1 /* -*- c++ -*- */
2 /*
3 * Copyright 2007,2012,2016 Free Software Foundation, Inc.
4 *
5 * This file is part of GNU Radio
6 *
7 * GNU Radio is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 3, or (at your option)
10 * any later version.
11 *
12 * GNU Radio is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with GNU Radio; see the file COPYING. If not, write to
19 * the Free Software Foundation, Inc., 51 Franklin Street,
20 * Boston, MA 02110-1301, USA.
21 */
22
23 #include <gnuradio/digital/glfsr.h>
24 #include <stdexcept>
25
26 namespace gr {
27 namespace digital {
28
29 static uint32_t s_polynomial_masks[] = {
30 0x00000000,
31 0x00000001, // x^1 + 1
32 0x00000003, // x^2 + x^1 + 1
33 0x00000005, // x^3 + x^1 + 1
34 0x00000009, // x^4 + x^1 + 1
35 0x00000012, // x^5 + x^2 + 1
36 0x00000021, // x^6 + x^1 + 1
37 0x00000041, // x^7 + x^1 + 1
38 0x0000008E, // x^8 + x^4 + x^3 + x^2 + 1
39 0x00000108, // x^9 + x^4 + 1
40 0x00000204, // x^10 + x^4 + 1
41 0x00000402, // x^11 + x^2 + 1
42 0x00000829, // x^12 + x^6 + x^4 + x^1 + 1
43 0x0000100D, // x^13 + x^4 + x^3 + x^1 + 1
44 0x00002015, // x^14 + x^5 + x^3 + x^1 + 1
45 0x00004001, // x^15 + x^1 + 1
46 0x00008016, // x^16 + x^5 + x^3 + x^2 + 1
47 0x00010004, // x^17 + x^3 + 1
48 0x00020013, // x^18 + x^5 + x^2 + x^1 + 1
49 0x00040013, // x^19 + x^5 + x^2 + x^1 + 1
50 0x00080004, // x^20 + x^3 + 1
51 0x00100002, // x^21 + x^2 + 1
52 0x00200001, // x^22 + x^1 + 1
53 0x00400010, // x^23 + x^5 + 1
54 0x0080000D, // x^24 + x^4 + x^3 + x^1 + 1
55 0x01000004, // x^25 + x^3 + 1
56 0x02000023, // x^26 + x^6 + x^2 + x^1 + 1
57 0x04000013, // x^27 + x^5 + x^2 + x^1 + 1
58 0x08000004, // x^28 + x^3 + 1
59 0x10000002, // x^29 + x^2 + 1
60 0x20000029, // x^30 + x^4 + x^1 + 1
61 0x40000004, // x^31 + x^3 + 1
62 0x80000057 // x^32 + x^7 + x^5 + x^3 + x^2 + x^1 + 1
63 };
64
~glfsr()65 glfsr::~glfsr() {}
66
glfsr_mask(unsigned int degree)67 uint32_t glfsr::glfsr_mask(unsigned int degree)
68 {
69 if (degree < 1 || degree > 32)
70 throw std::runtime_error(
71 "glfsr::glfsr_mask(): degree must be between 1 and 32 inclusive");
72 return s_polynomial_masks[degree];
73 }
74
next_bit()75 uint8_t glfsr::next_bit()
76 {
77 unsigned char bit = d_shift_register & 0x1;
78 d_shift_register >>= 1;
79 if (bit)
80 d_shift_register ^= d_mask;
81 return bit;
82 }
83
84 } /* namespace digital */
85 } /* namespace gr */
86