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The Go programming language
d5c45c541d
Three optimizations: First, special-case power of two bases that partion a Word(), bases 2, 4, 16, and 256. These can be moved directly from internal Word() storage to the output without multiprecision operations. Next, same approach for the other power-of-two bases, 8, 32, 64, and 128. These don't fill a Word() evenly, so special handling is needed for those cases where input spans the high-bits of one Word and the low bis of the next one. Finally, implement the general case for others bases in 2 <= base <= 256 using superbases, the largest power of base representable in a Word(). For base ten, this is 9 digits and a superbase of 10^9 for 32-bit Words and 19 digits and 10^19 for 64-bit compiles. This way we do just 1/9th or 1/19th of the expensive multiprecision divisions, unpacking superdigits using fast native machine arithmetic. The resulting code runs 7x to 800x the speed of the previous approach, depending on the length of the number to be converted--longer is relatively faster. Also, extended the tests and benchmarks for string to nat (scan()) and nat to string (string()) functions. A further enhancement awaits the next CL to make general cases about 7x faster for long cases. R=gri CC=golang-dev https://golang.org/cl/4595041 |
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This is the source code repository for the Go programming language.
For documentation about how to install and use Go,
visit http://golang.org/ or load doc/install.html in your web browser.
After installing Go, you can view a nicely formatted
doc/install.html by running godoc --http=:6060
and then visiting http://localhost:6060/doc/install.html.
Unless otherwise noted, the Go source files are distributed
under the BSD-style license found in the LICENSE file.
--
Binary Distribution Notes
If you have just untarred a binary Go distribution, you need to set
the environment variable $GOROOT to the full path of the go
directory (the one containing this README). You can omit the
variable if you unpack it into /usr/local/go, or if you rebuild
from sources by running all.bash (see doc/install.html).
You should also add the Go binary directory $GOROOT/bin
to your shell's path.
For example, if you extracted the tar file into $HOME/go, you might
put the following in your .profile:
export GOROOT=$HOME/go
export PATH=$PATH:$GOROOT/bin
See doc/install.html for more details.