ZSTD_frameParams => ZSTD_frameHeader
ZSTD_getFrameParams() -> ZSTD_getFrameHeader()
The new naming is more distinctive from ZSTD_frameParameters,
which is used during compression.
ZSTD_frameHeader is clearer in its intention to described frame header content.
It also implies we are decoding a ZSTD frame, hence we are at decoding stage.
added a parameter streaming,
to estimate memory allocation size
when the CCtx is used for streaming (CStream).
Note : this function is not able to estimate
memory cost of a potential internal CDict
which can only happen when starting with ZSTD_initCStream_usingDict()
It now only uses compressionParameters as argument.
It produces many changes throughout user code,
though hopefully they tend to be simple :
just provide the cParams part from existing ZSTD_parameters.
Some programs might depend on ZSTD_createCDict_advanced() to pass frame parameters.
This change will force them to revisit this strategy and fix it,
since frame parameters are effectively silently ignored in current version.
There used to be a (very small) chance that
loading prefix from previous segment
would be confused with a real zstd dictionary.
For that to happen, the prefix needs to start
with the same value as dictionary magic.
That's 1 chance in 4 billions if all values have equal probability.
But in fact, since some values are more common (0x00000000 for example)
others are less common, and dictionary magic was selected to be one of them,
so probabilities are likely even lower.
Anyway, this risk is no down to zero
by adding a new CCtx parameter : ZSTD_p_forceRawDict
Current parameter policy : the parameter "stick" to its CCtx,
so any dictionary loading after ZSTD_p_forceRawDict is set
will be loaded in "raw" ("content only") mode,
even if CCtx is re-used multiple times with multiple different dictionary.
It's up to the user to reset this value differently if it needs so.
- Add ZSTD_findDecompressedSize
- Traverses multiple frames to find total output size
- Add ZSTD_getFrameContentSize
- Gets the decompressed size of a single frame by reading header
- Deprecate ZSTD_getDecompressedSize
Like ZSTD_initCStream_usingDict(),
ZSTDMT_initCStream_usingDict() now keep a copy of dict internally.
This way, dict can be released :
it does not longer have to outlive all future compression sessions.
The new strategy involves cutting frame at block level.
The result is a single frame, preserving ZSTD_getDecompressedSize()
As a consequence, bench can now make a full round-trip,
since the result is compatible with ZSTD_decompress().
This strategy will not make it possible to decode the frame with multiple threads
since the exact cut between independent blocks is not known.
MT decoding needs further discussions.
