Portable_Speed2 9
Programmer's Reference Manuals
» Part 15 – SWI Calls
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» Portable_Speed2
» Portable_Speed2 9
Portable_Speed2 9
(SWI &42FCE)
| Entry | |
|---|---|
| R0 | 9 (Reason code) |
| Exit | |
|---|---|
| R0 | Preserved |
| R1 | Currently configured ‘slow’ speed, as index |
| R2 | Currently configured ‘fast’ speed, as index |
Use
The purpose of this call is to read the currently configured ‘slow’ and ‘fast’ speeds. These are the speeds that Portable_Speed will use when asked to switch the CPU to either the ‘slow’ or ‘fast’ speed.
Notes
Portable_Speed2 3 provides similar functionality to this call, but the speeds will be expressed as MHz values instead of speed indices.
Due to hardware restrictions or for performance reasons, most systems will only support a limited number of CPU clock rates. Portable_Speed2 4, Portable_Speed2 5, and Portable_Speed2 6 allow the user to enumerate the list of available clock rates. Index 0 is always the slowest available speed, and (return value of Portable_Speed2 4)-1 is always the highest available speed.
To set the CPU speed, see Portable_Speed2 2 or Portable_Speed2 8 (to set the desired ‘slow’ and ‘fast’ speeds), and Portable_Speed (to switch between the configured ‘slow’ and ‘fast’ speeds).