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39f83b7709
Chris made me aware that ASCII code 0 actually is a valid character (usually entered as Ctrl-Space or Ctrl-@) and that it is actually used (i.e. by EMACS). The Apple II allows to natively enter the ASCII code 0 via Ctrl-@. However so far get_key_if_available returned 0 in accumulator to signal that no key was pressed. In order to allow the Apple II get_key_if_available to return the ASCII code 0 in the accumulator I changed it to use the carry flag to signal that no key was pressed. Because get_key_if_available needs of course to behave the same on all targets I changed the other implementations to use the carry flag too. Unfortunately I don't know enough about input capabilities of the C64 to decide on how to best get Telnet65 to send ASCII code 0 there.
77 lines
1.9 KiB
ArmAsm
77 lines
1.9 KiB
ArmAsm
.export get_key
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.export check_for_abort_key
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.export get_key_if_available
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.export get_key_ip65
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.export abort_key
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.exportzp abort_key_default = $9b
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.exportzp abort_key_disable = $80
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.import ip65_process
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.data
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abort_key: .byte $9b ; ESC
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.code
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; use Apple 2 monitor ROM function to read from keyboard
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; inputs: none
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; outputs: A contains ASCII value of key just pressed
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get_key = $fd0c
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; inputs: none
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; outputs: sec if key pressed, clear otherwise
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; A contains ASCII value of key just pressed
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get_key_if_available:
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sec
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lda $c000 ; current key pressed
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bmi got_key
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clc
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rts
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; process inbound ip packets while waiting for a keypress
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get_key_ip65:
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jsr ip65_process
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lda $c000 ; key down?
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bpl get_key_ip65
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got_key:
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bit $c010 ; clear the keyboard strobe
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and #$7f
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rts
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; check whether the abort key is being pressed
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; inputs: none
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; outputs: sec if abort key pressed, clear otherwise
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check_for_abort_key:
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lda $c000 ; current key pressed
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cmp abort_key
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bne :+
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bit $c010 ; clear the keyboard strobe
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sec
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rts
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: clc
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rts
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; -- LICENSE FOR a2input.s --
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; The contents of this file are subject to the Mozilla Public License
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; Version 1.1 (the "License"); you may not use this file except in
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; compliance with the License. You may obtain a copy of the License at
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; http://www.mozilla.org/MPL/
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;
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; Software distributed under the License is distributed on an "AS IS"
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; basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
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; License for the specific language governing rights and limitations
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; under the License.
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;
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; The Original Code is ip65.
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;
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; The Initial Developer of the Original Code is Jonno Downes,
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; jonno@jamtronix.com.
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; Portions created by the Initial Developer are Copyright (C) 2009
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; Jonno Downes. All Rights Reserved.
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; -- LICENSE END --
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