48 lines
995 B
ArmAsm
48 lines
995 B
ArmAsm
;==========================================================
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; Get Key
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;==========================================================
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;
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get_key:
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lda KEYPRESS ; 3
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bpl no_key ; 2nt/3
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bit KEYRESET ; clear the keyboard buffer ; 4
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figure_out_key:
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cmp #' '+128 ; the mask destroys space ; 2
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beq return_key ; so handle it specially ; 2nt/3
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check_right_arrow:
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cmp #$95 ; 2
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bne check_left_arrow ; 2nt/3
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lda #'D' ; 2
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check_left_arrow:
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cmp #$88 ; 2
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bne check_up_arrow ; 2nt/3
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lda #'A' ; 2
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check_up_arrow:
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cmp #$8B ; 2
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bne check_down_arrow ; 2nt/3
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lda #'W' ; 2
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check_down_arrow:
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cmp #$8A ; 2
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bne check_escape ; 2nt/3
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lda #'S' ; 2
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check_escape:
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and #$5f ; mask, to make upper-case ; 2
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cmp #$1B ; 2
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bne return_key ; 2nt/3
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lda #'Q' ; 2
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bne return_key ; branch always ; 3
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no_key:
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lda #0 ; no key, so return a zero ; 2
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return_key:
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rts ; 6
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;============
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