Interestingly, Clang's `-Wformat-overflow` seems to only warn
about buffers so small they will *always* underflow,
whereas GCC tries to infer whether they can overflow *at all*.
(I'm guessing they lean towards false-negatives and false-positives resp.)
Anyway, calling `sprintf` here remains safe, since GCC (notably, via CI)
checks our work, and it simplifies the code ever so slightly while
also providing an (admittedly negligible) performance improvement.
Note that there may be more locations where we could use `sprintf`,
but a cursory glance at our other uses of `snprintf` didn't seem fruitful.
(One way to test is to set the target buffer size to 1, and see if a
warning pops up for such a trivially-wrong size. If not, you can be certain
the compiler won't be able to help you with a more realistic size.)
Massively simplified, by not trying to shoehorn differently-behaving
cases into the same one loop!
This may have introduced bugs (the test suite has caught three different
oversights, two of which via external projects, in fact!), but this also
makes the logic clearer and more streamlined, so that we are also less
likely to have any latent or future bugs.
In particular, previously, the first iteration of the loop could attempt
placement at an address not matching the section's constraints,
which made advancing to the next target address unnecessarily complicated
(https://github.com/gbdev/rgbds/pull/2064#discussion_r3985466596),
among other weirdness. The code ended up being defensive, and thus the
overall logic was murky.
I'm also expecting that this should provide a performance improvement due
to being essentially a form of loop-invariant code motion (and very likely
one a compiler couldn't have performed automatically), though I haven't
measured.
Fixes#2095
This code pre-dates the introduction of alignment offsets,
so it was never updated to take it into account.
That said, some of the code that I have factored out is a little awkward because
it will be used in an upcoming refactoring of the whole assignment loop,
since that turns out to be more byzantine than it ought to be due to
trying to handle a too disparate set of cases in a single loop.
Turns out the checks could fail spuriously if the starting alignment is non-zero,
e.g. `align 8,$C0` in HRAM. (Fixes #2113.)
This was tripped up by a test added to exercise the linker's section placement algorithm
on a similar aligment-related issue. :D
Note that this may be caused by the code in question pre-dating alignment offsets,
and we never checked. That said, these checks only work due to the regions' starting
addresses being no more aligned than their size (..if that makes sense?), so allowing
custom memory regions (#524) could violate that assumption and make those checks incorrect.
Assembling is never *supposed* to fail, but in this case I ended up adding
a test case that triggered a bug in the assembler, and that caused the rest
of the test to become garbled. This is thus more robust.
The only case where it is not generated by our own code
(which we ought to be `assume`ing is correct) is when the bank
is used-specified, but that is caught by an earlier check.
Moving both pieces of related code together, as it were.
This also ends up changing the behaviour of scrambling,
where sections could “leak” out of the scrambling's bank pool
and resume being placed normally.
We have discussed it offline, and decided that this was a bug.
The test suite has been updated accordingly, which even gives
the occasion to move this test from a special case to the main
generic loop!
This reverts a change introduced in fd78a9ae8, though it wasn't that commit's main point
so I'm feeling okay with undoing that.
This feels like an overkill change, using a static string is good enough for this
since we never modify this. I have considered using `string_view` instead, to have
the best of both worlds, but that's not NUL-terminated so our print functions
get a little grumpy.
If `nbBanks > 1` is true, then `sectionTypeInfo[type].firstBank !=
sectionTypeInfo[type].lastBank` must also be true, so checking
whether either is true is unnecessary.
(On the other hand, if `nbBanks == 1`, then we might still have
`sectionTypeInfo[type].firstBank != sectionTypeInfo[type].lastBank`,
since only one of many valid banks for `type` could be in use.)
This should remain equivalent for our current setups,
but play nicer with anyone wanting to experiment further.
It *may* break for someone building on an Intel Mac,
but this is a libpng limitation and thus out of our control.
Rangi
Rangi
ISSOtm