when src ptr is in very low memory area (< 64K),
the virtual reference to data in dictionary
might end up in a very high memory address.
Since it's not a "real" memory address,
just a virtual one, to calculate distance,
it doesn't matter : only distance matters.
The assert was to restrictive.
Fixed.
by enabling the fast decoder path.
Visual requires a different set of macro constants to detect x86 / x64.
On my laptop, decoding speed on x64 went up from 3.12 to 3.45 GB/s.
32-bit is less impressive, though still favorable,
with speed increasing from 2.55 to 2.60 GB/s.
So both cases are now enabled.
Suggested by Bartosz Taudul (@wolfpld).
Support the -D command line option for running benchmarks. The
benchmark code was slightly restructured to factor out the calls
that need to be different for each benchmark scenario. Since there
are now 4 scenarios (all combinations of fast/HC and with/without
dictionary), the logic was getting somewhat convoluted otherwise.
This was done by extending the compressionParameters struct that
previously contained just a single function pointer. It now
contains 4 function pointers for init/reset/compress/cleanup,
with the related state. The functions get a pointer to the
structure as their first argument (inspired by C++), so that they
can access the state values in the struct.
Add missing lz4 project to the VS2017 solution.
The project was made from scratch rather than importing and updated to
match the VS2010 options.
Any new options not present in the old VS2010 project we pulled from
other console binaries in the solution.
Signed-off-by: David A Kondrad <dkondrad.mscs+patches@gmail.com>
The `lz4` project was excluded from being checked in for VS2017.
Add some fixups to explicitly allow this project directory.
Also add an exclusion for VS2017 binaries and VS `ipch` directories.
Signed-off-by: David A Kondrad <dkondrad.mscs+patches@gmail.com>
Otherwise, the output from decoding LZ4-compressed input could be
platform dependent.
Also add a compile-time check to confirm the existing code's assumptions
that, if <stdint.h> isn't used, then sizeof(int) == 4.
Updates #792
Summary: Consuming bytes from the end of data instead of from the front to prevent "all-in-one" decisions.
Test Plan:
Reviewers:
Subscribers:
Tasks:
Tags:
PR#756 fixed the data corruption bug, but didn't clear `ip`. PR#760
fixed that off-by-one error, but missed the case where `ip == filledIp`,
which is harder for the fuzzers to find (it took 20 days not 1 day).
Verified this fixed the issue reported by OSS-Fuzz.
Credit to OSS-Fuzz.
When using an empty dictionary, we bail out of loading or attaching it in
ways that leave the working context in potentially slightly different states.
In particular, in some paths, we will cause the currentOffset to be non-zero,
while in others we would allow it to remain 0.
This difference in behavior is perfectly harmless, but in some situations, it
can produce slight differences in the compressed output. For sanity's sake,
we currently try to maintain a strict correspondence between the behavior of
the dict attachment and the dict loading paths. This patch restores them to
behaving identically.
This shouldn't have any negative side-effects, as far as I can tell. When
writing the dict attachment code, I tried to preserve zeroed currentOffsets
when possible, since they benchmarked as very slightly faster. However, the
case of attaching an empty dictionary is probably rare enought that it's
acceptable to minisculely degrade performance in that corner case.
