Routines
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84B9: Debounce keyboard
Used by the routines at PercentageAscii and SaveGame.
Waits until the current key has been released.
DebounceAnyKey 84B9 XOR A Read from the keyboard port.
84BA IN A,($FE)
84BC AND %00011111 Keep bits 0-4, one for each key in the half-row. XOR A then IN A,(FE) reads every half-row at once, and a pressed key reads as a reset bit.
84BE CP $1F Loop back to DebounceAnyKey if a key is being pressed.
84C0 JR NZ,DebounceAnyKey
Normal_AnyKey 84C2 XOR A Read from the keyboard port.
84C3 IN A,($FE)
84C5 AND %00011111 Keep bits 0-4, one for each key in the half-row. XOR A then IN A,(FE) reads every half-row at once, and a pressed key reads as a reset bit.
84C7 CP $1F Loop back to Normal_AnyKey until any key has been pressed.
84C9 JR Z,Normal_AnyKey
84CB RET Return.
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