1 #include <u.h> 2 #include <libc.h> 3 #include <ip.h> 4 5 static short endian = 1; 6 static uchar* aendian = (uchar*)&endian; 7 #define LITTLE *aendian 8 9 ushort ptclbsum(uchar * addr,int len)10ptclbsum(uchar *addr, int len) 11 { 12 ulong losum, hisum, mdsum, x; 13 ulong t1, t2; 14 15 losum = 0; 16 hisum = 0; 17 mdsum = 0; 18 19 x = 0; 20 if((uintptr)addr & 1) { 21 if(len) { 22 hisum += addr[0]; 23 len--; 24 addr++; 25 } 26 x = 1; 27 } 28 while(len >= 16) { 29 t1 = *(ushort*)(addr+0); 30 t2 = *(ushort*)(addr+2); mdsum += t1; 31 t1 = *(ushort*)(addr+4); mdsum += t2; 32 t2 = *(ushort*)(addr+6); mdsum += t1; 33 t1 = *(ushort*)(addr+8); mdsum += t2; 34 t2 = *(ushort*)(addr+10); mdsum += t1; 35 t1 = *(ushort*)(addr+12); mdsum += t2; 36 t2 = *(ushort*)(addr+14); mdsum += t1; 37 mdsum += t2; 38 len -= 16; 39 addr += 16; 40 } 41 while(len >= 2) { 42 mdsum += *(ushort*)addr; 43 len -= 2; 44 addr += 2; 45 } 46 if(x) { 47 if(len) 48 losum += addr[0]; 49 if(LITTLE) 50 losum += mdsum; 51 else 52 hisum += mdsum; 53 } else { 54 if(len) 55 hisum += addr[0]; 56 if(LITTLE) 57 hisum += mdsum; 58 else 59 losum += mdsum; 60 } 61 62 losum += hisum >> 8; 63 losum += (hisum & 0xff) << 8; 64 while(hisum = losum>>16) 65 losum = hisum + (losum & 0xffff); 66 67 return losum & 0xffff; 68 } 69