1 files changed, 201 insertions, 0 deletions
diff --git a/net/batman-adv/bitarray.c b/net/batman-adv/bitarray.c
new file mode 100644
index 00000000000..bbcd8f744cd
--- /dev/null
+++ b/net/batman-adv/bitarray.c
@@ -0,0 +1,201 @@
+/*
+ * Copyright (C) 2006-2010 B.A.T.M.A.N. contributors:
+ *
+ * Simon Wunderlich, Marek Lindner
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA
+ *
+ */
+
+#include "main.h"
+#include "bitarray.h"
+
+#include <linux/bitops.h>
+
+/* returns true if the corresponding bit in the given seq_bits indicates true
+ * and curr_seqno is within range of last_seqno */
+uint8_t get_bit_status(unsigned long *seq_bits, uint32_t last_seqno,
+		       uint32_t curr_seqno)
+{
+	int32_t diff, word_offset, word_num;
+
+	diff = last_seqno - curr_seqno;
+	if (diff < 0 || diff >= TQ_LOCAL_WINDOW_SIZE) {
+		return 0;
+	} else {
+		/* which word */
+		word_num = (last_seqno - curr_seqno) / WORD_BIT_SIZE;
+		/* which position in the selected word */
+		word_offset = (last_seqno - curr_seqno) % WORD_BIT_SIZE;
+
+		if (test_bit(word_offset, &seq_bits[word_num]))
+			return 1;
+		else
+			return 0;
+	}
+}
+
+/* turn corresponding bit on, so we can remember that we got the packet */
+void bit_mark(unsigned long *seq_bits, int32_t n)
+{
+	int32_t word_offset, word_num;
+
+	/* if too old, just drop it */
+	if (n < 0 || n >= TQ_LOCAL_WINDOW_SIZE)
+		return;
+
+	/* which word */
+	word_num = n / WORD_BIT_SIZE;
+	/* which position in the selected word */
+	word_offset = n % WORD_BIT_SIZE;
+
+	set_bit(word_offset, &seq_bits[word_num]); /* turn the position on */
+}
+
+/* shift the packet array by n places. */
+static void bit_shift(unsigned long *seq_bits, int32_t n)
+{
+	int32_t word_offset, word_num;
+	int32_t i;
+
+	if (n <= 0 || n >= TQ_LOCAL_WINDOW_SIZE)
+		return;
+
+	word_offset = n % WORD_BIT_SIZE;/* shift how much inside each word */
+	word_num = n / WORD_BIT_SIZE;	/* shift over how much (full) words */
+
+	for (i = NUM_WORDS - 1; i > word_num; i--) {
+		/* going from old to new, so we don't overwrite the data we copy
+		 * from.
+		 *
+		 * left is high, right is low: FEDC BA98 7654 3210
+		 *					  ^^ ^^
+		 *			       vvvv
+		 * ^^^^ = from, vvvvv =to, we'd have word_num==1 and
+		 * word_offset==WORD_BIT_SIZE/2 ????? in this example.
+		 * (=24 bits)
+		 *
+		 * our desired output would be: 9876 5432 1000 0000
+		 * */
+
+		seq_bits[i] =
+			(seq_bits[i - word_num] << word_offset) +
+			/* take the lower port from the left half, shift it left
+			 * to its final position */
+			(seq_bits[i - word_num - 1] >>
+			 (WORD_BIT_SIZE-word_offset));
+		/* and the upper part of the right half and shift it left to
+		 * it's position */
+		/* for our example that would be: word[0] = 9800 + 0076 =
+		 * 9876 */
+	}
+	/* now for our last word, i==word_num, we only have the it's "left"
+	 * half. that's the 1000 word in our example.*/
+
+	seq_bits[i] = (seq_bits[i - word_num] << word_offset);
+
+	/* pad the rest with 0, if there is anything */
+	i--;
+
+	for (; i >= 0; i--)
+		seq_bits[i] = 0;
+}
+
+static void bit_reset_window(unsigned long *seq_bits)
+{
+	int i;
+	for (i = 0; i < NUM_WORDS; i++)
+		seq_bits[i] = 0;
+}
+
+
+/* receive and process one packet within the sequence number window.
+ *
+ * returns:
+ *  1 if the window was moved (either new or very old)
+ *  0 if the window was not moved/shifted.
+ */
+char bit_get_packet(void *priv, unsigned long *seq_bits,
+		    int32_t seq_num_diff, int8_t set_mark)
+{
+	struct bat_priv *bat_priv = (struct bat_priv *)priv;
+
+	/* sequence number is slightly older. We already got a sequence number
+	 * higher than this one, so we just mark it. */
+
+	if ((seq_num_diff <= 0) && (seq_num_diff > -TQ_LOCAL_WINDOW_SIZE)) {
+		if (set_mark)
+			bit_mark(seq_bits, -seq_num_diff);
+		return 0;
+	}
+
+	/* sequence number is slightly newer, so we shift the window and
+	 * set the mark if required */
+
+	if ((seq_num_diff > 0) && (seq_num_diff < TQ_LOCAL_WINDOW_SIZE)) {
+		bit_shift(seq_bits, seq_num_diff);
+
+		if (set_mark)
+			bit_mark(seq_bits, 0);
+		return 1;
+	}
+
+	/* sequence number is much newer, probably missed a lot of packets */
+
+	if ((seq_num_diff >= TQ_LOCAL_WINDOW_SIZE)
+		|| (seq_num_diff < EXPECTED_SEQNO_RANGE)) {
+		bat_dbg(DBG_BATMAN, bat_priv,
+			"We missed a lot of packets (%i) !\n",
+			seq_num_diff - 1);
+		bit_reset_window(seq_bits);
+		if (set_mark)
+			bit_mark(seq_bits, 0);
+		return 1;
+	}
+
+	/* received a much older packet. The other host either restarted
+	 * or the old packet got delayed somewhere in the network. The
+	 * packet should be dropped without calling this function if the
+	 * seqno window is protected. */
+
+	if ((seq_num_diff <= -TQ_LOCAL_WINDOW_SIZE)
+		|| (seq_num_diff >= EXPECTED_SEQNO_RANGE)) {
+
+		bat_dbg(DBG_BATMAN, bat_priv,
+			"Other host probably restarted!\n");
+
+		bit_reset_window(seq_bits);
+		if (set_mark)
+			bit_mark(seq_bits, 0);
+
+		return 1;
+	}
+
+	/* never reached */
+	return 0;
+}
+
+/* count the hamming weight, how many good packets did we receive? just count
+ * the 1's.
+ */
+int bit_packet_count(unsigned long *seq_bits)
+{
+	int i, hamming = 0;
+
+	for (i = 0; i < NUM_WORDS; i++)
+		hamming += hweight_long(seq_bits[i]);
+
+	return hamming;
+}