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/*
* The MIT License (MIT)
*
* Copyright (c) 2015 Matthias P. Braendli
*
* 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 "common.h"
#include "FreeRTOS.h"
#include "timers.h"
#include <stm32f4xx.h>
static uint64_t common_timestamp = 0; // milliseconds since startup
static TimerHandle_t common_timer;
// The LFSR is used as random number generator
static const uint16_t lfsr_start_state = 0x12ABu;
static uint16_t lfsr;
static void common_increase_timestamp(TimerHandle_t t);
void common_init(void)
{
common_timer = xTimerCreate("Timer",
portTICK_PERIOD_MS,
pdTRUE, // Auto-reload
NULL, // No unique id
common_increase_timestamp
);
xTimerStart(common_timer, 0);
lfsr = lfsr_start_state;
}
static void common_increase_timestamp(TimerHandle_t t)
{
common_timestamp++;
}
uint64_t timestamp_now(void)
{
return common_timestamp;
}
// Return either 0 or 1, somewhat randomly
int random_bool(void)
{
uint16_t bit;
/* taps: 16 14 13 11; feedback polynomial: x^16 + x^14 + x^13 + x^11 + 1 */
bit = ((lfsr >> 0) ^ (lfsr >> 2) ^ (lfsr >> 3) ^ (lfsr >> 5) ) & 1;
lfsr = (lfsr >> 1) | (bit << 15);
return bit;
}
// For the debugger
static int faultsource = 0;
void trigger_fault(int source)
{
__disable_irq();
faultsource = source;
while (1) {}
}
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