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@ -38,14 +38,14 @@ package body Eval_Fat is
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-- case of anyone ever having to adjust this code for another value,
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-- and for documentation purposes.
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-- Another assumption is that the range of the floating-point type
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-- is symmetric around zero.
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type Radix_Power_Table is array (Int range 1 .. 4) of Int;
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Radix_Powers : constant Radix_Power_Table :=
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(Radix ** 1, Radix ** 2, Radix ** 3, Radix ** 4);
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function Float_Radix return T renames Ureal_2;
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-- Radix expressed in real form
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-----------------------
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-- Local Subprograms --
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-----------------------
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@ -74,6 +74,12 @@ package body Eval_Fat is
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-- even, a floor operation or a ceiling operation depending on the setting
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-- of Mode (see corresponding descriptions in Urealp).
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function Eps_Model (RT : R) return T;
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-- Return the smallest model number of R.
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function Eps_Denorm (RT : R) return T;
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-- Return the smallest denormal of type R.
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function Machine_Emin (RT : R) return Int;
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-- Return value of the Machine_Emin attribute
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@ -85,8 +91,10 @@ package body Eval_Fat is
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begin
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if Towards = X then
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return X;
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elsif Towards > X then
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return Succ (RT, X);
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else
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return Pred (RT, X);
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end if;
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@ -98,11 +106,14 @@ package body Eval_Fat is
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function Ceiling (RT : R; X : T) return T is
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XT : constant T := Truncation (RT, X);
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begin
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if UR_Is_Negative (X) then
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return XT;
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elsif X = XT then
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return X;
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else
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return XT + Ureal_1;
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end if;
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@ -371,10 +382,10 @@ package body Eval_Fat is
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Calculate_Fraction_And_Exponent : begin
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Uintp_Mark := Mark;
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-- Determine correct rounding based on the remainder which is in
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-- N and the divisor D. The rounding is performed on the absolute
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-- value of X, so Ceiling and Floor need to check for the sign of
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-- X explicitly.
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-- Determine correct rounding based on the remainder
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-- which is in N and the divisor D. The rounding is
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-- performed on the absolute value of X, so Ceiling
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-- and Floor need to check for the sign of X explicitly.
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case Mode is
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when Round_Even =>
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@ -429,6 +440,25 @@ package body Eval_Fat is
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end Calculate_Fraction_And_Exponent;
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end Decompose_Int;
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----------------
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-- Eps_Denorm --
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----------------
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function Eps_Denorm (RT : R) return T is
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begin
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return Float_Radix ** UI_From_Int
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(Machine_Emin (RT) - Machine_Mantissa (RT));
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end Eps_Denorm;
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---------------
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-- Eps_Model --
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---------------
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function Eps_Model (RT : R) return T is
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begin
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return Float_Radix ** UI_From_Int (Machine_Emin (RT));
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end Eps_Model;
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--------------
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-- Exponent --
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--------------
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@ -705,8 +735,37 @@ package body Eval_Fat is
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----------
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function Pred (RT : R; X : T) return T is
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Result_F : UI;
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Result_X : UI;
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begin
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return -Succ (RT, -X);
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if abs X < Eps_Model (RT) then
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if Denorm_On_Target then
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return X - Eps_Denorm (RT);
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elsif X > Ureal_0 then
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-- Target does not support denorms, so predecessor is 0.0
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return Ureal_0;
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else
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-- Target does not support denorms, and X is 0.0
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-- or at least bigger than -Eps_Model (RT)
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return -Eps_Model (RT);
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end if;
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else
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Decompose_Int (RT, X, Result_F, Result_X, Ceiling);
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return UR_From_Components
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(Num => Result_F - 1,
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Den => Machine_Mantissa (RT) - Result_X,
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Rbase => Radix,
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Negative => False);
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-- Result_F may be false, but this is OK as UR_From_Components
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-- handles that situation.
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end if;
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end Pred;
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---------------
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@ -833,38 +892,35 @@ package body Eval_Fat is
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----------
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function Succ (RT : R; X : T) return T is
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Emin : constant UI := UI_From_Int (Machine_Emin (RT));
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Mantissa : constant UI := UI_From_Int (Machine_Mantissa (RT));
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Exp : UI := UI_Max (Emin, Exponent (RT, X));
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Frac : T;
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New_Frac : T;
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Result_F : UI;
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Result_X : UI;
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begin
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if UR_Is_Zero (X) then
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Exp := Emin;
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end if;
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if abs X < Eps_Model (RT) then
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if Denorm_On_Target then
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return X + Eps_Denorm (RT);
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-- Set exponent such that the radix point will be directly
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-- following the mantissa after scaling
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elsif X < Ureal_0 then
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-- Target does not support denorms, so successor is 0.0
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return Ureal_0;
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if Denorm_On_Target or Exp /= Emin then
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Exp := Exp - Mantissa;
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else
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Exp := Exp - 1;
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end if;
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Frac := Scaling (RT, X, -Exp);
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New_Frac := Ceiling (RT, Frac);
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if New_Frac = Frac then
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if New_Frac = Scaling (RT, -Ureal_1, Mantissa - 1) then
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New_Frac := New_Frac + Scaling (RT, Ureal_1, Uint_Minus_1);
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else
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New_Frac := New_Frac + Ureal_1;
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end if;
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end if;
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-- Target does not support denorms, and X is 0.0
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-- or at least smaller than Eps_Model (RT)
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return Scaling (RT, New_Frac, Exp);
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return Eps_Model (RT);
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end if;
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else
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Decompose_Int (RT, X, Result_F, Result_X, Floor);
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return UR_From_Components
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(Num => Result_F + 1,
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Den => Machine_Mantissa (RT) - Result_X,
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Rbase => Radix,
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Negative => False);
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-- Result_F may be false, but this is OK as UR_From_Components
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-- handles that situation.
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end if;
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end Succ;
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----------------
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@ -873,6 +929,7 @@ package body Eval_Fat is
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function Truncation (RT : R; X : T) return T is
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pragma Warnings (Off, RT);
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begin
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return UR_From_Uint (UR_Trunc (X));
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end Truncation;
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