From 9e80202352dd49bdd9e67b8b906d86f058431505 Mon Sep 17 00:00:00 2001
From: Timothy Pearson <tpearson@raptorengineering.com>
Date: Sat, 11 May 2019 15:12:49 -0500
Subject: Initial import of abandoned HQEMU version 2.5.2
---
src/roms/openbios/libopenbios/ipchecksum.c | 55 ++++++++++++++++++++++++++++++
1 file changed, 55 insertions(+)
create mode 100644 src/roms/openbios/libopenbios/ipchecksum.c
(limited to 'src/roms/openbios/libopenbios/ipchecksum.c')
diff --git a/src/roms/openbios/libopenbios/ipchecksum.c b/src/roms/openbios/libopenbios/ipchecksum.c
new file mode 100644
index 0000000..83f39bc
--- /dev/null
+++ b/src/roms/openbios/libopenbios/ipchecksum.c
@@ -0,0 +1,55 @@
+/* Taken from Etherboot */
+
+#include "libopenbios/ipchecksum.h"
+
+unsigned short ipchksum(const void *data, unsigned long length)
+{
+ unsigned long sum;
+ unsigned long i;
+ const unsigned char *ptr;
+ union {
+ unsigned char byte[2];
+ unsigned short word;
+ } u;
+
+ /* In the most straight forward way possible,
+ * compute an ip style checksum.
+ */
+ sum = 0;
+ ptr = data;
+ 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;
+ }
+ }
+ u.byte[0] = (unsigned char) sum;
+ u.byte[1] = (unsigned char) (sum >> 8);
+ return (unsigned short) ~u.word;
+}
+
+unsigned short add_ipchksums(unsigned long offset, unsigned short sum, unsigned short new)
+{
+ unsigned long checksum;
+ sum = ~sum & 0xFFFF;
+ new = ~new & 0xFFFF;
+ if (offset & 1) {
+ /* byte swap the sum if it came from an odd offset
+ * since the computation is endian independant this
+ * works.
+ */
+ new = (new << 8) | (new >> 8);
+ }
+ checksum = sum + new;
+ if (checksum > 0xFFFF) {
+ checksum -= 0xFFFF;
+ }
+ return (~checksum) & 0xFFFF;
+}
--
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