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Irmen de Jong 2020-12-19 03:36:52 +01:00
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@ -54,7 +54,8 @@ These are usually declarations of kernel (ROM) routines or low-level assembly on
that have their arguments solely passed into specific registers. that have their arguments solely passed into specific registers.
Sometimes even via a processor status flag such as the Carry flag. Sometimes even via a processor status flag such as the Carry flag.
Return values also via designated registers. Return values also via designated registers.
The processor status flag is preserved on returning so you can immediately act on that for instance
via a special branch instruction such as ``if_z`` or ``if_cs`` etc.
regular subroutines regular subroutines
@ -73,8 +74,12 @@ regular subroutines
Float values will be put in the ``FAC1`` float 'register' (Basic allocated this somewhere in ram). Float values will be put in the ``FAC1`` float 'register' (Basic allocated this somewhere in ram).
Calls to builtin functions are treated in a special way: Calls to builtin functions are treated in a special way:
Generally if they have a single argument it's passed in a register or register pair. Generally if they have a single argument it's passed in a register or register pair.
Multiple arguments are passed like a normal subroutine, into variables. Multiple arguments are passed like a normal subroutine, into variables.
Some builtin functions have a fully custom implementation. Some builtin functions have a fully custom implementation.
The compiler will warn about routines that are called and that return a value, if you're not
doing something with that returnvalue. This can be on purpuse if you're simply not interested in it.
Use the ``void`` keyword in front of the subroutine call to get rid of the warning in that case.