Hourglass_LEDs
Hourglass
» SWI Calls
» Hourglass_LEDs
Hourglass_LEDs
(SWI &406C5)
| Entry | |
|---|---|
| R0 | EOR mask |
| R1 | AND mask |
| Exit | |
|---|---|
| R0 | Old LED state |
| - | All other registers preserved |
Use
The purpose of this call is to control the display of the hourglass ‘LEDs’. These LEDs can be used to convey additional state to the user, perhaps as a debugging aid.
Notes
The current version of the hourglass supports two LEDs (controlled by bits 0 and 1 of the LED mask), which both start in the off state when the hourglass is enabled.
The LED state is updated using the standard pattern:
new_value = (old_value AND and_mask) EOR eor_mask
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