SECTIONS {
	. = 0x00000000 ;
	.cortex_m4_vectors : {
		LONG(0x20007FFC);
		LONG(0x00000411);
	}
	. = 0x00000400 ;
	.flash_configuration : {
		LONG(0xFFFFFFFF);
		LONG(0xFFFFFFFF);
		LONG(0xFFFFFFFF);
		LONG(0xFFFFFFFE);
	}
	.text : {
		_linker_code = . ;
		init.o (.text)
		*(.text)
		*(.text.*)
		*(.rodata*)
		*(.gnu.linkonce.t*)
		*(.gnu.linkonce.r*)
	}
	.preinit_array : {
		__preinit_array_start = . ;
		*(.preinit_array)
		__preinit_array_end = . ;
	}
	.init_array : {
		__init_array_start = . ;
		*(.init_array)
		__init_array_end = . ;
	}
	.fini_array : {
		__fini_array_start = . ;
		*(.fini_array)
		__fini_array_end = . ;
	}
	.ctors : {
		__CTOR_LIST__ = . ;
		LONG((__CTOR_END__ - __CTOR_LIST__) / 4 - 2)
		*(.ctors)
		LONG(0)
		__CTOR_END__ = . ;
	}
	.dtors : {
		__DTOR_LIST__ = . ;
		LONG((__DTOR_END__ - __DTOR_LIST__) / 4 - 2)
		*(.dtors)
		LONG(0)
		__DTOR_END__ = . ;
	}
	flash_sdata = . ;
	. = 0x1FFF8000 ;
	ram_sdata = . ;
	.data : AT (flash_sdata) {
		_linker_data = . ;
		*(.data)
		*(.data.*)
		*(.gnu.linkonce.d*)
	}
	ram_edata = . ;
	data_size = ram_edata - ram_sdata;
	ram_sbssdata = . ;
	.bss : AT (LOADADDR(.data) + SIZEOF(.data)) {
		_linker_bss = . ;
		*(.bss)
		*(.bss.*)
		*(.gnu.linkonce.b.*)
		*(.COMMON)
	}
	ram_ebssdata = . ;
	bssdata_size = ram_ebssdata - ram_sbssdata;
	_linker_end = . ;
}

	.syntax unified
	.thumb    
	.thumb_func
	.global _startup
	.section .text

_init:
    mov     r0,#0
    mov     r1,#0
    mov     r2,#0
    mov     r3,#0
    mov     r4,#0
    mov     r5,#0
    mov     r6,#0
    mov     r7,#0
    mov     r8,#0
    mov     r9,#0
    mov     r10,#0
    mov     r11,#0
    mov     r12,#0

/* disable interrupts */
    CPSID i

/* unlock_watchdog */
    ldr r6, = 0x4005200e /* WDOG_UNLOCK doc: K20P64M50SF0RM.pdf ( Page: 423 ) */
    ldr r0, = 0xc520
    strh r0, [r6]
    ldr r0, = 0xd928
    strh r0, [r6]

/* disable_watchdog */
    ldr r6, = 0x40052000 /* WDOG_STCTRLH doc: K20P64M50SF0RM.pdf ( Page: 418 ) */
    ldr r0, = 0x01d2
    strh r0, [r6]

/* enable interrupts */
    CPSIE i

	/* copy data section from flash to ram */
	ldr r0, = flash_sdata
	ldr r1, = ram_sdata
	ldr r2, = data_size
	cmp r2, #0
	beq skip_copy
copy:
	ldrb r4, [r0], #1
	strb r4, [r1], #1
	subs r2, r2, #1
	bne copy
skip_copy:

	/* fill bssdata section with zeros */
	ldr r1, = ram_sbssdata
	ldr r2, = bssdata_size
	cmp r2, #0
	beq skip_fill
	mov r4, #0
fill:
	strb r4, [r1], #1
	subs r2, r2, #1
	bne fill
skip_fill:

	b _startup

    .end

#include <stdint.h>

using namespace std;

extern "C" {
	extern void (*__CTOR_LIST__)();
	extern void (*__DTOR_LIST__)();
	extern void (*__init_array_start)();
	extern void (*__init_array_end)();
	extern void (*__fini_array_start)();
	extern void (*__fini_array_end)();
}

void callInitArray() {
	void (**f)() = &__init_array_start;
	while (f != &__init_array_end) {
		(*f)();
		f++;
	}
}

void callConstructors() {
	void (**constructor)() = &__CTOR_LIST__;
	uint32_t total = *(uint32_t *) constructor;
	constructor++;
	while (total) {
		(*constructor)();
		total--;
		constructor++;
	}
}

void callDestructors() {
	void (**destructor)() = &__DTOR_LIST__;
	uint32_t total = *(uint32_t *) destructor;
	destructor++;
	while (total) {
		(*destructor)();
		total--;
		destructor++;
	}
}

void callFiniArray() {
	void (**f)() = &__fini_array_start;
	while (f != &__fini_array_end) {
		(*f)();
		f++;
	}
}

extern int main();

void _startup() asm("_startup");

void _startup() {
	callConstructors();
	callInitArray();
	main();
	callFiniArray();
	callDestructors();
	while (true)
		;
}

extern "C" void __cxa_pure_virtual() {}
void *__dso_handle = 0;
extern "C" void __cxa_atexit() {}

BIN_PREFIX=/opt/teensy/bin/
CXX=${BIN_PREFIX}arm-none-eabi-g++
OBJCOPY=${BIN_PREFIX}arm-none-eabi-objcopy
CXX_FLAGS=-mtune=cortex-m4 -mthumb -fno-exceptions -fno-rtti -nostdlib -nodefaultlibs -nostartfiles

main.hex: main.elf
	$(OBJCOPY) -O ihex -R .eeprom main.elf main.hex

main.elf: main.o init.o startup.o
	$(CXX) $(CXX_FLAGS) -Wl,-Tteensy31.ld -o main.elf main.o init.o startup.o

main.o: main.cc
	$(CXX) $(CXX_FLAGS) -c -o $@ $<

startup.o: startup.cc
	$(CXX) $(CXX_FLAGS) -c -o $@ $<

init.o: init.s
	$(CXX) $(CXX_FLAGS) -c -o $@ $<

clean:
	rm -f *.elf *.o *.hex *.bin

#include <stdint.h>

using namespace std;

#define  GPIO_ENABLE      (1 << 8)
#define  PULL_UP_ENABLE   (1 << 1)
#define  PULL_UP_SELECT   (1 << 0)
#define  DRIVE_STR        (1 << 6)
#define  PORT_CTRL_FLAGS  (DRIVE_STR | GPIO_ENABLE | PULL_UP_ENABLE | PULL_UP_SELECT)

#define  PORTC_PCR5    *((uint32_t *) 0x4004B014)
#define  GPIOC_PDDR    *((uint32_t *) 0x400FF094)
#define  GPIOC_PDOR    *((uint32_t *) 0x400FF080)
#define  SIM_SCGC5     *((uint32_t *) 0x40048038)
#define  WDOG_UNLOCK   *((uint32_t *) 0x4005200E)
#define  WDOG_STCTRLH  *((uint32_t *) 0x40052000)

#define  CLOCKS_ACTIVE_TO_ALL_GPIO  0x00043F82
#define  WATCHDOG_UNLOCK_VALUE_1    0xC520      
#define  WATCHDOG_UNLOCK_VALUE_2    0xD928      
#define  WATCHDOG_DISABLE_VALUE     0x01D2      

class Clase {
	public:
		uint32_t n;
		uint32_t v1, v2;
		Clase(uint32_t x1, uint32_t x2, uint32_t aux);
};

Clase::Clase(uint32_t x1, uint32_t x2, uint32_t aux) {
	this->v1 = x1;
	this->v2 = x2;
	this->n = aux;
}

Clase objeto(1, 2, 100000);
uint32_t a = 50000;
//uint32_t a = 100000;

int main() {
	// configure PTC5
	SIM_SCGC5 = CLOCKS_ACTIVE_TO_ALL_GPIO;
	PORTC_PCR5 = PORT_CTRL_FLAGS;
	// PORTC is output
	GPIOC_PDDR = (uint32_t) 0xFFFFFFFF;
	while (1) {
		volatile uint32_t i;
		// PORTC to 1
		GPIOC_PDOR = (uint32_t) 0xFFFFFFFF;
		for (i = 0; i < objeto.n; i++)
			;
		// PORTC to 0
		GPIOC_PDOR = (uint32_t) 0x00000000;
		for (i = 0; i < objeto.n; i++)
			;
	}
}