mouse

[jyrka]

i dont know much about C but i need to get access to my
PS/2 mouse driver. i found this:
Mouse driver functions are accessed through interrupt 33h. The following code sequence portrays what a typical call to the mouse driver looks like in assembly language:

MOV AX,5
MOV BX,l
INT 33H
TEST BX,l
Jz NOT_DEPRESSED

In general, function codes are passed in register AX, and other parameters in BX, CX, and DX. This particular sequence calls function 5 to retrieve the status of the right mouse button (BX=l for the right button, BX=O for the left). On return, bit I of the BX register is tested and a branch is made if it's set to 0, indicating the button is not currently depressed.

can anyone explain it and maby lighten me a lil bout syntax of accessing registers?

[Hamlin]

Are you looking for enlightenment concerning register access in C or ASM?

Unfortunately, under the current Windows regime a lot of 16-bit programming can no longer be performed do to the restrictions Windows places on direct access to the hardware.

In the meantime, the code snippet you've posted portrays a test of whether or not the right mouse button is depressed. When the interrupt returns, the BX register will contain the number of button presses ( between 0 and 32767 ), CX will contain the horizontal position at the last press, DX will contain the vertical position at last press, and AX will contain a bitfield detailing the status which is described like so:

Bit 0 - 1 = left button down, 0 = left button up
Bit 1 - 1 = right button down, 0 = right button up
Bit 2 - Unused
Bit 3 - Unused
Bit 4 - Unused
Bit 5 - Unused
Bit 6 - Unused
Bit 7 - Unused

Regardless, trying to access interrupt 33h under Windows outside of 16-bit DOS mode programs will certainly cause an error.

If you tell me why you need access to the mouse driver, I can probably help you out some, and maybe come up with a way around the problem you're trying to solve.