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Diffstat (limited to 'gcc-4.9/gcc/ada/uintp.adb')
| -rw-r--r-- | gcc-4.9/gcc/ada/uintp.adb | 2344 |
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diff --git a/gcc-4.9/gcc/ada/uintp.adb b/gcc-4.9/gcc/ada/uintp.adb new file mode 100644 index 000000000..f418b56ce --- /dev/null +++ b/gcc-4.9/gcc/ada/uintp.adb @@ -0,0 +1,2344 @@ +------------------------------------------------------------------------------ +-- -- +-- GNAT COMPILER COMPONENTS -- +-- -- +-- U I N T P -- +-- -- +-- B o d y -- +-- -- +-- Copyright (C) 1992-2013, 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. -- +-- -- +------------------------------------------------------------------------------ + +with Output; use Output; +with Tree_IO; use Tree_IO; + +with GNAT.HTable; use GNAT.HTable; + +package body Uintp is + + ------------------------ + -- Local Declarations -- + ------------------------ + + Uint_Int_First : Uint := Uint_0; + -- Uint value containing Int'First value, set by Initialize. The initial + -- value of Uint_0 is used for an assertion check that ensures that this + -- value is not used before it is initialized. This value is used in the + -- UI_Is_In_Int_Range predicate, and it is right that this is a host value, + -- since the issue is host representation of integer values. + + Uint_Int_Last : Uint; + -- Uint value containing Int'Last value set by Initialize + + UI_Power_2 : array (Int range 0 .. 64) of Uint; + -- This table is used to memoize exponentiations by powers of 2. The Nth + -- entry, if set, contains the Uint value 2 ** N. Initially UI_Power_2_Set + -- is zero and only the 0'th entry is set, the invariant being that all + -- entries in the range 0 .. UI_Power_2_Set are initialized. + + UI_Power_2_Set : Nat; + -- Number of entries set in UI_Power_2; + + UI_Power_10 : array (Int range 0 .. 64) of Uint; + -- This table is used to memoize exponentiations by powers of 10 in the + -- same manner as described above for UI_Power_2. + + UI_Power_10_Set : Nat; + -- Number of entries set in UI_Power_10; + + Uints_Min : Uint; + Udigits_Min : Int; + -- These values are used to make sure that the mark/release mechanism does + -- not destroy values saved in the U_Power tables or in the hash table used + -- by UI_From_Int. Whenever an entry is made in either of these tables, + -- Uints_Min and Udigits_Min are updated to protect the entry, and Release + -- never cuts back beyond these minimum values. + + Int_0 : constant Int := 0; + Int_1 : constant Int := 1; + Int_2 : constant Int := 2; + -- These values are used in some cases where the use of numeric literals + -- would cause ambiguities (integer vs Uint). + + ---------------------------- + -- UI_From_Int Hash Table -- + ---------------------------- + + -- UI_From_Int uses a hash table to avoid duplicating entries and wasting + -- storage. This is particularly important for complex cases of back + -- annotation. + + subtype Hnum is Nat range 0 .. 1022; + + function Hash_Num (F : Int) return Hnum; + -- Hashing function + + package UI_Ints is new Simple_HTable ( + Header_Num => Hnum, + Element => Uint, + No_Element => No_Uint, + Key => Int, + Hash => Hash_Num, + Equal => "="); + + ----------------------- + -- Local Subprograms -- + ----------------------- + + function Direct (U : Uint) return Boolean; + pragma Inline (Direct); + -- Returns True if U is represented directly + + function Direct_Val (U : Uint) return Int; + -- U is a Uint for is represented directly. The returned result is the + -- value represented. + + function GCD (Jin, Kin : Int) return Int; + -- Compute GCD of two integers. Assumes that Jin >= Kin >= 0 + + procedure Image_Out + (Input : Uint; + To_Buffer : Boolean; + Format : UI_Format); + -- Common processing for UI_Image and UI_Write, To_Buffer is set True for + -- UI_Image, and false for UI_Write, and Format is copied from the Format + -- parameter to UI_Image or UI_Write. + + procedure Init_Operand (UI : Uint; Vec : out UI_Vector); + pragma Inline (Init_Operand); + -- This procedure puts the value of UI into the vector in canonical + -- multiple precision format. The parameter should be of the correct size + -- as determined by a previous call to N_Digits (UI). The first digit of + -- Vec contains the sign, all other digits are always non-negative. Note + -- that the input may be directly represented, and in this case Vec will + -- contain the corresponding one or two digit value. The low bound of Vec + -- is always 1. + + function Least_Sig_Digit (Arg : Uint) return Int; + pragma Inline (Least_Sig_Digit); + -- Returns the Least Significant Digit of Arg quickly. When the given Uint + -- is less than 2**15, the value returned is the input value, in this case + -- the result may be negative. It is expected that any use will mask off + -- unnecessary bits. This is used for finding Arg mod B where B is a power + -- of two. Hence the actual base is irrelevant as long as it is a power of + -- two. + + procedure Most_Sig_2_Digits + (Left : Uint; + Right : Uint; + Left_Hat : out Int; + Right_Hat : out Int); + -- Returns leading two significant digits from the given pair of Uint's. + -- Mathematically: returns Left / (Base ** K) and Right / (Base ** K) where + -- K is as small as possible S.T. Right_Hat < Base * Base. It is required + -- that Left > Right for the algorithm to work. + + function N_Digits (Input : Uint) return Int; + pragma Inline (N_Digits); + -- Returns number of "digits" in a Uint + + procedure UI_Div_Rem + (Left, Right : Uint; + Quotient : out Uint; + Remainder : out Uint; + Discard_Quotient : Boolean := False; + Discard_Remainder : Boolean := False); + -- Compute Euclidean division of Left by Right. If Discard_Quotient is + -- False then the quotient is returned in Quotient (otherwise Quotient is + -- set to No_Uint). If Discard_Remainder is False, then the remainder is + -- returned in Remainder (otherwise Remainder is set to No_Uint). + -- + -- If Discard_Quotient is True, Quotient is set to No_Uint + -- If Discard_Remainder is True, Remainder is set to No_Uint + + function Vector_To_Uint + (In_Vec : UI_Vector; + Negative : Boolean) return Uint; + -- Functions that calculate values in UI_Vectors, call this function to + -- create and return the Uint value. In_Vec contains the multiple precision + -- (Base) representation of a non-negative value. Leading zeroes are + -- permitted. Negative is set if the desired result is the negative of the + -- given value. The result will be either the appropriate directly + -- represented value, or a table entry in the proper canonical format is + -- created and returned. + -- + -- Note that Init_Operand puts a signed value in the result vector, but + -- Vector_To_Uint is always presented with a non-negative value. The + -- processing of signs is something that is done by the caller before + -- calling Vector_To_Uint. + + ------------ + -- Direct -- + ------------ + + function Direct (U : Uint) return Boolean is + begin + return Int (U) <= Int (Uint_Direct_Last); + end Direct; + + ---------------- + -- Direct_Val -- + ---------------- + + function Direct_Val (U : Uint) return Int is + begin + pragma Assert (Direct (U)); + return Int (U) - Int (Uint_Direct_Bias); + end Direct_Val; + + --------- + -- GCD -- + --------- + + function GCD (Jin, Kin : Int) return Int is + J, K, Tmp : Int; + + begin + pragma Assert (Jin >= Kin); + pragma Assert (Kin >= Int_0); + + J := Jin; + K := Kin; + while K /= Uint_0 loop + Tmp := J mod K; + J := K; + K := Tmp; + end loop; + + return J; + end GCD; + + -------------- + -- Hash_Num -- + -------------- + + function Hash_Num (F : Int) return Hnum is + begin + return Types."mod" (F, Hnum'Range_Length); + end Hash_Num; + + --------------- + -- Image_Out -- + --------------- + + procedure Image_Out + (Input : Uint; + To_Buffer : Boolean; + Format : UI_Format) + is + Marks : constant Uintp.Save_Mark := Uintp.Mark; + Base : Uint; + Ainput : Uint; + + Digs_Output : Natural := 0; + -- Counts digits output. In hex mode, but not in decimal mode, we + -- put an underline after every four hex digits that are output. + + Exponent : Natural := 0; + -- If the number is too long to fit in the buffer, we switch to an + -- approximate output format with an exponent. This variable records + -- the exponent value. + + function Better_In_Hex return Boolean; + -- Determines if it is better to generate digits in base 16 (result + -- is true) or base 10 (result is false). The choice is purely a + -- matter of convenience and aesthetics, so it does not matter which + -- value is returned from a correctness point of view. + + procedure Image_Char (C : Character); + -- Internal procedure to output one character + + procedure Image_Exponent (N : Natural); + -- Output non-zero exponent. Note that we only use the exponent form in + -- the buffer case, so we know that To_Buffer is true. + + procedure Image_Uint (U : Uint); + -- Internal procedure to output characters of non-negative Uint + + ------------------- + -- Better_In_Hex -- + ------------------- + + function Better_In_Hex return Boolean is + T16 : constant Uint := Uint_2 ** Int'(16); + A : Uint; + + begin + A := UI_Abs (Input); + + -- Small values up to 2**16 can always be in decimal + + if A < T16 then + return False; + end if; + + -- Otherwise, see if we are a power of 2 or one less than a power + -- of 2. For the moment these are the only cases printed in hex. + + if A mod Uint_2 = Uint_1 then + A := A + Uint_1; + end if; + + loop + if A mod T16 /= Uint_0 then + return False; + + else + A := A / T16; + end if; + + exit when A < T16; + end loop; + + while A > Uint_2 loop + if A mod Uint_2 /= Uint_0 then + return False; + + else + A := A / Uint_2; + end if; + end loop; + + return True; + end Better_In_Hex; + + ---------------- + -- Image_Char -- + ---------------- + + procedure Image_Char (C : Character) is + begin + if To_Buffer then + if UI_Image_Length + 6 > UI_Image_Max then + Exponent := Exponent + 1; + else + UI_Image_Length := UI_Image_Length + 1; + UI_Image_Buffer (UI_Image_Length) := C; + end if; + else + Write_Char (C); + end if; + end Image_Char; + + -------------------- + -- Image_Exponent -- + -------------------- + + procedure Image_Exponent (N : Natural) is + begin + if N >= 10 then + Image_Exponent (N / 10); + end if; + + UI_Image_Length := UI_Image_Length + 1; + UI_Image_Buffer (UI_Image_Length) := + Character'Val (Character'Pos ('0') + N mod 10); + end Image_Exponent; + + ---------------- + -- Image_Uint -- + ---------------- + + procedure Image_Uint (U : Uint) is + H : constant array (Int range 0 .. 15) of Character := + "0123456789ABCDEF"; + + Q, R : Uint; + begin + UI_Div_Rem (U, Base, Q, R); + + if Q > Uint_0 then + Image_Uint (Q); + end if; + + if Digs_Output = 4 and then Base = Uint_16 then + Image_Char ('_'); + Digs_Output := 0; + end if; + + Image_Char (H (UI_To_Int (R))); + + Digs_Output := Digs_Output + 1; + end Image_Uint; + + -- Start of processing for Image_Out + + begin + if Input = No_Uint then + Image_Char ('?'); + return; + end if; + + UI_Image_Length := 0; + + if Input < Uint_0 then + Image_Char ('-'); + Ainput := -Input; + else + Ainput := Input; + end if; + + if Format = Hex + or else (Format = Auto and then Better_In_Hex) + then + Base := Uint_16; + Image_Char ('1'); + Image_Char ('6'); + Image_Char ('#'); + Image_Uint (Ainput); + Image_Char ('#'); + + else + Base := Uint_10; + Image_Uint (Ainput); + end if; + + if Exponent /= 0 then + UI_Image_Length := UI_Image_Length + 1; + UI_Image_Buffer (UI_Image_Length) := 'E'; + Image_Exponent (Exponent); + end if; + + Uintp.Release (Marks); + end Image_Out; + + ------------------- + -- Init_Operand -- + ------------------- + + procedure Init_Operand (UI : Uint; Vec : out UI_Vector) is + Loc : Int; + + pragma Assert (Vec'First = Int'(1)); + + begin + if Direct (UI) then + Vec (1) := Direct_Val (UI); + + if Vec (1) >= Base then + Vec (2) := Vec (1) rem Base; + Vec (1) := Vec (1) / Base; + end if; + + else + Loc := Uints.Table (UI).Loc; + + for J in 1 .. Uints.Table (UI).Length loop + Vec (J) := Udigits.Table (Loc + J - 1); + end loop; + end if; + end Init_Operand; + + ---------------- + -- Initialize -- + ---------------- + + procedure Initialize is + begin + Uints.Init; + Udigits.Init; + + Uint_Int_First := UI_From_Int (Int'First); + Uint_Int_Last := UI_From_Int (Int'Last); + + UI_Power_2 (0) := Uint_1; + UI_Power_2_Set := 0; + + UI_Power_10 (0) := Uint_1; + UI_Power_10_Set := 0; + + Uints_Min := Uints.Last; + Udigits_Min := Udigits.Last; + + UI_Ints.Reset; + end Initialize; + + --------------------- + -- Least_Sig_Digit -- + --------------------- + + function Least_Sig_Digit (Arg : Uint) return Int is + V : Int; + + begin + if Direct (Arg) then + V := Direct_Val (Arg); + + if V >= Base then + V := V mod Base; + end if; + + -- Note that this result may be negative + + return V; + + else + return + Udigits.Table + (Uints.Table (Arg).Loc + Uints.Table (Arg).Length - 1); + end if; + end Least_Sig_Digit; + + ---------- + -- Mark -- + ---------- + + function Mark return Save_Mark is + begin + return (Save_Uint => Uints.Last, Save_Udigit => Udigits.Last); + end Mark; + + ----------------------- + -- Most_Sig_2_Digits -- + ----------------------- + + procedure Most_Sig_2_Digits + (Left : Uint; + Right : Uint; + Left_Hat : out Int; + Right_Hat : out Int) + is + begin + pragma Assert (Left >= Right); + + if Direct (Left) then + Left_Hat := Direct_Val (Left); + Right_Hat := Direct_Val (Right); + return; + + else + declare + L1 : constant Int := + Udigits.Table (Uints.Table (Left).Loc); + L2 : constant Int := + Udigits.Table (Uints.Table (Left).Loc + 1); + + begin + -- It is not so clear what to return when Arg is negative??? + + Left_Hat := abs (L1) * Base + L2; + end; + end if; + + declare + Length_L : constant Int := Uints.Table (Left).Length; + Length_R : Int; + R1 : Int; + R2 : Int; + T : Int; + + begin + if Direct (Right) then + T := Direct_Val (Left); + R1 := abs (T / Base); + R2 := T rem Base; + Length_R := 2; + + else + R1 := abs (Udigits.Table (Uints.Table (Right).Loc)); + R2 := Udigits.Table (Uints.Table (Right).Loc + 1); + Length_R := Uints.Table (Right).Length; + end if; + + if Length_L = Length_R then + Right_Hat := R1 * Base + R2; + elsif Length_L = Length_R + Int_1 then + Right_Hat := R1; + else + Right_Hat := 0; + end if; + end; + end Most_Sig_2_Digits; + + --------------- + -- N_Digits -- + --------------- + + -- Note: N_Digits returns 1 for No_Uint + + function N_Digits (Input : Uint) return Int is + begin + if Direct (Input) then + if Direct_Val (Input) >= Base then + return 2; + else + return 1; + end if; + + else + return Uints.Table (Input).Length; + end if; + end N_Digits; + + -------------- + -- Num_Bits -- + -------------- + + function Num_Bits (Input : Uint) return Nat is + Bits : Nat; + Num : Nat; + + begin + -- Largest negative number has to be handled specially, since it is in + -- Int_Range, but we cannot take the absolute value. + + if Input = Uint_Int_First then + return Int'Size; + + -- For any other number in Int_Range, get absolute value of number + + elsif UI_Is_In_Int_Range (Input) then + Num := abs (UI_To_Int (Input)); + Bits := 0; + + -- If not in Int_Range then initialize bit count for all low order + -- words, and set number to high order digit. + + else + Bits := Base_Bits * (Uints.Table (Input).Length - 1); + Num := abs (Udigits.Table (Uints.Table (Input).Loc)); + end if; + + -- Increase bit count for remaining value in Num + + while Types.">" (Num, 0) loop + Num := Num / 2; + Bits := Bits + 1; + end loop; + + return Bits; + end Num_Bits; + + --------- + -- pid -- + --------- + + procedure pid (Input : Uint) is + begin + UI_Write (Input, Decimal); + Write_Eol; + end pid; + + --------- + -- pih -- + --------- + + procedure pih (Input : Uint) is + begin + UI_Write (Input, Hex); + Write_Eol; + end pih; + + ------------- + -- Release -- + ------------- + + procedure Release (M : Save_Mark) is + begin + Uints.Set_Last (Uint'Max (M.Save_Uint, Uints_Min)); + Udigits.Set_Last (Int'Max (M.Save_Udigit, Udigits_Min)); + end Release; + + ---------------------- + -- Release_And_Save -- + ---------------------- + + procedure Release_And_Save (M : Save_Mark; UI : in out Uint) is + begin + if Direct (UI) then + Release (M); + + else + declare + UE_Len : constant Pos := Uints.Table (UI).Length; + UE_Loc : constant Int := Uints.Table (UI).Loc; + + UD : constant Udigits.Table_Type (1 .. UE_Len) := + Udigits.Table (UE_Loc .. UE_Loc + UE_Len - 1); + + begin + Release (M); + + Uints.Append ((Length => UE_Len, Loc => Udigits.Last + 1)); + UI := Uints.Last; + + for J in 1 .. UE_Len loop + Udigits.Append (UD (J)); + end loop; + end; + end if; + end Release_And_Save; + + procedure Release_And_Save (M : Save_Mark; UI1, UI2 : in out Uint) is + begin + if Direct (UI1) then + Release_And_Save (M, UI2); + + elsif Direct (UI2) then + Release_And_Save (M, UI1); + + else + declare + UE1_Len : constant Pos := Uints.Table (UI1).Length; + UE1_Loc : constant Int := Uints.Table (UI1).Loc; + + UD1 : constant Udigits.Table_Type (1 .. UE1_Len) := + Udigits.Table (UE1_Loc .. UE1_Loc + UE1_Len - 1); + + UE2_Len : constant Pos := Uints.Table (UI2).Length; + UE2_Loc : constant Int := Uints.Table (UI2).Loc; + + UD2 : constant Udigits.Table_Type (1 .. UE2_Len) := + Udigits.Table (UE2_Loc .. UE2_Loc + UE2_Len - 1); + + begin + Release (M); + + Uints.Append ((Length => UE1_Len, Loc => Udigits.Last + 1)); + UI1 := Uints.Last; + + for J in 1 .. UE1_Len loop + Udigits.Append (UD1 (J)); + end loop; + + Uints.Append ((Length => UE2_Len, Loc => Udigits.Last + 1)); + UI2 := Uints.Last; + + for J in 1 .. UE2_Len loop + Udigits.Append (UD2 (J)); + end loop; + end; + end if; + end Release_And_Save; + + --------------- + -- Tree_Read -- + --------------- + + procedure Tree_Read is + begin + Uints.Tree_Read; + Udigits.Tree_Read; + + Tree_Read_Int (Int (Uint_Int_First)); + Tree_Read_Int (Int (Uint_Int_Last)); + Tree_Read_Int (UI_Power_2_Set); + Tree_Read_Int (UI_Power_10_Set); + Tree_Read_Int (Int (Uints_Min)); + Tree_Read_Int (Udigits_Min); + + for J in 0 .. UI_Power_2_Set loop + Tree_Read_Int (Int (UI_Power_2 (J))); + end loop; + + for J in 0 .. UI_Power_10_Set loop + Tree_Read_Int (Int (UI_Power_10 (J))); + end loop; + + end Tree_Read; + + ---------------- + -- Tree_Write -- + ---------------- + + procedure Tree_Write is + begin + Uints.Tree_Write; + Udigits.Tree_Write; + + Tree_Write_Int (Int (Uint_Int_First)); + Tree_Write_Int (Int (Uint_Int_Last)); + Tree_Write_Int (UI_Power_2_Set); + Tree_Write_Int (UI_Power_10_Set); + Tree_Write_Int (Int (Uints_Min)); + Tree_Write_Int (Udigits_Min); + + for J in 0 .. UI_Power_2_Set loop + Tree_Write_Int (Int (UI_Power_2 (J))); + end loop; + + for J in 0 .. UI_Power_10_Set loop + Tree_Write_Int (Int (UI_Power_10 (J))); + end loop; + + end Tree_Write; + + ------------- + -- UI_Abs -- + ------------- + + function UI_Abs (Right : Uint) return Uint is + begin + if Right < Uint_0 then + return -Right; + else + return Right; + end if; + end UI_Abs; + + ------------- + -- UI_Add -- + ------------- + + function UI_Add (Left : Int; Right : Uint) return Uint is + begin + return UI_Add (UI_From_Int (Left), Right); + end UI_Add; + + function UI_Add (Left : Uint; Right : Int) return Uint is + begin + return UI_Add (Left, UI_From_Int (Right)); + end UI_Add; + + function UI_Add (Left : Uint; Right : Uint) return Uint is + begin + -- Simple cases of direct operands and addition of zero + + if Direct (Left) then + if Direct (Right) then + return UI_From_Int (Direct_Val (Left) + Direct_Val (Right)); + + elsif Int (Left) = Int (Uint_0) then + return Right; + end if; + + elsif Direct (Right) and then Int (Right) = Int (Uint_0) then + return Left; + end if; + + -- Otherwise full circuit is needed + + declare + L_Length : constant Int := N_Digits (Left); + R_Length : constant Int := N_Digits (Right); + L_Vec : UI_Vector (1 .. L_Length); + R_Vec : UI_Vector (1 .. R_Length); + Sum_Length : Int; + Tmp_Int : Int; + Carry : Int; + Borrow : Int; + X_Bigger : Boolean := False; + Y_Bigger : Boolean := False; + Result_Neg : Boolean := False; + + begin + Init_Operand (Left, L_Vec); + Init_Operand (Right, R_Vec); + + -- At least one of the two operands is in multi-digit form. + -- Calculate the number of digits sufficient to hold result. + + if L_Length > R_Length then + Sum_Length := L_Length + 1; + X_Bigger := True; + else + Sum_Length := R_Length + 1; + + if R_Length > L_Length then + Y_Bigger := True; + end if; + end if; + + -- Make copies of the absolute values of L_Vec and R_Vec into X and Y + -- both with lengths equal to the maximum possibly needed. This makes + -- looping over the digits much simpler. + + declare + X : UI_Vector (1 .. Sum_Length); + Y : UI_Vector (1 .. Sum_Length); + Tmp_UI : UI_Vector (1 .. Sum_Length); + + begin + for J in 1 .. Sum_Length - L_Length loop + X (J) := 0; + end loop; + + X (Sum_Length - L_Length + 1) := abs L_Vec (1); + + for J in 2 .. L_Length loop + X (J + (Sum_Length - L_Length)) := L_Vec (J); + end loop; + + for J in 1 .. Sum_Length - R_Length loop + Y (J) := 0; + end loop; + + Y (Sum_Length - R_Length + 1) := abs R_Vec (1); + + for J in 2 .. R_Length loop + Y (J + (Sum_Length - R_Length)) := R_Vec (J); + end loop; + + if (L_Vec (1) < Int_0) = (R_Vec (1) < Int_0) then + + -- Same sign so just add + + Carry := 0; + for J in reverse 1 .. Sum_Length loop + Tmp_Int := X (J) + Y (J) + Carry; + + if Tmp_Int >= Base then + Tmp_Int := Tmp_Int - Base; + Carry := 1; + else + Carry := 0; + end if; + + X (J) := Tmp_Int; + end loop; + + return Vector_To_Uint (X, L_Vec (1) < Int_0); + + else + -- Find which one has bigger magnitude + + if not (X_Bigger or Y_Bigger) then + for J in L_Vec'Range loop + if abs L_Vec (J) > abs R_Vec (J) then + X_Bigger := True; + exit; + elsif abs R_Vec (J) > abs L_Vec (J) then + Y_Bigger := True; + exit; + end if; + end loop; + end if; + + -- If they have identical magnitude, just return 0, else swap + -- if necessary so that X had the bigger magnitude. Determine + -- if result is negative at this time. + + Result_Neg := False; + + if not (X_Bigger or Y_Bigger) then + return Uint_0; + + elsif Y_Bigger then + if R_Vec (1) < Int_0 then + Result_Neg := True; + end if; + + Tmp_UI := X; + X := Y; + Y := Tmp_UI; + + else + if L_Vec (1) < Int_0 then + Result_Neg := True; + end if; + end if; + + -- Subtract Y from the bigger X + + Borrow := 0; + + for J in reverse 1 .. Sum_Length loop + Tmp_Int := X (J) - Y (J) + Borrow; + + if Tmp_Int < Int_0 then + Tmp_Int := Tmp_Int + Base; + Borrow := -1; + else + Borrow := 0; + end if; + + X (J) := Tmp_Int; + end loop; + + return Vector_To_Uint (X, Result_Neg); + + end if; + end; + end; + end UI_Add; + + -------------------------- + -- UI_Decimal_Digits_Hi -- + -------------------------- + + function UI_Decimal_Digits_Hi (U : Uint) return Nat is + begin + -- The maximum value of a "digit" is 32767, which is 5 decimal digits, + -- so an N_Digit number could take up to 5 times this number of digits. + -- This is certainly too high for large numbers but it is not worth + -- worrying about. + + return 5 * N_Digits (U); + end UI_Decimal_Digits_Hi; + + -------------------------- + -- UI_Decimal_Digits_Lo -- + -------------------------- + + function UI_Decimal_Digits_Lo (U : Uint) return Nat is + begin + -- The maximum value of a "digit" is 32767, which is more than four + -- decimal digits, but not a full five digits. The easily computed + -- minimum number of decimal digits is thus 1 + 4 * the number of + -- digits. This is certainly too low for large numbers but it is not + -- worth worrying about. + + return 1 + 4 * (N_Digits (U) - 1); + end UI_Decimal_Digits_Lo; + + ------------ + -- UI_Div -- + ------------ + + function UI_Div (Left : Int; Right : Uint) return Uint is + begin + return UI_Div (UI_From_Int (Left), Right); + end UI_Div; + + function UI_Div (Left : Uint; Right : Int) return Uint is + begin + return UI_Div (Left, UI_From_Int (Right)); + end UI_Div; + + function UI_Div (Left, Right : Uint) return Uint is + Quotient : Uint; + Remainder : Uint; + pragma Warnings (Off, Remainder); + begin + UI_Div_Rem + (Left, Right, + Quotient, Remainder, + Discard_Remainder => True); + return Quotient; + end UI_Div; + + ---------------- + -- UI_Div_Rem -- + ---------------- + + procedure UI_Div_Rem + (Left, Right : Uint; + Quotient : out Uint; + Remainder : out Uint; + Discard_Quotient : Boolean := False; + Discard_Remainder : Boolean := False) + is + begin + pragma Assert (Right /= Uint_0); + + Quotient := No_Uint; + Remainder := No_Uint; + + -- Cases where both operands are represented directly + + if Direct (Left) and then Direct (Right) then + declare + DV_Left : constant Int := Direct_Val (Left); + DV_Right : constant Int := Direct_Val (Right); + + begin + if not Discard_Quotient then + Quotient := UI_From_Int (DV_Left / DV_Right); + end if; + + if not Discard_Remainder then + Remainder := UI_From_Int (DV_Left rem DV_Right); + end if; + + return; + end; + end if; + + declare + L_Length : constant Int := N_Digits (Left); + R_Length : constant Int := N_Digits (Right); + Q_Length : constant Int := L_Length - R_Length + 1; + L_Vec : UI_Vector (1 .. L_Length); + R_Vec : UI_Vector (1 .. R_Length); + D : Int; + Remainder_I : Int; + Tmp_Divisor : Int; + Carry : Int; + Tmp_Int : Int; + Tmp_Dig : Int; + + procedure UI_Div_Vector + (L_Vec : UI_Vector; + R_Int : Int; + Quotient : out UI_Vector; + Remainder : out Int); + pragma Inline (UI_Div_Vector); + -- Specialised variant for case where the divisor is a single digit + + procedure UI_Div_Vector + (L_Vec : UI_Vector; + R_Int : Int; + Quotient : out UI_Vector; + Remainder : out Int) + is + Tmp_Int : Int; + + begin + Remainder := 0; + for J in L_Vec'Range loop + Tmp_Int := Remainder * Base + abs L_Vec (J); + Quotient (Quotient'First + J - L_Vec'First) := Tmp_Int / R_Int; + Remainder := Tmp_Int rem R_Int; + end loop; + + if L_Vec (L_Vec'First) < Int_0 then + Remainder := -Remainder; + end if; + end UI_Div_Vector; + + -- Start of processing for UI_Div_Rem + + begin + -- Result is zero if left operand is shorter than right + + if L_Length < R_Length then + if not Discard_Quotient then + Quotient := Uint_0; + end if; + + if not Discard_Remainder then + Remainder := Left; + end if; + + return; + end if; + + Init_Operand (Left, L_Vec); + Init_Operand (Right, R_Vec); + + -- Case of right operand is single digit. Here we can simply divide + -- each digit of the left operand by the divisor, from most to least + -- significant, carrying the remainder to the next digit (just like + -- ordinary long division by hand). + + if R_Length = Int_1 then + Tmp_Divisor := abs R_Vec (1); + + declare + Quotient_V : UI_Vector (1 .. L_Length); + + begin + UI_Div_Vector (L_Vec, Tmp_Divisor, Quotient_V, Remainder_I); + + if not Discard_Quotient then + Quotient := + Vector_To_Uint + (Quotient_V, (L_Vec (1) < Int_0 xor R_Vec (1) < Int_0)); + end if; + + if not Discard_Remainder then + Remainder := UI_From_Int (Remainder_I); + end if; + + return; + end; + end if; + + -- The possible simple cases have been exhausted. Now turn to the + -- algorithm D from the section of Knuth mentioned at the top of + -- this package. + + Algorithm_D : declare + Dividend : UI_Vector (1 .. L_Length + 1); + Divisor : UI_Vector (1 .. R_Length); + Quotient_V : UI_Vector (1 .. Q_Length); + Divisor_Dig1 : Int; + Divisor_Dig2 : Int; + Q_Guess : Int; + R_Guess : Int; + + begin + -- [ NORMALIZE ] (step D1 in the algorithm). First calculate the + -- scale d, and then multiply Left and Right (u and v in the book) + -- by d to get the dividend and divisor to work with. + + D := Base / (abs R_Vec (1) + 1); + + Dividend (1) := 0; + Dividend (2) := abs L_Vec (1); + + for J in 3 .. L_Length + Int_1 loop + Dividend (J) := L_Vec (J - 1); + end loop; + + Divisor (1) := abs R_Vec (1); + + for J in Int_2 .. R_Length loop + Divisor (J) := R_Vec (J); + end loop; + + if D > Int_1 then + + -- Multiply Dividend by d + + Carry := 0; + for J in reverse Dividend'Range loop + Tmp_Int := Dividend (J) * D + Carry; + Dividend (J) := Tmp_Int rem Base; + Carry := Tmp_Int / Base; + end loop; + + -- Multiply Divisor by d + + Carry := 0; + for J in reverse Divisor'Range loop + Tmp_Int := Divisor (J) * D + Carry; + Divisor (J) := Tmp_Int rem Base; + Carry := Tmp_Int / Base; + end loop; + end if; + + -- Main loop of long division algorithm + + Divisor_Dig1 := Divisor (1); + Divisor_Dig2 := Divisor (2); + + for J in Quotient_V'Range loop + + -- [ CALCULATE Q (hat) ] (step D3 in the algorithm) + + -- Note: this version of step D3 is from the original published + -- algorithm, which is known to have a bug causing overflows. + -- See: http://www-cs-faculty.stanford.edu/~uno/err2-2e.ps.gz + -- and http://www-cs-faculty.stanford.edu/~uno/all2-pre.ps.gz. + -- The code below is the fixed version of this step. + + Tmp_Int := Dividend (J) * Base + Dividend (J + 1); + + -- Initial guess + + Q_Guess := Tmp_Int / Divisor_Dig1; + R_Guess := Tmp_Int rem Divisor_Dig1; + + -- Refine the guess + + while Q_Guess >= Base + or else Divisor_Dig2 * Q_Guess > + R_Guess * Base + Dividend (J + 2) + loop + Q_Guess := Q_Guess - 1; + R_Guess := R_Guess + Divisor_Dig1; + exit when R_Guess >= Base; + end loop; + + -- [ MULTIPLY & SUBTRACT ] (step D4). Q_Guess * Divisor is + -- subtracted from the remaining dividend. + + Carry := 0; + for K in reverse Divisor'Range loop + Tmp_Int := Dividend (J + K) - Q_Guess * Divisor (K) + Carry; + Tmp_Dig := Tmp_Int rem Base; + Carry := Tmp_Int / Base; + + if Tmp_Dig < Int_0 then + Tmp_Dig := Tmp_Dig + Base; + Carry := Carry - 1; + end if; + + Dividend (J + K) := Tmp_Dig; + end loop; + + Dividend (J) := Dividend (J) + Carry; + + -- [ TEST REMAINDER ] & [ ADD BACK ] (steps D5 and D6) + + -- Here there is a slight difference from the book: the last + -- carry is always added in above and below (cancelling each + -- other). In fact the dividend going negative is used as + -- the test. + + -- If the Dividend went negative, then Q_Guess was off by + -- one, so it is decremented, and the divisor is added back + -- into the relevant portion of the dividend. + + if Dividend (J) < Int_0 then + Q_Guess := Q_Guess - 1; + + Carry := 0; + for K in reverse Divisor'Range loop + Tmp_Int := Dividend (J + K) + Divisor (K) + Carry; + + if Tmp_Int >= Base then + Tmp_Int := Tmp_Int - Base; + Carry := 1; + else + Carry := 0; + end if; + + Dividend (J + K) := Tmp_Int; + end loop; + + Dividend (J) := Dividend (J) + Carry; + end if; + + -- Finally we can get the next quotient digit + + Quotient_V (J) := Q_Guess; + end loop; + + -- [ UNNORMALIZE ] (step D8) + + if not Discard_Quotient then + Quotient := Vector_To_Uint + (Quotient_V, (L_Vec (1) < Int_0 xor R_Vec (1) < Int_0)); + end if; + + if not Discard_Remainder then + declare + Remainder_V : UI_Vector (1 .. R_Length); + Discard_Int : Int; + pragma Warnings (Off, Discard_Int); + begin + UI_Div_Vector + (Dividend (Dividend'Last - R_Length + 1 .. Dividend'Last), + D, + Remainder_V, Discard_Int); + Remainder := Vector_To_Uint (Remainder_V, L_Vec (1) < Int_0); + end; + end if; + end Algorithm_D; + end; + end UI_Div_Rem; + + ------------ + -- UI_Eq -- + ------------ + + function UI_Eq (Left : Int; Right : Uint) return Boolean is + begin + return not UI_Ne (UI_From_Int (Left), Right); + end UI_Eq; + + function UI_Eq (Left : Uint; Right : Int) return Boolean is + begin + return not UI_Ne (Left, UI_From_Int (Right)); + end UI_Eq; + + function UI_Eq (Left : Uint; Right : Uint) return Boolean is + begin + return not UI_Ne (Left, Right); + end UI_Eq; + + -------------- + -- UI_Expon -- + -------------- + + function UI_Expon (Left : Int; Right : Uint) return Uint is + begin + return UI_Expon (UI_From_Int (Left), Right); + end UI_Expon; + + function UI_Expon (Left : Uint; Right : Int) return Uint is + begin + return UI_Expon (Left, UI_From_Int (Right)); + end UI_Expon; + + function UI_Expon (Left : Int; Right : Int) return Uint is + begin + return UI_Expon (UI_From_Int (Left), UI_From_Int (Right)); + end UI_Expon; + + function UI_Expon (Left : Uint; Right : Uint) return Uint is + begin + pragma Assert (Right >= Uint_0); + + -- Any value raised to power of 0 is 1 + + if Right = Uint_0 then + return Uint_1; + + -- 0 to any positive power is 0 + + elsif Left = Uint_0 then + return Uint_0; + + -- 1 to any power is 1 + + elsif Left = Uint_1 then + return Uint_1; + + -- Any value raised to power of 1 is that value + + elsif Right = Uint_1 then + return Left; + + -- Cases which can be done by table lookup + + elsif Right <= Uint_64 then + + -- 2 ** N for N in 2 .. 64 + + if Left = Uint_2 then + declare + Right_Int : constant Int := Direct_Val (Right); + + begin + if Right_Int > UI_Power_2_Set then + for J in UI_Power_2_Set + Int_1 .. Right_Int loop + UI_Power_2 (J) := UI_Power_2 (J - Int_1) * Int_2; + Uints_Min := Uints.Last; + Udigits_Min := Udigits.Last; + end loop; + + UI_Power_2_Set := Right_Int; + end if; + + return UI_Power_2 (Right_Int); + end; + + -- 10 ** N for N in 2 .. 64 + + elsif Left = Uint_10 then + declare + Right_Int : constant Int := Direct_Val (Right); + + begin + if Right_Int > UI_Power_10_Set then + for J in UI_Power_10_Set + Int_1 .. Right_Int loop + UI_Power_10 (J) := UI_Power_10 (J - Int_1) * Int (10); + Uints_Min := Uints.Last; + Udigits_Min := Udigits.Last; + end loop; + + UI_Power_10_Set := Right_Int; + end if; + + return UI_Power_10 (Right_Int); + end; + end if; + end if; + + -- If we fall through, then we have the general case (see Knuth 4.6.3) + + declare + N : Uint := Right; + Squares : Uint := Left; + Result : Uint := Uint_1; + M : constant Uintp.Save_Mark := Uintp.Mark; + + begin + loop + if (Least_Sig_Digit (N) mod Int_2) = Int_1 then + Result := Result * Squares; + end if; + + N := N / Uint_2; + exit when N = Uint_0; + Squares := Squares * Squares; + end loop; + + Uintp.Release_And_Save (M, Result); + return Result; + end; + end UI_Expon; + + ---------------- + -- UI_From_CC -- + ---------------- + + function UI_From_CC (Input : Char_Code) return Uint is + begin + return UI_From_Int (Int (Input)); + end UI_From_CC; + + ----------------- + -- UI_From_Int -- + ----------------- + + function UI_From_Int (Input : Int) return Uint is + U : Uint; + + begin + if Min_Direct <= Input and then Input <= Max_Direct then + return Uint (Int (Uint_Direct_Bias) + Input); + end if; + + -- If already in the hash table, return entry + + U := UI_Ints.Get (Input); + + if U /= No_Uint then + return U; + end if; + + -- For values of larger magnitude, compute digits into a vector and call + -- Vector_To_Uint. + + declare + Max_For_Int : constant := 3; + -- Base is defined so that 3 Uint digits is sufficient to hold the + -- largest possible Int value. + + V : UI_Vector (1 .. Max_For_Int); + + Temp_Integer : Int := Input; + + begin + for J in reverse V'Range loop + V (J) := abs (Temp_Integer rem Base); + Temp_Integer := Temp_Integer / Base; + end loop; + + U := Vector_To_Uint (V, Input < Int_0); + UI_Ints.Set (Input, U); + Uints_Min := Uints.Last; + Udigits_Min := Udigits.Last; + return U; + end; + end UI_From_Int; + + ------------ + -- UI_GCD -- + ------------ + + -- Lehmer's algorithm for GCD + + -- The idea is to avoid using multiple precision arithmetic wherever + -- possible, substituting Int arithmetic instead. See Knuth volume II, + -- Algorithm L (page 329). + + -- We use the same notation as Knuth (U_Hat standing for the obvious) + + function UI_GCD (Uin, Vin : Uint) return Uint is + U, V : Uint; + -- Copies of Uin and Vin + + U_Hat, V_Hat : Int; + -- The most Significant digits of U,V + + A, B, C, D, T, Q, Den1, Den2 : Int; + + Tmp_UI : Uint; + Marks : constant Uintp.Save_Mark := Uintp.Mark; + Iterations : Integer := 0; + + begin + pragma Assert (Uin >= Vin); + pragma Assert (Vin >= Uint_0); + + U := Uin; + V := Vin; + + loop + Iterations := Iterations + 1; + + if Direct (V) then + if V = Uint_0 then + return U; + else + return + UI_From_Int (GCD (Direct_Val (V), UI_To_Int (U rem V))); + end if; + end if; + + Most_Sig_2_Digits (U, V, U_Hat, V_Hat); + A := 1; + B := 0; + C := 0; + D := 1; + + loop + -- We might overflow and get division by zero here. This just + -- means we cannot take the single precision step + + Den1 := V_Hat + C; + Den2 := V_Hat + D; + exit when Den1 = Int_0 or else Den2 = Int_0; + + -- Compute Q, the trial quotient + + Q := (U_Hat + A) / Den1; + + exit when Q /= ((U_Hat + B) / Den2); + + -- A single precision step Euclid step will give same answer as a + -- multiprecision one. + + T := A - (Q * C); + A := C; + C := T; + + T := B - (Q * D); + B := D; + D := T; + + T := U_Hat - (Q * V_Hat); + U_Hat := V_Hat; + V_Hat := T; + + end loop; + + -- Take a multiprecision Euclid step + + if B = Int_0 then + + -- No single precision steps take a regular Euclid step + + Tmp_UI := U rem V; + U := V; + V := Tmp_UI; + + else + -- Use prior single precision steps to compute this Euclid step + + -- For constructs such as: + -- sqrt_2: constant := 1.41421_35623_73095_04880_16887_24209_698; + -- sqrt_eps: constant long_float := long_float( 1.0 / sqrt_2) + -- ** long_float'machine_mantissa; + -- + -- we spend 80% of our time working on this step. Perhaps we need + -- a special case Int / Uint dot product to speed things up. ??? + + -- Alternatively we could increase the single precision iterations + -- to handle Uint's of some small size ( <5 digits?). Then we + -- would have more iterations on small Uint. On the code above, we + -- only get 5 (on average) single precision iterations per large + -- iteration. ??? + + Tmp_UI := (UI_From_Int (A) * U) + (UI_From_Int (B) * V); + V := (UI_From_Int (C) * U) + (UI_From_Int (D) * V); + U := Tmp_UI; + end if; + + -- If the operands are very different in magnitude, the loop will + -- generate large amounts of short-lived data, which it is worth + -- removing periodically. + + if Iterations > 100 then + Release_And_Save (Marks, U, V); + Iterations := 0; + end if; + end loop; + end UI_GCD; + + ------------ + -- UI_Ge -- + ------------ + + function UI_Ge (Left : Int; Right : Uint) return Boolean is + begin + return not UI_Lt (UI_From_Int (Left), Right); + end UI_Ge; + + function UI_Ge (Left : Uint; Right : Int) return Boolean is + begin + return not UI_Lt (Left, UI_From_Int (Right)); + end UI_Ge; + + function UI_Ge (Left : Uint; Right : Uint) return Boolean is + begin + return not UI_Lt (Left, Right); + end UI_Ge; + + ------------ + -- UI_Gt -- + ------------ + + function UI_Gt (Left : Int; Right : Uint) return Boolean is + begin + return UI_Lt (Right, UI_From_Int (Left)); + end UI_Gt; + + function UI_Gt (Left : Uint; Right : Int) return Boolean is + begin + return UI_Lt (UI_From_Int (Right), Left); + end UI_Gt; + + function UI_Gt (Left : Uint; Right : Uint) return Boolean is + begin + return UI_Lt (Left => Right, Right => Left); + end UI_Gt; + + --------------- + -- UI_Image -- + --------------- + + procedure UI_Image (Input : Uint; Format : UI_Format := Auto) is + begin + Image_Out (Input, True, Format); + end UI_Image; + + ------------------------- + -- UI_Is_In_Int_Range -- + ------------------------- + + function UI_Is_In_Int_Range (Input : Uint) return Boolean is + begin + -- Make sure we don't get called before Initialize + + pragma Assert (Uint_Int_First /= Uint_0); + + if Direct (Input) then + return True; + else + return Input >= Uint_Int_First + and then Input <= Uint_Int_Last; + end if; + end UI_Is_In_Int_Range; + + ------------ + -- UI_Le -- + ------------ + + function UI_Le (Left : Int; Right : Uint) return Boolean is + begin + return not UI_Lt (Right, UI_From_Int (Left)); + end UI_Le; + + function UI_Le (Left : Uint; Right : Int) return Boolean is + begin + return not UI_Lt (UI_From_Int (Right), Left); + end UI_Le; + + function UI_Le (Left : Uint; Right : Uint) return Boolean is + begin + return not UI_Lt (Left => Right, Right => Left); + end UI_Le; + + ------------ + -- UI_Lt -- + ------------ + + function UI_Lt (Left : Int; Right : Uint) return Boolean is + begin + return UI_Lt (UI_From_Int (Left), Right); + end UI_Lt; + + function UI_Lt (Left : Uint; Right : Int) return Boolean is + begin + return UI_Lt (Left, UI_From_Int (Right)); + end UI_Lt; + + function UI_Lt (Left : Uint; Right : Uint) return Boolean is + begin + -- Quick processing for identical arguments + + if Int (Left) = Int (Right) then + return False; + + -- Quick processing for both arguments directly represented + + elsif Direct (Left) and then Direct (Right) then + return Int (Left) < Int (Right); + + -- At least one argument is more than one digit long + + else + declare + L_Length : constant Int := N_Digits (Left); + R_Length : constant Int := N_Digits (Right); + + L_Vec : UI_Vector (1 .. L_Length); + R_Vec : UI_Vector (1 .. R_Length); + + begin + Init_Operand (Left, L_Vec); + Init_Operand (Right, R_Vec); + + if L_Vec (1) < Int_0 then + + -- First argument negative, second argument non-negative + + if R_Vec (1) >= Int_0 then + return True; + + -- Both arguments negative + + else + if L_Length /= R_Length then + return L_Length > R_Length; + + elsif L_Vec (1) /= R_Vec (1) then + return L_Vec (1) < R_Vec (1); + + else + for J in 2 .. L_Vec'Last loop + if L_Vec (J) /= R_Vec (J) then + return L_Vec (J) > R_Vec (J); + end if; + end loop; + + return False; + end if; + end if; + + else + -- First argument non-negative, second argument negative + + if R_Vec (1) < Int_0 then + return False; + + -- Both arguments non-negative + + else + if L_Length /= R_Length then + return L_Length < R_Length; + else + for J in L_Vec'Range loop + if L_Vec (J) /= R_Vec (J) then + return L_Vec (J) < R_Vec (J); + end if; + end loop; + + return False; + end if; + end if; + end if; + end; + end if; + end UI_Lt; + + ------------ + -- UI_Max -- + ------------ + + function UI_Max (Left : Int; Right : Uint) return Uint is + begin + return UI_Max (UI_From_Int (Left), Right); + end UI_Max; + + function UI_Max (Left : Uint; Right : Int) return Uint is + begin + return UI_Max (Left, UI_From_Int (Right)); + end UI_Max; + + function UI_Max (Left : Uint; Right : Uint) return Uint is + begin + if Left >= Right then + return Left; + else + return Right; + end if; + end UI_Max; + + ------------ + -- UI_Min -- + ------------ + + function UI_Min (Left : Int; Right : Uint) return Uint is + begin + return UI_Min (UI_From_Int (Left), Right); + end UI_Min; + + function UI_Min (Left : Uint; Right : Int) return Uint is + begin + return UI_Min (Left, UI_From_Int (Right)); + end UI_Min; + + function UI_Min (Left : Uint; Right : Uint) return Uint is + begin + if Left <= Right then + return Left; + else + return Right; + end if; + end UI_Min; + + ------------- + -- UI_Mod -- + ------------- + + function UI_Mod (Left : Int; Right : Uint) return Uint is + begin + return UI_Mod (UI_From_Int (Left), Right); + end UI_Mod; + + function UI_Mod (Left : Uint; Right : Int) return Uint is + begin + return UI_Mod (Left, UI_From_Int (Right)); + end UI_Mod; + + function UI_Mod (Left : Uint; Right : Uint) return Uint is + Urem : constant Uint := Left rem Right; + + begin + if (Left < Uint_0) = (Right < Uint_0) + or else Urem = Uint_0 + then + return Urem; + else + return Right + Urem; + end if; + end UI_Mod; + + ------------------------------- + -- UI_Modular_Exponentiation -- + ------------------------------- + + function UI_Modular_Exponentiation + (B : Uint; + E : Uint; + Modulo : Uint) return Uint + is + M : constant Save_Mark := Mark; + + Result : Uint := Uint_1; + Base : Uint := B; + Exponent : Uint := E; + + begin + while Exponent /= Uint_0 loop + if Least_Sig_Digit (Exponent) rem Int'(2) = Int'(1) then + Result := (Result * Base) rem Modulo; + end if; + + Exponent := Exponent / Uint_2; + Base := (Base * Base) rem Modulo; + end loop; + + Release_And_Save (M, Result); + return Result; + end UI_Modular_Exponentiation; + + ------------------------ + -- UI_Modular_Inverse -- + ------------------------ + + function UI_Modular_Inverse (N : Uint; Modulo : Uint) return Uint is + M : constant Save_Mark := Mark; + U : Uint; + V : Uint; + Q : Uint; + R : Uint; + X : Uint; + Y : Uint; + T : Uint; + S : Int := 1; + + begin + U := Modulo; + V := N; + + X := Uint_1; + Y := Uint_0; + + loop + UI_Div_Rem (U, V, Quotient => Q, Remainder => R); + + U := V; + V := R; + + T := X; + X := Y + Q * X; + Y := T; + S := -S; + + exit when R = Uint_1; + end loop; + + if S = Int'(-1) then + X := Modulo - X; + end if; + + Release_And_Save (M, X); + return X; + end UI_Modular_Inverse; + + ------------ + -- UI_Mul -- + ------------ + + function UI_Mul (Left : Int; Right : Uint) return Uint is + begin + return UI_Mul (UI_From_Int (Left), Right); + end UI_Mul; + + function UI_Mul (Left : Uint; Right : Int) return Uint is + begin + return UI_Mul (Left, UI_From_Int (Right)); + end UI_Mul; + + function UI_Mul (Left : Uint; Right : Uint) return Uint is + begin + -- Case where product fits in the range of a 32-bit integer + + if Int (Left) <= Int (Uint_Max_Simple_Mul) + and then + Int (Right) <= Int (Uint_Max_Simple_Mul) + then + return UI_From_Int (Direct_Val (Left) * Direct_Val (Right)); + end if; + + -- Otherwise we have the general case (Algorithm M in Knuth) + + declare + L_Length : constant Int := N_Digits (Left); + R_Length : constant Int := N_Digits (Right); + L_Vec : UI_Vector (1 .. L_Length); + R_Vec : UI_Vector (1 .. R_Length); + Neg : Boolean; + + begin + Init_Operand (Left, L_Vec); + Init_Operand (Right, R_Vec); + Neg := (L_Vec (1) < Int_0) xor (R_Vec (1) < Int_0); + L_Vec (1) := abs (L_Vec (1)); + R_Vec (1) := abs (R_Vec (1)); + + Algorithm_M : declare + Product : UI_Vector (1 .. L_Length + R_Length); + Tmp_Sum : Int; + Carry : Int; + + begin + for J in Product'Range loop + Product (J) := 0; + end loop; + + for J in reverse R_Vec'Range loop + Carry := 0; + for K in reverse L_Vec'Range loop + Tmp_Sum := + L_Vec (K) * R_Vec (J) + Product (J + K) + Carry; + Product (J + K) := Tmp_Sum rem Base; + Carry := Tmp_Sum / Base; + end loop; + + Product (J) := Carry; + end loop; + + return Vector_To_Uint (Product, Neg); + end Algorithm_M; + end; + end UI_Mul; + + ------------ + -- UI_Ne -- + ------------ + + function UI_Ne (Left : Int; Right : Uint) return Boolean is + begin + return UI_Ne (UI_From_Int (Left), Right); + end UI_Ne; + + function UI_Ne (Left : Uint; Right : Int) return Boolean is + begin + return UI_Ne (Left, UI_From_Int (Right)); + end UI_Ne; + + function UI_Ne (Left : Uint; Right : Uint) return Boolean is + begin + -- Quick processing for identical arguments. Note that this takes + -- care of the case of two No_Uint arguments. + + if Int (Left) = Int (Right) then + return False; + end if; + + -- See if left operand directly represented + + if Direct (Left) then + + -- If right operand directly represented then compare + + if Direct (Right) then + return Int (Left) /= Int (Right); + + -- Left operand directly represented, right not, must be unequal + + else + return True; + end if; + + -- Right operand directly represented, left not, must be unequal + + elsif Direct (Right) then + return True; + end if; + + -- Otherwise both multi-word, do comparison + + declare + Size : constant Int := N_Digits (Left); + Left_Loc : Int; + Right_Loc : Int; + + begin + if Size /= N_Digits (Right) then + return True; + end if; + + Left_Loc := Uints.Table (Left).Loc; + Right_Loc := Uints.Table (Right).Loc; + + for J in Int_0 .. Size - Int_1 loop + if Udigits.Table (Left_Loc + J) /= + Udigits.Table (Right_Loc + J) + then + return True; + end if; + end loop; + + return False; + end; + end UI_Ne; + + ---------------- + -- UI_Negate -- + ---------------- + + function UI_Negate (Right : Uint) return Uint is + begin + -- Case where input is directly represented. Note that since the range + -- of Direct values is non-symmetrical, the result may not be directly + -- represented, this is taken care of in UI_From_Int. + + if Direct (Right) then + return UI_From_Int (-Direct_Val (Right)); + + -- Full processing for multi-digit case. Note that we cannot just copy + -- the value to the end of the table negating the first digit, since the + -- range of Direct values is non-symmetrical, so we can have a negative + -- value that is not Direct whose negation can be represented directly. + + else + declare + R_Length : constant Int := N_Digits (Right); + R_Vec : UI_Vector (1 .. R_Length); + Neg : Boolean; + + begin + Init_Operand (Right, R_Vec); + Neg := R_Vec (1) > Int_0; + R_Vec (1) := abs R_Vec (1); + return Vector_To_Uint (R_Vec, Neg); + end; + end if; + end UI_Negate; + + ------------- + -- UI_Rem -- + ------------- + + function UI_Rem (Left : Int; Right : Uint) return Uint is + begin + return UI_Rem (UI_From_Int (Left), Right); + end UI_Rem; + + function UI_Rem (Left : Uint; Right : Int) return Uint is + begin + return UI_Rem (Left, UI_From_Int (Right)); + end UI_Rem; + + function UI_Rem (Left, Right : Uint) return Uint is + Remainder : Uint; + Quotient : Uint; + pragma Warnings (Off, Quotient); + + begin + pragma Assert (Right /= Uint_0); + + if Direct (Right) and then Direct (Left) then + return UI_From_Int (Direct_Val (Left) rem Direct_Val (Right)); + + else + UI_Div_Rem + (Left, Right, Quotient, Remainder, Discard_Quotient => True); + return Remainder; + end if; + end UI_Rem; + + ------------ + -- UI_Sub -- + ------------ + + function UI_Sub (Left : Int; Right : Uint) return Uint is + begin + return UI_Add (Left, -Right); + end UI_Sub; + + function UI_Sub (Left : Uint; Right : Int) return Uint is + begin + return UI_Add (Left, -Right); + end UI_Sub; + + function UI_Sub (Left : Uint; Right : Uint) return Uint is + begin + if Direct (Left) and then Direct (Right) then + return UI_From_Int (Direct_Val (Left) - Direct_Val (Right)); + else + return UI_Add (Left, -Right); + end if; + end UI_Sub; + + -------------- + -- UI_To_CC -- + -------------- + + function UI_To_CC (Input : Uint) return Char_Code is + begin + if Direct (Input) then + return Char_Code (Direct_Val (Input)); + + -- Case of input is more than one digit + + else + declare + In_Length : constant Int := N_Digits (Input); + In_Vec : UI_Vector (1 .. In_Length); + Ret_CC : Char_Code; + + begin + Init_Operand (Input, In_Vec); + + -- We assume value is positive + + Ret_CC := 0; + for Idx in In_Vec'Range loop + Ret_CC := Ret_CC * Char_Code (Base) + + Char_Code (abs In_Vec (Idx)); + end loop; + + return Ret_CC; + end; + end if; + end UI_To_CC; + + ---------------- + -- UI_To_Int -- + ---------------- + + function UI_To_Int (Input : Uint) return Int is + pragma Assert (Input /= No_Uint); + + begin + if Direct (Input) then + return Direct_Val (Input); + + -- Case of input is more than one digit + + else + declare + In_Length : constant Int := N_Digits (Input); + In_Vec : UI_Vector (1 .. In_Length); + Ret_Int : Int; + + begin + -- Uints of more than one digit could be outside the range for + -- Ints. Caller should have checked for this if not certain. + -- Fatal error to attempt to convert from value outside Int'Range. + + pragma Assert (UI_Is_In_Int_Range (Input)); + + -- Otherwise, proceed ahead, we are OK + + Init_Operand (Input, In_Vec); + Ret_Int := 0; + + -- Calculate -|Input| and then negates if value is positive. This + -- handles our current definition of Int (based on 2s complement). + -- Is it secure enough??? + + for Idx in In_Vec'Range loop + Ret_Int := Ret_Int * Base - abs In_Vec (Idx); + end loop; + + if In_Vec (1) < Int_0 then + return Ret_Int; + else + return -Ret_Int; + end if; + end; + end if; + end UI_To_Int; + + -------------- + -- UI_Write -- + -------------- + + procedure UI_Write (Input : Uint; Format : UI_Format := Auto) is + begin + Image_Out (Input, False, Format); + end UI_Write; + + --------------------- + -- Vector_To_Uint -- + --------------------- + + function Vector_To_Uint + (In_Vec : UI_Vector; + Negative : Boolean) + return Uint + is + Size : Int; + Val : Int; + + begin + -- The vector can contain leading zeros. These are not stored in the + -- table, so loop through the vector looking for first non-zero digit + + for J in In_Vec'Range loop + if In_Vec (J) /= Int_0 then + + -- The length of the value is the length of the rest of the vector + + Size := In_Vec'Last - J + 1; + + -- One digit value can always be represented directly + + if Size = Int_1 then + if Negative then + return Uint (Int (Uint_Direct_Bias) - In_Vec (J)); + else + return Uint (Int (Uint_Direct_Bias) + In_Vec (J)); + end if; + + -- Positive two digit values may be in direct representation range + + elsif Size = Int_2 and then not Negative then + Val := In_Vec (J) * Base + In_Vec (J + 1); + + if Val <= Max_Direct then + return Uint (Int (Uint_Direct_Bias) + Val); + end if; + end if; + + -- The value is outside the direct representation range and must + -- therefore be stored in the table. Expand the table to contain + -- the count and digits. The index of the new table entry will be + -- returned as the result. + + Uints.Append ((Length => Size, Loc => Udigits.Last + 1)); + + if Negative then + Val := -In_Vec (J); + else + Val := +In_Vec (J); + end if; + + Udigits.Append (Val); + + for K in 2 .. Size loop + Udigits.Append (In_Vec (J + K - 1)); + end loop; + + return Uints.Last; + end if; + end loop; + + -- Dropped through loop only if vector contained all zeros + + return Uint_0; + end Vector_To_Uint; + +end Uintp; |