13.7.16. SYS_CLOCK (0x10)

Returns the number of centiseconds since the support code started executing.

Values returned by this SWI can be of limited use for some benchmarking purposes because of communication overhead or other agent-specific factors. For example, with the Multi-ICE debug agent the request is passed back to the host for execution. This can lead to unpredictable delays in transmission and process scheduling.

This function should be used only to calculate time intervals (the length of time some action took) by calculating the difference in the result on two occasions.

Entry

There are no parameters. Register r1 must contain zero.

Return

On exit, r0 contains:

  • the number of centiseconds since some arbitrary start point, if the call is successful

  • –1 if the call is unsuccessful (for example, because of a communications error).

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