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Add TODO note.

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Chris Pressey 2018-04-18 17:59:42 +01:00
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@ -75,6 +75,15 @@ TODO
To turn `word` type into `byte`. To turn `word` type into `byte`.
Trying to remember if we have a compelling case for this or now. The best I can think
of is for implementing 16-bit `cmp` in an efficient way. Maybe we should see if we
can get by with 16-bit `cmp` instead though.
The problem is that once a byte is extracted, putting it back into a word is awkward.
The address operators have to modify a destination in a special way. That is, when
you say `st a, >word`, you are updating `word` to be `word & $ff | a << 8`, somelike.
Is that consistent with `st`? Well, probably it is, but we have to explain it.
### Save registers on stack ### Save registers on stack
This preserves them, so that, semantically, they can be used later even though they This preserves them, so that, semantically, they can be used later even though they