Signed-off-by: Stefan Reinauer <stepan@coresystems.de>

Acked-by: Jordan Crouse <jordan.crouse@amd.com>


git-svn-id: svn://svn.coreboot.org/coreboot/trunk@2736 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1

util/lxbios/compute_ip_checksum.c

@@ -0,0 +1,44 @@
+/*****************************************************************************\
+ * compute_ip_checksum.c
+ * $Id: compute_ip_checksum.c,v 1.1.1.1 2005/12/02 22:35:19 dsp_llnl Exp $
+\*****************************************************************************/
+
+#include <stdint.h>
+#include "ip_checksum.h"
+
+/* Note: The contents of this file were borrowed from the LinuxBIOS source
+ *       code which may be obtained from http://www.linuxbios.org.
+ *       Specifically, this code was obtained from LinuxBIOS version 1.0.0.8.
+ */
+
+unsigned long compute_ip_checksum(void *addr, unsigned long length)
+{
+        uint8_t *ptr;
+        volatile union {
+                uint8_t  byte[2];
+                uint16_t word;
+        } value;
+        unsigned long sum;
+        unsigned long i;
+        /* In the most straight forward way possible,
+         * compute an ip style checksum.
+         */
+        sum = 0;
+        ptr = addr;
+        for(i = 0; i < length; i++) {
+                unsigned long value;
+                value = ptr[i];
+                if (i & 1) {
+                        value <<= 8;
+                }
+                /* Add the new value */
+                sum += value;
+                /* Wrap around the carry */
+                if (sum > 0xFFFF) {
+                        sum = (sum + (sum >> 16)) & 0xFFFF;
+                }
+        }
+        value.byte[0] = sum & 0xff;
+        value.byte[1] = (sum >> 8) & 0xff;
+        return (~value.word) & 0xFFFF;
+}