136 lines
2.0 KiB
NASM
136 lines
2.0 KiB
NASM
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.386
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.MODEL small
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.DATA
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.CODE
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IF 0
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#define PEL_WRITE_ADR 0x3c8
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#define PEL_READ_ADR 0x3c7
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#define PEL_DATA 0x3c9
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ENDIF
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;================
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;
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; I_DivException
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;
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;================
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PROC I_DivException_
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PUBLIC I_DivException_
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mov edx,03c9h
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mov al,63
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out dx,al
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mov ebx,0ffffffh
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mov eax,[ebx]
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retf
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ENDP
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;================
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;
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; I_SetDivException
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;
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;================
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PROC I_SetDivException_
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PUBLIC I_SetDivException_
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pusha
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mov eax,0212h
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mov ebx,0
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mov ecx,cs
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mov edx,OFFSET I_DivException_
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int 31h
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jnc good
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popa
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mov eax,0
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ret
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good:
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popa
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mov eax,1
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ret
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ENDP
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;================
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;
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; I_ReadJoystick
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;
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; Read the absolute joystick values
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; returns false if not connected
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;================
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.data
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_joystickx dd 0
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_joysticky dd 0
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PUBLIC _joystickx, _joysticky
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.code
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PROC I_ReadJoystick_
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PUBLIC I_ReadJoystick_
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pusha
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pushf ; state of interrupt flag
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cli
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mov dx,0201h
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in al,dx
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out dx,al ; Clear the resistors
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mov ah,1 ; Get masks into registers
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mov ch,2
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xor esi,esi ; Clear count registers
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xor edi,edi
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xor ebx,ebx ; Clear high byte of bx for later
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mov ebp,10000 ; joystick is disconnected if value is this big
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jloop:
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in al,dx ; Get bits indicating whether all are finished
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dec ebp ; Check bounding register
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jz bad ; We have a silly value - abort
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mov bl,al ; Duplicate the bits
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and bl,ah ; Mask off useless bits (in [xb])
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add esi,ebx ; Possibly increment count register
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mov cl,bl ; Save for testing later
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mov bl,al
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and bl,ch ; [yb]
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add edi,ebx
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add cl,bl
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jnz jloop ; If both bits were 0, drop out
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done:
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mov [_joystickx],esi
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shr edi,1 ; because 2s were added
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mov [_joysticky],edi
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popf ; restore interrupt flag
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popa
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mov eax,1 ; read was ok
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ret
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bad:
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popf ; restore interrupt flag
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popa
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xor eax, eax ; read was bad
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ret
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ENDP
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END
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