LXR linux/arch/avr32/include/asm/checksum.h

   1/*
   2 * Copyright (C) 2004-2006 Atmel Corporation
   3 *
   4 * This program is free software; you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License version 2 as
   6 * published by the Free Software Foundation.
   7 */
   8#ifndef __ASM_AVR32_CHECKSUM_H
   9#define __ASM_AVR32_CHECKSUM_H
  10
  11/*
  12 * computes the checksum of a memory block at buff, length len,
  13 * and adds in "sum" (32-bit)
  14 *
  15 * returns a 32-bit number suitable for feeding into itself
  16 * or csum_tcpudp_magic
  17 *
  18 * this function must be called with even lengths, except
  19 * for the last fragment, which may be odd
  20 *
  21 * it's best to have buff aligned on a 32-bit boundary
  22 */
  23__wsum csum_partial(const void *buff, int len, __wsum sum);
  24
  25/*
  26 * the same as csum_partial, but copies from src while it
  27 * checksums, and handles user-space pointer exceptions correctly, when needed.
  28 *
  29 * here even more important to align src and dst on a 32-bit (or even
  30 * better 64-bit) boundary
  31 */
  32__wsum csum_partial_copy_generic(const void *src, void *dst, int len,
  33                                       __wsum sum, int *src_err_ptr,
  34                                       int *dst_err_ptr);
  35
  36/*
  37 *      Note: when you get a NULL pointer exception here this means someone
  38 *      passed in an incorrect kernel address to one of these functions.
  39 *
  40 *      If you use these functions directly please don't forget the
  41 *      access_ok().
  42 */
  43static inline
  44__wsum csum_partial_copy_nocheck(const void *src, void *dst,
  45                                       int len, __wsum sum)
  46{
  47        return csum_partial_copy_generic(src, dst, len, sum, NULL, NULL);
  48}
  49
  50static inline
  51__wsum csum_partial_copy_from_user(const void __user *src, void *dst,
  52                                          int len, __wsum sum, int *err_ptr)
  53{
  54        return csum_partial_copy_generic((const void __force *)src, dst, len,
  55                                         sum, err_ptr, NULL);
  56}
  57
  58/*
  59 *      This is a version of ip_compute_csum() optimized for IP headers,
  60 *      which always checksum on 4 octet boundaries.
  61 */
  62static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
  63{
  64        unsigned int sum, tmp;
  65
  66        __asm__ __volatile__(
  67                "       ld.w    %0, %1++\n"
  68                "       ld.w    %3, %1++\n"
  69                "       sub     %2, 4\n"
  70                "       add     %0, %3\n"
  71                "       ld.w    %3, %1++\n"
  72                "       adc     %0, %0, %3\n"
  73                "       ld.w    %3, %1++\n"
  74                "       adc     %0, %0, %3\n"
  75                "       acr     %0\n"
  76                "1:     ld.w    %3, %1++\n"
  77                "       add     %0, %3\n"
  78                "       acr     %0\n"
  79                "       sub     %2, 1\n"
  80                "       brne    1b\n"
  81                "       lsl     %3, %0, 16\n"
  82                "       andl    %0, 0\n"
  83                "       mov     %2, 0xffff\n"
  84                "       add     %0, %3\n"
  85                "       adc     %0, %0, %2\n"
  86                "       com     %0\n"
  87                "       lsr     %0, 16\n"
  88                : "=r"(sum), "=r"(iph), "=r"(ihl), "=r"(tmp)
  89                : "1"(iph), "2"(ihl)
  90                : "memory", "cc");
  91        return (__force __sum16)sum;
  92}
  93
  94/*
  95 *      Fold a partial checksum
  96 */
  97
  98static inline __sum16 csum_fold(__wsum sum)
  99{
 100        unsigned int tmp;
 101
 102        asm("   bfextu  %1, %0, 0, 16\n"
 103            "   lsr     %0, 16\n"
 104            "   add     %0, %1\n"
 105            "   bfextu  %1, %0, 16, 16\n"
 106            "   add     %0, %1"
 107            : "=&r"(sum), "=&r"(tmp)
 108            : "0"(sum));
 109
 110        return (__force __sum16)~sum;
 111}
 112
 113static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
 114                                               unsigned short len,
 115                                               unsigned short proto,
 116                                               __wsum sum)
 117{
 118        asm("   add     %0, %1\n"
 119            "   adc     %0, %0, %2\n"
 120            "   adc     %0, %0, %3\n"
 121            "   acr     %0"
 122            : "=r"(sum)
 123            : "r"(daddr), "r"(saddr), "r"(len + proto),
 124              "0"(sum)
 125            : "cc");
 126
 127        return sum;
 128}
 129
 130/*
 131 * computes the checksum of the TCP/UDP pseudo-header
 132 * returns a 16-bit checksum, already complemented
 133 */
 134static inline __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
 135                                                   unsigned short len,
 136                                                   unsigned short proto,
 137                                                   __wsum sum)
 138{
 139        return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
 140}
 141
 142/*
 143 * this routine is used for miscellaneous IP-like checksums, mainly
 144 * in icmp.c
 145 */
 146
 147static inline __sum16 ip_compute_csum(const void *buff, int len)
 148{
 149    return csum_fold(csum_partial(buff, len, 0));
 150}
 151
 152#endif /* __ASM_AVR32_CHECKSUM_H */
 153