From: robertapengelly@gmail.com   
      
   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.    
   > __    
   > wolfgang   
   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.   
      
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