arch/sh64/lib/c-checksum.c

   1 /*
   2  * arch/sh64/lib/c-checksum.c
   3  *
   4  * This file contains network checksum routines that are better done
   5  * in an architecture-specific manner due to speed..
   6  */
   7
   8 #undef DEBUG
   9
  10 #include <linux/string.h>
  11 #include <linux/errno.h>
  12 #include <linux/kernel.h>
  13 #include <asm/byteorder.h>
  14 #include <asm/uaccess.h>
  15
  16 static inline unsigned short from64to16(unsigned long long x)
  17 {
  18         /* add up 32-bit words for 33 bits */
  19         x = (x & 0xffffffff) + (x >> 32);
  20         /* add up 16-bit and 17-bit words for 17+c bits */
  21         x = (x & 0xffff) + (x >> 16);
  22         /* add up 16-bit and 2-bit for 16+c bit */
  23         x = (x & 0xffff) + (x >> 16);
  24         /* add up carry.. */
  25         x = (x & 0xffff) + (x >> 16);
  26         return x;
  27 }
  28
  29 static inline unsigned short foldto16(unsigned long x)
  30 {
  31         /* add up 16-bit for 17 bits */
  32         x = (x & 0xffff) + (x >> 16);
  33         /* add up carry.. */
  34         x = (x & 0xffff) + (x >> 16);
  35         return x;
  36 }
  37
  38 static inline unsigned short myfoldto16(unsigned long long x)
  39 {
  40         /* Fold down to 32-bits so we don't loose in the typedef-less
  41            network stack.  */
  42         /* 64 to 33 */
  43         x = (x & 0xffffffff) + (x >> 32);
  44         /* 33 to 32 */
  45         x = (x & 0xffffffff) + (x >> 32);
  46
  47         /* add up 16-bit for 17 bits */
  48         x = (x & 0xffff) + (x >> 16);
  49         /* add up carry.. */
  50         x = (x & 0xffff) + (x >> 16);
  51         return x;
  52 }
  53
  54 #define odd(x) ((x)&1)
  55 #define U16(x) ntohs(x)
  56
  57 static unsigned long do_csum(const unsigned char *buff, int len)
  58 {
  59         int odd, count;
  60         unsigned long result = 0;
  61
  62         pr_debug("do_csum buff %p, len %d (0x%x)\n", buff, len, len);
  63 #ifdef DEBUG
  64         for (i = 0; i < len; i++) {
  65                 if ((i % 26) == 0)
  66                         printk("\n");
  67                 printk("%02X ", buff[i]);
  68         }
  69 #endif
  70
  71         if (len <= 0)
  72                 goto out;
  73
  74         odd = 1 & (unsigned long) buff;
  75         if (odd) {
  76                 result = *buff << 8;
  77                 len--;
  78                 buff++;
  79         }
  80         count = len >> 1;       /* nr of 16-bit words.. */
  81         if (count) {
  82                 if (2 & (unsigned long) buff) {
  83                         result += *(unsigned short *) buff;
  84                         count--;
  85                         len -= 2;
  86                         buff += 2;
  87                 }
  88                 count >>= 1;    /* nr of 32-bit words.. */
  89                 if (count) {
  90                         unsigned long carry = 0;
  91                         do {
  92                                 unsigned long w = *(unsigned long *) buff;
  93                                 buff += 4;
  94                                 count--;
  95                                 result += carry;
  96                                 result += w;
  97                                 carry = (w > result);
  98                         } while (count);
  99                         result += carry;
 100                         result = (result & 0xffff) + (result >> 16);
 101                 }
 102                 if (len & 2) {
 103                         result += *(unsigned short *) buff;
 104                         buff += 2;
 105                 }
 106         }
 107         if (len & 1)
 108                 result += *buff;
 109         result = foldto16(result);
 110         if (odd)
 111                 result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
 112
 113         pr_debug("\nCHECKSUM is 0x%x\n", result);
 114
 115       out:
 116         return result;
 117 }
 118
 119 /* computes the checksum of a memory block at buff, length len,
 120    and adds in "sum" (32-bit)  */
 121 unsigned int csum_partial(const unsigned char *buff, int len, unsigned int sum)
 122 {
 123         unsigned long long result = do_csum(buff, len);
 124
 125         /* add in old sum, and carry.. */
 126         result += sum;
 127         /* 32+c bits -> 32 bits */
 128         result = (result & 0xffffffff) + (result >> 32);
 129
 130         pr_debug("csum_partial, buff %p len %d sum 0x%x result=0x%016Lx\n",
 131                 buff, len, sum, result);
 132
 133         return result;
 134 }
 135
 136 /* Copy while checksumming, otherwise like csum_partial.  */
 137 unsigned int
 138 csum_partial_copy(const unsigned char *src, unsigned char *dst, int len, unsigned int sum)
 139 {
 140         sum = csum_partial(src, len, sum);
 141         memcpy(dst, src, len);
 142
 143         return sum;
 144 }
 145
 146 /* Copy from userspace and compute checksum.  If we catch an exception
 147    then zero the rest of the buffer.  */
 148 unsigned int
 149 csum_partial_copy_from_user(const unsigned char *src, unsigned char *dst, int len,
 150                             unsigned int sum, int *err_ptr)
 151 {
 152         int missing;
 153
 154         pr_debug
 155             ("csum_partial_copy_from_user src %p, dest %p, len %d, sum %08x, err_ptr %p\n",
 156              src, dst, len, sum, err_ptr);
 157         missing = copy_from_user(dst, src, len);
 158         pr_debug("  access_ok %d\n", __access_ok((unsigned long) src, len));
 159         pr_debug("  missing %d\n", missing);
 160         if (missing) {
 161                 memset(dst + len - missing, 0, missing);
 162                 *err_ptr = -EFAULT;
 163         }
 164
 165         return csum_partial(dst, len, sum);
 166 }
 167
 168 /* Copy to userspace and compute checksum.  */
 169 unsigned int
 170 csum_partial_copy_to_user(const unsigned char *src, unsigned char *dst, int len,
 171                           unsigned int sum, int *err_ptr)
 172 {
 173         sum = csum_partial(src, len, sum);
 174
 175         if (copy_to_user(dst, src, len))
 176                 *err_ptr = -EFAULT;
 177
 178         return sum;
 179 }
 180
 181 /*
 182  *      This is a version of ip_compute_csum() optimized for IP headers,
 183  *      which always checksum on 4 octet boundaries.
 184  */
 185 unsigned short ip_fast_csum(unsigned char *iph, unsigned int ihl)
 186 {
 187         pr_debug("ip_fast_csum %p,%d\n", iph, ihl);
 188
 189         return ~do_csum(iph, ihl * 4);
 190 }
 191
 192 unsigned int csum_tcpudp_nofold(unsigned long saddr,
 193                                 unsigned long daddr,
 194                                 unsigned short len,
 195                                 unsigned short proto, unsigned int sum)
 196 {
 197         unsigned long long result;
 198
 199         pr_debug("ntohs(0x%x)=0x%x\n", 0xdead, ntohs(0xdead));
 200         pr_debug("htons(0x%x)=0x%x\n", 0xdead, htons(0xdead));
 201
 202         result = ((unsigned long long) saddr +
 203                   (unsigned long long) daddr +
 204                   (unsigned long long) sum +
 205                   ((unsigned long long) ntohs(len) << 16) +
 206                   ((unsigned long long) proto << 8));
 207
 208         /* Fold down to 32-bits so we don't loose in the typedef-less
 209            network stack.  */
 210         /* 64 to 33 */
 211         result = (result & 0xffffffff) + (result >> 32);
 212         /* 33 to 32 */
 213         result = (result & 0xffffffff) + (result >> 32);
 214
 215         pr_debug("%s saddr %x daddr %x len %x proto %x sum %x result %08Lx\n",
 216                 __FUNCTION__, saddr, daddr, len, proto, sum, result);
 217
 218         return result;
 219 }
 220
 221 // Post SIM:
 222 unsigned int
 223 csum_partial_copy_nocheck(const unsigned char *src, unsigned char *dst, int len, unsigned int sum)
 224 {
 225         //  unsigned dummy;
 226         pr_debug("csum_partial_copy_nocheck src %p dst %p len %d\n", src, dst,
 227                 len);
 228
 229         return csum_partial_copy(src, dst, len, sum);
 230 }