gtpg2m09 | General Macros |
Registers usage is an important part of programming with macros. In the TPF system certain registers have specific uses:
These registers should not be used by application programs. Also various registers are guaranteed to remain the same across macro calls unless noted otherwise. These are R0 - R9.
In general, there are two types of macros:
Generally, an executable instruction is generated.
TPF system programs utilize a large set of macro instructions to generate linkage(s) or to simply generate inline code. Many of these macros are restricted to system programs because the macros are subject to change in future releases and represent an unprotected interface. A macro with an unprotected interface is called a restricted use macro. Because some TPF system programs run in the application execution environment, some of the restricted use macros also generate SVC linkages.