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------------------------------------------------------------------------------
-- --
-- GNAT RUNTIME COMPONENTS --
-- --
-- S Y S T E M . I M G _ D E C --
-- --
-- B o d y --
-- --
-- $Revision: 1.15 $ --
-- --
-- Copyright (C) 1992-1997 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, 59 Temple Place - Suite 330, Boston, --
-- MA 02111-1307, 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. --
-- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
-- --
------------------------------------------------------------------------------
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_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;
------------------------
-- 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;
end System.Img_Dec;
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