--------------------------------------------------------------------------
--
-- Copyright (C) 1993, Peter J. Ashenden
-- Mail: Dept. Computer Science
-- University of Adelaide, SA 5005, Australia
-- e-mail: petera@cs.adelaide.edu.au
--
-- This program is free software; you can redistribute it and/or modify
-- it under the terms of the GNU General Public License as published by
-- the Free Software Foundation; either version 1, or (at your option)
-- any later version.
--
-- This program is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-- GNU General Public License for more details.
--
-- You should have received a copy of the GNU General Public License
-- along with this program; if not, write to the Free Software
-- Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
--
--------------------------------------------------------------------------
--
-- $RCSfile: bv_arithmetic.vhdl,v $ $Revision: 2.1 $ $Date: 1993/10/31 20:10:41 $
--
--------------------------------------------------------------------------
--
-- Bit vector arithmetic package specification.
--
-- Does arithmetic and logical operations on bit vectors, treating them
-- as either unsigned or signed (2's complement) integers. Leftmost bit
-- is most significant or sign bit, rightmost bit is least significant
-- bit. Dyadic operations need the two arguments to be of the same
-- length, however their index ranges and directions may differ. Results
-- must be of the same length as the operands.
--
--------------------------------------------------------------------------
use std.textio.line;
package bv_arithmetic is
----------------------------------------------------------------
-- Type conversions
----------------------------------------------------------------
-- Convert bit vector encoded unsigned integer to natural.
function bv_to_natural (bv : in bit_vector) return natural;
-- Convert natural to bit vector encoded unsigned integer.
-- (length is used as the size of the result.)
function natural_to_bv (nat : in natural;
length : in natural) return bit_vector;
-- Convert bit vector encoded signed integer to integer
function bv_to_integer (bv : in bit_vector) return integer;
-- Convert integer to bit vector encoded signed integer.
-- (length is used as the size of the result.)
function integer_to_bv (int : in integer;
length : in natural) return bit_vector;
----------------------------------------------------------------
-- Arithmetic operations
----------------------------------------------------------------
-- Signed addition with overflow detection
procedure bv_add (bv1, bv2 : in bit_vector;
bv_result : out bit_vector;
overflow : out boolean);
-- Signed addition without overflow detection
function "+" (bv1, bv2 : in bit_vector) return bit_vector;
-- Signed subtraction with overflow detection
procedure bv_sub (bv1, bv2 : in bit_vector;
bv_result : out bit_vector;
overflow : out boolean);
-- Signed subtraction without overflow detection
function "-" (bv1, bv2 : in bit_vector) return bit_vector;
-- Unsigned addition with overflow detection
procedure bv_addu (bv1, bv2 : in bit_vector;
bv_result : out bit_vector;
overflow : out boolean);
-- Unsigned addition without overflow detection
procedure bv_addu (bv1, bv2 : in bit_vector;
bv_result : out bit_vector);
-- Unsigned subtraction with overflow detection
procedure bv_subu (bv1, bv2 : in bit_vector;
bv_result : out bit_vector;
overflow : out boolean);
-- Unsigned subtraction without overflow detection
procedure bv_subu (bv1, bv2 : in bit_vector;
bv_result : out bit_vector);
-- Signed negation with overflow detection
procedure bv_neg (bv : in bit_vector;
bv_result : out bit_vector;
overflow : out boolean);
-- Signed negation without overflow detection
function "-" (bv : in bit_vector) return bit_vector;
-- Signed multiplication with overflow detection
procedure bv_mult (bv1, bv2 : in bit_vector;
bv_result : out bit_vector;
overflow : out boolean);
-- Signed multiplication without overflow detection
function "*" (bv1, bv2 : in bit_vector) return bit_vector;
-- Unsigned multiplication with overflow detection
procedure bv_multu (bv1, bv2 : in bit_vector;
bv_result : out bit_vector;
overflow : out boolean);
-- Unsigned multiplication without overflow detection
procedure bv_multu (bv1, bv2 : in bit_vector;
bv_result : out bit_vector);
-- Signed division with divide by zero and overflow detection
procedure bv_div (bv1, bv2 : in bit_vector;
bv_result : out bit_vector;
div_by_zero : out boolean;
overflow : out boolean);
-- Signed division without divide by zero and overflow detection
function "/" (bv1, bv2 : in bit_vector) return bit_vector;
-- Unsigned division with divide by zero detection
procedure bv_divu (bv1, bv2 : in bit_vector;
bv_result : out bit_vector;
div_by_zero : out boolean);
-- Unsigned division without divide by zero detection
procedure bv_divu (bv1, bv2 : in bit_vector;
bv_result : out bit_vector);
----------------------------------------------------------------
-- Logical operators
-- (Provided for VHDL-87, built in for VHDL-93)
----------------------------------------------------------------
-- Shift left logical (fill with '0' bits)
function bv_sll (bv : in bit_vector;
shift_count : in natural) return bit_vector;
-- Shift right logical (fill with '0' bits)
function bv_srl (bv : in bit_vector;
shift_count : in natural) return bit_vector;
-- Shift right arithmetic (fill with copy of sign bit)
function bv_sra (bv : in bit_vector;
shift_count : in natural) return bit_vector;
-- Rotate left
function bv_rol (bv : in bit_vector;
rotate_count : in natural) return bit_vector;
-- Rotate right
function bv_ror (bv : in bit_vector;
rotate_count : in natural) return bit_vector;
----------------------------------------------------------------
-- Arithmetic comparison operators.
-- Perform comparisons on bit vector encoded signed integers.
-- (For unsigned integers, built in lexical comparison does
-- the required operation.)
----------------------------------------------------------------
-- Signed less than comparison
function bv_lt (bv1, bv2 : in bit_vector) return boolean;
-- Signed less than or equal comparison
function bv_le (bv1, bv2 : in bit_vector) return boolean;
-- Signed greater than comparison
function bv_gt (bv1, bv2 : in bit_vector) return boolean;
-- Signed greater than or equal comparison
function bv_ge (bv1, bv2 : in bit_vector) return boolean;
----------------------------------------------------------------
-- Extension operators - convert a bit vector to a longer one
----------------------------------------------------------------
-- Sign extension - replicate the sign bit of the operand into
-- the most significant bits of the result. Length parameter
-- determines size of result. If length < bv'length, result is
-- rightmost length bits of bv.
function bv_sext (bv : in bit_vector;
length : in natural) return bit_vector;
-- Zero extension - replicate zero bits into the most significant
-- bits of the result. Length parameter determines size of result.
-- If length < bv'length, result is rightmost length bits of bv.
function bv_zext (bv : in bit_vector;
length : in natural) return bit_vector;
end bv_arithmetic;
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