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Commit 694fc88ce2 ("powerpc/string: Implement optimized
memset variants") added memset16(), memset32() and memset64()
for the 64 bits PPC.
On 32 bits, memset64() is not relevant, and as shown below,
the generic version of memset32() gives a good code, so only
memset16() is candidate for an optimised version.
000009c0 <memset32>:
9c0: 2c 05 00 00 cmpwi r5,0
9c4: 39 23 ff fc addi r9,r3,-4
9c8: 4d 82 00 20 beqlr
9cc: 7c a9 03 a6 mtctr r5
9d0: 94 89 00 04 stwu r4,4(r9)
9d4: 42 00 ff fc bdnz 9d0 <memset32+0x10>
9d8: 4e 80 00 20 blr
The last part of memset() handling the not 4-bytes multiples
operates on bytes, making it unsuitable for handling word without
modification. As it would increase memset() complexity, it is
better to implement memset16() from scratch. In addition it
has the advantage of allowing a more optimised memset16() than what
we would have by using the memset() function.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. 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.