Function Calls

For external functions, it is necessary to:

1. Set up the arguments for the function call.

2. Call the function.

3. Retrieve the result and do any necessary final actions.

A function call involves the following:

1. Load arguments into registers, beginning with %o0. Floating arguments must be stored in a temporary at [%sp+88] and then loaded into %o0.

2. Execute a call instruction:

   
         call    sin    !  sin(%o0) -->  %f0
         nop
   

   The nop can be replaced by an instruction that is useful, e.g., loading the argument into %o0.

3. Floating results are returned in %f0. Integer results are returned in %o0.

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