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Commit aa9c33b4 authored by Michael Hennerich's avatar Michael Hennerich Committed by Bryan Wu
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Blackfin arch: Faster Implementation of csum_tcpudp_nofold() 



Avoid conditional branch instructions during carry bit additions.
Special thanks to Bernd.
Simplify: Use ((len + proto) << 8) like every other __LITTLE_ENDIAN__ machine

Cc: Bernd Schmidt <bernds_cb1@t-online.de>
Signed-off-by: default avatarMichael Hennerich <michael.hennerich@analog.com>
Signed-off-by: default avatarBryan Wu <cooloney@kernel.org>
parent 0ce5eaf8

arch/blackfin/include/asm/checksum.h

+17 −17
Original line number Diff line number Diff line
@@ -63,22 +63,22 @@ static inline __wsum 
csum_tcpudp_nofold(__be32 saddr, __be32 daddr, unsigned short len,

		   unsigned short proto, __wsum sum)

{

	unsigned int carry;



	__asm__ ("%0 = %0 + %1;\n\t"

	__asm__ ("%0 = %0 + %2;\n\t"

		"CC = AC0;\n\t"

		 "if !CC jump 4;\n\t"

		 "%0 = %0 + %4;\n\t"

		 "%0 = %0 + %2;\n\t"

		 "CC = AC0;\n\t"

                 "if !CC jump 4;\n\t"

                 "%0 = %0 + %4;\n\t"

		"%1 = CC;\n\t"

		"%0 = %0 + %1;\n\t"

		"%0 = %0 + %3;\n\t"

		"CC = AC0;\n\t"

                 "if !CC jump 4;\n\t"

		"%1 = CC;\n\t"

		"%0 = %0 + %1;\n\t"

		"%0 = %0 + %4;\n\t"

                 "NOP;\n\t"

 		 : "=d" (sum)

		 : "d" (daddr), "d" (saddr), "d" ((ntohs(len)<<16)+proto*256), "d" (1), "0"(sum)

		"CC = AC0;\n\t"

		"%1 = CC;\n\t"

		"%0 = %0 + %1;\n\t"

		: "=d" (sum), "=&d" (carry)

		: "d" (daddr), "d" (saddr), "d" ((len + proto) << 8), "0"(sum)

		: "CC");



	return (sum);