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perlebcdic - Considerations for running Perl on EBCDIC platforms
An exploration of some of the issues facing Perl programmers
on EBCDIC based computers. We do not cover localization,
internationalization, or multi byte character set issues other
than some discussion of UTF-8 and UTF-EBCDIC.
Portions that are still incomplete are marked with XXX.
The American Standard Code for Information Interchange is a set of
integers running from 0 to 127 (decimal) that imply character
interpretation by the display and other system(s) of computers.
The range 0..127 can be covered by setting the bits in a 7-bit binary
digit, hence the set is sometimes referred to as a "7-bit ASCII".
ASCII was described by the American National Standards Institute
document ANSI X3.4-1986. It was also described by ISO 646:1991
(with localization for currency symbols). The full ASCII set is
given in the table below as the first 128 elements. Languages that
can be written adequately with the characters in ASCII include
English, Hawaiian, Indonesian, Swahili and some Native American
languages.
There are many character sets that extend the range of integers
from 0..2**7-1 up to 2**8-1, or 8 bit bytes (octets if you prefer).
One common one is the ISO 8859-1 character set.
The ISO 8859-$n are a collection of character code sets from the
International Organization for Standardization (ISO) each of which
adds characters to the ASCII set that are typically found in European
languages many of which are based on the Roman, or Latin, alphabet.
A particular 8-bit extension to ASCII that includes grave and acute
accented Latin characters. Languages that can employ ISO 8859-1
include all the languages covered by ASCII as well as Afrikaans,
Albanian, Basque, Catalan, Danish, Faroese, Finnish, Norwegian,
Portuguese, Spanish, and Swedish. Dutch is covered albeit without
the ij ligature. French is covered too but without the oe ligature.
German can use ISO 8859-1 but must do so without German-style
quotation marks. This set is based on Western European extensions
to ASCII and is commonly encountered in world wide web work.
In IBM character code set identification terminology ISO 8859-1 is
also known as CCSID 819 (or sometimes 0819 or even 00819).
The Extended Binary Coded Decimal Interchange Code refers to a
large collection of slightly different single and multi byte
coded character sets that are different from ASCII or ISO 8859-1
and typically run on host computers. The EBCDIC encodings derive
from 8 bit byte extensions of Hollerith punched card encodings.
The layout on the cards was such that high bits were set for the
upper and lower case alphabet characters [a-z] and [A-Z], but there
were gaps within each latin alphabet range.
Some IBM EBCDIC character sets may be known by character code set
identification numbers (CCSID numbers) or code page numbers. Leading
zero digits in CCSID numbers within this document are insignificant.
E.g. CCSID 0037 may be referred to as 37 in places.
Among IBM EBCDIC character code sets there are 13 characters that
are often mapped to different integer values. Those characters
are known as the 13 "variant" characters and are:
\ [ ] { } ^ ~ !
Character code set ID 0037 is a mapping of the ASCII plus Latin-1
characters (i.e. ISO 8859-1) to an EBCDIC set. 0037 is used
in North American English locales on the OS/400 operating system
that runs on AS/400 computers. CCSID 37 differs from ISO 8859-1
in 237 places, in other words they agree on only 19 code point values.
Character code set ID 1047 is also a mapping of the ASCII plus
Latin-1 characters (i.e. ISO 8859-1) to an EBCDIC set. 1047 is
used under Unix System Services for OS/390 or z/OS, and OpenEdition
for VM/ESA. CCSID 1047 differs from CCSID 0037 in eight places.
The EBCDIC code page in use on Siemens' BS2000 system is distinct from
1047 and 0037. It is identified below as the POSIX-BC set.
In Unicode terminology a code point is the number assigned to a
character: for example, in EBCDIC the character "A" is usually assigned
the number 193. In Unicode the character "A" is assigned the number 65.
This causes a problem with the semantics of the pack/unpack "U", which
are supposed to pack Unicode code points to characters and back to numbers.
The problem is: which code points to use for code points less than 256?
(for 256 and over there's no problem: Unicode code points are used)
In EBCDIC, for the low 256 the EBCDIC code points are used. This
means that the equivalences
pack("U", ord($character)) eq $character
unpack("U", $character) == ord $character
will hold. (If Unicode code points were applied consistently over
all the possible code points, pack("U",ord("A")) would in EBCDIC
equal A with acute or chr(101), and unpack("U", "A") would equal
65, or non-breaking space, not 193, or ord "A".)
-
Many of the remaining seem to be related to case-insensitive matching:
for example, /[\x{131}]/ (LATIN SMALL LETTER DOTLESS I) does
not match "I" case-insensitively, as it should under Unicode.
(The match succeeds in ASCII-derived platforms.)
-
The extensions Unicode::Collate and Unicode::Normalized are not
supported under EBCDIC, likewise for the encoding pragma.
UTF is a Unicode Transformation Format. UTF-8 is a Unicode conforming
representation of the Unicode standard that looks very much like ASCII.
UTF-EBCDIC is an attempt to represent Unicode characters in an EBCDIC
transparent manner.
Starting from Perl 5.8 you can use the standard new module Encode
to translate from EBCDIC to Latin-1 code points
use Encode 'from_to';
my %ebcdic = ( 176 => 'cp37', 95 => 'cp1047', 106 => 'posix-bc' );
from_to($a, $ebcdic{ord '^'}, 'latin1');
and from Latin-1 code points to EBCDIC code points
use Encode 'from_to';
my %ebcdic = ( 176 => 'cp37', 95 => 'cp1047', 106 => 'posix-bc' );
from_to($a, 'latin1', $ebcdic{ord '^'});
For doing I/O it is suggested that you use the autotranslating features
of PerlIO, see the perluniintro manpage.
Since version 5.8 Perl uses the new PerlIO I/O library. This enables
you to use different encodings per IO channel. For example you may use
use Encode;
open($f, ">:encoding(ascii)", "test.ascii");
print $f "Hello World!\n";
open($f, ">:encoding(cp37)", "test.ebcdic");
print $f "Hello World!\n";
open($f, ">:encoding(latin1)", "test.latin1");
print $f "Hello World!\n";
open($f, ">:encoding(utf8)", "test.utf8");
print $f "Hello World!\n";
to get two files containing "Hello World!\n" in ASCII, CP 37 EBCDIC,
ISO 8859-1 (Latin-1) (in this example identical to ASCII) respective
UTF-EBCDIC (in this example identical to normal EBCDIC). See the
documentation of Encode::PerlIO for details.
As the PerlIO layer uses raw IO (bytes) internally, all this totally
ignores things like the type of your filesystem (ASCII or EBCDIC).
The following tables list the ASCII and Latin 1 ordered sets including
the subsets: C0 controls (0..31), ASCII graphics (32..7e), delete (7f),
C1 controls (80..9f), and Latin-1 (a.k.a. ISO 8859-1) (a0..ff). In the
table non-printing control character names as well as the Latin 1
extensions to ASCII have been labelled with character names roughly
corresponding to The Unicode Standard, Version 3.0 albeit with
substitutions such as s/LATIN// and s/VULGAR// in all cases,
s/CAPITAL LETTER// in some cases, and s/SMALL LETTER ([A-Z])/\l$1/
in some other cases (the charnames pragma names unfortunately do
not list explicit names for the C0 or C1 control characters). The
"names" of the C1 control set (128..159 in ISO 8859-1) listed here are
somewhat arbitrary. The differences between the 0037 and 1047 sets are
flagged with ***. The differences between the 1047 and POSIX-BC sets
are flagged with ###. All ord() numbers listed are decimal. If you
would rather see this table listing octal values then run the table
(that is, the pod version of this document since this recipe may not
work with a pod2_other_format translation) through:
- recipe 0
perl -ne 'if(/(.{33})(\d+)\s+(\d+)\s+(\d+)\s+(\d+)/)' \
-e '{printf("%s%-9o%-9o%-9o%o\n",$1,$2,$3,$4,$5)}' perlebcdic.pod
If you want to retain the UTF-x code points then in script form you
might want to write:
- recipe 1
open(FH,"<perlebcdic.pod") or die "Could not open perlebcdic.pod: $!";
while (<FH>) {
if (/(.{33})(\d+)\s+(\d+)\s+(\d+)\s+(\d+)\s+(\d+)\.?(\d*)\s+(\d+)\.?(\d*)/) {
if ($7 ne '' && $9 ne '') {
printf("%s%-9o%-9o%-9o%-9o%-3o.%-5o%-3o.%o\n",$1,$2,$3,$4,$5,$6,$7,$8,$9);
}
elsif ($7 ne '') {
printf("%s%-9o%-9o%-9o%-9o%-3o.%-5o%o\n",$1,$2,$3,$4,$5,$6,$7,$8);
}
else {
printf("%s%-9o%-9o%-9o%-9o%-9o%o\n",$1,$2,$3,$4,$5,$6,$8);
}
}
}
If you would rather see this table listing hexadecimal values then
run the table through:
- recipe 2
perl -ne 'if(/(.{33})(\d+)\s+(\d+)\s+(\d+)\s+(\d+)/)' \
-e '{printf("%s%-9X%-9X%-9X%X\n",$1,$2,$3,$4,$5)}' perlebcdic.pod
Or, in order to retain the UTF-x code points in hexadecimal:
- recipe 3
open(FH,"<perlebcdic.pod") or die "Could not open perlebcdic.pod: $!";
while (<FH>) {
if (/(.{33})(\d+)\s+(\d+)\s+(\d+)\s+(\d+)\s+(\d+)\.?(\d*)\s+(\d+)\.?(\d*)/) {
if ($7 ne '' && $9 ne '') {
printf("%s%-9X%-9X%-9X%-9X%-2X.%-6X%-2X.%X\n",$1,$2,$3,$4,$5,$6,$7,$8,$9);
}
elsif ($7 ne '') {
printf("%s%-9X%-9X%-9X%-9X%-2X.%-6X%X\n",$1,$2,$3,$4,$5,$6,$7,$8);
}
else {
printf("%s%-9X%-9X%-9X%-9X%-9X%X\n",$1,$2,$3,$4,$5,$6,$8);
}
}
}
incomp- incomp-
8859-1 lete lete
chr 0819 0037 1047 POSIX-BC UTF-8 UTF-EBCDIC
------------------------------------------------------------------------------------
<NULL> 0 0 0 0 0 0
<START OF HEADING> 1 1 1 1 1 1
<START OF TEXT> 2 2 2 2 2 2
<END OF TEXT> 3 3 3 3 3 3
<END OF TRANSMISSION> 4 55 55 55 4 55
<ENQUIRY> 5 45 45 45 5 45
<ACKNOWLEDGE> 6 46 46 46 6 46
<BELL> 7 47 47 47 7 47
<BACKSPACE> 8 22 22 22 8 22
<HORIZONTAL TABULATION> 9 5 5 5 9 5
<LINE FEED> 10 37 21 21 10 21 ***
<VERTICAL TABULATION> 11 11 11 11 11 11
<FORM FEED> 12 12 12 12 12 12
<CARRIAGE RETURN> 13 13 13 13 13 13
<SHIFT OUT> 14 14 14 14 14 14
<SHIFT IN> 15 15 15 15 15 15
<DATA LINK ESCAPE> 16 16 16 16 16 16
<DEVICE CONTROL ONE> 17 17 17 17 17 17
<DEVICE CONTROL TWO> 18 18 18 18 18 18
<DEVICE CONTROL THREE> 19 19 19 19 19 19
<DEVICE CONTROL FOUR> 20 60 60 60 20 60
<NEGATIVE ACKNOWLEDGE> 21 61 61 61 21 61
<SYNCHRONOUS IDLE> 22 50 50 50 22 50
<END OF TRANSMISSION BLOCK> 23 38 38 38 23 38
<CANCEL> 24 24 24 24 24 24
<END OF MEDIUM> 25 25 25 25 25 25
<SUBSTITUTE> 26 63 63 63 26 63
<ESCAPE> 27 39 39 39 27 39
<FILE SEPARATOR> 28 28 28 28 28 28
<GROUP SEPARATOR> 29 29 29 29 29 29
<RECORD SEPARATOR> 30 30 30 30 30 30
<UNIT SEPARATOR> 31 31 31 31 31 31
<SPACE> 32 64 64 64 32 64
! 33 90 90 90 33 90
" 34 127 127 127 34 127
# 35 123 123 123 35 123
$ 36 91 91 91 36 91
% 37 108 108 108 37 108
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