kern/src/net/ptclbsum.c

   1 // INFERNO
   2 #include <vfs.h>
   3 #include <kfs.h>
   4 #include <slab.h>
   5 #include <kmalloc.h>
   6 #include <kref.h>
   7 #include <string.h>
   8 #include <stdio.h>
   9 #include <assert.h>
  10 #include <error.h>
  11 #include <cpio.h>
  12 #include <pmap.h>
  13 #include <smp.h>
  14 #include <ip.h>
  15
  16 static  short   endian  = 1;
  17 static  uint8_t*        aendian = ( uint8_t *)&endian;
  18 #define LITTLE  *aendian
  19
  20 uint16_t
  21 ptclbsum(uint8_t *addr, int len)
  22 {
  23         uint32_t losum, hisum, mdsum, x;
  24         uint32_t t1, t2;
  25
  26         losum = 0;
  27         hisum = 0;
  28         mdsum = 0;
  29
  30         x = 0;
  31         if((uint32_t)addr & 1) {
  32                 if(len) {
  33                         hisum += addr[0];
  34                         len--;
  35                         addr++;
  36                 }
  37                 x = 1;
  38         }
  39         while(len >= 16) {
  40                 t1 = *(uint16_t*)(addr+0);
  41                 t2 = *(uint16_t*)(addr+2);      mdsum += t1;
  42                 t1 = *(uint16_t*)(addr+4);      mdsum += t2;
  43                 t2 = *(uint16_t*)(addr+6);      mdsum += t1;
  44                 t1 = *(uint16_t*)(addr+8);      mdsum += t2;
  45                 t2 = *(uint16_t*)(addr+10);     mdsum += t1;
  46                 t1 = *(uint16_t*)(addr+12);     mdsum += t2;
  47                 t2 = *(uint16_t*)(addr+14);     mdsum += t1;
  48                 mdsum += t2;
  49                 len -= 16;
  50                 addr += 16;
  51         }
  52         while(len >= 2) {
  53                 mdsum += *(uint16_t*)addr;
  54                 len -= 2;
  55                 addr += 2;
  56         }
  57         if(x) {
  58                 if(len)
  59                         losum += addr[0];
  60                 if(LITTLE)
  61                         losum += mdsum;
  62                 else
  63                         hisum += mdsum;
  64         } else {
  65                 if(len)
  66                         hisum += addr[0];
  67                 if(LITTLE)
  68                         hisum += mdsum;
  69                 else
  70                         losum += mdsum;
  71         }
  72
  73         losum += hisum >> 8;
  74         losum += (hisum & 0xff) << 8;
  75         while(hisum = losum>>16)
  76                 losum = hisum + (losum & 0xffff);
  77
  78         return losum & 0xffff;
  79 }