as suggested in #1441.
generally U32 and unsigned are the same thing,
except when they are not ...
case : 32-bit compilation for MIPS (uint32_t == unsigned long)
A vast majority of transformation consists in transforming U32 into unsigned.
In rare cases, it's the other way around (typically for internal code, such as seeds).
Among a few issues this patches solves :
- some parameters were declared with type `unsigned` in *.h,
but with type `U32` in their implementation *.c .
- some parameters have type unsigned*,
but the caller user a pointer to U32 instead.
These fixes are useful.
However, the bulk of changes is about %u formating,
which requires unsigned type,
but generally receives U32 values instead,
often just for brevity (U32 is shorter than unsigned).
These changes are generally minor, or even annoying.
As a consequence, the amount of code changed is larger than I would expect for such a patch.
Testing is also a pain :
it requires manually modifying `mem.h`,
in order to lie about `U32`
and force it to be an `unsigned long` typically.
On a 64-bit system, this will break the equivalence unsigned == U32.
Unfortunately, it will also break a few static_assert(), controlling structure sizes.
So it also requires modifying `debug.h` to make `static_assert()` a noop.
And then reverting these changes.
So it's inconvenient, and as a consequence,
this property is currently not checked during CI tests.
Therefore, these problems can emerge again in the future.
I wonder if it is worth ensuring proper distinction of U32 != unsigned in CI tests.
It's another restriction for coding, adding more frustration during merge tests,
since most platforms don't need this distinction (hence contributor will not see it),
and while this can matter in theory, the number of platforms impacted seems minimal.
Thoughts ?
The problem was already masked,
due to no longer accepting tiny blocks for statistics.
But in case it could still happen with not-so-tiny blocks,
there is a stricter control which ensures that
nothing was already loaded prior to statistics collection.
depending on initialization,
the first byte of a new frame was invalidated or not.
As a consequence, one match opportunity was available or not,
resulting in slightly different compressed sizes
(on average, 1 or 2 bytes once every 20 frames).
It impacted ratio comparison between one-shot and streaming modes.
This fix makes the first byte of a new frame always a valid match.
Now compressed size is always the same.
It also improves compressed size by a negligible amount.
* Fix `ZSTD_estimateCCtxSize()` with negative levels.
* Fix `ZSTD_estimateCStreamSize()` with negative levels.
* Add a unit test to test for this error.
