NAME

Convert::IBM390 -- functions for manipulating mainframe data

SYNOPSIS

  use Convert::IBM390 qw(...those desired... or :all);

  $eb  = asc2eb($string);
  $asc = eb2asc($string);
  $asc = eb2ascp($string);

  $num = pdi($packed [,ndec]);
  $packed = pdo($num [,outbytes [,ndec]]);

  @fields = unpackeb($template, $record);
  @lines = hexdump($string [,startaddr [,charset]]);

DESCRIPTION

Convert::IBM390 supplies various functions that you may find useful when messing with IBM System/3[679]0 data. No functions are exported automatically; you must ask for the ones you want. "use ... qw(:all)" exports all functions.

By the way, this module is called "IBM390" because it will deal with data from any mainframe operating system. Nothing about it is specific to MVS, VM, VSE, or OS/390.

FUNCTIONS

asc2eb STRING

Converts a character string from ASCII to EBCDIC. The translation table is taken from the LE/370 code set converter EDCUI1EY; it translates ISO8859-1 to IBM-1047. For more information, see "IBM C/C++ for MVS/ESA V3R2 Programming Guide", SC09-2164.

eb2asc STRING

Converts a character string from EBCDIC to ASCII. EBCDIC character strings ordinarily come from files transferred from mainframes via the binary option of FTP. The translation table is taken from the LE/370 code set converter EDCUEYI1; it translates IBM-1047 to ISO8859-1 (see above).

eb2ascp STRING

Like eb2asc, but the output will contain only printable ASCII characters.

pdi PACKED [NDEC]

Packed Decimal In: converts an EBCDIC packed number to a Perl number. The first argument is the packed field; the second (optional) is a number of decimal places to assume (default = 0). For instance:

  pdi(x'00123C')    => 123
  pdi(x'01235D', 2) => -12.35
  pdi(x'0C', 1)     => 0

If the first argument is not a valid packed field, pdi will return the undefined value. By default, no warning message will be issued in this case, but if you set the variable $Convert::IBM390::warninv to 1 (or any other true value), a warning will be issued.

pdo NUMBER [OUTBYTES [NDEC]]

Packed Decimal Out: converts a Perl number to a packed field. The first argument is a Perl number; the second is the number of bytes to put in the output field (default = 8); the third is the number of decimal places to round to (default = 0). For instance:

  pdo(-234)          => x'000000000000234D'
  pdo(-234, 5)       => x'000000234D'
  pdo(356.777, 5, 2) => x'000035678C'
  pdo(0, 4)          => x'0000000C'

If the first argument is not a valid Perl number, pdo will return the undefined value. By default, no warning message will be issued in this case, but if you set the variable $Convert::IBM390::warninv to 1 (or any other true value), a warning will be issued.

unpackeb TEMPLATE RECORD

This function is much like Perl's built-in "unpack". It takes an EBCDIC record (structure) and unpacks it into a list of values. If called in scalar context, it will return only the first unpacked value. The TEMPLATE is patterned after Perl's unpack template but allows fewer options. The following characters are allowed in the template:

  c or C (1)   Character string without translation
  e or E (1)   EBCDIC string to be translated into ASCII
  i      (2)   Signed integer (S/390 fullword)
  I      (2)   Unsigned integer (4 bytes)
  p      (1)   Packed-decimal field
  s      (2)   Signed short integer (S/390 halfword)
  S      (2)   Unsigned short integer (2 bytes) 
  v      (2)   EBCDIC varchar string
  x      (1)   Ignore these bytes

 (1) May be followed by a number giving the length of the field.
 (2) May be followed by a number giving the repeat count.

Each character may be followed by a number giving either the length of the field or a repeat count, as shown above, or by '*', which means to use however many items are left in the string. The number must immediately follow the character, but whitespace may appear between field specifiers.

The length for packed (p) fields may include a number of decimal places, which is added after the byte count and a '.'. For instance, "p3.2" indicates a 3-byte (5-digit) packed field with 2 implied decimal places; if this field contains x'02468C', the result will be 24.68. The number of implied decimals may be greater than the number of digits; e.g., unpacking the above field with "p3.6" would yield 0.002468. If the field is not a valid packed field, the resulting element of the list will be undefined.

Varchar (v) fields are assumed to consist of a signed halfword (16-bit) integer followed by EBCDIC characters. If the number appearing in the initial halfword is N, the following N bytes are translated from EBCDIC to ASCII and returned as one string. This format is used, for instance, by DB2/MVS. A repeat count may be specified; e.g., "v2" does not mean a length of 2 bytes, but that there are two such fields in succession. If the length is found to be less than 0, the resulting element of the list will be undefined.

The EBCDIC-to-ASCII translation used by [Eev] is the same as in eb2asc().

The maximum length of a packed field is 16 bytes. All other fields may have a maximum specifier (length or repeat count) of 32767. These maxima are enforced.

In most cases, you should use 'i' rather than 'I' when unpacking fullword integers. Unsigned long integers are not handled cleanly by all systems.

hexdump STRING [STARTADDR [CHARSET]]

Generate a hexadecimal dump of STRING. The dump is similar to a SYSABEND dump in MVS: each line contains an address, 32 bytes of hexadecimal data, and the same data in printable form. This function returns a list of lines, each of which is terminated with a newline. This allows them to be printed immediately; for instance, you can say "print hexdump($crud);".

The second and third arguments are optional. The second specifies a starting address for the dump (default = 0); the third specifies the character set to use for the printable data at the end of each line ("ascii" or "ebcdic", in upper or lower case; default = ascii).

AUTHOR

Convert::IBM390 was written by Geoffrey Rommel <grommel@sears.com> in January 1999.