1------------------------------------------------------------------------------ 2-- -- 3-- GNAT COMPILER COMPONENTS -- 4-- -- 5-- E V A L _ F A T -- 6-- -- 7-- S p e c -- 8-- -- 9-- Copyright (C) 1992-2012, Free Software Foundation, Inc. -- 10-- -- 11-- GNAT is free software; you can redistribute it and/or modify it under -- 12-- terms of the GNU General Public License as published by the Free Soft- -- 13-- ware Foundation; either version 3, or (at your option) any later ver- -- 14-- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- 15-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- 16-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- 17-- for more details. You should have received a copy of the GNU General -- 18-- Public License distributed with GNAT; see file COPYING3. If not, go to -- 19-- http://www.gnu.org/licenses for a complete copy of the license. -- 20-- -- 21-- GNAT was originally developed by the GNAT team at New York University. -- 22-- Extensive contributions were provided by Ada Core Technologies Inc. -- 23-- -- 24------------------------------------------------------------------------------ 25 26-- This package provides for compile-time evaluation of static calls to the 27-- floating-point attribute functions. It is the compile-time equivalent of 28-- the System.Fat_Gen runtime package. The coding is quite similar, as are 29-- the subprogram specs, except that the type is passed as an explicit 30-- first parameter (and used via ttypes, to obtain the necessary information 31-- about the characteristics of the type for computing the results. 32 33with Types; use Types; 34with Uintp; use Uintp; 35with Urealp; use Urealp; 36 37package Eval_Fat is 38 39 subtype UI is Uint; 40 -- The compile time representation of universal integer 41 42 subtype T is Ureal; 43 -- The compile time representation of floating-point values 44 45 subtype R is Entity_Id; 46 -- The compile time representation of the floating-point root type 47 48 -- The following functions perform the operation implied by their name 49 -- which corresponds to the name of the attribute which they compute. 50 -- The arguments correspond to the attribute function arguments. 51 52 function Adjacent (RT : R; X, Towards : T) return T; 53 54 function Ceiling (RT : R; X : T) return T; 55 56 function Compose (RT : R; Fraction : T; Exponent : UI) return T; 57 58 function Copy_Sign (RT : R; Value, Sign : T) return T; 59 60 function Exponent (RT : R; X : T) return UI; 61 62 function Floor (RT : R; X : T) return T; 63 64 function Fraction (RT : R; X : T) return T; 65 66 function Leading_Part (RT : R; X : T; Radix_Digits : UI) return T; 67 68 function Model (RT : R; X : T) return T; 69 70 function Pred (RT : R; X : T) return T; 71 72 function Remainder (RT : R; X, Y : T) return T; 73 74 function Rounding (RT : R; X : T) return T; 75 76 function Scaling (RT : R; X : T; Adjustment : UI) return T; 77 78 function Succ (RT : R; X : T) return T; 79 80 function Truncation (RT : R; X : T) return T; 81 82 function Unbiased_Rounding (RT : R; X : T) return T; 83 84 -- The following global declarations are used by the Machine attribute 85 86 type Rounding_Mode is (Floor, Ceiling, Round, Round_Even); 87 for Rounding_Mode use (0, 1, 2, 3); 88 -- Used to indicate rounding mode for Machine attribute 89 -- Note that C code in gigi knows that Round_Even is 3 90 91 -- The Machine attribute is special, in that it takes an extra argument 92 -- indicating the rounding mode, and also an argument Enode that is a 93 -- node used to post warnings (e.g. if asked to convert a negative zero 94 -- on a machine for which Signed_Zeros is False). 95 96 function Machine 97 (RT : R; 98 X : T; 99 Mode : Rounding_Mode; 100 Enode : Node_Id) return T; 101 102 procedure Decompose_Int 103 (RT : R; 104 X : T; 105 Fraction : out UI; 106 Exponent : out UI; 107 Mode : Rounding_Mode); 108 -- Decomposes a floating-point number into fraction and exponent parts. 109 -- The Fraction value returned is an integer representing the value 110 -- Fraction * Scale, where Scale is the value (Machine_Radix_Value (RT) ** 111 -- Machine_Mantissa_Value (RT)). The value is obtained by using biased 112 -- rounding (halfway cases round away from zero), round to even, a floor 113 -- operation or a ceiling operation depending on the setting of Mode (see 114 -- corresponding descriptions in Urealp). 115 116end Eval_Fat; 117