#include <stdlib.h>

#include "Driver_GPIO.h"
#include "stm32f4xx.h"

#include "sram_vtor.h"

#include "cmsis_dv.h"
#include "cmsis_os2.h"

volatile long gTicks;
void tick(void)
{
	gTicks++;
}

osStatus_t osDelay (uint32_t t)
{
	uint32_t start = gTicks;
	// modular subtraction is resillient against
	// up to a single overflow in gTicks
	while (gTicks - start < t)
		__WFI();
	return 0;
}

void init_clock(void)
{
	SystemCoreClockUpdate();
	SysTick_Config(SystemCoreClock / 1000);
	NVIC_SetVector(SysTick_IRQn, (uintptr_t)tick);
	NVIC_EnableIRQ(SysTick_IRQn);

	RCC->AHB1ENR |= RCC_AHB1ENR_GPIOAEN;
	(void)RCC->AHB1ENR;
	(void)RCC->AHB1ENR;
}

int main(void)
{
	NVIC_Relocate_VTOR();
	init_clock();

	cmsis_dv(NULL);
	return EXIT_SUCCESS;
}