------------------------------------------------------------------------------ -- -- -- GNAT RUN-TIME COMPONENTS -- -- -- -- S Y S T E M . I M G _ D E C -- -- -- -- B o d y -- -- -- -- Copyright (C) 1992-2005 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 2, 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. See the GNU General Public License -- -- for more details. You should have received a copy of the GNU General -- -- Public License distributed with GNAT; see file COPYING. If not, write -- -- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, -- -- Boston, MA 02110-1301, USA. -- -- -- -- As a special exception, if other files instantiate generics from this -- -- unit, or you link this unit with other files to produce an executable, -- -- this unit does not by itself cause the resulting executable to be -- -- covered by the GNU General Public License. This exception does not -- -- however invalidate any other reasons why the executable file might be -- -- covered by the GNU Public License. -- -- -- -- GNAT was originally developed by the GNAT team at New York University. -- -- Extensive contributions were provided by Ada Core Technologies Inc. -- -- -- ------------------------------------------------------------------------------ with System.Img_Int; use System.Img_Int; package body System.Img_Dec is ------------------- -- Image_Decimal -- ------------------- function Image_Decimal (V : Integer; Scale : Integer) return String is P : Natural := 0; S : String (1 .. 64); begin Set_Image_Decimal (V, S, P, Scale, 1, Integer'Max (1, Scale), 0); -- Mess around to make sure we have the objectionable space at the -- start for positive numbers in accordance with the annoying rules! if S (1) /= ' ' and then S (1) /= '-' then S (2 .. P + 1) := S (1 .. P); S (1) := ' '; return S (1 .. P + 1); else return S (1 .. P); end if; end Image_Decimal; ------------------------ -- Set_Decimal_Digits -- ------------------------ procedure Set_Decimal_Digits (Digs : in out String; NDigs : Natural; S : out String; P : in out Natural; Scale : Integer; Fore : Natural; Aft : Natural; Exp : Natural) is Minus : constant Boolean := (Digs (1) = '-'); -- Set True if input is negative Zero : Boolean := (Digs (2) = '0'); -- Set True if input is exactly zero (only case when a leading zero -- is permitted in the input string given to this procedure). This -- flag can get set later if rounding causes the value to become zero. FD : Natural := 2; -- First digit position of digits remaining to be processed LD : Natural := NDigs; -- Last digit position of digits remaining to be processed ND : Natural := NDigs - 1; -- Number of digits remaining to be processed (LD - FD + 1) Digits_Before_Point : Integer := ND - Scale; -- Number of digits before decimal point in the input value. This -- value can be negative if the input value is less than 0.1, so -- it is an indication of the current exponent. Digits_Before_Point -- is adjusted if the rounding step generates an extra digit. Digits_After_Point : constant Natural := Integer'Max (1, Aft); -- Digit positions after decimal point in result string Expon : Integer; -- Integer value of exponent procedure Round (N : Natural); -- Round the number in Digs. N is the position of the last digit to be -- retained in the rounded position (rounding is based on Digs (N + 1) -- FD, LD, ND are reset as necessary if required. Note that if the -- result value rounds up (e.g. 9.99 => 10.0), an extra digit can be -- placed in the sign position as a result of the rounding, this is -- the case in which FD is adjusted. procedure Set (C : Character); pragma Inline (Set); -- Sets character C in output buffer procedure Set_Blanks_And_Sign (N : Integer); -- Sets leading blanks and minus sign if needed. N is the number of -- positions to be filled (a minus sign is output even if N is zero -- or negative, For a positive value, if N is non-positive, then -- a leading blank is filled. procedure Set_Digits (S, E : Natural); pragma Inline (Set_Digits); -- Set digits S through E from Digs, no effect if S > E procedure Set_Zeroes (N : Integer); pragma Inline (Set_Zeroes); -- Set N zeroes, no effect if N is negative procedure Round (N : Natural) is D : Character; begin -- Nothing to do if rounding at or past last digit if N >= LD then return; -- Cases of rounding before the initial digit elsif N < FD then -- The result is zero, unless we are rounding just before -- the first digit, and the first digit is five or more. if N = 1 and then Digs (2) >= '5' then Digs (1) := '1'; else Digs (1) := '0'; Zero := True; end if; Digits_Before_Point := Digits_Before_Point + 1; FD := 1; LD := 1; ND := 1; -- Normal case of rounding an existing digit else LD := N; ND := LD - 1; if Digs (N + 1) >= '5' then for J in reverse 2 .. N loop D := Character'Succ (Digs (J)); if D <= '9' then Digs (J) := D; return; else Digs (J) := '0'; end if; end loop; -- Here the rounding overflows into the sign position. That's -- OK, because we already captured the value of the sign and -- we are in any case destroying the value in the Digs buffer Digs (1) := '1'; FD := 1; ND := ND + 1; Digits_Before_Point := Digits_Before_Point + 1; end if; end if; end Round; procedure Set (C : Character) is begin P := P + 1; S (P) := C; end Set; procedure Set_Blanks_And_Sign (N : Integer) is W : Integer := N; begin if Minus then W := W - 1; for J in 1 .. W loop Set (' '); end loop; Set ('-'); else for J in 1 .. W loop Set (' '); end loop; end if; end Set_Blanks_And_Sign; procedure Set_Digits (S, E : Natural) is begin for J in S .. E loop Set (Digs (J)); end loop; end Set_Digits; procedure Set_Zeroes (N : Integer) is begin for J in 1 .. N loop Set ('0'); end loop; end Set_Zeroes; -- Start of processing for Set_Decimal_Digits begin -- Case of exponent given if Exp > 0 then Set_Blanks_And_Sign (Fore - 1); Round (Aft + 2); Set (Digs (FD)); FD := FD + 1; ND := ND - 1; Set ('.'); if ND >= Digits_After_Point then Set_Digits (FD, FD + Digits_After_Point - 1); else Set_Digits (FD, LD); Set_Zeroes (Digits_After_Point - ND); end if; -- Calculate exponent. The number of digits before the decimal point -- in the input is Digits_Before_Point, and the number of digits -- before the decimal point in the output is 1, so we can get the -- exponent as the difference between these two values. The one -- exception is for the value zero, which by convention has an -- exponent of +0. if Zero then Expon := 0; else Expon := Digits_Before_Point - 1; end if; Set ('E'); ND := 0; if Expon >= 0 then Set ('+'); Set_Image_Integer (Expon, Digs, ND); else Set ('-'); Set_Image_Integer (-Expon, Digs, ND); end if; Set_Zeroes (Exp - ND - 1); Set_Digits (1, ND); return; -- Case of no exponent given. To make these cases clear, we use -- examples. For all the examples, we assume Fore = 2, Aft = 3. -- A P in the example input string is an implied zero position, -- not included in the input string. else -- Round at correct position -- Input: 4PP => unchanged -- Input: 400.03 => unchanged -- Input 3.4567 => 3.457 -- Input: 9.9999 => 10.000 -- Input: 0.PPP5 => 0.001 -- Input: 0.PPP4 => 0 -- Input: 0.00003 => 0 Round (LD - (Scale - Digits_After_Point)); -- No digits before point in input -- Input: .123 Output: 0.123 -- Input: .PP3 Output: 0.003 if Digits_Before_Point <= 0 then Set_Blanks_And_Sign (Fore - 1); Set ('0'); Set ('.'); Set_Zeroes (Digits_After_Point - ND); Set_Digits (FD, LD); -- At least one digit before point in input else Set_Blanks_And_Sign (Fore - Digits_Before_Point); -- Less digits in input than are needed before point -- Input: 1PP Output: 100.000 if ND < Digits_Before_Point then Set_Digits (FD, LD); Set_Zeroes (Digits_Before_Point - ND); Set ('.'); Set_Zeroes (Digits_After_Point); -- Input has full amount of digits before decimal point else Set_Digits (FD, FD + Digits_Before_Point - 1); Set ('.'); Set_Digits (FD + Digits_Before_Point, LD); Set_Zeroes (Digits_After_Point - (ND - Digits_Before_Point)); end if; end if; end if; end Set_Decimal_Digits; ----------------------- -- Set_Image_Decimal -- ----------------------- procedure Set_Image_Decimal (V : Integer; S : out String; P : in out Natural; Scale : Integer; Fore : Natural; Aft : Natural; Exp : Natural) is Digs : String := Image_Integer (V); -- Sign and digits of decimal value begin Set_Decimal_Digits (Digs, Digs'Length, S, P, Scale, Fore, Aft, Exp); end Set_Image_Decimal; end System.Img_Dec;