© Thomas Kunz 2000
SCE 574
100
äHow do we pass parameters?
äCan push parameters onto the stack before calling to pass parameters, the subprogram can then reference the stack for the parameters
äThey can be discarded from the stack using the following variant of the RET operation
äRET nn
äWhere nn is the number added to the SP  just after the return address is popped off
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äBy Value
äPush the value
äBy Reference
äPush the address, the called routine must also assume the parameter will be accessed indirectly
   Passing Parameters
Return address pushed by CALL instruction
Pushed Parameters, nn words for passed and returned parameters
Old stack
Ret nn, sets the IP to the
return address, then advances
the SP to the Old Stack
Stack Top