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------------------------------------------------------------------------------
-- --
-- GNAT RUN-TIME COMPONENTS --
-- --
-- S Y S T E M . I M G _ D E C --
-- --
-- B o d y --
-- --
-- Copyright (C) 1992-2015, 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 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'Min (DA, -Digits_Before_Point);
-- Number of leading zeroes after point. Note: there used to be
-- a Max of this result with zero, but that's redundant, since
-- we know DA is positive, and because of the test above, we
-- know that -Digits_Before_Point >= 0.
begin
Set_Zeroes (LZ);
DA := DA - LZ;
if DA < ND then
-- Note: it is definitely possible for the above condition
-- to be True, for example:
-- V => 1234, Scale => 5, Fore => 0, After => 1, Exp => 0
-- but in this case DA = 0, ND = 1, FD = 1, FD + DA-1 = 0
-- so the arguments in the call are (1, 0) meaning that no
-- digits are output.
-- No obvious example exists where the following call to
-- Set_Digits actually outputs some digits, but we lack a
-- proof that no such example exists.
-- So it is safer to retain this call, even though as a
-- result it is hard (or perhaps impossible) to create a
-- coverage test for the inlined code of the call.
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;