1 files changed, 68 insertions, 0 deletions
diff --git a/src/libip/ptclbsum.c b/src/libip/ptclbsum.c
new file mode 100644
index 00000000..d87815bc
--- /dev/null
+++ b/src/libip/ptclbsum.c
@@ -0,0 +1,68 @@
+#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;
+}