1 |
dashley |
71 |
//$Header$ |
2 |
|
|
//------------------------------------------------------------------------------------------------- |
3 |
|
|
//This file is part of "David T. Ashley's Shared Source Code", a set of shared components |
4 |
|
|
//integrated into many of David T. Ashley's projects. |
5 |
|
|
//------------------------------------------------------------------------------------------------- |
6 |
|
|
//This source code and any program in which it is compiled/used is provided under the MIT License, |
7 |
|
|
//reproduced below. |
8 |
|
|
//------------------------------------------------------------------------------------------------- |
9 |
|
|
//Permission is hereby granted, free of charge, to any person obtaining a copy of |
10 |
|
|
//this software and associated documentation files(the "Software"), to deal in the |
11 |
|
|
//Software without restriction, including without limitation the rights to use, |
12 |
|
|
//copy, modify, merge, publish, distribute, sublicense, and / or sell copies of the |
13 |
|
|
//Software, and to permit persons to whom the Software is furnished to do so, |
14 |
|
|
//subject to the following conditions : |
15 |
|
|
// |
16 |
|
|
//The above copyright notice and this permission notice shall be included in all |
17 |
|
|
//copies or substantial portions of the Software. |
18 |
|
|
// |
19 |
|
|
//THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
20 |
|
|
//IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
21 |
|
|
//FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE |
22 |
|
|
//AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
23 |
|
|
//LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
24 |
|
|
//OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE |
25 |
|
|
//SOFTWARE. |
26 |
|
|
//------------------------------------------------------------------------------------------------- |
27 |
|
|
#define MODULE_ESRG_RAND_INT |
28 |
|
|
|
29 |
|
|
#include <assert.h> |
30 |
|
|
#include <string.h> |
31 |
|
|
#include <time.h> |
32 |
|
|
|
33 |
|
|
#include "esrg_rand_int.h" |
34 |
|
|
#include "intfunc.h" |
35 |
|
|
|
36 |
|
|
|
37 |
|
|
void ESRG_RAND_INT_Alg01_Init(struct ESRG_RAND_INT_Alg01RngState *state, |
38 |
|
|
int init_val) |
39 |
|
|
{ |
40 |
|
|
int i; |
41 |
|
|
|
42 |
|
|
assert(state != NULL); |
43 |
|
|
assert((init_val==-1) || (init_val>0)); |
44 |
|
|
|
45 |
|
|
//Regardless of init type, zero out the structure. Among other things, |
46 |
|
|
//this sets the number of remaining random bits to zero. |
47 |
|
|
memset(state, 0, sizeof(*state)); |
48 |
|
|
|
49 |
|
|
if (init_val == -1) |
50 |
|
|
{ |
51 |
|
|
//This is the system randomness initialization case. Some value |
52 |
|
|
//of system time should be adequate to start with. |
53 |
|
|
state->rn_seed_whole = time(NULL); |
54 |
|
|
state->rn_seed_fractional = time(NULL); |
55 |
|
|
|
56 |
|
|
//Flip a few bits in the seeds to hopefully make them different |
57 |
|
|
//(but it doesn't matter if they aren't). |
58 |
|
|
state->rn_seed_whole ^= 0xA5A5A5A5; |
59 |
|
|
state->rn_seed_fractional ^= 0x5A5A5A5A; |
60 |
|
|
|
61 |
|
|
//Be absolutely sure that the seeds can't be zero. |
62 |
|
|
state->rn_seed_whole |= 0x1; |
63 |
|
|
state->rn_seed_fractional |= 0x2; |
64 |
|
|
|
65 |
|
|
//Iterate a small number of times to add further randomness |
66 |
|
|
//to the two seeds. |
67 |
|
|
for (i=0; i<3; i++) |
68 |
|
|
{ |
69 |
|
|
state->rn_seed_whole |
70 |
|
|
= INTFUNC_rn_power_res_16807_mapping(state->rn_seed_whole); |
71 |
|
|
} |
72 |
|
|
|
73 |
|
|
for (i=0; i<7; i++) |
74 |
|
|
{ |
75 |
|
|
state->rn_seed_fractional |
76 |
|
|
= INTFUNC_rn_power_res_16807_mapping(state->rn_seed_fractional); |
77 |
|
|
} |
78 |
|
|
} |
79 |
|
|
else |
80 |
|
|
{ |
81 |
|
|
//This is the branch where the random seed is supplied. We can |
82 |
|
|
//use very much the same approach as above to try to get something |
83 |
|
|
//random. |
84 |
|
|
state->rn_seed_whole = init_val; |
85 |
|
|
state->rn_seed_fractional = init_val; |
86 |
|
|
|
87 |
|
|
//Flip a few bits in the seeds to hopefully make them different |
88 |
|
|
//(but it doesn't matter if they aren't). |
89 |
|
|
state->rn_seed_whole ^= 0xA5A5A5A5; |
90 |
|
|
state->rn_seed_fractional ^= 0x5A5A5A5A; |
91 |
|
|
|
92 |
|
|
//Be absolutely sure that the seeds can't be zero. |
93 |
|
|
state->rn_seed_whole |= 0x1; |
94 |
|
|
state->rn_seed_fractional |= 0x2; |
95 |
|
|
|
96 |
|
|
//Iterate a small number of times to add further randomness |
97 |
|
|
//to the two seeds. |
98 |
|
|
for (i=0; i<3; i++) |
99 |
|
|
{ |
100 |
|
|
state->rn_seed_whole |
101 |
|
|
= INTFUNC_rn_power_res_16807_mapping(state->rn_seed_whole); |
102 |
|
|
} |
103 |
|
|
|
104 |
|
|
for (i=0; i<7; i++) |
105 |
|
|
{ |
106 |
|
|
state->rn_seed_fractional |
107 |
|
|
= INTFUNC_rn_power_res_16807_mapping(state->rn_seed_fractional); |
108 |
|
|
} |
109 |
|
|
} |
110 |
|
|
|
111 |
|
|
//At this point the state is randomized. The number of bits valid |
112 |
|
|
//in the bit reservoir is set to zero, so will force a restock |
113 |
|
|
//next time. |
114 |
|
|
} |
115 |
|
|
|
116 |
|
|
|
117 |
|
|
//Restocks the bit reservoir. |
118 |
|
|
static void ESRG_RAND_INT_Alg01_RestockBitBuffer( |
119 |
|
|
struct ESRG_RAND_INT_Alg01RngState *state |
120 |
|
|
) |
121 |
|
|
{ |
122 |
|
|
assert(state != NULL); |
123 |
|
|
|
124 |
|
|
//We need to keep chugging along until we get an integer with the top two |
125 |
|
|
//bits clear. This is the only way to get a random distribution of bits. |
126 |
|
|
do |
127 |
|
|
{ |
128 |
|
|
assert(state->rn_seed_fractional != 0); |
129 |
|
|
state->rn_seed_fractional |
130 |
|
|
= INTFUNC_rn_power_res_16807_mapping(state->rn_seed_fractional); |
131 |
|
|
} while (state->rn_seed_fractional & 0xC0000000); |
132 |
|
|
|
133 |
|
|
//At this point the lower 30 bits should be random. |
134 |
|
|
state->bit_buffer = state->rn_seed_fractional; |
135 |
|
|
state->n_bb_valid = 30; |
136 |
|
|
} |
137 |
|
|
|
138 |
|
|
|
139 |
|
|
unsigned int ESRG_RAND_INT_Alg01_RandomBit( |
140 |
|
|
struct ESRG_RAND_INT_Alg01RngState *state |
141 |
|
|
) |
142 |
|
|
{ |
143 |
|
|
int rv; |
144 |
|
|
|
145 |
|
|
assert(state != NULL); |
146 |
|
|
|
147 |
|
|
//Restock the supply of bits if necessary. |
148 |
|
|
if (state->n_bb_valid == 0) |
149 |
|
|
ESRG_RAND_INT_Alg01_RestockBitBuffer(state); |
150 |
|
|
|
151 |
|
|
if (state->bit_buffer & 0x01) |
152 |
|
|
rv = 1; |
153 |
|
|
else |
154 |
|
|
rv = 0; |
155 |
|
|
|
156 |
|
|
state->bit_buffer >>= 1; |
157 |
|
|
state->n_bb_valid--; |
158 |
|
|
|
159 |
|
|
return(rv); |
160 |
|
|
} |
161 |
|
|
|
162 |
|
|
|
163 |
|
|
unsigned int ESRG_RAND_INT_Alg01_RandomByte( |
164 |
|
|
struct ESRG_RAND_INT_Alg01RngState *state |
165 |
|
|
) |
166 |
|
|
{ |
167 |
|
|
int rv; |
168 |
|
|
|
169 |
|
|
assert(state != NULL); |
170 |
|
|
|
171 |
|
|
//Be sure enough bits to yank a byte. |
172 |
|
|
if (state->n_bb_valid < 8) |
173 |
|
|
ESRG_RAND_INT_Alg01_RestockBitBuffer(state); |
174 |
|
|
|
175 |
|
|
//Grab the byte and return. |
176 |
|
|
rv = state->bit_buffer & 0xFF; |
177 |
|
|
state->bit_buffer >>= 8; //Must roll down to get new set of bits. |
178 |
|
|
state->n_bb_valid -= 8; |
179 |
|
|
|
180 |
|
|
return(rv); |
181 |
|
|
} |
182 |
|
|
|
183 |
|
|
|
184 |
|
|
const char *ESRG_RAND_INT_cvcinfo(void) |
185 |
|
|
{ |
186 |
|
|
return("$Header$"); |
187 |
|
|
} |
188 |
|
|
|
189 |
|
|
|
190 |
|
|
const char *ESRG_RAND_INT_hvcinfo(void) |
191 |
|
|
{ |
192 |
|
|
return(ESRG_RAND_INT_H_VERSION); |
193 |
|
|
} |
194 |
|
|
|
195 |
|
|
//End of esrg_rand_int.c. |