GeneveOS XOP Definitions

From Ninerpedia
(Redirected from MDOS XOP Definitions)
Jump to navigation Jump to search

GeneveOS makes frequent use of XOPs and offers them for user programs. An XOP (extended operation) is a special command of the TMS processor family which causes a context switch, transferring control to a location that is specified in a table.

Compared to common architecture concepts, the XOP is TI's way of implementing a system call.

The XOP instruction takes two arguments; the first delivers data for the call, the second is a number from 0 to 15 and indicates the XOP number. In GeneveOS, all system calls are XOP 0 with specific arguments:

ARGUM  DATA <number>
       ...
       XOP  @ARGUM,0
       ...

Overview

XOP argument Category
5 Keyboard
6 Video display
7 Memory Management
8 Devices (Files)
9 Utility functions
10 Mathematical functions

Used workspaces

The XOPs use workspaces F0C0 and F0A0.