1/*
2 * This file is part of the MicroPython project, http://micropython.org/
3 *
4 * The MIT License (MIT)
5 *
6 * Copyright (c) 2016 Paul Sokolovsky
7 *
8 * Permission is hereby granted, free of charge, to any person obtaining a copy
9 * of this software and associated documentation files (the "Software"), to deal
10 * in the Software without restriction, including without limitation the rights
11 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
12 * copies of the Software, and to permit persons to whom the Software is
13 * furnished to do so, subject to the following conditions:
14 *
15 * The above copyright notice and this permission notice shall be included in
16 * all copies or substantial portions of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
21 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
22 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
23 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
24 * THE SOFTWARE.
25 */
26
27#include <assert.h>
28#include <string.h>
29
30#include "py/runtime.h"
31
32#if MICROPY_PY_URANDOM
33
34// Work out if the seed will be set on import or not.
35#if MICROPY_MODULE_BUILTIN_INIT && defined(MICROPY_PY_URANDOM_SEED_INIT_FUNC)
36#define SEED_ON_IMPORT (1)
37#else
38#define SEED_ON_IMPORT (0)
39#endif
40
41// Yasmarang random number generator
42// by Ilya Levin
43// http://www.literatecode.com/yasmarang
44// Public Domain
45
46#if !MICROPY_ENABLE_DYNRUNTIME
47#if SEED_ON_IMPORT
48// If the state is seeded on import then keep these variables in the BSS.
49STATIC uint32_t yasmarang_pad, yasmarang_n, yasmarang_d;
50STATIC uint8_t yasmarang_dat;
51#else
52// Without seed-on-import these variables must be initialised via the data section.
53STATIC uint32_t yasmarang_pad = 0xeda4baba, yasmarang_n = 69, yasmarang_d = 233;
54STATIC uint8_t yasmarang_dat = 0;
55#endif
56#endif
57
58STATIC uint32_t yasmarang(void) {
59 yasmarang_pad += yasmarang_dat + yasmarang_d * yasmarang_n;
60 yasmarang_pad = (yasmarang_pad << 3) + (yasmarang_pad >> 29);
61 yasmarang_n = yasmarang_pad | 2;
62 yasmarang_d ^= (yasmarang_pad << 31) + (yasmarang_pad >> 1);
63 yasmarang_dat ^= (char)yasmarang_pad ^ (yasmarang_d >> 8) ^ 1;
64
65 return yasmarang_pad ^ (yasmarang_d << 5) ^ (yasmarang_pad >> 18) ^ (yasmarang_dat << 1);
66} /* yasmarang */
67
68// End of Yasmarang
69
70#if MICROPY_PY_URANDOM_EXTRA_FUNCS
71
72// returns an unsigned integer below the given argument
73// n must not be zero
74STATIC uint32_t yasmarang_randbelow(uint32_t n) {
75 uint32_t mask = 1;
76 while ((n & mask) < n) {
77 mask = (mask << 1) | 1;
78 }
79 uint32_t r;
80 do {
81 r = yasmarang() & mask;
82 } while (r >= n);
83 return r;
84}
85
86#endif
87
88STATIC mp_obj_t mod_urandom_getrandbits(mp_obj_t num_in) {
89 int n = mp_obj_get_int(num_in);
90 if (n > 32 || n == 0) {
91 mp_raise_ValueError(NULL);
92 }
93 uint32_t mask = ~0;
94 // Beware of C undefined behavior when shifting by >= than bit size
95 mask >>= (32 - n);
96 return mp_obj_new_int_from_uint(yasmarang() & mask);
97}
98STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_urandom_getrandbits_obj, mod_urandom_getrandbits);
99
100STATIC mp_obj_t mod_urandom_seed(size_t n_args, const mp_obj_t *args) {
101 mp_uint_t seed;
102 if (n_args == 0 || args[0] == mp_const_none) {
103 #ifdef MICROPY_PY_URANDOM_SEED_INIT_FUNC
104 seed = MICROPY_PY_URANDOM_SEED_INIT_FUNC;
105 #else
106 mp_raise_ValueError(MP_ERROR_TEXT("no default seed"));
107 #endif
108 } else {
109 seed = mp_obj_get_int_truncated(args[0]);
110 }
111 yasmarang_pad = seed;
112 yasmarang_n = 69;
113 yasmarang_d = 233;
114 yasmarang_dat = 0;
115 return mp_const_none;
116}
117STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mod_urandom_seed_obj, 0, 1, mod_urandom_seed);
118
119#if MICROPY_PY_URANDOM_EXTRA_FUNCS
120
121STATIC mp_obj_t mod_urandom_randrange(size_t n_args, const mp_obj_t *args) {
122 mp_int_t start = mp_obj_get_int(args[0]);
123 if (n_args == 1) {
124 // range(stop)
125 if (start > 0) {
126 return mp_obj_new_int(yasmarang_randbelow(start));
127 } else {
128 goto error;
129 }
130 } else {
131 mp_int_t stop = mp_obj_get_int(args[1]);
132 if (n_args == 2) {
133 // range(start, stop)
134 if (start < stop) {
135 return mp_obj_new_int(start + yasmarang_randbelow(stop - start));
136 } else {
137 goto error;
138 }
139 } else {
140 // range(start, stop, step)
141 mp_int_t step = mp_obj_get_int(args[2]);
142 mp_int_t n;
143 if (step > 0) {
144 n = (stop - start + step - 1) / step;
145 } else if (step < 0) {
146 n = (stop - start + step + 1) / step;
147 } else {
148 goto error;
149 }
150 if (n > 0) {
151 return mp_obj_new_int(start + step * yasmarang_randbelow(n));
152 } else {
153 goto error;
154 }
155 }
156 }
157
158error:
159 mp_raise_ValueError(NULL);
160}
161STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mod_urandom_randrange_obj, 1, 3, mod_urandom_randrange);
162
163STATIC mp_obj_t mod_urandom_randint(mp_obj_t a_in, mp_obj_t b_in) {
164 mp_int_t a = mp_obj_get_int(a_in);
165 mp_int_t b = mp_obj_get_int(b_in);
166 if (a <= b) {
167 return mp_obj_new_int(a + yasmarang_randbelow(b - a + 1));
168 } else {
169 mp_raise_ValueError(NULL);
170 }
171}
172STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_urandom_randint_obj, mod_urandom_randint);
173
174STATIC mp_obj_t mod_urandom_choice(mp_obj_t seq) {
175 mp_int_t len = mp_obj_get_int(mp_obj_len(seq));
176 if (len > 0) {
177 return mp_obj_subscr(seq, mp_obj_new_int(yasmarang_randbelow(len)), MP_OBJ_SENTINEL);
178 } else {
179 mp_raise_type(&mp_type_IndexError);
180 }
181}
182STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_urandom_choice_obj, mod_urandom_choice);
183
184#if MICROPY_PY_BUILTINS_FLOAT
185
186// returns a number in the range [0..1) using Yasmarang to fill in the fraction bits
187STATIC mp_float_t yasmarang_float(void) {
188 mp_float_union_t u;
189 u.p.sgn = 0;
190 u.p.exp = (1 << (MP_FLOAT_EXP_BITS - 1)) - 1;
191 if (MP_FLOAT_FRAC_BITS <= 32) {
192 u.p.frc = yasmarang();
193 } else {
194 u.p.frc = ((uint64_t)yasmarang() << 32) | (uint64_t)yasmarang();
195 }
196 return u.f - 1;
197}
198
199STATIC mp_obj_t mod_urandom_random(void) {
200 return mp_obj_new_float(yasmarang_float());
201}
202STATIC MP_DEFINE_CONST_FUN_OBJ_0(mod_urandom_random_obj, mod_urandom_random);
203
204STATIC mp_obj_t mod_urandom_uniform(mp_obj_t a_in, mp_obj_t b_in) {
205 mp_float_t a = mp_obj_get_float(a_in);
206 mp_float_t b = mp_obj_get_float(b_in);
207 return mp_obj_new_float(a + (b - a) * yasmarang_float());
208}
209STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_urandom_uniform_obj, mod_urandom_uniform);
210
211#endif
212
213#endif // MICROPY_PY_URANDOM_EXTRA_FUNCS
214
215#if SEED_ON_IMPORT
216STATIC mp_obj_t mod_urandom___init__() {
217 // This module may be imported by more than one name so need to ensure
218 // that it's only ever seeded once.
219 static bool seeded = false;
220 if (!seeded) {
221 seeded = true;
222 mod_urandom_seed(0, NULL);
223 }
224 return mp_const_none;
225}
226STATIC MP_DEFINE_CONST_FUN_OBJ_0(mod_urandom___init___obj, mod_urandom___init__);
227#endif
228
229#if !MICROPY_ENABLE_DYNRUNTIME
230STATIC const mp_rom_map_elem_t mp_module_urandom_globals_table[] = {
231 { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_urandom) },
232 #if SEED_ON_IMPORT
233 { MP_ROM_QSTR(MP_QSTR___init__), MP_ROM_PTR(&mod_urandom___init___obj) },
234 #endif
235 { MP_ROM_QSTR(MP_QSTR_getrandbits), MP_ROM_PTR(&mod_urandom_getrandbits_obj) },
236 { MP_ROM_QSTR(MP_QSTR_seed), MP_ROM_PTR(&mod_urandom_seed_obj) },
237 #if MICROPY_PY_URANDOM_EXTRA_FUNCS
238 { MP_ROM_QSTR(MP_QSTR_randrange), MP_ROM_PTR(&mod_urandom_randrange_obj) },
239 { MP_ROM_QSTR(MP_QSTR_randint), MP_ROM_PTR(&mod_urandom_randint_obj) },
240 { MP_ROM_QSTR(MP_QSTR_choice), MP_ROM_PTR(&mod_urandom_choice_obj) },
241 #if MICROPY_PY_BUILTINS_FLOAT
242 { MP_ROM_QSTR(MP_QSTR_random), MP_ROM_PTR(&mod_urandom_random_obj) },
243 { MP_ROM_QSTR(MP_QSTR_uniform), MP_ROM_PTR(&mod_urandom_uniform_obj) },
244 #endif
245 #endif
246};
247
248STATIC MP_DEFINE_CONST_DICT(mp_module_urandom_globals, mp_module_urandom_globals_table);
249
250const mp_obj_module_t mp_module_urandom = {
251 .base = { &mp_type_module },
252 .globals = (mp_obj_dict_t *)&mp_module_urandom_globals,
253};
254#endif
255
256#endif // MICROPY_PY_URANDOM
257