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Code logic is similar with arithmetic right shift by constant, and NFP
get indirect shift amount through source A operand of PREV_ALU.
It is possible to fall back to logic right shift if the MSB is known to be
zero from range info, however there is no benefit to do this given logic
indirect right shift use the same number and cycle of instruction sequence.
Suppose the MSB of regX is the bit we want to replicate to fill in all the
vacant positions, and regY contains the shift amount, then we could use
single instruction to set up both.
[alu, --, regY, OR, regX]
--
NOTE: the PREV_ALU result doesn't need to write to any destination
register.
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.