include/asm-powerpc/checksum.h

   1 #ifndef _ASM_POWERPC_CHECKSUM_H
   2 #define _ASM_POWERPC_CHECKSUM_H
   3
   4 /*
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License
   7  * as published by the Free Software Foundation; either version
   8  * 2 of the License, or (at your option) any later version.
   9  */
  10
  11 /*
  12  * This is a version of ip_compute_csum() optimized for IP headers,
  13  * which always checksum on 4 octet boundaries.  ihl is the number
  14  * of 32-bit words and is always >= 5.
  15  */
  16 extern unsigned short ip_fast_csum(unsigned char * iph, unsigned int ihl);
  17
  18 /*
  19  * computes the checksum of the TCP/UDP pseudo-header
  20  * returns a 16-bit checksum, already complemented
  21  */
  22 extern unsigned short csum_tcpudp_magic(unsigned long saddr,
  23                                         unsigned long daddr,
  24                                         unsigned short len,
  25                                         unsigned short proto,
  26                                         unsigned int 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  */
  40 extern unsigned int csum_partial(const unsigned char * buff, int len,
  41                                  unsigned int sum);
  42
  43 /*
  44  * Computes the checksum of a memory block at src, length len,
  45  * and adds in "sum" (32-bit), while copying the block to dst.
  46  * If an access exception occurs on src or dst, it stores -EFAULT
  47  * to *src_err or *dst_err respectively (if that pointer is not
  48  * NULL), and, for an error on src, zeroes the rest of dst.
  49  *
  50  * Like csum_partial, this must be called with even lengths,
  51  * except for the last fragment.
  52  */
  53 extern unsigned int csum_partial_copy_generic(const char *src, char *dst,
  54                                               int len, unsigned int sum,
  55                                               int *src_err, int *dst_err);
  56 /*
  57  * the same as csum_partial, but copies from src to dst while it
  58  * checksums.
  59  */
  60 unsigned int csum_partial_copy_nocheck(const char *src,
  61                                        char *dst,
  62                                        int len,
  63                                        unsigned int sum);
  64
  65 #define csum_partial_copy_from_user(src, dst, len, sum, errp)   \
  66         csum_partial_copy_generic((src), (dst), (len), (sum), (errp), NULL)
  67
  68 #define csum_partial_copy_nocheck(src, dst, len, sum)   \
  69         csum_partial_copy_generic((src), (dst), (len), (sum), NULL, NULL)
  70
  71
  72 /*
  73  * turns a 32-bit partial checksum (e.g. from csum_partial) into a
  74  * 1's complement 16-bit checksum.
  75  */
  76 static inline unsigned int csum_fold(unsigned int sum)
  77 {
  78         unsigned int tmp;
  79
  80         /* swap the two 16-bit halves of sum */
  81         __asm__("rlwinm %0,%1,16,0,31" : "=r" (tmp) : "r" (sum));
  82         /* if there is a carry from adding the two 16-bit halves,
  83            it will carry from the lower half into the upper half,
  84            giving us the correct sum in the upper half. */
  85         sum = ~(sum + tmp) >> 16;
  86         return sum;
  87 }
  88
  89 /*
  90  * this routine is used for miscellaneous IP-like checksums, mainly
  91  * in icmp.c
  92  */
  93 static inline unsigned short ip_compute_csum(unsigned char * buff, int len)
  94 {
  95         return csum_fold(csum_partial(buff, len, 0));
  96 }
  97
  98 #ifdef __powerpc64__
  99 static inline u32 csum_tcpudp_nofold(u32 saddr,
 100                                      u32 daddr,
 101                                      unsigned short len,
 102                                      unsigned short proto,
 103                                      unsigned int sum)
 104 {
 105         unsigned long s = sum;
 106
 107         s += saddr;
 108         s += daddr;
 109         s += (proto << 16) + len;
 110         s += (s >> 32);
 111         return (u32) s;
 112 }
 113 #else
 114 static inline unsigned long csum_tcpudp_nofold(unsigned long saddr,
 115                                                    unsigned long daddr,
 116                                                    unsigned short len,
 117                                                    unsigned short proto,
 118                                                    unsigned int sum)
 119 {
 120     __asm__("\n\
 121         addc %0,%0,%1 \n\
 122         adde %0,%0,%2 \n\
 123         adde %0,%0,%3 \n\
 124         addze %0,%0 \n\
 125         "
 126         : "=r" (sum)
 127         : "r" (daddr), "r"(saddr), "r"((proto<<16)+len), "0"(sum));
 128     return sum;
 129 }
 130
 131 #endif
 132 #endif