circuitpython/ports/nrf/modules/random/modrandom.c

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/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2016 Paul Sokolovsky
* Copyright (c) 2016 Damien P. George
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <assert.h>
#include <string.h>
#include "py/runtime.h"
#include "hal_rng.h"
#if MICROPY_PY_HW_RNG
static inline int rand30() {
uint32_t val = hal_rng_generate();
return (val & 0x3fffffff); // binary mask b00111111111111111111111111111111
}
static inline int randbelow(int n) {
return rand30() % n;
}
STATIC mp_obj_t mod_random_getrandbits(mp_obj_t num_in) {
int n = mp_obj_get_int(num_in);
if (n > 30 || n == 0) {
nlr_raise(mp_obj_new_exception(&mp_type_ValueError));
}
uint32_t mask = ~0;
// Beware of C undefined behavior when shifting by >= than bit size
mask >>= (32 - n);
return mp_obj_new_int_from_uint(rand30() & mask);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_random_getrandbits_obj, mod_random_getrandbits);
STATIC mp_obj_t mod_random_randrange(size_t n_args, const mp_obj_t *args) {
mp_int_t start = mp_obj_get_int(args[0]);
if (n_args == 1) {
// range(stop)
if (start > 0) {
return mp_obj_new_int(randbelow(start));
} else {
nlr_raise(mp_obj_new_exception(&mp_type_ValueError));
}
} else {
mp_int_t stop = mp_obj_get_int(args[1]);
if (n_args == 2) {
// range(start, stop)
if (start < stop) {
return mp_obj_new_int(start + randbelow(stop - start));
} else {
nlr_raise(mp_obj_new_exception(&mp_type_ValueError));
}
} else {
// range(start, stop, step)
mp_int_t step = mp_obj_get_int(args[2]);
mp_int_t n;
if (step > 0) {
n = (stop - start + step - 1) / step;
} else if (step < 0) {
n = (stop - start + step + 1) / step;
} else {
nlr_raise(mp_obj_new_exception(&mp_type_ValueError));
}
if (n > 0) {
return mp_obj_new_int(start + step * randbelow(n));
} else {
nlr_raise(mp_obj_new_exception(&mp_type_ValueError));
}
}
}
}
STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mod_random_randrange_obj, 1, 3, mod_random_randrange);
STATIC mp_obj_t mod_random_randint(mp_obj_t a_in, mp_obj_t b_in) {
mp_int_t a = mp_obj_get_int(a_in);
mp_int_t b = mp_obj_get_int(b_in);
if (a <= b) {
return mp_obj_new_int(a + randbelow(b - a + 1));
} else {
nlr_raise(mp_obj_new_exception(&mp_type_ValueError));
}
}
STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_random_randint_obj, mod_random_randint);
STATIC mp_obj_t mod_random_choice(mp_obj_t seq) {
mp_int_t len = mp_obj_get_int(mp_obj_len(seq));
if (len > 0) {
return mp_obj_subscr(seq, mp_obj_new_int(randbelow(len)), MP_OBJ_SENTINEL);
} else {
nlr_raise(mp_obj_new_exception(&mp_type_IndexError));
}
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_random_choice_obj, mod_random_choice);
#if MICROPY_PY_BUILTINS_FLOAT
// returns a number in the range [0..1) using RNG to fill in the fraction bits
STATIC mp_float_t randfloat(void) {
#if MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_DOUBLE
typedef uint64_t mp_float_int_t;
#elif MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_FLOAT
typedef uint32_t mp_float_int_t;
#endif
union {
mp_float_t f;
#if MP_ENDIANNESS_LITTLE
struct { mp_float_int_t frc:MP_FLOAT_FRAC_BITS, exp:MP_FLOAT_EXP_BITS, sgn:1; } p;
#else
struct { mp_float_int_t sgn:1, exp:MP_FLOAT_EXP_BITS, frc:MP_FLOAT_FRAC_BITS; } p;
#endif
} u;
u.p.sgn = 0;
u.p.exp = (1 << (MP_FLOAT_EXP_BITS - 1)) - 1;
if (MP_FLOAT_FRAC_BITS <= 30) {
u.p.frc = rand30();
} else {
u.p.frc = ((uint64_t)rand30() << 30) | (uint64_t)rand30();
}
return u.f - 1;
}
STATIC mp_obj_t mod_random_random(void) {
return mp_obj_new_float(randfloat());
}
STATIC MP_DEFINE_CONST_FUN_OBJ_0(mod_random_random_obj, mod_random_random);
STATIC mp_obj_t mod_random_uniform(mp_obj_t a_in, mp_obj_t b_in) {
mp_float_t a = mp_obj_get_float(a_in);
mp_float_t b = mp_obj_get_float(b_in);
return mp_obj_new_float(a + (b - a) * randfloat());
}
STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_random_uniform_obj, mod_random_uniform);
#endif
STATIC const mp_rom_map_elem_t mp_module_random_globals_table[] = {
{ MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_random) },
{ MP_ROM_QSTR(MP_QSTR_getrandbits), MP_ROM_PTR(&mod_random_getrandbits_obj) },
{ MP_ROM_QSTR(MP_QSTR_randrange), MP_ROM_PTR(&mod_random_randrange_obj) },
{ MP_ROM_QSTR(MP_QSTR_randint), MP_ROM_PTR(&mod_random_randint_obj) },
{ MP_ROM_QSTR(MP_QSTR_choice), MP_ROM_PTR(&mod_random_choice_obj) },
#if MICROPY_PY_BUILTINS_FLOAT
{ MP_ROM_QSTR(MP_QSTR_random), MP_ROM_PTR(&mod_random_random_obj) },
{ MP_ROM_QSTR(MP_QSTR_uniform), MP_ROM_PTR(&mod_random_uniform_obj) },
#endif
};
STATIC MP_DEFINE_CONST_DICT(mp_module_random_globals, mp_module_random_globals_table);
const mp_obj_module_t random_module = {
.base = { &mp_type_module },
.globals = (mp_obj_dict_t*)&mp_module_random_globals,
};
#endif // MICROPY_PY_HW_RNG