| /* |
| * Copyright (c) 2016 Nordic Semiconductor ASA |
| * Copyright (c) 2016 Vinayak Kariappa Chettimada |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include <soc.h> |
| |
| #include "rand.h" |
| |
| #include "debug.h" |
| |
| #define RAND_RESERVED (4) |
| |
| struct rand { |
| uint8_t count; |
| uint8_t first; |
| uint8_t last; |
| uint8_t rand[1]; |
| }; |
| |
| static struct rand *_rand; |
| |
| void rand_init(uint8_t *context, uint8_t context_len) |
| { |
| LL_ASSERT(context_len > sizeof(struct rand)); |
| |
| _rand = (struct rand *)context; |
| _rand->count = context_len - sizeof(struct rand) + 1; |
| _rand->first = _rand->last = 0; |
| |
| NRF_RNG->CONFIG = RNG_CONFIG_DERCEN_Msk; |
| NRF_RNG->EVENTS_VALRDY = 0; |
| NRF_RNG->INTENSET = RNG_INTENSET_VALRDY_Msk; |
| NRF_RNG->TASKS_START = 1; |
| } |
| |
| uint32_t rand_get(uint8_t octets, uint8_t *rand) |
| { |
| uint8_t reserved; |
| uint8_t first; |
| |
| while (octets) { |
| if (_rand->first == _rand->last) { |
| break; |
| } |
| |
| rand[--octets] = _rand->rand[_rand->first]; |
| |
| first = _rand->first + 1; |
| if (first == _rand->count) { |
| first = 0; |
| } |
| _rand->first = first; |
| } |
| |
| reserved = RAND_RESERVED; |
| first = _rand->first; |
| while (reserved--) { |
| if (first == _rand->last) { |
| NRF_RNG->TASKS_START = 1; |
| |
| break; |
| } |
| |
| first++; |
| if (first == _rand->count) { |
| first = 0; |
| } |
| } |
| |
| return octets; |
| } |
| |
| void rng_isr(void) |
| { |
| if (NRF_RNG->EVENTS_VALRDY) { |
| uint8_t last; |
| |
| last = _rand->last + 1; |
| if (last == _rand->count) { |
| last = 0; |
| } |
| |
| if (last == _rand->first) { |
| /* this condition should not happen |
| * , but due to probable bug in HW |
| * , new value could be generated |
| * before task is stopped. |
| */ |
| NRF_RNG->TASKS_STOP = 1; |
| NRF_RNG->EVENTS_VALRDY = 0; |
| |
| return; |
| } |
| |
| _rand->rand[_rand->last] = NRF_RNG->VALUE; |
| _rand->last = last; |
| |
| last = _rand->last + 1; |
| if (last == _rand->count) { |
| last = 0; |
| } |
| |
| NRF_RNG->EVENTS_VALRDY = 0; |
| |
| if (last == _rand->first) { |
| NRF_RNG->TASKS_STOP = 1; |
| } |
| } |
| } |