include/asm-cris/checksum.h

   1 /* TODO: csum_tcpudp_magic could be speeded up, and csum_fold as well */
   2
   3 #ifndef _CRIS_CHECKSUM_H
   4 #define _CRIS_CHECKSUM_H
   5
   6 #include <asm/arch/checksum.h>
   7
   8 /*
   9  * computes the checksum of a memory block at buff, length len,
  10  * and adds in "sum" (32-bit)
  11  *
  12  * returns a 32-bit number suitable for feeding into itself
  13  * or csum_tcpudp_magic
  14  *
  15  * this function must be called with even lengths, except
  16  * for the last fragment, which may be odd
  17  *
  18  * it's best to have buff aligned on a 32-bit boundary
  19  */
  20 unsigned int csum_partial(const unsigned char * buff, int len, unsigned int sum);
  21
  22 /*
  23  * the same as csum_partial, but copies from src while it
  24  * checksums
  25  *
  26  * here even more important to align src and dst on a 32-bit (or even
  27  * better 64-bit) boundary
  28  */
  29
  30 unsigned int csum_partial_copy_nocheck(const char *src, char *dst,
  31                                        int len, unsigned int sum);
  32
  33 /*
  34  *      Fold a partial checksum into a word
  35  */
  36
  37 static inline unsigned int csum_fold(unsigned int sum)
  38 {
  39         /* the while loop is unnecessary really, it's always enough with two
  40            iterations */
  41
  42         while(sum >> 16)
  43                 sum = (sum & 0xffff) + (sum >> 16); /* add in end-around carry */
  44
  45         return ~sum;
  46 }
  47
  48 extern unsigned int csum_partial_copy_from_user(const char *src, char *dst,
  49                                                 int len, unsigned int sum,
  50                                                 int *errptr);
  51
  52 /*
  53  *      This is a version of ip_compute_csum() optimized for IP headers,
  54  *      which always checksum on 4 octet boundaries.
  55  *
  56  */
  57
  58 static inline unsigned short ip_fast_csum(unsigned char * iph,
  59                                           unsigned int ihl)
  60 {
  61         return csum_fold(csum_partial(iph, ihl * 4, 0));
  62 }
  63
  64 /*
  65  * computes the checksum of the TCP/UDP pseudo-header
  66  * returns a 16-bit checksum, already complemented
  67  */
  68
  69 static inline unsigned short int csum_tcpudp_magic(unsigned long saddr,
  70                                                    unsigned long daddr,
  71                                                    unsigned short len,
  72                                                    unsigned short proto,
  73                                                    unsigned int sum)
  74 {
  75         return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
  76 }
  77
  78 /*
  79  * this routine is used for miscellaneous IP-like checksums, mainly
  80  * in icmp.c
  81  */
  82
  83 static inline unsigned short ip_compute_csum(unsigned char * buff, int len) {
  84         return csum_fold (csum_partial(buff, len, 0));
  85 }
  86
  87 #endif