--- /dev/null
+/*
+ * Copyright (c) 1988, 1992, 1993
+ * The Regents of the University of California. 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. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
+ *
+ * @(#)in_cksum.c 8.1 (Berkeley) 6/10/93
+ * in_cksum.c,v 1.2 1994/08/02 07:48:16 davidg Exp
+ */
+
+#include <slirp.h>
+
+/*
+ * Checksum routine for Internet Protocol family headers (Portable Version).
+ *
+ * This routine is very heavily used in the network
+ * code and should be modified for each CPU to be as fast as possible.
+ *
+ * XXX Since we will never span more than 1 mbuf, we can optimise this
+ */
+
+#define ADDCARRY(x) (x > 65535 ? x -= 65535 : x)
+#define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; \
+ (void)ADDCARRY(sum);}
+
+int cksum(struct mbuf *m, int len)
+{
+ register uint16_t *w;
+ register int sum = 0;
+ register int mlen = 0;
+ int byte_swapped = 0;
+
+ union {
+ uint8_t c[2];
+ uint16_t s;
+ } s_util;
+ union {
+ uint16_t s[2];
+ uint32_t l;
+ } l_util;
+
+ if (m->m_len == 0)
+ goto cont;
+ w = mtod(m, uint16_t *);
+
+ mlen = m->m_len;
+
+ if (len < mlen)
+ mlen = len;
+#ifdef DEBUG
+ len -= mlen;
+#endif
+ /*
+ * Force to even boundary.
+ */
+ if ((1 & (uintptr_t)w) && (mlen > 0)) {
+ REDUCE;
+ sum <<= 8;
+ s_util.c[0] = *(uint8_t *)w;
+ w = (uint16_t *)((int8_t *)w + 1);
+ mlen--;
+ byte_swapped = 1;
+ }
+ /*
+ * Unroll the loop to make overhead from
+ * branches &c small.
+ */
+ while ((mlen -= 32) >= 0) {
+ sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
+ sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
+ sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
+ sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
+ w += 16;
+ }
+ mlen += 32;
+ while ((mlen -= 8) >= 0) {
+ sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
+ w += 4;
+ }
+ mlen += 8;
+ if (mlen == 0 && byte_swapped == 0)
+ goto cont;
+ REDUCE;
+ while ((mlen -= 2) >= 0) {
+ sum += *w++;
+ }
+
+ if (byte_swapped) {
+ REDUCE;
+ sum <<= 8;
+ if (mlen == -1) {
+ s_util.c[1] = *(uint8_t *)w;
+ sum += s_util.s;
+ mlen = 0;
+ } else
+
+ mlen = -1;
+ } else if (mlen == -1)
+ s_util.c[0] = *(uint8_t *)w;
+
+cont:
+#ifdef DEBUG
+ if (len) {
+ DEBUG_ERROR((dfd, "cksum: out of data\n"));
+ DEBUG_ERROR((dfd, " len = %d\n", len));
+ }
+#endif
+ if (mlen == -1) {
+ /* The last mbuf has odd # of bytes. Follow the
+ standard (the odd byte may be shifted left by 8 bits
+ or not as determined by endian-ness of the machine) */
+ s_util.c[1] = 0;
+ sum += s_util.s;
+ }
+ REDUCE;
+ return (~sum & 0xffff);
+}
Code Review / kvmfornfv.git / blobdiff