bitoperations.def

<B>Digital的Unix操作系统VAX 4.2源码</B>

(*#@(#)bitoperations.def	4.1	Ultrix	7/17/90 *)
(* $Header: bitoperations.def,v 1.3 84/05/19 11:39:38 powell Exp $ *)
This module should not be compiled, but is supplied for documentation purposes.
definition module bitoperations;
(* This is a dummy definition module to indicate what is in the built-in *)
(* bitoperations module.  Note that case is ignored in built-in identifiers *)

from system import BITSPERWORD;

export qualified BitNot, BitAnd, BitOr, BitXor, BitShiftLeft, BitShiftRight,
		    BitInsert, BitExtract;

type
    FieldOffset = [0..WORDSIZE-1];
    FieldSize = [1..WORDSIZE];

procedure BitNot(a : integer) : integer;
    (* returns bit-by-bit not of a *)

procedure BitAnd(a, b : integer) : integer;
    (* returns bit-by-bit and of a and b *)

procedure BitOr(a, b : integer) : integer;
    (* returns bit-by-bit or of a and b *)

procedure BitXor(a, b : integer) : integer;
    (* returns bit-by-bit exclusive or of a and b *)

procedure BitShiftLeft(a : integer; n : cardinal) : integer;
    (* returns a (logically) shifted left n (>=0) bits *)

procedure BitShiftRight(a : integer; n : cardinal) : integer;
    (* returns a (logically) shifted right n (>=0) bits *)

procedure BitExtract(word : integer; offset : FieldOffset; size : FieldSize)
		    : integer;
    (* returns the field of size bits starting at bit offset of word *)
    (* field is returned right-justified and zero filled *)

procedure BitInsert(field : integer; offset : FieldOffset; size : FieldSize;
		word : integer) : integer;
    (* returns word with rightmost size bits of field inserted starting *)
    (* at bit offset *)

end bitoperations.