full list of system and sized datatypes include:
   LOC, WORD, BYTE, ADDRESS,

   (and the non language standard target types)

   INTEGER8, INTEGER16, INTEGER32, INTEGER64,
   CARDINAL8, CARDINAL16, CARDINAL32, CARDINAL64,
   WORD16, WORD32, WORD64, BITSET8, BITSET16,
   BITSET32, REAL32, REAL64, REAL128, COMPLEX32,
   COMPLEX64, COMPLEX128, CSIZE_T, CSSIZE_T.

   Also note that the non-standard data types will
   move into another module in the future.  *)


(* The following types are supported on this target:
TYPE
   (* Target specific data types.  *)
*)


(*
   all the functions below are declared internally to gm2
   ======================================================

@findex ADR
PROCEDURE ADR (VAR v: <anytype>): ADDRESS;
  (* Returns the address of variable v. *)

@findex SIZE
PROCEDURE SIZE (v: <type>) : ZType;
  (* Returns the number of BYTES used to store a v of
     any specified <type>.  Only available if -fpim2 is used.
  *)

@findex TSIZE
PROCEDURE TSIZE (<type>) : CARDINAL;
  (* Returns the number of BYTES used to store a value of the
     specified <type>.
  *)

@findex ROTATE
PROCEDURE ROTATE (val: <a set type>;
                  num: INTEGER): <type of first parameter>;
  (* Returns a bit sequence obtained from val by rotating up/right
     or down/right by the absolute value of num.  The direction is
     down/right if the sign of num is negative, otherwise the direction
     is up/left.
  *)

@findex SHIFT
PROCEDURE SHIFT (val: <a set type>;
                 num: INTEGER): <type of first parameter>;
  (* Returns a bit sequence obtained from val by shifting up/left
     or down/right by the absolute value of num, introducing
     zeros as necessary.  The direction is down/right if the sign of
     num is negative, otherwise the direction is up/left.
  *)

@findex THROW
PROCEDURE THROW (i: INTEGER) <* noreturn *> ;
  (*
     THROW is a GNU extension and was not part of the PIM or ISO
     standards.  It throws an exception which will be caught by the
     EXCEPT block (assuming it exists).  This is a compiler builtin
     function which interfaces to the GCC exception handling runtime
     system.
     GCC uses the term throw, hence the naming distinction between
     the GCC builtin and the Modula-2 runtime library procedure Raise.
     The later library procedure Raise will call SYSTEM.THROW after
     performing various housekeeping activities.
  *)

@findex TBITSIZE
PROCEDURE TBITSIZE (<type>) : CARDINAL ;
  (* Returns the minimum number of bits necessary to represent
     <type>.  This procedure function is only useful for determining
     the number of bits used for any type field within a packed RECORD.
     It is not particularly useful elsewhere since <type> might be
     optimized for speed, for example a BOOLEAN could occupy a WORD.
  *)
*)

(* The following procedures are invoked by GNU Modula-2 to
   shift non word sized set types. They are not strictly part
   of the core PIM Modula-2, however they are used
   to implement the SHIFT procedure defined above,
   which are in turn used by the Logitech compatible libraries.

   Users will access these procedures by using the procedure
   SHIFT above and GNU Modula-2 will map SHIFT onto one of
   the following procedures.
*)

(*
   ShiftVal - is a runtime procedure whose job is to implement
              the SHIFT procedure of ISO SYSTEM. GNU Modula-2 will
              inline a SHIFT of a single WORD sized set and will only
              call this routine for larger sets.
*)

@findex ShiftVal
PROCEDURE ShiftVal (VAR s, d: ARRAY OF BITSET;
                    SetSizeInBits: CARDINAL;
                    ShiftCount: INTEGER) ;


(*
   ShiftLeft - performs the shift left for a multi word set.
               This procedure might be called by the back end of
               GNU Modula-2 depending whether amount is known at
               compile time.
*)

@findex ShiftLeft
PROCEDURE ShiftLeft (VAR s, d: ARRAY OF BITSET;
                     SetSizeInBits: CARDINAL;
                     ShiftCount: CARDINAL) ;

(*
   ShiftRight - performs the shift left for a multi word set.
                This procedure might be called by the back end of
                GNU Modula-2 depending whether amount is known at
                compile time.
*)

@findex ShiftRight
PROCEDURE ShiftRight (VAR s, d: ARRAY OF BITSET;
                      SetSizeInBits: CARDINAL;
                      ShiftCount: CARDINAL) ;


(*
   RotateVal - is a runtime procedure whose job is to implement
               the ROTATE procedure of ISO SYSTEM. GNU Modula-2 will
               inline a ROTATE of a single WORD (or less)
               sized set and will only call this routine for larger
               sets.
*)

@findex RotateVal
PROCEDURE RotateVal (VAR s, d: ARRAY OF BITSET;
                     SetSizeInBits: CARDINAL;
                     RotateCount: INTEGER) ;


(*
   RotateLeft - performs the rotate left for a multi word set.
                This procedure might be called by the back end of
                GNU Modula-2 depending whether amount is known at
                compile time.
*)

@findex RotateLeft
PROCEDURE RotateLeft (VAR s, d: ARRAY OF BITSET;
                      SetSizeInBits: CARDINAL;
                      RotateCount: CARDINAL) ;


(*
   RotateRight - performs the rotate right for a multi word set.
                 This procedure might be called by the back end of
                 GNU Modula-2 depending whether amount is known at
                 compile time.
*)

@findex RotateRight
PROCEDURE RotateRight (VAR s, d: ARRAY OF BITSET;
                       SetSizeInBits: CARDINAL;
                       RotateCount: CARDINAL) ;


END SYSTEM.
@end example
