--- /dev/null
+/**
+ * @file
+ * Functions common to all TCP/IPv6 modules, such as the Internet checksum and the
+ * byte order functions.
+ *
+ */
+
+/*
+ * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ * derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
+ * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
+ * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
+ * OF SUCH DAMAGE.
+ *
+ * This file is part of the lwIP TCP/IP stack.
+ *
+ * Author: Adam Dunkels <adam@sics.se>
+ *
+ */
+
+#include "lwip/opt.h"
+
+#include "lwip/def.h"
+#include "lwip/inet.h"
+
+/* chksum:
+ *
+ * Sums up all 16 bit words in a memory portion. Also includes any odd byte.
+ * This function is used by the other checksum functions.
+ *
+ * For now, this is not optimized. Must be optimized for the particular processor
+ * arcitecture on which it is to run. Preferebly coded in assembler.
+ */
+
+static u32_t
+chksum(void *dataptr, u16_t len)
+{
+ u16_t *sdataptr = dataptr;
+ u32_t acc;
+
+
+ for(acc = 0; len > 1; len -= 2) {
+ acc += *sdataptr++;
+ }
+
+ /* add up any odd byte */
+ if (len == 1) {
+ acc += htons((u16_t)(*(u8_t *)dataptr) << 8);
+ }
+
+ return acc;
+
+}
+
+/* inet_chksum_pseudo:
+ *
+ * Calculates the pseudo Internet checksum used by TCP and UDP for a pbuf chain.
+ */
+
+u16_t
+inet_chksum_pseudo(struct pbuf *p,
+ struct ip_addr *src, struct ip_addr *dest,
+ u8_t proto, u32_t proto_len)
+{
+ u32_t acc;
+ struct pbuf *q;
+ u8_t swapped, i;
+
+ acc = 0;
+ swapped = 0;
+ for(q = p; q != NULL; q = q->next) {
+ acc += chksum(q->payload, q->len);
+ while (acc >> 16) {
+ acc = (acc & 0xffff) + (acc >> 16);
+ }
+ if (q->len % 2 != 0) {
+ swapped = 1 - swapped;
+ acc = ((acc & 0xff) << 8) | ((acc & 0xff00) >> 8);
+ }
+ }
+
+ if (swapped) {
+ acc = ((acc & 0xff) << 8) | ((acc & 0xff00) >> 8);
+ }
+
+ for(i = 0; i < 8; i++) {
+ acc += ((u16_t *)src->addr)[i] & 0xffff;
+ acc += ((u16_t *)dest->addr)[i] & 0xffff;
+ while (acc >> 16) {
+ acc = (acc & 0xffff) + (acc >> 16);
+ }
+ }
+ acc += (u16_t)htons((u16_t)proto);
+ acc += ((u16_t *)&proto_len)[0] & 0xffff;
+ acc += ((u16_t *)&proto_len)[1] & 0xffff;
+
+ while (acc >> 16) {
+ acc = (acc & 0xffff) + (acc >> 16);
+ }
+ return ~(acc & 0xffff);
+}
+
+/* inet_chksum:
+ *
+ * Calculates the Internet checksum over a portion of memory. Used primarely for IP
+ * and ICMP.
+ */
+
+u16_t
+inet_chksum(void *dataptr, u16_t len)
+{
+ u32_t acc, sum;
+
+ acc = chksum(dataptr, len);
+ sum = (acc & 0xffff) + (acc >> 16);
+ sum += (sum >> 16);
+ return ~(sum & 0xffff);
+}
+
+u16_t
+inet_chksum_pbuf(struct pbuf *p)
+{
+ u32_t acc;
+ struct pbuf *q;
+ u8_t swapped;
+
+ acc = 0;
+ swapped = 0;
+ for(q = p; q != NULL; q = q->next) {
+ acc += chksum(q->payload, q->len);
+ while (acc >> 16) {
+ acc = (acc & 0xffff) + (acc >> 16);
+ }
+ if (q->len % 2 != 0) {
+ swapped = 1 - swapped;
+ acc = (acc & 0xff << 8) | (acc & 0xff00 >> 8);
+ }
+ }
+
+ if (swapped) {
+ acc = ((acc & 0xff) << 8) | ((acc & 0xff00) >> 8);
+ }
+ return ~(acc & 0xffff);
+}
