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(* Library module defined by the International Standard
Information technology - programming languages
BS ISO/IEC 10514-1:1996E Part 1: Modula-2, Base Language.
Copyright ISO/IEC (International Organization for Standardization
and International Electrotechnical Commission) 1996-2021.
It may be freely copied for the purpose of implementation (see page
707 of the Information technology - Programming languages Part 1:
Modula-2, Base Language. BS ISO/IEC 10514-1:1996). *)
IMPLEMENTATION MODULE LongIO;
(* Input and output of real numbers in decimal text form
over specified channels. The read result is of the
type IOConsts.ReadResults.
*)
FROM TextIO IMPORT WriteChar, ReadChar ;
FROM StringChan IMPORT writeString ;
FROM IOChan IMPORT SetReadResult ;
FROM IOConsts IMPORT ReadResults ;
FROM ConvStringLong IMPORT RealToFixedString, RealToFloatString,
RealToEngString ;
FROM ConvTypes IMPORT ScanClass, ScanState ;
FROM TextIO IMPORT WriteChar, ReadChar ;
FROM DynamicStrings IMPORT String, char, KillString, Length, InitString, ConCatChar, string ;
FROM LongConv IMPORT ScanReal ;
FROM StringChan IMPORT writeString, writeFieldWidth ;
FROM ldtoa IMPORT strtold ;
FROM TextUtil IMPORT SkipSpaces ;
(* The text form of a signed fixed-point real number is
["+" | "-"], decimal digit, {decimal digit},
[".", {decimal digit}]
The text form of a signed floating-point real number is
signed fixed-point real number,
"E", ["+" | "-"], decimal digit, {decimal digit}
*)
PROCEDURE ReadReal (cid: IOChan.ChanId; VAR real: LONGREAL);
(* Skips leading spaces, and removes any remaining characters
from cid that form part of a signed fixed or floating
point number. The value of this number is assigned to real.
The read result is set to the value allRight, outOfRange,
wrongFormat, endOfLine, or endOfInput.
*)
VAR
chClass : ScanClass ;
nextState: ScanState ;
ch : CHAR ;
s : String ;
error : BOOLEAN ;
BEGIN
SkipSpaces (cid) ;
ReadChar(cid, ch) ;
nextState := ScanReal ;
REPEAT
nextState(ch, chClass, nextState) ;
IF chClass=padding
THEN
ReadChar(cid, ch)
END
UNTIL chClass#padding ;
IF chClass=valid
THEN
s := InitString('') ;
WHILE chClass=valid DO
s := ConCatChar(s, ch) ;
ReadChar(cid, ch) ;
nextState(ch, chClass, nextState)
END ;
real := strtold(string(s), error) ;
s := KillString(s) ;
IF error
THEN
SetReadResult(cid, outOfRange)
ELSE
SetReadResult(cid, allRight)
END
ELSE
SetReadResult(cid, wrongFormat)
END
END ReadReal ;
PROCEDURE WriteFloat (cid: IOChan.ChanId; real: LONGREAL;
sigFigs: CARDINAL; width: CARDINAL);
(* Writes the value of real to cid in floating-point text form,
with sigFigs significant figures, in a field of the given
minimum width.
*)
VAR
s: String ;
BEGIN
s := RealToFloatString(real, sigFigs) ;
writeFieldWidth(cid, s, width) ;
s := KillString(s)
END WriteFloat ;
PROCEDURE WriteEng (cid: IOChan.ChanId; real: LONGREAL;
sigFigs: CARDINAL; width: CARDINAL);
(* As for WriteFloat, except that the number is scaled with
one to three digits in the whole number part, and with an
exponent that is a multiple of three.
*)
VAR
s: String ;
BEGIN
s := RealToEngString(real, sigFigs) ;
writeFieldWidth(cid, s, width) ;
s := KillString(s)
END WriteEng ;
PROCEDURE WriteFixed (cid: IOChan.ChanId; real: LONGREAL;
place: INTEGER; width: CARDINAL);
(* Writes the value of real to cid in fixed-point text form,
rounded to the given place relative to the decimal point,
in a field of the given minimum width.
*)
VAR
s: String ;
BEGIN
s := RealToFixedString(real, place) ;
writeFieldWidth(cid, s, width) ;
s := KillString(s)
END WriteFixed ;
PROCEDURE WriteReal (cid: IOChan.ChanId;
real: LONGREAL; width: CARDINAL);
(* Writes the value of real to cid, as WriteFixed if the sign
and magnitude can be shown in the given width, or otherwise
as WriteFloat. The number of places or significant digits
depends on the given width.
*)
VAR
sigFigs: CARDINAL ;
s : String ;
BEGIN
sigFigs := width ;
WHILE sigFigs>1 DO
s := RealToFixedString(real, sigFigs) ;
IF Length(s)<=width
THEN
writeFieldWidth(cid, s, width) ;
s := KillString(s) ;
RETURN
END ;
s := KillString(s) ;
DEC(sigFigs)
END ;
sigFigs := width ;
WHILE sigFigs#0 DO
s := RealToFloatString(real, sigFigs) ;
IF Length(s)<=width
THEN
writeFieldWidth(cid, s, width) ;
s := KillString(s) ;
RETURN
END ;
s := KillString(s) ;
DEC(sigFigs)
END
END WriteReal ;
END LongIO.
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