linux/arch/cris/include/arch-v10/arch/checksum.h
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   1#ifndef _CRIS_ARCH_CHECKSUM_H
   2#define _CRIS_ARCH_CHECKSUM_H
   3
   4/* Checksum some values used in TCP/UDP headers.
   5 *
   6 * The gain by doing this in asm is that C will not generate carry-additions
   7 * for the 32-bit components of the checksum, so otherwise we would have had
   8 * to split all of those into 16-bit components, then add.
   9 */
  10
  11static inline __wsum
  12csum_tcpudp_nofold(__be32 saddr, __be32 daddr, unsigned short len,
  13                   unsigned short proto, __wsum sum)
  14{
  15        __wsum res;
  16        __asm__ ("add.d %2, %0\n\t"
  17                 "ax\n\t"
  18                 "add.d %3, %0\n\t"
  19                 "ax\n\t"
  20                 "add.d %4, %0\n\t"
  21                 "ax\n\t"
  22                 "addq 0, %0\n"
  23        : "=r" (res)
  24        : "0" (sum), "r" (daddr), "r" (saddr), "r" ((len + proto) << 8));
  25
  26        return res;
  27}       
  28
  29#endif
  30