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- #include <u.h>
- #include <libc.h>
- #include <ip.h>
- static short endian = 1;
- static uchar* aendian = (uchar*)&endian;
- #define LITTLE *aendian
- ushort
- ptclbsum(uchar *addr, int len)
- {
- ulong losum, hisum, mdsum, x;
- ulong t1, t2;
- losum = 0;
- hisum = 0;
- mdsum = 0;
- x = 0;
- if((ulong)addr & 1) {
- if(len) {
- hisum += addr[0];
- len--;
- addr++;
- }
- x = 1;
- }
- while(len >= 16) {
- t1 = *(ushort*)(addr+0);
- t2 = *(ushort*)(addr+2); mdsum += t1;
- t1 = *(ushort*)(addr+4); mdsum += t2;
- t2 = *(ushort*)(addr+6); mdsum += t1;
- t1 = *(ushort*)(addr+8); mdsum += t2;
- t2 = *(ushort*)(addr+10); mdsum += t1;
- t1 = *(ushort*)(addr+12); mdsum += t2;
- t2 = *(ushort*)(addr+14); mdsum += t1;
- mdsum += t2;
- len -= 16;
- addr += 16;
- }
- while(len >= 2) {
- mdsum += *(ushort*)addr;
- len -= 2;
- addr += 2;
- }
- if(x) {
- if(len)
- losum += addr[0];
- if(LITTLE)
- losum += mdsum;
- else
- hisum += mdsum;
- } else {
- if(len)
- hisum += addr[0];
- if(LITTLE)
- hisum += mdsum;
- else
- losum += mdsum;
- }
- losum += hisum >> 8;
- losum += (hisum & 0xff) << 8;
- while(hisum = losum>>16)
- losum = hisum + (losum & 0xffff);
- return losum & 0xffff;
- }
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