183 lines
3.8 KiB
C
183 lines
3.8 KiB
C
/*
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* This file is part of the Pico HSM distribution (https://github.com/polhenarejos/pico-hsm).
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* Copyright (c) 2022 Pol Henarejos.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, version 3.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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//Part of the code is taken from GnuK (GPLv3)
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#include <stdint.h>
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#include <string.h>
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#include <stdio.h>
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#include "pico/stdlib.h"
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#include "neug.h"
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#include "hardware/structs/rosc.h"
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#include "hardware/gpio.h"
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#include "hardware/adc.h"
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#include "bsp/board.h"
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#include "pico/unique_id.h"
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void adc_start() {
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adc_init();
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adc_gpio_init(27);
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adc_select_input(1);
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}
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void adc_stop() {
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}
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static uint64_t random_word = 0xcbf29ce484222325;
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static uint8_t ep_round = 0;
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static void ep_init() {
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random_word = 0xcbf29ce484222325;
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ep_round = 0;
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}
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/* Here, we assume a little endian architecture. */
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static int ep_process () {
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if (ep_round == 0) {
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ep_init();
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}
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uint64_t word = 0x0;
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for (int n = 0; n < 64; n++) {
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uint8_t bit1, bit2;
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do
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{
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bit1 = rosc_hw->randombit&0xff;
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//sleep_ms(1);
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bit2 = rosc_hw->randombit&0xff;
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} while(bit1 == bit2);
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word = (word << 1) | bit1;
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}
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random_word ^= word^board_millis()^adc_read();
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random_word *= 0x00000100000001B3;
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if (++ep_round == 8) {
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ep_round = 0;
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return 2; //2 words
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}
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return 0;
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}
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static const uint32_t *ep_output() {
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return (uint32_t *)&random_word;
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}
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struct rng_rb {
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uint32_t *buf;
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uint8_t head, tail;
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uint8_t size;
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unsigned int full :1;
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unsigned int empty :1;
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};
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static void rb_init(struct rng_rb *rb, uint32_t *p, uint8_t size) {
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rb->buf = p;
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rb->size = size;
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rb->head = rb->tail = 0;
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rb->full = 0;
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rb->empty = 1;
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}
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static void rb_add(struct rng_rb *rb, uint32_t v) {
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rb->buf[rb->tail++] = v;
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if (rb->tail == rb->size)
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rb->tail = 0;
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if (rb->tail == rb->head)
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rb->full = 1;
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rb->empty = 0;
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}
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static uint32_t rb_del(struct rng_rb *rb) {
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uint32_t v = rb->buf[rb->head++];
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if (rb->head == rb->size)
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rb->head = 0;
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if (rb->head == rb->tail)
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rb->empty = 1;
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rb->full = 0;
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return v;
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}
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static struct rng_rb the_ring_buffer;
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void *neug_task() {
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struct rng_rb *rb = &the_ring_buffer;
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int n;
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if ((n = ep_process())) {
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int i;
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const uint32_t *vp;
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vp = ep_output();
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for (i = 0; i < n; i++) {
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rb_add (rb, *vp++);
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if (rb->full)
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break;
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}
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}
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return NULL;
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}
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void neug_init(uint32_t *buf, uint8_t size) {
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pico_unique_board_id_t unique_id;
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pico_get_unique_board_id(&unique_id);
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const uint32_t *u = (const uint32_t *)unique_id.id;
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struct rng_rb *rb = &the_ring_buffer;
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int i;
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rb_init(rb, buf, size);
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adc_start();
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ep_init();
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}
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void neug_flush(void) {
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struct rng_rb *rb = &the_ring_buffer;
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while (!rb->empty)
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rb_del (rb);
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}
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uint32_t neug_get(int kick) {
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struct rng_rb *rb = &the_ring_buffer;
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uint32_t v;
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while (rb->empty)
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neug_task();
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v = rb_del(rb);
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return v;
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}
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void neug_wait_full(void) { //should be called only on core1
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struct rng_rb *rb = &the_ring_buffer;
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while (!rb->full) {
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sleep_ms(1);
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}
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}
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void neug_fini(void) {
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neug_get(1);
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}
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