LFSR伪随机数发生器

淡淡的烟草味﹌ 2022-11-26 08:46 238阅读 0赞

----------------------------------------------------------------------------
    ---- Create Date:    14:30:08 07/28/2010 											----		
    ---- Design Name: lfsr_pkg														   	----				
    ---- Project Name: lfsr_randgen													   ----	
    ---- Description: 																		----	
    ----  This is the package file used in the lfsr_randgen project.The     ----
    ----  package contain the function for XORing bits from various tap     ----
    ----  locations depending on the generic parameter(width of lfsr )      ----	
    ----																							----	
    ----------------------------------------------------------------------------
    ----                                                                    ----
    ---- This file is a part of the lfsr_randgen project at                 ----
    ---- http://www.opencores.org/						                        ----
    ----                                                                    ----
    ---- Author(s):                                                         ----
    ----   Vipin Lal, lalnitt@gmail.com                                     ----
    ----                                                                    ----
    ----------------------------------------------------------------------------
    ----                                                                    ----
    ---- Copyright (C) 2010 Authors and OPENCORES.ORG                       ----
    ----                                                                    ----
    ---- This source file may be used and distributed without               ----
    ---- restriction provided that this copyright statement is not          ----
    ---- removed from the file and that any derivative work contains        ----
    ---- the original copyright notice and the associated disclaimer.       ----
    ----                                                                    ----
    ---- This source file is free software; you can redistribute it         ----
    ---- and/or modify it under the terms of the GNU Lesser General         ----
    ---- Public License as published by the Free Software Foundation;       ----
    ---- either version 2.1 of the License, or (at your option) any         ----
    ---- later version.                                                     ----
    ----                                                                    ----
    ---- This source 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 Lesser General Public License for more        ----
    ---- details.                                                           ----
    ----                                                                    ----
    ---- You should have received a copy of the GNU Lesser General          ----
    ---- Public License along with this source; if not, download it         ----
    ---- from http://www.opencores.org/lgpl.shtml                           ----
    ----                                                                    ----
    ----------------------------------------------------------------------------
    
    library ieee;
    use ieee.std_logic_1164.all;
    use ieee.std_logic_arith.all;
    use ieee.std_logic_unsigned.all;
    
    package lfsr_pkg is
    
    function xor_gates( random : std_logic_vector) return std_logic;
    
    end lfsr_pkg;
    
    --Package body starts from here.
    package body lfsr_pkg is
    
    --function for XORing from tap values.
    function xor_gates( random : std_logic_vector ) return std_logic is
    
    variable xor_out : std_logic:='0';
    variable rand : std_logic_vector(random'length-1 downto 0):=random;
    
    begin
    if(rand'length = 3) then           --3
    xor_out := rand(2) xor rand(1);
    elsif(rand'length = 4) then		  --4	
    xor_out := rand(3) xor rand(2);
    elsif(rand'length = 5) then		  --5
    xor_out := rand(4) xor rand(2);
    elsif(rand'length = 6) then		  --6
    xor_out := rand(5) xor rand(4);
    elsif(rand'length = 7) then		  --7	
    xor_out := rand(6) xor rand(5);
    elsif(rand'length = 8) then		  --8
    xor_out := rand(7) xor rand(5) xor rand(4) xor rand(3);  
    elsif(rand'length = 9) then		  --9	
    xor_out := rand(8) xor rand(4);
    elsif(rand'length = 10)then		  --10	
    xor_out := rand(9) xor rand(6);
    elsif(rand'length =11) then		  --11
    xor_out := rand(10) xor rand(8);
    elsif(rand'length = 12) then		  --12
    xor_out := rand(11) xor rand(5) xor rand(3) xor rand(0);
    elsif(rand'length = 13) then		  --13	
    xor_out := rand(12) xor rand(3) xor rand(2) xor rand(0);
    elsif(rand'length = 14) then		  --14	
    xor_out := rand(13) xor rand(4) xor rand(2) xor rand(0);
    elsif(rand'length = 15) then		  --15
    xor_out := rand(14) xor rand(13);
    elsif(rand'length = 16) then		  --16
    xor_out := rand(15) xor rand(14) xor rand(12) xor rand(3);
    elsif(rand'length = 17) then		  --17
    xor_out := rand(16) xor rand(13);
    elsif(rand'length = 18) then		  --18
    xor_out := rand(17) xor rand(10);
    elsif(rand'length = 19) then		  --19
    xor_out := rand(18) xor rand(5) xor rand(1) xor rand(0);
    elsif(rand'length = 20) then		  --20
    xor_out := rand(19) xor rand(16);
    elsif(rand'length = 21) then		  --21
    xor_out := rand(20) xor rand(18);
    elsif(rand'length = 22) then		  --22
    xor_out := rand(21) xor rand(20);
    elsif(rand'length = 23) then		  --23
    xor_out := rand(22) xor rand(17);
    elsif(rand'length = 24) then		  --24
    xor_out := rand(23) xor rand(22) xor rand(21) xor rand(16);
    elsif(rand'length = 25) then		  --25
    xor_out := rand(24) xor rand(21);
    elsif(rand'length = 26) then		  --26
    xor_out := rand(25) xor rand(5) xor rand(1) xor rand(0);
    elsif(rand'length = 27) then		  --27
    xor_out := rand(26) xor rand(4) xor rand(1) xor rand(0);
    elsif(rand'length = 28) then		  --28
    xor_out := rand(27) xor rand(24);
    elsif(rand'length = 29) then		  --29
    xor_out := rand(28) xor rand(26);
    elsif(rand'length = 30) then		  --30
    xor_out := rand(29) xor rand(5) xor rand(3) xor rand(0);
    elsif(rand'length = 31) then		  --31
    xor_out := rand(30) xor rand(27);
    elsif(rand'length = 32) then		  --32
    xor_out := rand(31) xor rand(21) xor rand(1) xor rand(0);
    elsif(rand'length = 33) then		  --33
    xor_out := rand(32) xor rand(19);
    elsif(rand'length = 34) then		  --34
    xor_out := rand(33) xor rand(26) xor rand(1) xor rand(0);
    elsif(rand'length = 35) then		  --35
    xor_out := rand(34) xor rand(32);
    elsif(rand'length = 36) then		  --36
    xor_out := rand(35) xor rand(24);
    elsif(rand'length = 37) then		  --37
    xor_out := rand(36) xor rand(4) xor rand(3) xor rand(2) xor rand(1) xor rand(0);
    elsif(rand'length = 38) then		  --38
    xor_out := rand(37) xor rand(5) xor rand(4) xor rand(0);
    elsif(rand'length = 39) then		  --39
    xor_out := rand(38) xor rand(34);
    elsif(rand'length = 40) then		  --40
    xor_out := rand(39) xor rand(37) xor rand(20) xor rand(18);
    elsif(rand'length = 41) then		  --41
    xor_out := rand(40) xor rand(37);
    elsif(rand'length = 42) then		  --42
    xor_out := rand(41) xor rand(40) xor rand(19) xor rand(18);
    elsif(rand'length = 43) then		  --43
    xor_out := rand(42) xor rand(41) xor rand(37) xor rand(36);
    elsif(rand'length = 44) then		  --44
    xor_out := rand(43) xor rand(42) xor rand(17) xor rand(16);
    elsif(rand'length = 45) then		  --45
    xor_out := rand(44) xor rand(43) xor rand(41) xor rand(40);
    elsif(rand'length = 46) then		  --46
    xor_out := rand(45) xor rand(44) xor rand(25) xor rand(24);
    elsif(rand'length = 47) then		  --47
    xor_out := rand(46) xor rand(41);
    elsif(rand'length = 48) then		  --48
    xor_out := rand(47) xor rand(46) xor rand(20) xor rand(19);
    elsif(rand'length = 49) then		  --49
    xor_out := rand(48) xor rand(39);
    elsif(rand'length = 50) then		  --50
    xor_out := rand(49) xor rand(48) xor rand(23) xor rand(22);
    elsif(rand'length = 51) then		  --51
    xor_out := rand(50) xor rand(49) xor rand(35) xor rand(34);
    elsif(rand'length = 52) then		  --52
    xor_out := rand(51) xor rand(48);
    elsif(rand'length = 53) then		  --53
    xor_out := rand(52) xor rand(51) xor rand(37) xor rand(36);
    elsif(rand'length = 54) then		  --54
    xor_out := rand(53) xor rand(52) xor rand(17) xor rand(16);
    elsif(rand'length = 55) then		  --55
    xor_out := rand(54) xor rand(30);
    elsif(rand'length = 56) then		  --56
    xor_out := rand(55) xor rand(54) xor rand(34) xor rand(33);
    elsif(rand'length = 57) then		  --57
    xor_out := rand(56) xor rand(49);
    elsif(rand'length = 58) then		  --58
    xor_out := rand(57) xor rand(38);
    elsif(rand'length = 59) then		  --59
    xor_out := rand(58) xor rand(57) xor rand(37) xor rand(36);
    elsif(rand'length = 60) then		  --60
    xor_out := rand(59) xor rand(58);
    elsif(rand'length = 61) then		  --61
    xor_out := rand(60) xor rand(59) xor rand(45) xor rand(44);
    elsif(rand'length = 62) then		  --62
    xor_out := rand(61) xor rand(60) xor rand(5) xor rand(4);
    elsif(rand'length = 63) then		  --63
    xor_out := rand(62) xor rand(61);
    elsif(rand'length = 64) then		  --64
    xor_out := rand(63) xor rand(62) xor rand(60) xor rand(59);
    elsif(rand'length = 65) then		  --65
    xor_out := rand(64) xor rand(46);
    elsif(rand'length = 66) then		  --66
    xor_out := rand(65) xor rand(64) xor rand(56) xor rand(55);
    elsif(rand'length = 67) then		  --67
    xor_out := rand(66) xor rand(65) xor rand(57) xor rand(56);
    elsif(rand'length = 68) then		  --68
    xor_out := rand(67) xor rand(58);
    elsif(rand'length = 69) then		  --69
    xor_out := rand(68) xor rand(66) xor rand(41) xor rand(39);
    elsif(rand'length = 70) then		  --70
    xor_out := rand(69) xor rand(68) xor rand(54) xor rand(53);
    elsif(rand'length = 71) then		  --71
    xor_out := rand(70) xor rand(64);
    elsif(rand'length = 72) then		  --72
    xor_out := rand(71) xor rand(65) xor rand(24) xor rand(18);
    elsif(rand'length = 73) then		  --73
    xor_out := rand(72) xor rand(47);
    elsif(rand'length = 74) then		  --74
    xor_out := rand(73) xor rand(72) xor rand(58) xor rand(57);
    elsif(rand'length = 75) then		  --75
    xor_out := rand(74) xor rand(73) xor rand(64) xor rand(63);
    elsif(rand'length = 76) then		  --76
    xor_out := rand(75) xor rand(74) xor rand(40) xor rand(39);
    elsif(rand'length = 77) then		  --77
    xor_out := rand(76) xor rand(75) xor rand(46) xor rand(45);
    elsif(rand'length = 78) then		  --78
    xor_out := rand(77) xor rand(76) xor rand(58) xor rand(57);
    elsif(rand'length = 79) then		  --79
    xor_out := rand(78) xor rand(69);
    elsif(rand'length = 80) then		  --80
    xor_out := rand(79) xor rand(78) xor rand(42) xor rand(41);
    elsif(rand'length = 81) then		  --81
    xor_out := rand(80) xor rand(76);
    elsif(rand'length = 82) then		  --82
    xor_out := rand(81) xor rand(78) xor rand(46) xor rand(43);
    elsif(rand'length = 83) then		  --83
    xor_out := rand(82) xor rand(81) xor rand(37) xor rand(36);
    elsif(rand'length = 84) then		  --84
    xor_out := rand(83) xor rand(70);
    elsif(rand'length = 85) then		  --85
    xor_out := rand(84) xor rand(83) xor rand(57) xor rand(56);
    elsif(rand'length = 86) then		  --86
    xor_out := rand(85) xor rand(84) xor rand(73) xor rand(72);
    elsif(rand'length = 87) then		  --87
    xor_out := rand(86) xor rand(73);
    elsif(rand'length = 88) then		  --88
    xor_out := rand(87) xor rand(86) xor rand(16) xor rand(15);
    elsif(rand'length = 89) then		  --89
    xor_out := rand(88) xor rand(50);
    elsif(rand'length = 90) then		  --90
    xor_out := rand(89) xor rand(88) xor rand(71) xor rand(70);
    elsif(rand'length = 91) then		  --91
    xor_out := rand(90) xor rand(89) xor rand(7) xor rand(6);
    elsif(rand'length = 92) then		  --92
    xor_out := rand(91) xor rand(90) xor rand(79) xor rand(78);
    elsif(rand'length = 93) then		  --93
    xor_out := rand(92) xor rand(90);
    elsif(rand'length = 94) then		  --94
    xor_out := rand(93) xor rand(72);
    elsif(rand'length = 95) then		  --95
    xor_out := rand(94) xor rand(83);
    elsif(rand'length = 96) then		  --96
    xor_out := rand(95) xor rand(93) xor rand(48) xor rand(46);
    elsif(rand'length = 97) then		  --97
    xor_out := rand(96) xor rand(90);
    elsif(rand'length = 98) then		  --98
    xor_out := rand(97) xor rand(86);
    elsif(rand'length = 99) then		  --99
    xor_out := rand(98) xor rand(96) xor rand(53) xor rand(51);
    elsif(rand'length = 100) then		  --100
    xor_out := rand(99) xor rand(62);
    elsif(rand'length = 101) then		  --101
    xor_out := rand(100) xor rand(99) xor rand(94) xor rand(93);
    elsif(rand'length = 102) then		  --102
    xor_out := rand(101) xor rand(100) xor rand(35) xor rand(34);
    elsif(rand'length = 103) then		  --103
    xor_out := rand(102) xor rand(93);
    elsif(rand'length = 104) then		  --104	
    xor_out := rand(103) xor rand(102) xor rand(93) xor rand(92);
    elsif(rand'length = 105) then		  --105
    xor_out := rand(104) xor rand(88);
    elsif(rand'length = 106) then		  --106
    xor_out := rand(105) xor rand(90);
    elsif(rand'length = 107) then		  --107	
    xor_out := rand(106) xor rand(104) xor rand(43) xor rand(41);
    elsif(rand'length = 108) then		  --108
    xor_out := rand(107) xor rand(76);
    elsif(rand'length = 109) then		  --109	
    xor_out := rand(108) xor rand(107) xor rand(102) xor rand(101);
    elsif(rand'length = 110)then		  --110	
    xor_out := rand(109) xor rand(108) xor rand(97) xor rand(96);
    elsif(rand'length = 111) then		  --111
    xor_out := rand(110) xor rand(100);
    elsif(rand'length = 112) then		  --112
    xor_out := rand(111) xor rand(109) xor rand(68) xor rand(66);
    elsif(rand'length = 113) then		  --113	
    xor_out := rand(112) xor rand(103);
    elsif(rand'length = 114) then		  --114	
    xor_out := rand(113) xor rand(112) xor rand(32) xor rand(31);
    elsif(rand'length = 115) then		  --115
    xor_out := rand(114) xor rand(113) xor rand(100) xor rand(99);
    elsif(rand'length = 116) then		  --116
    xor_out := rand(115) xor rand(114) xor rand(45) xor rand(44);
    elsif(rand'length = 117) then		  --117
    xor_out := rand(116) xor rand(114) xor rand(98) xor rand(96);
    elsif(rand'length = 118) then		  --118
    xor_out := rand(117) xor rand(84);
    elsif(rand'length = 119) then		  --119
    xor_out := rand(118) xor rand(110);
    elsif(rand'length = 120) then		  --120
    xor_out := rand(119) xor rand(112) xor rand(8) xor rand(1);
    elsif(rand'length = 121) then		  --121
    xor_out := rand(120) xor rand(102);
    elsif(rand'length = 122) then		  --122
    xor_out := rand(121) xor rand(120) xor rand(62) xor rand(61);
    elsif(rand'length = 123) then		  --123
    xor_out := rand(122) xor rand(120);
    elsif(rand'length = 124) then		  --124
    xor_out := rand(123) xor rand(86);
    elsif(rand'length = 125) then		  --125
    xor_out := rand(124) xor rand(123) xor rand(17) xor rand(16);
    elsif(rand'length = 126) then		  --126
    xor_out := rand(125) xor rand(124) xor rand(89) xor rand(88);
    elsif(rand'length = 127) then		  --127
    xor_out := rand(126) xor rand(125);
    elsif(rand'length = 128) then		  --128
    xor_out := rand(127) xor rand(125) xor rand(100) xor rand(98);
    elsif(rand'length = 129) then		  --129
    xor_out := rand(128) xor rand(123);
    elsif(rand'length = 130) then		  --130
    xor_out := rand(129) xor rand(126);
    elsif(rand'length = 131) then		  --131
    xor_out := rand(130) xor rand(129) xor rand(83) xor rand(82);
    elsif(rand'length = 132) then		  --132
    xor_out := rand(131) xor rand(102);
    elsif(rand'length = 133) then		  --133
    xor_out := rand(132) xor rand(131) xor rand(81) xor rand(80);
    elsif(rand'length = 134) then		  --134
    xor_out := rand(133) xor rand(76);
    elsif(rand'length = 135) then		  --135
    xor_out := rand(134) xor rand(123);
    elsif(rand'length = 136) then		  --136
    xor_out := rand(135) xor rand(134) xor rand(10) xor rand(9);
    elsif(rand'length = 137) then		  --137
    xor_out := rand(136) xor rand(115);
    elsif(rand'length = 138) then		  --138
    xor_out := rand(137) xor rand(136) xor rand(130) xor rand(129);
    elsif(rand'length = 139) then		  --139
    xor_out := rand(138) xor rand(135) xor rand(133) xor rand(130);
    elsif(rand'length = 140) then		  --140
    xor_out := rand(139) xor rand(110);
    elsif(rand'length = 141) then		  --141
    xor_out := rand(140) xor rand(139) xor rand(109) xor rand(108);
    elsif(rand'length = 142) then		  --142
    xor_out := rand(141) xor rand(120);
    elsif(rand'length = 143) then		  --143
    xor_out := rand(142) xor rand(141) xor rand(122) xor rand(121);
    elsif(rand'length = 144) then		  --144
    xor_out := rand(143) xor rand(142) xor rand(74) xor rand(73);
    elsif(rand'length = 145) then		  --145
    xor_out := rand(144) xor rand(92);
    elsif(rand'length = 146) then		  --146
    xor_out := rand(145) xor rand(144) xor rand(86) xor rand(85);
    elsif(rand'length = 147) then		  --147
    xor_out := rand(146) xor rand(145) xor rand(109) xor rand(108);
    elsif(rand'length = 148) then		  --148
    xor_out := rand(147) xor rand(120);
    elsif(rand'length = 149) then		  --149
    xor_out := rand(148) xor rand(147) xor rand(39) xor rand(38);
    elsif(rand'length = 150) then		  --150
    xor_out := rand(149) xor rand(96);
    elsif(rand'length = 151) then		  --151
    xor_out := rand(150) xor rand(147);
    elsif(rand'length = 152) then		  --152
    xor_out := rand(151) xor rand(150) xor rand(86) xor rand(85);
    elsif(rand'length = 153) then		  --153
    xor_out := rand(152) xor rand(151);
    elsif(rand'length = 154) then		  --154
    xor_out := rand(153) xor rand(151) xor rand(26) xor rand(24);
    elsif(rand'length = 155) then		  --155
    xor_out := rand(154) xor rand(153) xor rand(123) xor rand(122);
    elsif(rand'length = 156) then		  --156
    xor_out := rand(155) xor rand(154) xor rand(40) xor rand(39);
    elsif(rand'length = 157) then		  --157
    xor_out := rand(156) xor rand(155) xor rand(130) xor rand(129);
    elsif(rand'length = 158) then		  --158
    xor_out := rand(157) xor rand(156) xor rand(131) xor rand(130);
    elsif(rand'length = 159) then		  --159
    xor_out := rand(158) xor rand(127);
    elsif(rand'length = 160) then		  --160
    xor_out := rand(159) xor rand(158) xor rand(141) xor rand(140);
    elsif(rand'length = 161) then		  --161
    xor_out := rand(160) xor rand(142);
    elsif(rand'length = 162) then		  --162
    xor_out := rand(161) xor rand(160) xor rand(74) xor rand(73);
    elsif(rand'length = 163) then		  --163
    xor_out := rand(162) xor rand(161) xor rand(103) xor rand(102);
    elsif(rand'length = 164) then		  --164
    xor_out := rand(163) xor rand(162) xor rand(150) xor rand(149);
    elsif(rand'length = 165) then		  --165
    xor_out := rand(164) xor rand(163) xor rand(134) xor rand(133);
    elsif(rand'length = 166) then		  --166
    xor_out := rand(165) xor rand(164) xor rand(127) xor rand(126);
    elsif(rand'length = 167) then		  --167
    xor_out := rand(166) xor rand(160);
    elsif(rand'length = 168) then		  --168
    xor_out := rand(167) xor rand(165) xor rand(152) xor rand(150);
    end if;
    
    return xor_out;
    end xor_gates;
    --END function for XORing using tap values.
    
    end lfsr_pkg;
    --End of the package.

----------------------------------------------------------------------------
    ---- Create Date:    13:06:08 07/28/2010 											----		
    ---- Design Name: lfsr																	----				
    ---- Project Name: lfsr_randgen													   ----	
    ---- Description: 																		----	
    ----  A random number generator based on linear feedback shift          ----
    ----  register(LFSR).A LFSR is a shift register whose input bit is a    ----
    ----  linear function of its previous state.The detailed documentation  ----	
    ----  is available in the file named manual.pdf.   							----	
    ----																							----	
    ----------------------------------------------------------------------------
    ----                                                                    ----
    ---- This file is a part of the lfsr_randgen project at                 ----
    ---- http://www.opencores.org/						                        ----
    ----                                                                    ----
    ---- Author(s):                                                         ----
    ----   Vipin Lal, lalnitt@gmail.com                                     ----
    ----                                                                    ----
    ----------------------------------------------------------------------------
    ----                                                                    ----
    ---- Copyright (C) 2010 Authors and OPENCORES.ORG                       ----
    ----                                                                    ----
    ---- This source file may be used and distributed without               ----
    ---- restriction provided that this copyright statement is not          ----
    ---- removed from the file and that any derivative work contains        ----
    ---- the original copyright notice and the associated disclaimer.       ----
    ----                                                                    ----
    ---- This source file is free software; you can redistribute it         ----
    ---- and/or modify it under the terms of the GNU Lesser General         ----
    ---- Public License as published by the Free Software Foundation;       ----
    ---- either version 2.1 of the License, or (at your option) any         ----
    ---- later version.                                                     ----
    ----                                                                    ----
    ---- This source 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 Lesser General Public License for more        ----
    ---- details.                                                           ----
    ----                                                                    ----
    ---- You should have received a copy of the GNU Lesser General          ----
    ---- Public License along with this source; if not, download it         ----
    ---- from http://www.opencores.org/lgpl.shtml                           ----
    ----                                                                    ----
    ----------------------------------------------------------------------------
    
    library ieee;
    use ieee.std_logic_1164.all;
    use ieee.std_logic_arith.all;
    use ieee.std_logic_unsigned.all;
    library work;
    use work.lfsr_pkg.ALL; 
    
    entity lfsr is
       generic (width : integer := 4);
    port (clk : in std_logic;
    		set_seed : in std_logic; 
          seed : in std_logic_vector(width-1 downto 0);
          rand_out : out std_logic_vector(width-1 downto 0)  		
        );
    end lfsr;
    
    architecture Behavioral of lfsr is
    
    begin
    
    process(clk)
    
    variable rand_temp : std_logic_vector (width-1 downto 0):=(0 => '1',others => '0');
    variable temp : std_logic := '0';
    
    begin
    
    if(rising_edge(clk)) then
    
    if(set_seed = '1') then
    rand_temp := seed;
    end if;
    
    temp := xor_gates(rand_temp);
    rand_temp(width-1 downto 1) := rand_temp(width-2 downto 0);
    rand_temp(0) := temp;
    
    end if;
    rand_out <= rand_temp;
    
    end process;
    
    end Behavioral;

C语言版本：

#include "stdio.h"
    unsigned int k=0;
    unsigned int lfsr(unsigned int i)
    {
    	unsigned int t = 0;
    	unsigned int idc = 0;
    	unsigned char c[32] = {0};
    	unsigned int r = 0;
    	 unsigned char xor = 0;
    
    
    	t=i;
    	idc =0;
    	 printf("\r\n----------%d:\t\r\n",k++);
        while(t)
    	{
           if(t%2)
    		    c[idc]=1;
    	   else
    		    c[idc]=0;
    	   idc++;
    	   t>>=1;
    	  // printf("%d",c[idc-1]);
    	}
    	while(idc<32)
        {
    	    c[idc]=0;
    		idc++;
    	//	printf("%d",c[idc-1]);
    	}
        //
    
    	r = i <<1;
    
    	//
    	idc=0;
    
    
    	xor = c[0]^c[1]^c[21]^c[31];
    
        	r+=xor;
        
    
        printf("\t%d %#x\r\n",xor,r);
        //
    	return r;
    }
    
    
    void main()
    {
    	unsigned int s;
    	unsigned int t1,t2;
    	unsigned int id = 0;
        printf("hello \r\n");
    	s= 0x12345678;
    	printf("%#x %d\r\n",s,sizeof(unsigned int));
    	t1 = s;
    	//
        FILE* fp;
        if ((fp = fopen("./lfsr.txt", "w")) == NULL) {
    
            printf("create file failed！");
            return;
        }
    
    	//
    	unsigned int cnt =0;
    	while((t2=lfsr(t1))!=s)
    	{
    	   //fprintf(fp, "%d\t%#x\n",cnt++, t2);
    	   t1 =t2;
    	  // if(id++ > 100)  break;
    	}
    
    	//
    	fclose(fp);
        return;
    }

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTEzMjk5Njc_size_16_color_FFFFFF_t_70][]

[https://www.xilinx.com/support/documentation/application\_notes/xapp052.pdf][https_www.xilinx.com_support_documentation_application_notes_xapp052.pdf]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTEzMjk5Njc_size_16_color_FFFFFF_t_70 1][]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTEzMjk5Njc_size_16_color_FFFFFF_t_70]: /images/20221124/a30e907de7d74b00a268fe22afb9ded2.png
[https_www.xilinx.com_support_documentation_application_notes_xapp052.pdf]: https://www.xilinx.com/support/documentation/application_notes/xapp052.pdf
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTEzMjk5Njc_size_16_color_FFFFFF_t_70 1]: /images/20221124/b98d9785649843e68b2d8f26e6e12ccb.png