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------------------------------------------------------------------------------

--                                                                          --

--                         GNAT COMPILER COMPONENTS                         --

--                                                                          --

--                                U I N T P                                 --

--                                                                          --

--                                 S p e c                                  --

--                                                                          --

--          Copyright (C) 1992-2010, 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.      --

--                                                                          --

------------------------------------------------------------------------------

--  Support for universal integer arithmetic

--  WARNING: There is a C version of this package. Any changes to this

--  source file must be properly reflected in the C header file sinfo.h

with Alloc;

with Table;

pragma Elaborate_All (Table);

with Types; use Types;

package Uintp is

   -------------------------------------------------

   -- Basic Types and Constants for Uintp Package --

   -------------------------------------------------

   type Uint is private;

   --  The basic universal integer type

   No_Uint : constant Uint;

   --  A constant value indicating a missing or unset Uint value

   Uint_0   : constant Uint;

   Uint_1   : constant Uint;

   Uint_2   : constant Uint;

   Uint_3   : constant Uint;

   Uint_4   : constant Uint;

   Uint_5   : constant Uint;

   Uint_6   : constant Uint;

   Uint_7   : constant Uint;

   Uint_8   : constant Uint;

   Uint_9   : constant Uint;

   Uint_10  : constant Uint;

   Uint_11  : constant Uint;

   Uint_12  : constant Uint;

   Uint_13  : constant Uint;

   Uint_14  : constant Uint;

   Uint_15  : constant Uint;

   Uint_16  : constant Uint;

   Uint_24  : constant Uint;

   Uint_32  : constant Uint;

   Uint_63  : constant Uint;

   Uint_64  : constant Uint;

   Uint_80  : constant Uint;

   Uint_128 : constant Uint;

   Uint_Minus_1   : constant Uint;

   Uint_Minus_2   : constant Uint;

   Uint_Minus_3   : constant Uint;

   Uint_Minus_4   : constant Uint;

   Uint_Minus_5   : constant Uint;

   Uint_Minus_6   : constant Uint;

   Uint_Minus_7   : constant Uint;

   Uint_Minus_8   : constant Uint;

   Uint_Minus_9   : constant Uint;

   Uint_Minus_12  : constant Uint;

   Uint_Minus_36  : constant Uint;

   Uint_Minus_63  : constant Uint;

   Uint_Minus_80  : constant Uint;

   Uint_Minus_128 : constant Uint;

   -----------------

   -- Subprograms --

   -----------------

   procedure Initialize;

   --  Initialize Uint tables. Note that Initialize must not be called if

   --  Tree_Read is used. Note also that there is no lock routine in this

   --  unit, these are among the few tables that can be expanded during

   --  gigi processing.

   procedure Tree_Read;

   --  Initializes internal tables from current tree file using the relevant

   --  Table.Tree_Read routines. Note that Initialize should not be called if

   --  Tree_Read is used. Tree_Read includes all necessary initialization.

   procedure Tree_Write;

   --  Writes out internal tables to current tree file using the relevant

   --  Table.Tree_Write routines.

   function UI_Abs (Right : Uint) return Uint;

   pragma Inline (UI_Abs);

   --  Returns abs function of universal integer

   function UI_Add (Left : Uint; Right : Uint) return Uint;

   function UI_Add (Left : Int;  Right : Uint) return Uint;

   function UI_Add (Left : Uint; Right : Int)  return Uint;

   --  Returns sum of two integer values

   function UI_Decimal_Digits_Hi (U : Uint) return Nat;

   --  Returns an estimate of the number of decimal digits required to

   --  represent the absolute value of U. This estimate is correct or high,

   --  i.e. it never returns a value that is too low. The accuracy of the

   --  estimate affects only the effectiveness of comparison optimizations

   --  in Urealp.

   function UI_Decimal_Digits_Lo (U : Uint) return Nat;

   --  Returns an estimate of the number of decimal digits required to

   --  represent the absolute value of U. This estimate is correct or low,

   --  i.e. it never returns a value that is too high. The accuracy of the

   --  estimate affects only the effectiveness of comparison optimizations

   --  in Urealp.

   function UI_Div (Left : Uint; Right : Uint) return Uint;

   function UI_Div (Left : Int;  Right : Uint) return Uint;

   function UI_Div (Left : Uint; Right : Int)  return Uint;

   --  Returns quotient of two integer values. Fatal error if Right = 0

   function UI_Eq (Left : Uint; Right : Uint) return Boolean;

   function UI_Eq (Left : Int;  Right : Uint) return Boolean;

   function UI_Eq (Left : Uint; Right : Int)  return Boolean;

   pragma Inline (UI_Eq);

   --  Compares integer values for equality

   function UI_Expon (Left : Uint; Right : Uint) return Uint;

   function UI_Expon (Left : Int;  Right : Uint) return Uint;

   function UI_Expon (Left : Uint; Right : Int)  return Uint;

   function UI_Expon (Left : Int;  Right : Int)  return Uint;

   --  Returns result of exponentiating two integer values.

   --  Fatal error if Right is negative.

   function UI_GCD (Uin, Vin : Uint) return Uint;

   --  Computes GCD of input values. Assumes Uin >= Vin >= 0

   function UI_Ge (Left : Uint; Right : Uint) return Boolean;

   function UI_Ge (Left : Int;  Right : Uint) return Boolean;

   function UI_Ge (Left : Uint; Right : Int)  return Boolean;

   pragma Inline (UI_Ge);

   --  Compares integer values for greater than or equal

   function UI_Gt (Left : Uint; Right : Uint) return Boolean;

   function UI_Gt (Left : Int;  Right : Uint) return Boolean;

   function UI_Gt (Left : Uint; Right : Int)  return Boolean;

   pragma Inline (UI_Gt);

   --  Compares integer values for greater than

   function UI_Is_In_Int_Range (Input : Uint) return Boolean;

   pragma Inline (UI_Is_In_Int_Range);

   --  Determines if universal integer is in Int range

   function UI_Le (Left : Uint; Right : Uint) return Boolean;

   function UI_Le (Left : Int;  Right : Uint) return Boolean;

   function UI_Le (Left : Uint; Right : Int)  return Boolean;

   pragma Inline (UI_Le);

   --  Compares integer values for less than or equal

   function UI_Lt (Left : Uint; Right : Uint) return Boolean;

   function UI_Lt (Left : Int;  Right : Uint) return Boolean;

   function UI_Lt (Left : Uint; Right : Int)  return Boolean;

   --  Compares integer values for less than

   function UI_Max (Left : Uint; Right : Uint) return Uint;

   function UI_Max (Left : Int;  Right : Uint) return Uint;

   function UI_Max (Left : Uint; Right : Int)  return Uint;

   --  Returns maximum of two integer values

   function UI_Min (Left : Uint; Right : Uint) return Uint;

   function UI_Min (Left : Int;  Right : Uint) return Uint;

   function UI_Min (Left : Uint; Right : Int)  return Uint;

   --  Returns minimum of two integer values

   function UI_Mod (Left : Uint; Right : Uint) return Uint;

   function UI_Mod (Left : Int;  Right : Uint) return Uint;

   function UI_Mod (Left : Uint; Right : Int)  return Uint;

   pragma Inline (UI_Mod);

   --  Returns mod function of two integer values

   function UI_Mul (Left : Uint; Right : Uint) return Uint;

   function UI_Mul (Left : Int;  Right : Uint) return Uint;

   function UI_Mul (Left : Uint; Right : Int)  return Uint;

   --  Returns product of two integer values

   function UI_Ne (Left : Uint; Right : Uint) return Boolean;

   function UI_Ne (Left : Int;  Right : Uint) return Boolean;

   function UI_Ne (Left : Uint; Right : Int)  return Boolean;

   pragma Inline (UI_Ne);

   --  Compares integer values for inequality

   function UI_Negate (Right : Uint) return Uint;

   pragma Inline (UI_Negate);

   --  Returns negative of universal integer

   function UI_Rem (Left : Uint; Right : Uint) return Uint;

   function UI_Rem (Left : Int;  Right : Uint) return Uint;

   function UI_Rem (Left : Uint; Right : Int)  return Uint;

   --  Returns rem of two integer values

   function UI_Sub (Left : Uint; Right : Uint) return Uint;

   function UI_Sub (Left : Int;  Right : Uint) return Uint;

   function UI_Sub (Left : Uint; Right : Int)  return Uint;

   pragma Inline (UI_Sub);

   --  Returns difference of two integer values

   function UI_Modular_Exponentiation

     (B      : Uint;

      E      : Uint;

      Modulo : Uint) return Uint;

   --  Efficiently compute (B ** E) rem Modulo

   function UI_Modular_Inverse (N : Uint; Modulo : Uint) return Uint;

   --  Compute the multiplicative inverse of N in modular arithmetics with the

   --  given Modulo (uses Euclid's algorithm). Note: the call is considered

   --  to be erroneous (and the behavior is undefined) if n is not invertible.

   function UI_From_Int (Input : Int) return Uint;

   --  Converts Int value to universal integer form

   function UI_From_CC (Input : Char_Code) return Uint;

   --  Converts Char_Code value to universal integer form

   function UI_To_Int (Input : Uint) return Int;

   --  Converts universal integer value to Int. Fatal error if value is not in

   --  appropriate range.

   function UI_To_CC (Input : Uint) return Char_Code;

   --  Converts universal integer value to Char_Code. Fatal error if value is

   --  not in Char_Code range.

   function Num_Bits (Input : Uint) return Nat;

   --  Approximate number of binary bits in given universal integer.

   --  This function is used for capacity checks, and it can be one

   --  bit off without affecting its usage.

   ---------------------

   -- Output Routines --

   ---------------------

   type UI_Format is (Hex, Decimal, Auto);

   --  Used to determine whether UI_Image/UI_Write output is in hexadecimal

   --  or decimal format. Auto, the default setting, lets the routine make

   --  a decision based on the value.

   UI_Image_Max    : constant := 48; -- Enough for a 128-bit number

   UI_Image_Buffer : String (1 .. UI_Image_Max);

   UI_Image_Length : Natural;

   --  Buffer used for UI_Image as described below

   procedure UI_Image (Input : Uint; Format : UI_Format := Auto);

   --  Places a representation of Uint, consisting of a possible minus sign,

   --  followed by the value in UI_Image_Buffer. The form of the value is an

   --  integer literal in either decimal (no base) or hexadecimal (base 16)

   --  format. If Hex is True on entry, then hex mode is forced, otherwise

   --  UI_Image makes a guess at which output format is more convenient. The

   --  value must fit in UI_Image_Buffer. If necessary, the result is an

   --  approximation of the proper value, using an exponential format. The

   --  image of No_Uint is output as a single question mark.

   procedure UI_Write (Input : Uint; Format : UI_Format := Auto);

   --  Writes a representation of Uint, consisting of a possible minus sign,

   --  followed by the value to the output file. The form of the value is an

   --  integer literal in either decimal (no base) or hexadecimal (base 16)

   --  format as appropriate. UI_Format shows which format to use. Auto,

   --  the default, asks UI_Write to make a guess at which output format

   --  will be more convenient to read.

   procedure pid (Input : Uint);

   pragma Export (Ada, pid);

   --  Writes representation of Uint in decimal with a terminating line

   --  return. This is intended for use from the debugger.

   procedure pih (Input : Uint);

   pragma Export (Ada, pih);

   --  Writes representation of Uint in hex with a terminating line return.

   --  This is intended for use from the debugger.

   ------------------------

   -- Operator Renamings --

   ------------------------

   function "+" (Left : Uint; Right : Uint) return Uint renames UI_Add;

   function "+" (Left : Int;  Right : Uint) return Uint renames UI_Add;

   function "+" (Left : Uint; Right : Int)  return Uint renames UI_Add;

   function "/" (Left : Uint; Right : Uint) return Uint renames UI_Div;

   function "/" (Left : Int;  Right : Uint) return Uint renames UI_Div;

   function "/" (Left : Uint; Right : Int)  return Uint renames UI_Div;

   function "*" (Left : Uint; Right : Uint) return Uint renames UI_Mul;

   function "*" (Left : Int;  Right : Uint) return Uint renames UI_Mul;

   function "*" (Left : Uint; Right : Int)  return Uint renames UI_Mul;

   function "-" (Left : Uint; Right : Uint) return Uint renames UI_Sub;

   function "-" (Left : Int;  Right : Uint) return Uint renames UI_Sub;

   function "-" (Left : Uint; Right : Int)  return Uint renames UI_Sub;

   function "**"  (Left : Uint; Right : Uint) return Uint renames UI_Expon;

   function "**"  (Left : Uint; Right : Int)  return Uint renames UI_Expon;

   function "**"  (Left : Int;  Right : Uint) return Uint renames UI_Expon;

   function "**"  (Left : Int;  Right : Int)  return Uint renames UI_Expon;

   function "abs" (Real : Uint) return Uint renames UI_Abs;

   function "mod" (Left : Uint; Right : Uint) return Uint renames UI_Mod;

   function "mod" (Left : Int;  Right : Uint) return Uint renames UI_Mod;

   function "mod" (Left : Uint; Right : Int)  return Uint renames UI_Mod;

   function "rem" (Left : Uint; Right : Uint) return Uint renames UI_Rem;

   function "rem" (Left : Int;  Right : Uint) return Uint renames UI_Rem;

   function "rem" (Left : Uint; Right : Int)  return Uint renames UI_Rem;

   function "-"   (Real : Uint) return Uint renames UI_Negate;

   function "="   (Left : Uint; Right : Uint) return Boolean renames UI_Eq;

   function "="   (Left : Int;  Right : Uint) return Boolean renames UI_Eq;

   function "="   (Left : Uint; Right : Int)  return Boolean renames UI_Eq;

   function ">="  (Left : Uint; Right : Uint) return Boolean renames UI_Ge;

   function ">="  (Left : Int;  Right : Uint) return Boolean renames UI_Ge;

   function ">="  (Left : Uint; Right : Int)  return Boolean renames UI_Ge;

   function ">"   (Left : Uint; Right : Uint) return Boolean renames UI_Gt;

   function ">"   (Left : Int;  Right : Uint) return Boolean renames UI_Gt;

   function ">"   (Left : Uint; Right : Int)  return Boolean renames UI_Gt;

   function "<="  (Left : Uint; Right : Uint) return Boolean renames UI_Le;

   function "<="  (Left : Int;  Right : Uint) return Boolean renames UI_Le;

   function "<="  (Left : Uint; Right : Int)  return Boolean renames UI_Le;

   function "<"   (Left : Uint; Right : Uint) return Boolean renames UI_Lt;

   function "<"   (Left : Int;  Right : Uint) return Boolean renames UI_Lt;

   function "<"   (Left : Uint; Right : Int)  return Boolean renames UI_Lt;

   -----------------------------

   -- Mark/Release Processing --

   -----------------------------

   --  The space used by Uint data is not automatically reclaimed. However,

   --  a mark-release regime is implemented which allows storage to be

   --  released back to a previously noted mark. This is used for example

   --  when doing comparisons, where only intermediate results get stored

   --  that do not need to be saved for future use.

   type Save_Mark is private;

   function Mark return Save_Mark;

   --  Note mark point for future release

   procedure Release (M : Save_Mark);

   --  Release storage allocated since mark was noted

   procedure Release_And_Save (M : Save_Mark; UI : in out Uint);

   --  Like Release, except that the given Uint value (which is typically

   --  among the data being released) is recopied after the release, so

   --  that it is the most recent item, and UI is updated to point to

   --  its copied location.

   procedure Release_And_Save (M : Save_Mark; UI1, UI2 : in out Uint);

   --  Like Release, except that the given Uint values (which are typically

   --  among the data being released) are recopied after the release, so

   --  that they are the most recent items, and UI1 and UI2 are updated if

   --  necessary to point to the copied locations. This routine is careful

   --  to do things in the right order, so that the values do not clobber

   --  one another.

   -----------------------------------

   -- Representation of Uint Values --

   -----------------------------------

private

   type Uint is new Int range Uint_Low_Bound .. Uint_High_Bound;

   for Uint'Size use 32;

   No_Uint : constant Uint := Uint (Uint_Low_Bound);

   --  Uint values are represented as multiple precision integers stored in

   --  a multi-digit format using Base as the base. This value is chosen so

   --  that the product Base*Base is within the range of allowed Int values.

   --  Base is defined to allow efficient execution of the primitive operations

   --  (a0, b0, c0) defined in the section "The Classical Algorithms"

   --  (sec. 4.3.1) of Donald Knuth's "The Art of Computer  Programming",

   --  Vol. 2. These algorithms are used in this package. In particular,

   --  the product of two single digits in this base fits in a 32-bit integer.

   Base_Bits : constant := 15;

   --  Number of bits in base value

   Base : constant Int := 2 ** Base_Bits;

   --  Values in the range -(Base+1) .. Max_Direct are encoded directly as

   --  Uint values by adding a bias value. The value of Max_Direct is chosen

   --  so that a directly represented number always fits in two digits when

   --  represented in base format.

   Min_Direct : constant Int := -(Base - 1);

   Max_Direct : constant Int := (Base - 1) * (Base - 1);

   --  The following values define the bias used to store Uint values which

   --  are in this range, as well as the biased values for the first and last

   --  values in this range. We use a new derived type for these constants to

   --  avoid accidental use of Uint arithmetic on these values, which is never

   --  correct.

   type Ctrl is range Int'First .. Int'Last;

   Uint_Direct_Bias  : constant Ctrl := Ctrl (Uint_Low_Bound) + Ctrl (Base);

   Uint_Direct_First : constant Ctrl := Uint_Direct_Bias + Ctrl (Min_Direct);

   Uint_Direct_Last  : constant Ctrl := Uint_Direct_Bias + Ctrl (Max_Direct);

   Uint_0   : constant Uint := Uint (Uint_Direct_Bias);

   Uint_1   : constant Uint := Uint (Uint_Direct_Bias + 1);

   Uint_2   : constant Uint := Uint (Uint_Direct_Bias + 2);

   Uint_3   : constant Uint := Uint (Uint_Direct_Bias + 3);

   Uint_4   : constant Uint := Uint (Uint_Direct_Bias + 4);

   Uint_5   : constant Uint := Uint (Uint_Direct_Bias + 5);

   Uint_6   : constant Uint := Uint (Uint_Direct_Bias + 6);

   Uint_7   : constant Uint := Uint (Uint_Direct_Bias + 7);

   Uint_8   : constant Uint := Uint (Uint_Direct_Bias + 8);

   Uint_9   : constant Uint := Uint (Uint_Direct_Bias + 9);

   Uint_10  : constant Uint := Uint (Uint_Direct_Bias + 10);

   Uint_11  : constant Uint := Uint (Uint_Direct_Bias + 11);

   Uint_12  : constant Uint := Uint (Uint_Direct_Bias + 12);

   Uint_13  : constant Uint := Uint (Uint_Direct_Bias + 13);

   Uint_14  : constant Uint := Uint (Uint_Direct_Bias + 14);

   Uint_15  : constant Uint := Uint (Uint_Direct_Bias + 15);

   Uint_16  : constant Uint := Uint (Uint_Direct_Bias + 16);

   Uint_24  : constant Uint := Uint (Uint_Direct_Bias + 24);

   Uint_32  : constant Uint := Uint (Uint_Direct_Bias + 32);

   Uint_63  : constant Uint := Uint (Uint_Direct_Bias + 63);

   Uint_64  : constant Uint := Uint (Uint_Direct_Bias + 64);

   Uint_80  : constant Uint := Uint (Uint_Direct_Bias + 80);

   Uint_128 : constant Uint := Uint (Uint_Direct_Bias + 128);

   Uint_Minus_1   : constant Uint := Uint (Uint_Direct_Bias - 1);

   Uint_Minus_2   : constant Uint := Uint (Uint_Direct_Bias - 2);

   Uint_Minus_3   : constant Uint := Uint (Uint_Direct_Bias - 3);

   Uint_Minus_4   : constant Uint := Uint (Uint_Direct_Bias - 4);

   Uint_Minus_5   : constant Uint := Uint (Uint_Direct_Bias - 5);

   Uint_Minus_6   : constant Uint := Uint (Uint_Direct_Bias - 6);

   Uint_Minus_7   : constant Uint := Uint (Uint_Direct_Bias - 7);

   Uint_Minus_8   : constant Uint := Uint (Uint_Direct_Bias - 8);

   Uint_Minus_9   : constant Uint := Uint (Uint_Direct_Bias - 9);

   Uint_Minus_12  : constant Uint := Uint (Uint_Direct_Bias - 12);

   Uint_Minus_36  : constant Uint := Uint (Uint_Direct_Bias - 36);

   Uint_Minus_63  : constant Uint := Uint (Uint_Direct_Bias - 63);

   Uint_Minus_80  : constant Uint := Uint (Uint_Direct_Bias - 80);

   Uint_Minus_128 : constant Uint := Uint (Uint_Direct_Bias - 128);

   Uint_Max_Simple_Mul : constant := Uint_Direct_Bias + 2 ** 15;

   --  If two values are directly represented and less than or equal to this

   --  value, then we know the product fits in a 32-bit integer. This allows

   --  UI_Mul to efficiently compute the product in this case.

   type Save_Mark is record

      Save_Uint   : Uint;

      Save_Udigit : Int;

   end record;

   --  Values outside the range that is represented directly are stored using

   --  two tables. The secondary table Udigits contains sequences of Int values

   --  consisting of the digits of the number in a radix Base system. The

   --  digits are stored from most significant to least significant with the

   --  first digit only carrying the sign.

   --  There is one entry in the primary Uints table for each distinct Uint

   --  value. This table entry contains the length (number of digits) and

   --  a starting offset of the value in the Udigits table.

   Uint_First_Entry : constant Uint := Uint (Uint_Table_Start);

   --  Some subprograms defined in this package manipulate the Udigits table

   --  directly, while for others it is more convenient to work with locally

   --  defined arrays of the digits of the Universal Integers. The type

   --  UI_Vector is defined for this purpose and some internal subprograms

   --  used for converting from one to the other are defined.

   type UI_Vector is array (Pos range <>) of Int;

   --  Vector containing the integer values of a Uint value

   --  Note: An earlier version of this package used pointers of arrays

   --  of Ints (dynamically allocated) for the Uint type. The change

   --  leads to a few less natural idioms used throughout this code, but

   --  eliminates all uses of the heap except for the table package itself.

   --  For example, Uint parameters are often converted to UI_Vectors for

   --  internal manipulation. This is done by creating the local UI_Vector

   --  using the function N_Digits on the Uint to find the size needed for

   --  the vector, and then calling Init_Operand to copy the values out

   --  of the table into the vector.

   type Uint_Entry is record

      Length : Pos;

      --  Length of entry in Udigits table in digits (i.e. in words)

      Loc : Int;

      --  Starting location in Udigits table of this Uint value

   end record;

   package Uints is new Table.Table (

     Table_Component_Type => Uint_Entry,

     Table_Index_Type     => Uint'Base,

     Table_Low_Bound      => Uint_First_Entry,

     Table_Initial        => Alloc.Uints_Initial,

     Table_Increment      => Alloc.Uints_Increment,

     Table_Name           => "Uints");

   package Udigits is new Table.Table (

     Table_Component_Type => Int,

     Table_Index_Type     => Int,

     Table_Low_Bound      => 0,

     Table_Initial        => Alloc.Udigits_Initial,

     Table_Increment      => Alloc.Udigits_Increment,

     Table_Name           => "Udigits");

   --  Note: the reason these tables are defined here in the private part of

   --  the spec, rather than in the body, is that they are referenced directly

   --  by gigi.

end Uintp;