206 lines
6.5 KiB
C
206 lines
6.5 KiB
C
// Copyright (c) 2016 Paul Sokolovsky
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// SPDX-FileCopyrightText: 2014 MicroPython & CircuitPython contributors (https://github.com/adafruit/circuitpython/graphs/contributors)
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//
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// SPDX-License-Identifier: MIT
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#include <assert.h>
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#include <string.h>
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#include "py/runtime.h"
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#if MICROPY_PY_URANDOM
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// Yasmarang random number generator
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// by Ilya Levin
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// http://www.literatecode.com/yasmarang
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// Public Domain
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STATIC uint32_t yasmarang_pad = 0xeda4baba, yasmarang_n = 69, yasmarang_d = 233;
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STATIC uint8_t yasmarang_dat = 0;
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STATIC uint32_t yasmarang(void) {
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yasmarang_pad += yasmarang_dat + yasmarang_d * yasmarang_n;
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yasmarang_pad = (yasmarang_pad << 3) + (yasmarang_pad >> 29);
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yasmarang_n = yasmarang_pad | 2;
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yasmarang_d ^= (yasmarang_pad << 31) + (yasmarang_pad >> 1);
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yasmarang_dat ^= (char)yasmarang_pad ^ (yasmarang_d >> 8) ^ 1;
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return yasmarang_pad ^ (yasmarang_d << 5) ^ (yasmarang_pad >> 18) ^ (yasmarang_dat << 1);
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} /* yasmarang */
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// End of Yasmarang
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#if MICROPY_PY_URANDOM_EXTRA_FUNCS
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// returns an unsigned integer below the given argument
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// n must not be zero
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STATIC uint32_t yasmarang_randbelow(uint32_t n) {
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uint32_t mask = 1;
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while ((n & mask) < n) {
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mask = (mask << 1) | 1;
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}
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uint32_t r;
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do {
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r = yasmarang() & mask;
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} while (r >= n);
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return r;
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}
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#endif
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STATIC mp_obj_t mod_urandom_getrandbits(mp_obj_t num_in) {
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int n = mp_obj_get_int(num_in);
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if (n > 32 || n == 0) {
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mp_raise_ValueError(NULL);
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}
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uint32_t mask = ~0;
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// Beware of C undefined behavior when shifting by >= than bit size
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mask >>= (32 - n);
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return mp_obj_new_int_from_uint(yasmarang() & mask);
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}
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STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_urandom_getrandbits_obj, mod_urandom_getrandbits);
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STATIC mp_obj_t mod_urandom_seed(mp_obj_t seed_in) {
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mp_uint_t seed = mp_obj_get_int_truncated(seed_in);
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yasmarang_pad = seed;
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yasmarang_n = 69;
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yasmarang_d = 233;
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yasmarang_dat = 0;
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return mp_const_none;
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}
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STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_urandom_seed_obj, mod_urandom_seed);
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#if MICROPY_PY_URANDOM_EXTRA_FUNCS
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STATIC mp_obj_t mod_urandom_randrange(size_t n_args, const mp_obj_t *args) {
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mp_int_t start = mp_obj_get_int(args[0]);
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if (n_args == 1) {
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// range(stop)
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if (start > 0) {
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return mp_obj_new_int(yasmarang_randbelow(start));
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} else {
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goto error;
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}
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} else {
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mp_int_t stop = mp_obj_get_int(args[1]);
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if (n_args == 2) {
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// range(start, stop)
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if (start < stop) {
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return mp_obj_new_int(start + yasmarang_randbelow(stop - start));
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} else {
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goto error;
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}
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} else {
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// range(start, stop, step)
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mp_int_t step = mp_obj_get_int(args[2]);
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mp_int_t n;
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if (step > 0) {
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n = (stop - start + step - 1) / step;
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} else if (step < 0) {
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n = (stop - start + step + 1) / step;
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} else {
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goto error;
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}
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if (n > 0) {
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return mp_obj_new_int(start + step * yasmarang_randbelow(n));
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} else {
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goto error;
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}
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}
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}
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error:
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mp_raise_ValueError(NULL);
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}
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STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mod_urandom_randrange_obj, 1, 3, mod_urandom_randrange);
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STATIC mp_obj_t mod_urandom_randint(mp_obj_t a_in, mp_obj_t b_in) {
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mp_int_t a = mp_obj_get_int(a_in);
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mp_int_t b = mp_obj_get_int(b_in);
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if (a <= b) {
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return mp_obj_new_int(a + yasmarang_randbelow(b - a + 1));
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} else {
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mp_raise_ValueError(NULL);
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}
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}
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STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_urandom_randint_obj, mod_urandom_randint);
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STATIC mp_obj_t mod_urandom_choice(mp_obj_t seq) {
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mp_int_t len = mp_obj_get_int(mp_obj_len(seq));
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if (len > 0) {
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return mp_obj_subscr(seq, mp_obj_new_int(yasmarang_randbelow(len)), MP_OBJ_SENTINEL);
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} else {
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nlr_raise(mp_obj_new_exception(&mp_type_IndexError));
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}
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}
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STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_urandom_choice_obj, mod_urandom_choice);
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#if MICROPY_PY_BUILTINS_FLOAT
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// returns a number in the range [0..1) using Yasmarang to fill in the fraction bits
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STATIC mp_float_t yasmarang_float(void) {
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#if MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_DOUBLE
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typedef uint64_t mp_float_int_t;
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#elif MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_FLOAT
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typedef uint32_t mp_float_int_t;
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#endif
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union {
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mp_float_t f;
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#if MP_ENDIANNESS_LITTLE
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struct { mp_float_int_t frc : MP_FLOAT_FRAC_BITS, exp : MP_FLOAT_EXP_BITS, sgn : 1;
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} p;
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#else
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struct { mp_float_int_t sgn : 1, exp : MP_FLOAT_EXP_BITS, frc : MP_FLOAT_FRAC_BITS;
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} p;
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#endif
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} u;
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u.p.sgn = 0;
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u.p.exp = (1 << (MP_FLOAT_EXP_BITS - 1)) - 1;
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if (MP_FLOAT_FRAC_BITS <= 32) {
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u.p.frc = yasmarang();
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} else {
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u.p.frc = ((uint64_t)yasmarang() << 32) | (uint64_t)yasmarang();
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}
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return u.f - 1;
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}
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STATIC mp_obj_t mod_urandom_random(void) {
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return mp_obj_new_float(yasmarang_float());
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}
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STATIC MP_DEFINE_CONST_FUN_OBJ_0(mod_urandom_random_obj, mod_urandom_random);
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STATIC mp_obj_t mod_urandom_uniform(mp_obj_t a_in, mp_obj_t b_in) {
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mp_float_t a = mp_obj_get_float(a_in);
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mp_float_t b = mp_obj_get_float(b_in);
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return mp_obj_new_float(a + (b - a) * yasmarang_float());
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}
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STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_urandom_uniform_obj, mod_urandom_uniform);
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#endif
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#endif // MICROPY_PY_URANDOM_EXTRA_FUNCS
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STATIC const mp_rom_map_elem_t mp_module_urandom_globals_table[] = {
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{ MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_urandom) },
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{ MP_ROM_QSTR(MP_QSTR_getrandbits), MP_ROM_PTR(&mod_urandom_getrandbits_obj) },
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{ MP_ROM_QSTR(MP_QSTR_seed), MP_ROM_PTR(&mod_urandom_seed_obj) },
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#if MICROPY_PY_URANDOM_EXTRA_FUNCS
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{ MP_ROM_QSTR(MP_QSTR_randrange), MP_ROM_PTR(&mod_urandom_randrange_obj) },
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{ MP_ROM_QSTR(MP_QSTR_randint), MP_ROM_PTR(&mod_urandom_randint_obj) },
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{ MP_ROM_QSTR(MP_QSTR_choice), MP_ROM_PTR(&mod_urandom_choice_obj) },
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#if MICROPY_PY_BUILTINS_FLOAT
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{ MP_ROM_QSTR(MP_QSTR_random), MP_ROM_PTR(&mod_urandom_random_obj) },
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{ MP_ROM_QSTR(MP_QSTR_uniform), MP_ROM_PTR(&mod_urandom_uniform_obj) },
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#endif
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#endif
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};
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STATIC MP_DEFINE_CONST_DICT(mp_module_urandom_globals, mp_module_urandom_globals_table);
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const mp_obj_module_t mp_module_urandom = {
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.base = { &mp_type_module },
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.globals = (mp_obj_dict_t *)&mp_module_urandom_globals,
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};
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#endif // MICROPY_PY_URANDOM
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