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author | Sven Eckelmann <sven@narfation.org> | 2010-12-13 11:19:28 +0000 |
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committer | David S. Miller <davem@davemloft.net> | 2010-12-16 13:44:24 -0800 |
commit | c6c8fea29769d998d94fcec9b9f14d4b52b349d3 (patch) | |
tree | 2c8dc8d1a64d48c5737a5745e3c510ff53a23047 /net/batman-adv/bitarray.c | |
parent | b236da6931e2482bfe44a7865dd4e7bb036f3496 (diff) | |
download | kernel_samsung_crespo-c6c8fea29769d998d94fcec9b9f14d4b52b349d3.zip kernel_samsung_crespo-c6c8fea29769d998d94fcec9b9f14d4b52b349d3.tar.gz kernel_samsung_crespo-c6c8fea29769d998d94fcec9b9f14d4b52b349d3.tar.bz2 |
net: Add batman-adv meshing protocol
B.A.T.M.A.N. (better approach to mobile ad-hoc networking) is a routing
protocol for multi-hop ad-hoc mesh networks. The networks may be wired or
wireless. See http://www.open-mesh.org/ for more information and user space
tools.
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/batman-adv/bitarray.c')
-rw-r--r-- | net/batman-adv/bitarray.c | 201 |
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 0000000..bbcd8f7 --- /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; +} |