1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
|
/*
* Copyright 2012 Dominic Spill
*
* This file is part of Project Ubertooth.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* 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; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#include "bluetooth.h"
/* these values for hop() can be precalculated (at leastin part) */
u8 a1, b, c1, e;
u16 d1;
/* frequency register bank */
u8 bank[NUM_BREDR_CHANNELS];
u8 afh_bank[NUM_BREDR_CHANNELS];
/* count the number of 1 bits in a uint64_t */
static uint8_t count_bits(uint64_t n)
{
uint8_t i = 0;
for (i = 0; n != 0; i++)
n &= n - 1;
return i;
}
/* do all of the one time precalculation */
void precalc(void)
{
u8 i, j, chan;
u32 address;
address = target.address & 0xffffffff;
syncword = 0;
/* populate frequency register bank*/
for (i = 0; i < NUM_BREDR_CHANNELS; i++)
bank[i] = ((i * 2) % NUM_BREDR_CHANNELS);
/* actual frequency is 2402 + bank[i] MHz */
/* precalculate some of next_hop()'s variables */
a1 = (address >> 23) & 0x1f;
b = (address >> 19) & 0x0f;
c1 = ((address >> 4) & 0x10) +
((address >> 3) & 0x08) +
((address >> 2) & 0x04) +
((address >> 1) & 0x02) +
(address & 0x01);
d1 = (address >> 10) & 0x1ff;
e = ((address >> 7) & 0x40) +
((address >> 6) & 0x20) +
((address >> 5) & 0x10) +
((address >> 4) & 0x08) +
((address >> 3) & 0x04) +
((address >> 2) & 0x02) +
((address >> 1) & 0x01);
if(afh_enabled) {
used_channels = 0;
for(i = 0; i < 10; i++)
used_channels += count_bits((uint64_t) afh_map[i]);
j = 0;
for (i = 0; i < NUM_BREDR_CHANNELS; i++)
chan = (i * 2) % NUM_BREDR_CHANNELS;
if(afh_map[chan/8] & (0x1 << (chan % 8)))
bank[j++] = chan;
}
}
/* 5 bit permutation */
static u8 perm5(u8 z, u8 p_high, u16 p_low)
{
/* z is constrained to 5 bits, p_high to 5 bits, p_low to 9 bits */
z &= 0x1f;
p_high &= 0x1f;
p_low &= 0x1ff;
int i;
u8 tmp, output, z_bit[5], p[14];
static const u8 index1[] = {0, 2, 1, 3, 0, 1, 0, 3, 1, 0, 2, 1, 0, 1};
static const u8 index2[] = {1, 3, 2, 4, 4, 3, 2, 4, 4, 3, 4, 3, 3, 2};
/* bits of p_low and p_high are control signals */
for (i = 0; i < 9; i++)
p[i] = (p_low >> i) & 0x01;
for (i = 0; i < 5; i++)
p[i+9] = (p_high >> i) & 0x01;
/* bit swapping will be easier with an array of bits */
for (i = 0; i < 5; i++)
z_bit[i] = (z >> i) & 0x01;
/* butterfly operations */
for (i = 13; i >= 0; i--) {
/* swap bits according to index arrays if control signal tells us to */
if (p[i]) {
tmp = z_bit[index1[i]];
z_bit[index1[i]] = z_bit[index2[i]];
z_bit[index2[i]] = tmp;
}
}
/* reconstruct output from rearranged bits */
output = 0;
for (i = 0; i < 5; i++)
output += z_bit[i] << i;
return output;
}
u16 next_hop(u32 clock)
{
u8 a, c, x, y1, perm, next_channel;
u16 d, y2;
u32 base_f, f, f_dash;
clock &= 0xffffffff;
/* Variable names used in Vol 2, Part B, Section 2.6 of the spec */
x = (clock >> 2) & 0x1f;
y1 = (clock >> 1) & 0x01;
y2 = y1 << 5;
a = (a1 ^ (clock >> 21)) & 0x1f;
/* b is already defined */
c = (c1 ^ (clock >> 16)) & 0x1f;
d = (d1 ^ (clock >> 7)) & 0x1ff;
/* e is already defined */
base_f = (clock >> 3) & 0x1fffff0;
f = base_f % 79;
perm = perm5(
((x + a) % 32) ^ b,
(y1 * 0x1f) ^ c,
d);
/* hop selection */
next_channel = bank[(perm + e + f + y2) % NUM_BREDR_CHANNELS];
if(afh_enabled) {
f_dash = base_f % used_channels;
next_channel = afh_bank[(perm + e + f_dash + y2) % used_channels];
}
return (2402 + next_channel);
}
int find_access_code(u8 *idle_rxbuf)
{
/* Looks for an AC in the stream */
u8 bit_errors, curr_buf;
int i = 0, count = 0;
if (syncword == 0) {
for (; i<8; i++) {
syncword <<= 8;
syncword = (syncword & 0xffffffffffffff00) | idle_rxbuf[i];
}
count = 64;
}
curr_buf = idle_rxbuf[i];
// Search until we're 64 symbols from the end of the buffer
for(; count < ((8 * DMA_SIZE) - 64); count++)
{
bit_errors = count_bits(syncword ^ target.syncword);
if (bit_errors < MAX_SYNCWORD_ERRS)
return count;
if (count%8 == 0)
curr_buf = idle_rxbuf[++i];
syncword <<= 1;
syncword = (syncword & 0xfffffffffffffffe) | ((curr_buf & 0x80) >> 7);
curr_buf <<= 1;
}
return -1;
}
|
