switch to single-pass mode directly into output buffer
when outputSize >= ZSTD_compressBound(inputSize).
Speed gains observed with fullbench (~+15% on level 1)
now ZSTD_customCMem is promoted as new default.
Advantages : ZSTD_customCMem = { NULL, NULL, NULL},
so it's natural default after a memset.
ZSTD_customCMem is public constant
(defaultCustomMem was private only).
Also : makes it possible to introduce ZSTD_calloc(),
which can now default to stdlib's calloc()
when it detects system default.
Fixed zlibwrapper which depended on defaultCustomMem.
XXH_STATIC_LINKING_ONLY protection macro is intended to be triggered just before the include.
The main idea is to keep this setting local :
user module shall explicitly understand and accept the static linking restriction
which becomes transparent when triggering the macro at project level.
Global definition also triggers redefinition warnings for user modules which do locally define the macro.
This new version compiles lib and cli without warning when the macro is set globally.
That's not a scenario to be recommended, since it trades a local effect for a global one,
but it was easy enough to provide from zstd side.
MT compression generates a single frame.
Multi-threading operates by breaking the frames into independent sections.
But from a decoder perspective, there is no difference :
it's just a suite of blocks.
Problem is, decoder preserves repCodes from previous block to start decoding next block.
This is also valid between sections, since they are no different than changing block.
Previous version would incorrectly initialize repcodes to their default value at the beginning of each section.
When using them, there was a mismatch between encoder (default values) and decoder (values from previous block).
This change ensures that repcodes won't be used at the beginning of a new section.
It works by setting them to 0.
This only works with regular (single segment) variants : extDict variants will fail !
Fortunately, sections beyond the 1st one belong to this category.
To be checked : btopt strategy.
This change was only validated from fast to btlazy2 strategies.
execSequence relied on pointer overflow to handle cases where
`sequence.matchLength < 8`. Instead of passing an `size_t` to
wildcopy, pass a `ptrdiff_t`.
The zstd reference compressor will not emit a match in the last 7
bytes of a block. The decompressor will also not accept a match
in the last 7 bytes. This patch makes the decompressor accept a
match in the last 7 bytes.
Yann Collet
cyan4973
Nick Terrell
Przemyslaw Skibinski