#include "stm32f4xx.h"
#include "sram_vtor.h"

// #include <assert.h>
#include <string.h>

// symbol from picolibc stored in flash memory

extern const void *__interrupt_vector[];

// Reference manual for STM32F411xC/E
// 10.1.3:
//
// The full vector table takes 0x198=408 bytes, with each entry requiring four
// bytes.
//
// Arm®v7-M Architecture Reference Manual
// B1.5.3:
//
// The Vector table must be naturally aligned to a power of two whose alignment
// value is greater than or equal to (Number of Exceptions supported x 4), with
// a minimum alignment of 128 bytes.

static
void (*sram_vectors[408/4])(void)
	__attribute__((aligned(512)));

void NVIC_Relocate_VTOR(void)
{
	// sanity-check that the memory alignment is such that no bits of the
	// address fall outside the VTOR register's bector table base offset field

	// assert( 0U == (((uintptr_t)sram_vectors) & ~SCB_VTOR_TBLOFF_Msk) );

	// picolibc arm/interrupt.c assigns vectors up through systick (0x40
	// bytes), which we'll relocate to the new sram location
	memcpy(sram_vectors, __interrupt_vector, 0x40);
	__DSB(); // ensure all memory is written before pointing VTOR at it
	SCB->VTOR = (uintptr_t)sram_vectors;
}