Hi Markus,
On 5/25/07, Markus F.X.J. Oberhumer <[email protected]> wrote:
Please do _not_ rewrite the LZO implementation just for coding style principles.
The current miniLZO implementation is _extrememly_ well tested, pretty
optimized and quite portable.
I agree that the implementation may look confusing, but you should be able to
make it look much better by removing all the unused #defines and #ifdef code
paths - LZO supports exotic things like 16-bit DOS and CRAY PVP memory models
which obviously are not needed in the kernel and account for quite a number of
abstractions (which are implemented through the preprocessor).
Finally the current version has been tested with a lot of compilers and
contains accumulated knowledge about some hairy things - see
http://gcc.gnu.org/PR25196 for an example, as well as some not-yet identified
aliasing issue.
~Markus
I did not rewrite any part of your code except replacing COPY4() macro
and some open-coded byte-by-byte copying with memcpy(). But this has
resulted in very significant perf. loss (as suggested by results from
Richard's tests) - so will rollback these changes.
Additionally following was done to _greatly_ reduce no. of LOC I had
to retain. These should not affect code correctness and performance:
- Used standard/kernel defined data types equivalent of lzo_* types.
This resulted in removal of huge chunks of #ifdefs:
lzo_byptep -> unsigned char *
lzo_uint -> size_t
lzo_xint -> size_t
lzo_uintptr_t -> unsigned long
lzo_uint32p -> uint32_t *
- Removed everything #ifdefed under COPY_DICT -- from minilzo code I
see that this is not #defined for LZO1X (safe/unsafe) (though I could
not understand meaning behind COPY_DICT).
- Removed everthing #ifdef'ed for LZO1Y, LZO1Z, other variants.
Thanks,
Nitin
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