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-- GHDL Run Time (GRT) - Floating point conversions.
-- Copyright (C) 2017 Tristan Gingold
--
-- GHDL 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 2, or (at your option) any later
-- version.
--
-- GHDL 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 GCC; see the file COPYING. If not, write to the Free
-- Software Foundation, 59 Temple Place - Suite 330, Boston, MA
-- 02111-1307, USA.
--
-- As a special exception, if other files instantiate generics from this
-- unit, or you link this unit with other files to produce an executable,
-- this unit does not by itself cause the resulting executable to be
-- covered by the GNU General Public License. This exception does not
-- however invalidate any other reasons why the executable file might be
-- covered by the GNU Public License.
-- IMPORTANT: this unit can also be used by the front-end, so it must NOT
-- depend on anything else from grt (except the grt parent package), including
-- grt.types.
with Interfaces; use Interfaces;
package Grt.Fcvt is
-- Convert V to 10-based number stored (in ASCII) in STR/LEN [using at most
-- NDIGITS digits.]
-- LEN is the number of characters needed (so it may be greater than
-- STR'Length).
-- Requires STR'First = 1.
procedure To_String (Str : out String;
Len : out Natural;
V : IEEE_Float_64);
-- Input format is [+-]int[.int][e[+-]int]
-- where int is digit { _ digit }
-- and [+-] means optional + or -.
-- The input string must be correctly formatted.
function From_String (Str : String) return IEEE_Float_64;
-- Ad-hoc implementation of bignums, with the minimal features to support
-- radix conversion.
type Bignum is private;
-- Compute L * R + CARRY_IN.
procedure Bignum_Mul_Int
(L : in out Bignum; R : Positive; Carry_In : Natural := 0);
-- Multiply two bignums.
function Bignum_Mul (L, R : Bignum) return Bignum;
-- Compute L**N
function Bignum_Pow (L : Natural; N : Natural) return Bignum;
-- Create a bignum from a natural.
procedure Bignum_Int (Res : out Bignum; N : Natural);
-- Convert N to RES. OK is set to True if the number fits in RES.
procedure Bignum_To_Int
(N : Bignum; Res : out Unsigned_64; OK : out Boolean);
-- Return (-1)**Neg * F * BASE**EXP to a float.
function To_Float_64
(Neg : Boolean; F : Bignum; Base : Positive; Exp : Integer)
return IEEE_Float_64;
private
type Unsigned_32_Array is array (Natural range <>) of Unsigned_32;
type Bignum is record
-- Number of digits. Must be 0 for number 0.
N : Natural;
-- Digits. The leading digit V(N + 1) must not be 0.
V : Unsigned_32_Array (1 .. 37);
end record;
end Grt.Fcvt;
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