OS_ReadEscapeState (changes)

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Programmer's OS Reference SWI Manuals Calls

» OS_ReadEscapeStatePart 15 – SWI Calls

OS_ReadEscapeState

(SWI &2C)

Use

The purpose of this call is to check whether an escape condition has occurred

Notes

Once an escape condition has been detected, (either through this or for example, with OS_ReadC), it should be acknowledged with OS_Byte 126 or cleared using OS_Byte 124.

This call is useful if a program is executing in a loop which the user may want to escape from, but isn’t performing any input operations which would let it know about the escape.

Note that this may be called from an interrupt routine. However, OS_Byte 126 may not be, so if an escape is detected under interrupts, the interrupt routine must set a flag which is checked by the foreground task rather than try to acknowledge the escape itself.

See also

• OS_Byte 124
• OS_Byte 126
• OS_ReadC