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Chris Pressey 2018-04-19 09:54:24 +01:00
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@ -83,6 +83,8 @@ The problem is that once a byte is extracted, putting it back into a word is awk
The address operators have to modify a destination in a special way. That is, when 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. 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. Is that consistent with `st`? Well, probably it is, but we have to explain it.
It might make more sense, then, for it to be "part of the operation" instead of "part of
the reference"; something like `st.hi x, word`; `st.lo y, word`. Dunno.
### Save registers on stack ### Save registers on stack
@ -91,9 +93,17 @@ are trashed inside the block.
### Associate each pointer with the buffer it points into ### Associate each pointer with the buffer it points into
Check that the buffer being read or written to through pointer, appears in appropriate inputs or outputs set. Check that the buffer being read or written to through pointer, appears in appropriate
inputs or outputs set.
### `static` tables In the analysis, when we obtain a pointer, we need to record, in contect, what buffer
that pointer came from.
When we write through that pointer, we need to set that buffer as written.
When we read through the pointer, we need to check that the buffer is readable.
### table overlays
They are uninitialized, but the twist is, the address is a buffer that is They are uninitialized, but the twist is, the address is a buffer that is
an input to and/or output of the routine. So, they are defined (insofar an input to and/or output of the routine. So, they are defined (insofar
@ -104,8 +114,14 @@ They are therefore a "view" of a section of a buffer.
This is slightly dangerous since it does permit aliases: the buffer and the This is slightly dangerous since it does permit aliases: the buffer and the
table refer to the same memory. table refer to the same memory.
`static` tables overlayed on buffers is an alternative to `static` pointers Although, if they are `static`, you could say, in the routine in which they
(which are currently not possible because pointers must be zero-page, thus `@`, thus uninitialized.) are `static`, as soon as you've established one, you can no longer use the
buffer; and the ones you establish must be disjoint.
(That seems to be the most compelling case for restricting them to `static`.)
An alternative would be `static` pointers, which are currently not possible because
pointers must be zero-page, thus `@`, thus uninitialized.
### Question "consistent initialization" ### Question "consistent initialization"