Following #2545,
I noticed that one field in `seq_t` is optional,
and only used in combination with prefetching.
(This may have contributed to static analyzer failure to detect correct initialization).
I then wondered if it would be possible to rewrite the code
so that this optional part is handled directly by the prefetching code
rather than delegated as an option into `ZSTD_decodeSequence()`.
This resulted into this refactoring exercise
where the prefetching responsibility is better isolated into its own function
and `ZSTD_decodeSequence()` is streamlined to contain strictly Sequence decoding operations.
Incidently, due to better code locality,
it reduces the need to send information around,
leading to simplified interface, and smaller state structures.
* Move `counting` to a struct in `FSE_decompress_wksp_body()`
* Fix error code in `FSE_decompress_wksp_body()`
* Rename a variable in `HUF_ReadDTableX2_Workspace`
The simple compression functions are intended to ignore the advanced
parameters, but they were accidentally using them. All the
`ZSTD_parameters` were set correctly, but any extra parameters were
used as-is. E.g. `ZSTD_c_format`.
This PR makes all the simple single-pass functions listed below ignore
the advanced parameters, as intended.
* `ZSTD_compressCCtx()`
* `ZSTD_compress_usingDict()`
* `ZSTD_compress_usingCDict()`
* `ZSTD_compress_advanced()`
* `ZSTD_compress_usingCDict_advanced()`
It also adds a test case that ensures that each of these functions
ignore the advanced parameters.
Forward the correct compressionLevel to the appliedParams in all cases.
It was already correct for the advanced API, so only the old single-pass
functions needed to be fixed.
This compression level is unused by the library, but is set so that the
tracing framework can consume it.
The most common information that you want to track between begin() and
end() is the timestamp of the begin function, so you can measure the
duration of the (de)compression call. Allow the tracing library to put
this information inside the `ZSTD_TraceCtx`, so it doesn't need to keep
a global map in this case. If a single uint64_t is not enough, the
tracing library can return a unique identifier (like the context
pointer) instead, and use it as a key in a map.
This keeps the simple case simple.
