Two conditional assembly instructions, SETAF and SETCF, let you call routines written in a programming language that conforms to standard OS Linkage conventions. The assembler calls the external function load module and passes the address of an external function parameter list in Register 1. Each differently named external function called in the same assembly is provided with a separate parameter list.

The SETAF instruction calls an external function module, and passes to the module any number of parameters containing arithmetic values. The SET symbol in the instruction is assigned the fullword value returned by the external function module.

The SETCF instruction calls an external function module, and passes to the module any number of parameters containing character values. The SET symbol in the instruction is assigned the character string value returned by the external function module. The character string value can be up to 1024 characters long.

This chapter describes the external function processing requirements, the linkage conventions for generating an external function module, and the contents of the parameter list that the assembler passes to the module