The collation descriptor exits 1 through 8 (CDX01 through CDX08) are used for encoding and decoding values for the corresponding collation descriptors.
A collation descriptor may be defined for a field with alphanumeric or wide format. Its values are stored in the index, not in the record itself. The number of the collation descriptor exit used to derive the values is associated with the collation descriptor.
A sample collation descriptor exit CDXE2A is provided in the Adabas source dataset. It converts EBCDIC to ASCII for the encoding function and the reverse (ASCII to EBCDIC) for the decoding function.
The Collation Exit implements three function entry points which are called on the following events:
nucleus session start
utility initialization when collation exits have been defined (ADARUN parameters)
update/insert/delete of the parent's value (Nucleus)
Search specifying the collation descriptor with the search value (Nucleus)
compression of a record (ADACMP)
Read Index (L9) by Collation DE, only if the exit supports the DECODE function (Nucleus)
This document covers the following topics:
The collation descriptor exit interface is defined in the CDXPARM DSECT in the Adabas source dataset. The interface has three functions:
initialization
encoding
decoding (optional)
R1 points to a list of addresses that point to five storage areas of the caller. The collation descriptor exit must set the five areas as follows:
| CDXSPC | default space character; a maximum of 4 bytes |
| CDXSPCL | fullword containing the size of the space character |
| CDXENC | address of encoding function |
| CDXDEC | address of decoding function If the returned address is zero, decoding is not supported. The collation descriptor cannot then be used for L9 processing. |
| CDXVER | address of zero-byte delimited version string |
R1 points to a list of five fullword-sized parameters:
| CDXIA | address of the input string |
| CDXIL | length of the input string |
| CDXOA | address of the output string |
| CDXOL | size of the output area |
| CDXARL | address of the length of the returned output string |
The collation descriptor exit stores
the output string in the area at the address specified by CDXOA; and
the input string length in the fullword at the address specified by CDXARL.
