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  */
  43 static 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
  50 static 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  */
  62 static 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
  98 static 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
 113 static 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  */
 134 static 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
 147 static 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 */