#include <stdint.h>

/* linker script symbols */
extern uint32_t _sidata;  /* load address of .data in Flash */
extern uint32_t _sdata;   /* start of .data in RAM */
extern uint32_t _edata;   /* end of .data in RAM */
extern uint32_t _sbss;
extern uint32_t _ebss;
extern uint32_t _estack;  /* address equals initial SP value */

extern int main(void);

void Reset_Handler(void);

static void __attribute__((used)) Default_Handler(void)
{
    while (1);
}

/* ARM Cortex-M4 core exceptions */
void NMI_Handler(void)        __attribute__((weak, alias("Default_Handler")));
void HardFault_Handler(void)  __attribute__((weak, alias("Default_Handler")));
void MemManage_Handler(void)  __attribute__((weak, alias("Default_Handler")));
void BusFault_Handler(void)   __attribute__((weak, alias("Default_Handler")));
void UsageFault_Handler(void) __attribute__((weak, alias("Default_Handler")));
void SVC_Handler(void)        __attribute__((weak, alias("Default_Handler")));
void DebugMon_Handler(void)   __attribute__((weak, alias("Default_Handler")));
void PendSV_Handler(void)     __attribute__((weak, alias("Default_Handler")));
void SysTick_Handler(void)    __attribute__((weak, alias("Default_Handler")));

/* nRF52840 peripheral IRQs (IRQ0-IRQ47) */
void POWER_CLOCK_IRQHandler(void)                        __attribute__((weak, alias("Default_Handler")));
void RADIO_IRQHandler(void)                              __attribute__((weak, alias("Default_Handler")));
void UARTE0_UART0_IRQHandler(void)                       __attribute__((weak, alias("Default_Handler")));
void SPIM0_SPIS0_TWIM0_TWIS0_SPI0_TWI0_IRQHandler(void) __attribute__((weak, alias("Default_Handler")));
void SPIM1_SPIS1_TWIM1_TWIS1_SPI1_TWI1_IRQHandler(void) __attribute__((weak, alias("Default_Handler")));
void NFCT_IRQHandler(void)                               __attribute__((weak, alias("Default_Handler")));
void GPIOTE_IRQHandler(void)                             __attribute__((weak, alias("Default_Handler")));
void SAADC_IRQHandler(void)                              __attribute__((weak, alias("Default_Handler")));
void TIMER0_IRQHandler(void)                             __attribute__((weak, alias("Default_Handler")));
void TIMER1_IRQHandler(void)                             __attribute__((weak, alias("Default_Handler")));
void TIMER2_IRQHandler(void)                             __attribute__((weak, alias("Default_Handler")));
void RTC0_IRQHandler(void)                               __attribute__((weak, alias("Default_Handler")));
void TEMP_IRQHandler(void)                               __attribute__((weak, alias("Default_Handler")));
void RNG_IRQHandler(void)                                __attribute__((weak, alias("Default_Handler")));
void ECB_IRQHandler(void)                                __attribute__((weak, alias("Default_Handler")));
void CCM_AAR_IRQHandler(void)                            __attribute__((weak, alias("Default_Handler")));
void WDT_IRQHandler(void)                                __attribute__((weak, alias("Default_Handler")));
void RTC1_IRQHandler(void)                               __attribute__((weak, alias("Default_Handler")));
void QDEC_IRQHandler(void)                               __attribute__((weak, alias("Default_Handler")));
void COMP_LPCOMP_IRQHandler(void)                        __attribute__((weak, alias("Default_Handler")));
void SWI0_EGU0_IRQHandler(void)                          __attribute__((weak, alias("Default_Handler")));
void SWI1_EGU1_IRQHandler(void)                          __attribute__((weak, alias("Default_Handler")));
void SWI2_EGU2_IRQHandler(void)                          __attribute__((weak, alias("Default_Handler")));
void SWI3_EGU3_IRQHandler(void)                          __attribute__((weak, alias("Default_Handler")));
void SWI4_EGU4_IRQHandler(void)                          __attribute__((weak, alias("Default_Handler")));
void SWI5_EGU5_IRQHandler(void)                          __attribute__((weak, alias("Default_Handler")));
void TIMER3_IRQHandler(void)                             __attribute__((weak, alias("Default_Handler")));
void TIMER4_IRQHandler(void)                             __attribute__((weak, alias("Default_Handler")));
void PWM0_IRQHandler(void)                               __attribute__((weak, alias("Default_Handler")));
void PDM_IRQHandler(void)                                __attribute__((weak, alias("Default_Handler")));
void MWU_IRQHandler(void)                                __attribute__((weak, alias("Default_Handler")));
void PWM1_IRQHandler(void)                               __attribute__((weak, alias("Default_Handler")));
void PWM2_IRQHandler(void)                               __attribute__((weak, alias("Default_Handler")));
void SPIM2_SPIS2_SPI2_IRQHandler(void)                  __attribute__((weak, alias("Default_Handler")));
void RTC2_IRQHandler(void)                               __attribute__((weak, alias("Default_Handler")));
void I2S_IRQHandler(void)                                __attribute__((weak, alias("Default_Handler")));
void FPU_IRQHandler(void)                                __attribute__((weak, alias("Default_Handler")));
void USBD_IRQHandler(void)                               __attribute__((weak, alias("Default_Handler")));
void UARTE1_IRQHandler(void)                             __attribute__((weak, alias("Default_Handler")));
void QSPI_IRQHandler(void)                               __attribute__((weak, alias("Default_Handler")));
void CRYPTOCELL_IRQHandler(void)                         __attribute__((weak, alias("Default_Handler")));
void PWM3_IRQHandler(void)                               __attribute__((weak, alias("Default_Handler")));
void SPIM3_IRQHandler(void)                              __attribute__((weak, alias("Default_Handler")));

/* vector table: 64 entries (16 core + 48 IRQs) */

typedef void (*vector_fn)(void);

__attribute__((section(".isr_vector"), used))
const vector_fn vectors[64] = {
    /* 0  */ (vector_fn)&_estack,
    /* 1  */ Reset_Handler,
    /* 2  */ NMI_Handler,
    /* 3  */ HardFault_Handler,
    /* 4  */ MemManage_Handler,
    /* 5  */ BusFault_Handler,
    /* 6  */ UsageFault_Handler,
    /* 7  */ 0,
    /* 8  */ 0,
    /* 9  */ 0,
    /* 10 */ 0,
    /* 11 */ SVC_Handler,
    /* 12 */ DebugMon_Handler,
    /* 13 */ 0,
    /* 14 */ PendSV_Handler,
    /* 15 */ SysTick_Handler,

    /* IRQ0  */ POWER_CLOCK_IRQHandler,
    /* IRQ1  */ RADIO_IRQHandler,
    /* IRQ2  */ UARTE0_UART0_IRQHandler,
    /* IRQ3  */ SPIM0_SPIS0_TWIM0_TWIS0_SPI0_TWI0_IRQHandler,
    /* IRQ4  */ SPIM1_SPIS1_TWIM1_TWIS1_SPI1_TWI1_IRQHandler,
    /* IRQ5  */ NFCT_IRQHandler,
    /* IRQ6  */ GPIOTE_IRQHandler,
    /* IRQ7  */ SAADC_IRQHandler,
    /* IRQ8  */ TIMER0_IRQHandler,
    /* IRQ9  */ TIMER1_IRQHandler,
    /* IRQ10 */ TIMER2_IRQHandler,
    /* IRQ11 */ RTC0_IRQHandler,
    /* IRQ12 */ TEMP_IRQHandler,
    /* IRQ13 */ RNG_IRQHandler,
    /* IRQ14 */ ECB_IRQHandler,
    /* IRQ15 */ CCM_AAR_IRQHandler,
    /* IRQ16 */ WDT_IRQHandler,
    /* IRQ17 */ RTC1_IRQHandler,
    /* IRQ18 */ QDEC_IRQHandler,
    /* IRQ19 */ COMP_LPCOMP_IRQHandler,
    /* IRQ20 */ SWI0_EGU0_IRQHandler,
    /* IRQ21 */ SWI1_EGU1_IRQHandler,
    /* IRQ22 */ SWI2_EGU2_IRQHandler,
    /* IRQ23 */ SWI3_EGU3_IRQHandler,
    /* IRQ24 */ SWI4_EGU4_IRQHandler,
    /* IRQ25 */ SWI5_EGU5_IRQHandler,
    /* IRQ26 */ TIMER3_IRQHandler,
    /* IRQ27 */ TIMER4_IRQHandler,
    /* IRQ28 */ PWM0_IRQHandler,
    /* IRQ29 */ PDM_IRQHandler,
    /* IRQ30 */ 0,  /* reserved */
    /* IRQ31 */ 0,  /* reserved */
    /* IRQ32 */ MWU_IRQHandler,
    /* IRQ33 */ PWM1_IRQHandler,
    /* IRQ34 */ PWM2_IRQHandler,
    /* IRQ35 */ SPIM2_SPIS2_SPI2_IRQHandler,
    /* IRQ36 */ RTC2_IRQHandler,
    /* IRQ37 */ I2S_IRQHandler,
    /* IRQ38 */ FPU_IRQHandler,
    /* IRQ39 */ USBD_IRQHandler,
    /* IRQ40 */ UARTE1_IRQHandler,
    /* IRQ41 */ QSPI_IRQHandler,
    /* IRQ42 */ CRYPTOCELL_IRQHandler,
    /* IRQ43 */ 0,  /* reserved */
    /* IRQ44 */ 0,  /* reserved */
    /* IRQ45 */ PWM3_IRQHandler,
    /* IRQ46 */ 0,  /* reserved */
    /* IRQ47 */ SPIM3_IRQHandler,
};

/* Reset_Handler */

void Reset_Handler(void)
{
    /* copy .data initializers from Flash to RAM */
    uint32_t *src = &_sidata;
    uint32_t *dst = &_sdata;
    while (dst < &_edata) {
        *dst++ = *src++;
    }

    /* zero .bss */
    dst = &_sbss;
    while (dst < &_ebss) {
        *dst++ = 0u;
    }

    main();
    while (1);
}