LXR linux/arch/powerpc/include/asm/checksum.h

   1#ifndef _ASM_POWERPC_CHECKSUM_H
   2#define _ASM_POWERPC_CHECKSUM_H
   3#ifdef __KERNEL__
   4
   5/*
   6 * This program is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU General Public License
   8 * as published by the Free Software Foundation; either version
   9 * 2 of the License, or (at your option) any later version.
  10 */
  11
  12/*
  13 * This is a version of ip_compute_csum() optimized for IP headers,
  14 * which always checksum on 4 octet boundaries.  ihl is the number
  15 * of 32-bit words and is always >= 5.
  16 */
  17extern __sum16 ip_fast_csum(const void *iph, unsigned int ihl);
  18
  19/*
  20 * computes the checksum of the TCP/UDP pseudo-header
  21 * returns a 16-bit checksum, already complemented
  22 */
  23extern __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
  24                                        unsigned short len,
  25                                        unsigned short proto,
  26                                        __wsum sum);
  27
  28/*
  29 * computes the checksum of a memory block at buff, length len,
  30 * and adds in "sum" (32-bit)
  31 *
  32 * returns a 32-bit number suitable for feeding into itself
  33 * or csum_tcpudp_magic
  34 *
  35 * this function must be called with even lengths, except
  36 * for the last fragment, which may be odd
  37 *
  38 * it's best to have buff aligned on a 32-bit boundary
  39 */
  40extern __wsum csum_partial(const void *buff, int len, __wsum sum);
  41
  42/*
  43 * Computes the checksum of a memory block at src, length len,
  44 * and adds in "sum" (32-bit), while copying the block to dst.
  45 * If an access exception occurs on src or dst, it stores -EFAULT
  46 * to *src_err or *dst_err respectively (if that pointer is not
  47 * NULL), and, for an error on src, zeroes the rest of dst.
  48 *
  49 * Like csum_partial, this must be called with even lengths,
  50 * except for the last fragment.
  51 */
  52extern __wsum csum_partial_copy_generic(const void *src, void *dst,
  53                                              int len, __wsum sum,
  54                                              int *src_err, int *dst_err);
  55/*
  56 * the same as csum_partial, but copies from src to dst while it
  57 * checksums.
  58 */
  59#define csum_partial_copy_from_user(src, dst, len, sum, errp)   \
  60        csum_partial_copy_generic((__force const void *)(src), (dst), (len), (sum), (errp), NULL)
  61
  62#define csum_partial_copy_nocheck(src, dst, len, sum)   \
  63        csum_partial_copy_generic((src), (dst), (len), (sum), NULL, NULL)
  64
  65
  66/*
  67 * turns a 32-bit partial checksum (e.g. from csum_partial) into a
  68 * 1's complement 16-bit checksum.
  69 */
  70static inline __sum16 csum_fold(__wsum sum)
  71{
  72        unsigned int tmp;
  73
  74        /* swap the two 16-bit halves of sum */
  75        __asm__("rlwinm %0,%1,16,0,31" : "=r" (tmp) : "r" (sum));
  76        /* if there is a carry from adding the two 16-bit halves,
  77           it will carry from the lower half into the upper half,
  78           giving us the correct sum in the upper half. */
  79        return (__force __sum16)(~((__force u32)sum + tmp) >> 16);
  80}
  81
  82/*
  83 * this routine is used for miscellaneous IP-like checksums, mainly
  84 * in icmp.c
  85 */
  86static inline __sum16 ip_compute_csum(const void *buff, int len)
  87{
  88        return csum_fold(csum_partial(buff, len, 0));
  89}
  90
  91static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
  92                                     unsigned short len,
  93                                     unsigned short proto,
  94                                     __wsum sum)
  95{
  96#ifdef __powerpc64__
  97        unsigned long s = (__force u32)sum;
  98
  99        s += (__force u32)saddr;
 100        s += (__force u32)daddr;
 101        s += proto + len;
 102        s += (s >> 32);
 103        return (__force __wsum) s;
 104#else
 105    __asm__("\n\
 106        addc %0,%0,%1 \n\
 107        adde %0,%0,%2 \n\
 108        adde %0,%0,%3 \n\
 109        addze %0,%0 \n\
 110        "
 111        : "=r" (sum)
 112        : "r" (daddr), "r"(saddr), "r"(proto + len), "0"(sum));
 113        return sum;
 114#endif
 115}
 116#endif /* __KERNEL__ */
 117#endif
 118