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mirror of https://github.com/trezor/trezor-firmware.git synced 2024-12-05 22:18:16 +00:00
trezor-firmware/legacy/random_delays.c
2021-05-21 13:42:53 +02:00

42 lines
1.1 KiB
C

/*
* This file is part of the Trezor project, https://trezor.io/
*
* Copyright (c) SatoshiLabs
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "random_delays.h"
#include "common.h"
#include "rng.h"
#include "util.h"
void wait_random(void) {
int wait = random32() & 0xff;
volatile int i = 0;
volatile int j = wait;
while (i < wait) {
if (i + j != wait) {
shutdown();
}
++i;
--j;
}
// Double-check loop completion.
if (i != wait || j != 0) {
shutdown();
}
}