include/asm-avr32/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 unsigned int csum_partial(const unsigned char * buff, int len,
  24                           unsigned int sum);
  25
  26 /*
  27  * the same as csum_partial, but copies from src while it
  28  * checksums, and handles user-space pointer exceptions correctly, when needed.
  29  *
  30  * here even more important to align src and dst on a 32-bit (or even
  31  * better 64-bit) boundary
  32  */
  33 unsigned int csum_partial_copy_generic(const char *src, char *dst, int len,
  34                                        int sum, int *src_err_ptr,
  35                                        int *dst_err_ptr);
  36
  37 /*
  38  *      Note: when you get a NULL pointer exception here this means someone
  39  *      passed in an incorrect kernel address to one of these functions.
  40  *
  41  *      If you use these functions directly please don't forget the
  42  *      verify_area().
  43  */
  44 static inline
  45 unsigned int csum_partial_copy_nocheck(const char *src, char *dst,
  46                                        int len, int sum)
  47 {
  48         return csum_partial_copy_generic(src, dst, len, sum, NULL, NULL);
  49 }
  50
  51 static inline
  52 unsigned int csum_partial_copy_from_user (const char __user *src, char *dst,
  53                                           int len, int sum, int *err_ptr)
  54 {
  55         return csum_partial_copy_generic((const char __force *)src, dst, len,
  56                                          sum, err_ptr, NULL);
  57 }
  58
  59 /*
  60  *      This is a version of ip_compute_csum() optimized for IP headers,
  61  *      which always checksum on 4 octet boundaries.
  62  */
  63 static inline unsigned short ip_fast_csum(unsigned char *iph,
  64                                           unsigned int ihl)
  65 {
  66         unsigned int sum, tmp;
  67
  68         __asm__ __volatile__(
  69                 "       ld.w    %0, %1++\n"
  70                 "       ld.w    %3, %1++\n"
  71                 "       sub     %2, 4\n"
  72                 "       add     %0, %3\n"
  73                 "       ld.w    %3, %1++\n"
  74                 "       adc     %0, %0, %3\n"
  75                 "       ld.w    %3, %1++\n"
  76                 "       adc     %0, %0, %3\n"
  77                 "       acr     %0\n"
  78                 "1:     ld.w    %3, %1++\n"
  79                 "       add     %0, %3\n"
  80                 "       acr     %0\n"
  81                 "       sub     %2, 1\n"
  82                 "       brne    1b\n"
  83                 "       lsl     %3, %0, 16\n"
  84                 "       andl    %0, 0\n"
  85                 "       mov     %2, 0xffff\n"
  86                 "       add     %0, %3\n"
  87                 "       adc     %0, %0, %2\n"
  88                 "       com     %0\n"
  89                 "       lsr     %0, 16\n"
  90                 : "=r"(sum), "=r"(iph), "=r"(ihl), "=r"(tmp)
  91                 : "1"(iph), "2"(ihl)
  92                 : "memory", "cc");
  93         return sum;
  94 }
  95
  96 /*
  97  *      Fold a partial checksum
  98  */
  99
 100 static inline unsigned int csum_fold(unsigned int sum)
 101 {
 102         unsigned int tmp;
 103
 104         asm("   bfextu  %1, %0, 0, 16\n"
 105             "   lsr     %0, 16\n"
 106             "   add     %0, %1\n"
 107             "   bfextu  %1, %0, 16, 16\n"
 108             "   add     %0, %1"
 109             : "=&r"(sum), "=&r"(tmp)
 110             : "0"(sum));
 111
 112         return ~sum;
 113 }
 114
 115 static inline unsigned long csum_tcpudp_nofold(unsigned long saddr,
 116                                                unsigned long daddr,
 117                                                unsigned short len,
 118                                                unsigned short proto,
 119                                                unsigned int sum)
 120 {
 121         asm("   add     %0, %1\n"
 122             "   adc     %0, %0, %2\n"
 123             "   adc     %0, %0, %3\n"
 124             "   acr     %0"
 125             : "=r"(sum)
 126             : "r"(daddr), "r"(saddr), "r"(ntohs(len) | (proto << 16)),
 127               "0"(sum)
 128             : "cc");
 129
 130         return sum;
 131 }
 132
 133 /*
 134  * computes the checksum of the TCP/UDP pseudo-header
 135  * returns a 16-bit checksum, already complemented
 136  */
 137 static inline unsigned short int csum_tcpudp_magic(unsigned long saddr,
 138                                                    unsigned long daddr,
 139                                                    unsigned short len,
 140                                                    unsigned short proto,
 141                                                    unsigned int sum)
 142 {
 143         return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
 144 }
 145
 146 /*
 147  * this routine is used for miscellaneous IP-like checksums, mainly
 148  * in icmp.c
 149  */
 150
 151 static inline unsigned short ip_compute_csum(unsigned char * buff, int len)
 152 {
 153     return csum_fold(csum_partial(buff, len, 0));
 154 }
 155
 156 #endif /* __ASM_AVR32_CHECKSUM_H */