Error Checking

The status parameter of HPSORTINIT and HPMERGEINIT is a 32-bit integer variable that returns the status of each sort or merge intrinsic call. If no errors or warnings are encountered, status returns 32 bits of zero. If errors are encountered, status is interpreted as two 16-bit fields. Bits (0:16), the leftmost halfword, is status.info. A negative value here indicates an error condition. Bits (16:16) are status.subsys. A number here is coded to indicate the subsystem where the error occurred. A value of 195 indicates SORT/XL. A value of 196 identifies MERGE/XL. Although status is an optional parameter, it is good programming practice to specify it. If it is not specified and an error occurs, the calling process will abort.

You use HPSORTERRORMESS and HPMERGEERRORMESS to display a descriptive message to the user if errors occur during a sort or merge. The HPSORTERRORMESS and HPMERGEERRORMESS status parameter accepts the error number returned from the HPSORTINIT and HPMERGEINIT status parameter. Other error message parameters return the text message associated with that error number, and the length of the message.

The syntax of HPSORTERRORMESS and HPMERGEERRORMESS is:

   HPSORTERRORMESS (status, message, length);
 
   HPMERGEERRORMESS (status, message, length);

The HPSORTERRORMESS and HPMERGEERRORMESS expect to interpret errors, not successes. The merge and sort status parameters return zero if no errors occurred. If you do not check this value before calling HPSORTERRORMESS or HPMERGEERRORMESS as the example below does, the result could be confusing. Passing zero to the error message intrinsics status parameter, causes the message parameter to return the message: "HPERRORMSG failed inside HPSORTERRORMESS" or "HPERRORMSG failed inside HPMERGEERRORMESS".

If the HPSORTERRORMESS or HPMERGEERRORMESS intrinsic call fails, status returns the error number associated with that failure.

The error numbers and messages for sort and merge intrinsics are listed in Appendixes A and B.

For more information about calculating status.info and status.subsys, refer to the MPE XL Intrinsics Reference Manual.

The following is part of the core sort example, and shows how HPSORTERRORMESS is used.