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- XDEF Keypad
- XREF __SEG_END_SSTACK,Debounce,KVS,pressed_key,pressed_num,PORT_U,SEQUENCE,PORT_S,await_key_release,keypad_timeout,await_key_press
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- Variables: Section
- Constants: Section
- Code: Section
- Keypad: ;push register and accumulator values for retention
- PSHA
- PSHB
- PSHD
- PSHX
- PSHY
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- ;do not go to the task at the end of the array
- ;when first starting i.e. ckip ArrayEnd for now
- BRA InitSequence
- ArrayEnd: ;check the flag to await or not (await for passwords)
- LDAB await_key_press
- CMPB #$00 ;await is false
- BEQ Return ;don't do anything else (do not await a keypress)
- ;otherwise re-initialze the sequence
- InitSequence:
- LDX #SEQUENCE ;load the sequence into the X register
- ReadKeypress:
- ;check wether or not to await
- LDAA 1,X+ ;load the value at address in reg X to A
- CMPA #$00 ;check the value of A to zero
- BEQ ArrayEnd ;this is the end of the array
-
- ;
- ;
- ;
- ;given in instructions
- STAA PORT_U ;output to port U
- JSR Debounce ;delay 1 ms
- LDAA PORT_U ;read port U back into acc. A
- STAA pressed_key ;save the value of acc. A into memory (the value of the KVS array)
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- ANDA #$0F ;mask the upper nibble
- CMPA #$0F ;check if masked A == #$0F (no key pressed)
- BEQ ReadKeypress ;send the next item in the sequence
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- ;
- ;
- ;
- ;skip the release wait if the variable is set
- LDAA await_key_release
- CMPA #$00
- BEQ InitLookup
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- AwaitRelease: ;a key is pressed
- LDAA PORT_U ;read port U
- ANDA #$0F ;mask the upper nibble
- CMPA #$0F ;check if masked A == #$0F (no key pressed)
- BNE AwaitRelease ;wait for the key to be released
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-
- InitLookup: ;check for a match in the lookup table
- LDY #KVS ;load the initital value of KVS array
- LDAB #$00 ;iteration counter
- Lookup:
- LDAA 1,Y+ ;load a value from the lookup table into A
- CMPA pressed_key ;compare the LUT value to the pressed key
- BEQ Found ;pressed key reached/found within LUT
- INCB ;increment the counter
- BRA Lookup ;check the value at the next index
- Found:
- STAB pressed_num ;the index of the PRESSED value (the numeral of the pressed key) in the KVS/LUT from B -> memory
- ;AwaitPress:
- ; LDAB await_key_press
- ; CMPB #$FF
- ; BEQ InitSequence
-
- Return:
- ;clear the keypad timeout
- ;CLR keypad_timeout
- ;restore registers and accumulators
- PULY
- PULX
- PULD
- PULB
- PULA
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- RTS
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