Routing mechanism

The routing mechanism invokes the appropriate error processor depending on the error code provided by the node abnormal condition program.

Groups of one or more error codes are defined in the DFHSNEP macro. Each group is associated with an index (in the range X'01' through X'FF') and an error processor. A translate table is generated and the group index is placed at the appropriate offset for each error code. Error codes not defined in groups have a zero value in the table. An error processor vector table (EPVT) contains the addresses of the error group processors, positioned according to their indexes. The vector table extends up to the maximum index defined; undefined intermediate values are represented by zero addresses.

The error code is translated to obtain the error group index. A zero value causes the node error program to take no further action; otherwise the index is used to obtain the address of the appropriate error processor from the EPVT. A zero address causes the node error program to take no further action; otherwise a call is made to the error processor. This is entered with direct addressability to the NET and CSVT areas. When the error processor has been executed, the node error program returns control to the node abnormal condition program.