------------------------------------------------------------------------------ | |

-- -- | |

-- GNAT COMPILER COMPONENTS -- | |

-- -- | |

-- S Y S T E M . A R I T H _ D O U B L E -- | |

-- -- | |

-- S p e c -- | |

-- -- | |

-- Copyright (C) 1992-2021, Free Software Foundation, Inc. -- | |

-- -- | |

-- GNAT is free software; you can redistribute it and/or modify it under -- | |

-- terms of the GNU General Public License as published by the Free Soft- -- | |

-- ware Foundation; either version 3, or (at your option) any later ver- -- | |

-- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- | |

-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- | |

-- or FITNESS FOR A PARTICULAR PURPOSE. -- | |

-- -- | |

-- As a special exception under Section 7 of GPL version 3, you are granted -- | |

-- additional permissions described in the GCC Runtime Library Exception, -- | |

-- version 3.1, as published by the Free Software Foundation. -- | |

-- -- | |

-- You should have received a copy of the GNU General Public License and -- | |

-- a copy of the GCC Runtime Library Exception along with this program; -- | |

-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- | |

-- <http://www.gnu.org/licenses/>. -- | |

-- -- | |

-- GNAT was originally developed by the GNAT team at New York University. -- | |

-- Extensive contributions were provided by Ada Core Technologies Inc. -- | |

-- -- | |

------------------------------------------------------------------------------ | |

-- This package provides software routines for doing arithmetic on "double" | |

-- signed integer values in cases where either overflow checking is required, | |

-- or intermediate results are longer than the result type. | |

generic | |

type Double_Int is range <>; | |

type Double_Uns is mod <>; | |

type Single_Uns is mod <>; | |

with function Shift_Left (A : Double_Uns; B : Natural) return Double_Uns | |

is <>; | |

with function Shift_Right (A : Double_Uns; B : Natural) return Double_Uns | |

is <>; | |

with function Shift_Left (A : Single_Uns; B : Natural) return Single_Uns | |

is <>; | |

package System.Arith_Double is | |

pragma Pure; | |

function Add_With_Ovflo_Check (X, Y : Double_Int) return Double_Int; | |

-- Raises Constraint_Error if sum of operands overflows Double_Int, | |

-- otherwise returns the signed integer sum. | |

function Subtract_With_Ovflo_Check (X, Y : Double_Int) return Double_Int; | |

-- Raises Constraint_Error if difference of operands overflows Double_Int, | |

-- otherwise returns the signed integer difference. | |

function Multiply_With_Ovflo_Check (X, Y : Double_Int) return Double_Int; | |

pragma Convention (C, Multiply_With_Ovflo_Check); | |

-- Raises Constraint_Error if product of operands overflows Double_Int, | |

-- otherwise returns the signed integer product. Gigi may also call this | |

-- routine directly. | |

procedure Scaled_Divide | |

(X, Y, Z : Double_Int; | |

Q, R : out Double_Int; | |

Round : Boolean); | |

-- Performs the division of (X * Y) / Z, storing the quotient in Q | |

-- and the remainder in R. Constraint_Error is raised if Z is zero, | |

-- or if the quotient does not fit in Double_Int. Round indicates if | |

-- the result should be rounded. If Round is False, then Q, R are | |

-- the normal quotient and remainder from a truncating division. | |

-- If Round is True, then Q is the rounded quotient. The remainder | |

-- R is not affected by the setting of the Round flag. | |

procedure Double_Divide | |

(X, Y, Z : Double_Int; | |

Q, R : out Double_Int; | |

Round : Boolean); | |

-- Performs the division X / (Y * Z), storing the quotient in Q and | |

-- the remainder in R. Constraint_Error is raised if Y or Z is zero, | |

-- or if the quotient does not fit in Double_Int. Round indicates if the | |

-- result should be rounded. If Round is False, then Q, R are the normal | |

-- quotient and remainder from a truncating division. If Round is True, | |

-- then Q is the rounded quotient. The remainder R is not affected by the | |

-- setting of the Round flag. | |

end System.Arith_Double; |