From: nowhere@never.at   
      
   On 12/11/2023 14:27, Robert Pengelly wrote:   
   > On Sunday, 12 November 2023 at 12:08:42 UTC, wolfgang kern wrote:   
   >> On 12/11/2023 12:11, Robert Pengelly wrote:   
   >> ...   
   >>> I'm having a little bit of trouble with the cooridnates from the IRQ4.   
   Going by https://roborooter.com/post/serial-mice/ I have:   
   >>>   
   >>> mov dx, HEX (03FD)   
   >>> xor ax, ax   
   >>> in al, dx   
   >>> nop   
   >>>   
   >>> test al, 0b01000000   
   >>> jz serial_handler.done   
   >>>   
   >>> test al, 0b00000001   
   >>> jz serial_handler.done   
   >>>   
   >>> mov dx, HEX (03F8)   
   >>> xor ax, ax   
   >>> in al, dx   
   >>> nop   
   >>>   
   >>> mov si, ax   
   >>> mov di, ax   
   >>>   
   >>> and si, 0b00001100   
   >>> and di, 0b00000011   
   >>>   
   >>> mov cl, 4   
   >>> shl si, cl   
   >>>   
   >>> mov cl, 6   
   >>> shl di, cl   
   >>>   
   >>> mov dx, HEX (03F8)   
   >>> xor ax, ax   
   >>> in al, dx   
   >>> nop   
   >>>   
   >>> or di, ax   
   >>> add di, cs:[mouse_x]   
   >>>   
   >>> mov dx, HEX (03F8)   
   >>> xor ax, ax   
   >>> in al, dx   
   >>> nop   
   >>>   
   >>> or si, ax   
   >>> add si, cs:[mouse_y]   
   >>>   
   >>> but the initial values seem a bit off (e.g. for Y I have 205 and X is 77),   
   have I mixed up the values or am I just doing the calculations wrong after I   
   read the port?   
   >> the mouse sends a sequence of bytes where every byte causes in IRQ.   
   >> so you first need to fill a buffer with the gotten bytes before you can   
   >> calculate/scale/interpret the values. mouse IRQs can easy come out of   
   >> sync, so checking always for the first byte mark is a good idea.   
      
      
   > Oh I thought you had to get them all at the same time when the interrupt was   
   fired.  As for filling the buffer how would I tell the interrupts apart?  I   
   can test for 0x40 and 0x01 (which I'm already doing) I'm just a little   
   confused how I would know    
   whether it's the 1st, 2nd and 3rd bytes.   
      
   there is a mark for the first byte (reread the RBIL I posted)   
   I use one variable for count down (easier than count up) and use this   
   with BX as an index into my buffer.   
   and when the buffer is filled I adjust all my mouse-variables which I   
   later use on my mSec timer-base schedule to update cursor and act on   
   buttons.   
   __   
   wolfgang   
      
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