133 lines
4.3 KiB
C
133 lines
4.3 KiB
C
/*
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* This file is part of the MicroPython project, http://micropython.org/
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*
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* The MIT License (MIT)
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*
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* Copyright (c) 2016 Paul Sokolovsky
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* Copyright (c) 2017 Scott Shawcroft for Adafruit Industries
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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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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#include "shared-bindings/os/__init__.h"
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#include "shared-bindings/random/__init__.h"
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#include "shared-bindings/time/__init__.h"
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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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if (yasmarang_pad == 0xeda4baba) {
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if (!common_hal_os_urandom((uint8_t *)&yasmarang_pad, sizeof(uint32_t))) {
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yasmarang_pad = common_hal_time_monotonic_ms() & 0xffffffff;
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}
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}
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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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// 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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void shared_modules_random_seed(mp_uint_t seed) {
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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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}
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mp_uint_t shared_modules_random_getrandbits(uint8_t n) {
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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 yasmarang() & mask;
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}
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mp_int_t shared_modules_random_randrange(mp_int_t start, mp_int_t stop, mp_int_t step) {
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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 {
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n = (stop - start + step + 1) / step;
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}
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return start + step * yasmarang_randbelow(n);
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}
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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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mp_float_t shared_modules_random_random(void) {
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return yasmarang_float();
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}
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mp_float_t shared_modules_random_uniform(mp_float_t a, mp_float_t b) {
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return a + (b - a) * yasmarang_float();
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}
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