LXR linux/arch/cris/include/arch-v32/arch/checksum.h

   1#ifndef _ASM_CRIS_ARCH_CHECKSUM_H
   2#define _ASM_CRIS_ARCH_CHECKSUM_H
   3
   4/*
   5 * Check values used in TCP/UDP headers.
   6 *
   7 * The gain of doing this in assembler instead of C, is that C doesn't
   8 * generate carry-additions for the 32-bit components of the
   9 * checksum. Which means it would be necessary to split all those into
  10 * 16-bit components and then add.
  11 */
  12static inline __wsum
  13csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
  14                   unsigned short len, unsigned short proto, __wsum sum)
  15{
  16        __wsum res;
  17
  18        __asm__ __volatile__ ("add.d %2, %0\n\t"
  19                              "addc %3, %0\n\t"
  20                              "addc %4, %0\n\t"
  21                              "addc 0, %0\n\t"
  22                              : "=r" (res)
  23                              : "0" (sum), "r" (daddr), "r" (saddr), \
  24                              "r" ((len + proto) << 8));
  25
  26        return res;
  27}
  28
  29#endif /* _ASM_CRIS_ARCH_CHECKSUM_H */
  30