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1.1 Types of Procedure Calls

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Procedure calls can be grouped into three categories, depending on the location of the callee. The possibilities are:

  1. Procedures residing in the same load module (intra-module call)

  2. Procedures residing in other load modules (inter-module call)

  3. Operating system or subsystem procedures

NOTE: Throughout the rest of this document, local is used as a synonym for intra-module and external is used interchangeably with inter-module or OS/Subsystem.

In order to simplify code generation, all three types of calls are mapped into the local (intra-module) case, thus requiring the compiler to recognize only a single type of call. This is accomplished through the use of two types of stubs – calling stubs and called stubs – which establish the external branching and linking necessary for inter-module calls. Inter-module calls and specific stub usages are discussed in more detail in Chapter 5, Inter-Module Procedure Calls.



Chapter 1 Overview

1.2 Interfaces