release/src-rt-6.x.4708/linux/linux-2.6.36/arch/ia64/lib/csum_partial_copy.c

   1 /*
   2  * Network Checksum & Copy routine
   3  *
   4  * Copyright (C) 1999, 2003-2004 Hewlett-Packard Co
   5  *      Stephane Eranian <eranian@hpl.hp.com>
   6  *
   7  * Most of the code has been imported from Linux/Alpha
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/types.h>
  12 #include <linux/string.h>
  13
  14 #include <asm/uaccess.h>
  15
  16 static inline unsigned
  17 short from64to16(unsigned long x)
  18 {
  19         /* add up 32-bit words for 33 bits */
  20         x = (x & 0xffffffff) + (x >> 32);
  21         /* add up 16-bit and 17-bit words for 17+c bits */
  22         x = (x & 0xffff) + (x >> 16);
  23         /* add up 16-bit and 2-bit for 16+c bit */
  24         x = (x & 0xffff) + (x >> 16);
  25         /* add up carry.. */
  26         x = (x & 0xffff) + (x >> 16);
  27         return x;
  28 }
  29
  30 static inline
  31 unsigned long do_csum_c(const unsigned char * buff, int len, unsigned int psum)
  32 {
  33         int odd, count;
  34         unsigned long result = (unsigned long)psum;
  35
  36         if (len <= 0)
  37                 goto out;
  38         odd = 1 & (unsigned long) buff;
  39         if (odd) {
  40                 result = *buff << 8;
  41                 len--;
  42                 buff++;
  43         }
  44         count = len >> 1;               /* nr of 16-bit words.. */
  45         if (count) {
  46                 if (2 & (unsigned long) buff) {
  47                         result += *(unsigned short *) buff;
  48                         count--;
  49                         len -= 2;
  50                         buff += 2;
  51                 }
  52                 count >>= 1;            /* nr of 32-bit words.. */
  53                 if (count) {
  54                         if (4 & (unsigned long) buff) {
  55                                 result += *(unsigned int *) buff;
  56                                 count--;
  57                                 len -= 4;
  58                                 buff += 4;
  59                         }
  60                         count >>= 1;    /* nr of 64-bit words.. */
  61                         if (count) {
  62                                 unsigned long carry = 0;
  63                                 do {
  64                                         unsigned long w = *(unsigned long *) buff;
  65                                         count--;
  66                                         buff += 8;
  67                                         result += carry;
  68                                         result += w;
  69                                         carry = (w > result);
  70                                 } while (count);
  71                                 result += carry;
  72                                 result = (result & 0xffffffff) + (result >> 32);
  73                         }
  74                         if (len & 4) {
  75                                 result += *(unsigned int *) buff;
  76                                 buff += 4;
  77                         }
  78                 }
  79                 if (len & 2) {
  80                         result += *(unsigned short *) buff;
  81                         buff += 2;
  82                 }
  83         }
  84         if (len & 1)
  85                 result += *buff;
  86
  87         result = from64to16(result);
  88
  89         if (odd)
  90                 result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
  91
  92 out:
  93         return result;
  94 }
  95
  96 extern unsigned long do_csum(const unsigned char *, long);
  97
  98 __wsum
  99 csum_partial_copy_from_user(const void __user *src, void *dst,
 100                                 int len, __wsum psum, int *errp)
 101 {
 102         unsigned long result;
 103
 104
 105         if (__copy_from_user(dst, src, len) != 0 && errp)
 106                 *errp = -EFAULT;
 107
 108         result = do_csum(dst, len);
 109
 110         /* add in old sum, and carry.. */
 111         result += (__force u32)psum;
 112         /* 32+c bits -> 32 bits */
 113         result = (result & 0xffffffff) + (result >> 32);
 114         return (__force __wsum)result;
 115 }
 116
 117 EXPORT_SYMBOL(csum_partial_copy_from_user);
 118
 119 __wsum
 120 csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum)
 121 {
 122         return csum_partial_copy_from_user((__force const void __user *)src,
 123                                            dst, len, sum, NULL);
 124 }
 125
 126 EXPORT_SYMBOL(csum_partial_copy_nocheck);