diff options
Diffstat (limited to 'gcc/ada/urealp.adb')
| -rw-r--r-- | gcc/ada/urealp.adb | 148 |
1 files changed, 124 insertions, 24 deletions
diff --git a/gcc/ada/urealp.adb b/gcc/ada/urealp.adb index 88cb681..1367ad3 100644 --- a/gcc/ada/urealp.adb +++ b/gcc/ada/urealp.adb @@ -6,7 +6,7 @@ -- -- -- B o d y -- -- -- --- Copyright (C) 1992-2020, Free Software Foundation, Inc. -- +-- 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- -- @@ -174,16 +174,30 @@ package body Urealp is return UI_Decimal_Digits_Hi (Val.Num) - UI_Decimal_Digits_Lo (Val.Den); - -- For based numbers, just subtract the decimal exponent from the - -- high estimate of the number of digits in the numerator and add - -- one to accommodate possible round off errors for non-decimal - -- bases. For example: + -- For based numbers, get the maximum number of digits in the numerator + -- minus one and the either exact or floor value of the decimal exponent + -- of the denominator, and subtract. For example: - -- 1_500_000 / 10**4 = 1.50E-2 + -- 321 / 10**3 = 3.21E-1 + -- 435 / 5**7 = 5.57E-3 - else -- Val.Rbase /= 0 - return UI_Decimal_Digits_Hi (Val.Num) - - Equivalent_Decimal_Exponent (Val) + 1; + else + declare + E : Int; + + begin + if Val.Rbase = 10 then + E := UI_To_Int (Val.Den); + + else + E := Equivalent_Decimal_Exponent (Val); + if E < 0 then + E := E - 1; + end if; + end if; + + return UI_Decimal_Digits_Hi (Val.Num) - 1 - E; + end; end if; end Decimal_Exponent_Hi; @@ -213,16 +227,30 @@ package body Urealp is return UI_Decimal_Digits_Lo (Val.Num) - UI_Decimal_Digits_Hi (Val.Den) - 1; - -- For based numbers, just subtract the decimal exponent from the - -- low estimate of the number of digits in the numerator and subtract - -- one to accommodate possible round off errors for non-decimal - -- bases. For example: + -- For based numbers, get the minimum number of digits in the numerator + -- minus one and the either exact or ceil value of the decimal exponent + -- of the denominator, and subtract. For example: - -- 1_500_000 / 10**4 = 1.50E-2 + -- 321 / 10**3 = 3.21E-1 + -- 435 / 5**7 = 5.57E-3 - else -- Val.Rbase /= 0 - return UI_Decimal_Digits_Lo (Val.Num) - - Equivalent_Decimal_Exponent (Val) - 1; + else + declare + E : Int; + + begin + if Val.Rbase = 10 then + E := UI_To_Int (Val.Den); + + else + E := Equivalent_Decimal_Exponent (Val); + if E > 0 then + E := E + 1; + end if; + end if; + + return UI_Decimal_Digits_Lo (Val.Num) - 1 - E; + end; end if; end Decimal_Exponent_Lo; @@ -270,23 +298,21 @@ package body Urealp is 15 => (Num => 53_385_559, Den => 45_392_361), -- 1.176091259055681 16 => (Num => 78_897_839, Den => 65_523_237)); -- 1.204119982655924 - function Scale (X : Int; R : Ratio) return Int; + function Scale (X : Uint; R : Ratio) return Int; -- Compute the value of X scaled by R ----------- -- Scale -- ----------- - function Scale (X : Int; R : Ratio) return Int is - type Wide_Int is range -2**63 .. 2**63 - 1; - + function Scale (X : Uint; R : Ratio) return Int is begin - return Int (Wide_Int (X) * Wide_Int (R.Num) / Wide_Int (R.Den)); + return UI_To_Int (X * R.Num / R.Den); end Scale; begin pragma Assert (U.Rbase /= 0); - return Scale (UI_To_Int (U.Den), Logs (U.Rbase)); + return Scale (U.Den, Logs (U.Rbase)); end Equivalent_Decimal_Exponent; ---------------- @@ -376,7 +402,7 @@ package body Urealp is Tmp : Uint; Num : Uint; Den : Uint; - M : constant Uintp.Save_Mark := Uintp.Mark; + M : constant Uintp.Save_Mark := Mark; begin -- Start by setting J to the greatest of the absolute values of the @@ -1488,6 +1514,80 @@ package body Urealp is end if; end UR_Write; + ---------------------- + -- UR_Write_To_JSON -- + ---------------------- + + -- We defer to the implementation of UR_Write in all cases, either directly + -- for values that are naturally written in a JSON compatible format, or by + -- first computing a decimal approxixmation for other values. + + procedure UR_Write_To_JSON (Real : Ureal) is + Val : constant Ureal_Entry := Ureals.Table (Real); + Imrk : constant Uintp.Save_Mark := Mark; + Rmrk : constant Urealp.Save_Mark := Mark; + + T : Ureal; + + begin + -- Zero is zero + + if Val.Num = 0 then + T := Real; + + -- For constants with a denominator of zero, the value is simply the + -- numerator value, since we are dividing by base**0, which is 1. + + elsif Val.Den = 0 then + T := Real; + + -- Small powers of 2 get written in decimal fixed-point format + + elsif Val.Rbase = 2 + and then Val.Den <= 3 + and then Val.Den >= -16 + then + T := Real; + + -- Constants in base 10 can be written in normal Ada literal style + + elsif Val.Rbase = 10 then + T := Real; + + -- Rationals where numerator is divisible by denominator can be output + -- as literals after we do the division. This includes the common case + -- where the denominator is 1. + + elsif Val.Rbase = 0 and then Val.Num mod Val.Den = 0 then + T := Real; + + -- For other constants, compute an approxixmation in base 10 + + else + declare + A : constant Ureal := UR_Abs (Real); + -- The absolute value + + E : constant Uint := + (if A < Ureal_1 + then UI_From_Int (3 - Decimal_Exponent_Lo (Real)) + else Uint_3); + -- The exponent for at least 3 digits after the decimal point + + Num : constant Uint := + UR_To_Uint (UR_Mul (A, UR_Exponentiate (Ureal_10, E))); + -- The numerator appropriately rounded + + begin + T := UR_From_Components (Num, E, 10, Val.Negative); + end; + end if; + + UR_Write (T); + Release (Imrk); + Release (Rmrk); + end UR_Write_To_JSON; + ------------- -- Ureal_0 -- ------------- |