USR command

[Heaven/TQA]

maybe I am getting old but I wanted to check my distance calc routine in basic... but please refresh my memories

 

a=usr(adr,px,py,mx,my,dist)

 

first I would need to pull the vars from stack

 

pla ; amount of arguments

pla ;dist

sta dist

pla ;my

sta my

...

 

 

so... actually

 

are the vars pushed on stack 16 bit? or 8 bit?

 

and the content of the accumulator when switching back to basic with RTS is then stored in the a var?

[Rybags]

8 bit value with # of parameters. 16 bit values for parameters. High byte of parm1, low byte parm1 etc.

 

And to pass anything back to BASIC, you store it in $D4,$D5.