IEEE is the most commonly used CRC-32 polynomial, used by zip, gzip and others.
Based on http://www.intel.com/content/dam/www/public/us/en/documents/white-papers/fast-crc-computation-generic-polynomials-pclmulqdq-paper.pdf
benchmark old ns/op new ns/op delta
BenchmarkIEEECrc1KB-8 3193 352 -88.98%
BenchmarkIEEECrc4KB-8 5025 1307 -73.99%
BenchmarkCastagnoliCrc1KB-8 126 126 +0.00%
benchmark old MB/s new MB/s speedup
BenchmarkIEEECrc1KB-8 320.68 2901.92 9.05x
BenchmarkIEEECrc4KB-8 815.08 3131.80 3.84x
BenchmarkCastagnoliCrc1KB-8 8100.80 8109.78 1.00x
Change-Id: I99c9a48365f631827f516e44f97e86155f03cb90
Reviewed-on: https://go-review.googlesource.com/14080
Reviewed-by: Keith Randall <khr@golang.org>
Explicitly say that *Table returned by MakeTable may not be
modified. Otherwise, this leads to very subtle bugs that may
or may not manifest themselves.
Same comment was made on package crc64, to keep the future
open to the caching tables that crc32 effectively does.
Fixes: #12487.
Change-Id: I2881bebb8b16f6f8564412172774c79c2593c6c1
Reviewed-on: https://go-review.googlesource.com/14258
Reviewed-by: Ian Lance Taylor <iant@golang.org>
The URL is shown on go docs and is an eye-sore.
For go1.6.
Change-Id: I8b8ea3751200d06ed36acfe22f47ebb38107f8db
Reviewed-on: https://go-review.googlesource.com/13282
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
The Slicing-By-8 [1] algorithm has much performance improvements than
current approach. This patch only uses it for IEEE, which is the most
common case in practice.
There is the benchmark on Mac OS X 10.9:
benchmark old MB/s new MB/s speedup
BenchmarkIEEECrc1KB 349.40 353.03 1.01x
BenchmarkIEEECrc4KB 351.55 934.35 2.66x
BenchmarkCastagnoliCrc1KB 7037.58 7392.63 1.05x
This algorithm need 8K lookup table, so it's enabled only for block
larger than 4K.
We can see about 2.6x improvement for IEEE.
Change-Id: I7f786d20f0949245e4aa101d7921669f496ed0f7
Reviewed-on: https://go-review.googlesource.com/1863
Reviewed-by: Russ Cox <rsc@golang.org>
Explicitly specify that we represent polynomial in reversed notation
Fixes#8229
Change-Id: Idf094c01fd82f133cd0c1b50fa967d12c577bdb5
Reviewed-on: https://go-review.googlesource.com/9237
Reviewed-by: David Chase <drchase@google.com>
This also removes pkg/runtime/traceback_lr.c, which was ported
to Go in an earlier commit and then moved to
runtime/traceback.go.
Reviewer: rsc@golang.org
rsc: LGTM
