------------------------------------------------------------------------------ -- -- -- GNAT RUN-TIME COMPONENTS -- -- -- -- S Y S T E M . I M G _ D E C -- -- -- -- B o d y -- -- -- -- Copyright (C) 1992-2009, 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 -- -- . -- -- -- -- 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 -- ------------------- procedure Image_Decimal (V : Integer; S : in out String; P : out Natural; Scale : Integer) is pragma Assert (S'First = 1); begin -- Add space at start for non-negative numbers if V >= 0 then S (1) := ' '; P := 1; else P := 0; end if; Set_Image_Decimal (V, S, P, Scale, 1, Integer'Max (1, Scale), 0); 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 (Digs'First) = '-'); -- Set True if input is negative Zero : Boolean := (Digs (Digs'First + 1) = '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 : Integer); -- 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. The call to Round has no effect -- if N is outside the range FD .. LD. 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 ----------- -- Round -- ----------- procedure Round (N : Integer) is D : Character; begin -- Nothing to do if rounding past the last digit we have 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 (Digs'First + 1) >= '5' then Digs (Digs'First) := '1'; else Digs (Digs'First) := '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 (Digs'First) := '1'; FD := 1; ND := ND + 1; Digits_Before_Point := Digits_Before_Point + 1; end if; end if; end Round; --------- -- Set -- --------- procedure Set (C : Character) is begin P := P + 1; S (P) := C; end Set; ------------------------- -- Set_Blanks_And_Sign -- ------------------------- 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; ---------------- -- Set_Digits -- ---------------- procedure Set_Digits (S, E : Natural) is begin for J in S .. E loop Set (Digs (J)); end loop; end Set_Digits; ---------------- -- Set_Zeroes -- ---------------- 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 (Digits_After_Point + 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. Expon := (if Zero then 0 else Digits_Before_Point - 1); 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 ('.'); declare DA : Natural := Digits_After_Point; -- Digits remaining to output after point LZ : constant Integer := Integer'Max (0, Integer'Min (DA, -Digits_Before_Point)); -- Number of leading zeroes after point begin Set_Zeroes (LZ); DA := DA - LZ; if DA < ND then Set_Digits (FD, FD + DA - 1); else Set_Digits (FD, LD); Set_Zeroes (DA - ND); end if; end; -- At least one digit before point in input else -- Less digits in input than are needed before point -- Input: 1PP Output: 100.000 if ND < Digits_Before_Point then -- Special case, if the input is the single digit 0, then we -- do not want 000.000, but instead 0.000. if ND = 1 and then Digs (FD) = '0' then Set_Blanks_And_Sign (Fore - 1); Set ('0'); -- Normal case where we need to output scaling zeroes else Set_Blanks_And_Sign (Fore - Digits_Before_Point); Set_Digits (FD, LD); Set_Zeroes (Digits_Before_Point - ND); end if; -- Set period and zeroes after the period Set ('.'); Set_Zeroes (Digits_After_Point); -- Input has full amount of digits before decimal point else Set_Blanks_And_Sign (Fore - Digits_Before_Point); 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 : in out String; P : in out Natural; Scale : Integer; Fore : Natural; Aft : Natural; Exp : Natural) is Digs : String := Integer'Image (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;