include/asm-ppc/checksum.h

   1 #ifdef __KERNEL__
   2 #ifndef _PPC_CHECKSUM_H
   3 #define _PPC_CHECKSUM_H
   4
   5
   6 /*
   7  * computes the checksum of a memory block at buff, length len,
   8  * and adds in "sum" (32-bit)
   9  *
  10  * returns a 32-bit number suitable for feeding into itself
  11  * or csum_tcpudp_magic
  12  *
  13  * this function must be called with even lengths, except
  14  * for the last fragment, which may be odd
  15  *
  16  * it's best to have buff aligned on a 32-bit boundary
  17  */
  18 extern unsigned int csum_partial(const unsigned char * buff, int len,
  19                                  unsigned int sum);
  20
  21 /*
  22  * Computes the checksum of a memory block at src, length len,
  23  * and adds in "sum" (32-bit), while copying the block to dst.
  24  * If an access exception occurs on src or dst, it stores -EFAULT
  25  * to *src_err or *dst_err respectively (if that pointer is not
  26  * NULL), and, for an error on src, zeroes the rest of dst.
  27  *
  28  * Like csum_partial, this must be called with even lengths,
  29  * except for the last fragment.
  30  */
  31 extern unsigned int csum_partial_copy_generic(const char *src, char *dst,
  32                                               int len, unsigned int sum,
  33                                               int *src_err, int *dst_err);
  34
  35 #define csum_partial_copy_from_user(src, dst, len, sum, errp)   \
  36         csum_partial_copy_generic((__force void *)(src), (dst), (len), (sum), (errp), NULL)
  37
  38 /* FIXME: this needs to be written to really do no check -- Cort */
  39 #define csum_partial_copy_nocheck(src, dst, len, sum)   \
  40         csum_partial_copy_generic((src), (dst), (len), (sum), NULL, NULL)
  41
  42 /*
  43  * turns a 32-bit partial checksum (e.g. from csum_partial) into a
  44  * 1's complement 16-bit checksum.
  45  */
  46 static inline unsigned int csum_fold(unsigned int sum)
  47 {
  48         unsigned int tmp;
  49
  50         /* swap the two 16-bit halves of sum */
  51         __asm__("rlwinm %0,%1,16,0,31" : "=r" (tmp) : "r" (sum));
  52         /* if there is a carry from adding the two 16-bit halves,
  53            it will carry from the lower half into the upper half,
  54            giving us the correct sum in the upper half. */
  55         sum = ~(sum + tmp) >> 16;
  56         return sum;
  57 }
  58
  59 /*
  60  * this routine is used for miscellaneous IP-like checksums, mainly
  61  * in icmp.c
  62  */
  63 static inline unsigned short ip_compute_csum(unsigned char * buff, int len)
  64 {
  65         return csum_fold(csum_partial(buff, len, 0));
  66 }
  67
  68 /*
  69  * FIXME: I swiped this one from the sparc and made minor modifications.
  70  * It may not be correct.  -- Cort
  71  */
  72 static inline unsigned long csum_tcpudp_nofold(unsigned long saddr,
  73                                                    unsigned long daddr,
  74                                                    unsigned short len,
  75                                                    unsigned short proto,
  76                                                    unsigned int sum)
  77 {
  78     __asm__("\n\
  79         addc %0,%0,%1 \n\
  80         adde %0,%0,%2 \n\
  81         adde %0,%0,%3 \n\
  82         addze %0,%0 \n\
  83         "
  84         : "=r" (sum)
  85         : "r" (daddr), "r"(saddr), "r"((proto<<16)+len), "0"(sum));
  86     return sum;
  87 }
  88
  89 /*
  90  * This is a version of ip_compute_csum() optimized for IP headers,
  91  * which always checksum on 4 octet boundaries.  ihl is the number
  92  * of 32-bit words and is always >= 5.
  93  */
  94 extern unsigned short ip_fast_csum(unsigned char * iph, unsigned int ihl);
  95
  96 /*
  97  * computes the checksum of the TCP/UDP pseudo-header
  98  * returns a 16-bit checksum, already complemented
  99  */
 100 extern unsigned short csum_tcpudp_magic(unsigned long saddr,
 101                                         unsigned long daddr,
 102                                         unsigned short len,
 103                                         unsigned short proto,
 104                                         unsigned int sum);
 105
 106 #endif
 107 #endif /* __KERNEL__ */