37 lines
937 B
NASM
37 lines
937 B
NASM
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; GAMEPORT.ASM
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;
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.MODEL TINY
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.DATA
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yes DB 13,10,"Game port is installed.",13,10,"$"
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no DB 13,10,"Game port is not installed.",13,10,"$"
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.CODE
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ORG 100h
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start: mov al, 1 ;value to write to port
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mov dx, 201h ;port number
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out dx, al ;write to port
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mov cx, 0F00h ;# of loops
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port_loop:
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in al, dx ;read from port
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and al, 0Fh ;if jstick present, then AL should be
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cmp al, 0Fh ; 0Fh after ANDing with 0Fh.
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je jstick_exists
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loop port_loop
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mov dx, OFFSET no ;gameport not installed
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jmp SHORT done
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jstick_exists:
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mov dx, OFFSET yes ;gameport installed
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done: mov ah, 9h
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int 21h
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mov ax, 4c00h
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int 21h
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END start
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