h6. [[Hourglass]] h6(. » [[Hourglass SWI Calls|SWI Calls]] h6((. » Hourglass_LEDs h2. Hourglass_LEDs h5. (SWI &406C5) |_<^{width:3em}. Entry | | |<^. R0 |<^. EOR mask | |<^. R1 |<^. AND mask | |_<^{width:3em}. Exit || |<^. R0 |<^. Old LED state | |<^. - |<^. All other registers preserved| h4. 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. h4. 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: <pre>new_value = (old_value AND and_mask) EOR eor_mask</pre>