#include <stdint.h>

#include "ch573/gpio.h"

#define GPIO_PORT_A ch573_gpio__gpio_port_a
#define GPIO_PORT CH573_GPIO__GPIO_PORT_T_INTF

static void start(void);

/*
 * Function (or really pointer to code) for the reset interrupt handler.
 */
void on_reset(void);

/*
 * Function which delays for a bit.
 */
void delay(void);

/* Type def to a void function to make things mor ereadable. */
typedef void (*isr_routine)(void);

/** The ISR Vector structure. This is linked to starting at address 0. */
// __attribute((__section__(".isr_vector"))) volatile struct {
//   // What NULL points to. nothing useful.
//   uint32_t reserved__;
//   // Called when the device boots or reset is pressed.
//   isr_routine reset_cb;
//   isr_routine nmi_cb;
//   isr_routine exc_cb;
// } isr_vectors = {.reset_cb = on_reset};

/*
 * The reset callback.This has to be a naked function because the stack pointer
 * may not be initialized!!.
 */
__attribute((naked)) void on_reset(void)
{
  // Set up the stack pointer to point to the end of SRAM.
  asm volatile(
      "li	sp,0x20008000\n"
      "addi	sp,sp,-4\n"
      "jalr %0\n"
      "spin:\n"
      "j spin\n"
      :
      : "r"(start));
}

uint32_t collatz(uint32_t n)
{
  uint32_t c = 0;

  while (n > 1) {
    if (n % 2 == 0) {
      n /= 2;
    } else {
      n = n * 3 + 1;
    }
    c++;
  }

  return c;
}

void blink_n(int n)
{
  uint32_t bit = 1 << 8;
  while (n > 0) {
    GPIO_PORT.out.set(GPIO_PORT_A, OFF, 8);
    delay();
    GPIO_PORT.out.set(GPIO_PORT_A, ON, 8);
    delay();
    --n;
  }
}

void delay(void)
{
  for (volatile uint32_t i = 0; i < 10000; ++i);
}

/* Main routine. This is called on_reset once everything else has been set up.
 */
static void start(void)
{
  GPIO_PORT.dir.set(GPIO_PORT_A, DIR_OUT, 8);
  GPIO_PORT.pd_drv.set(GPIO_PORT_A, PD_DRV_OPEN_DRAIN, 8);

  for (;;) {
    GPIO_PORT.out.set(GPIO_PORT_A, ON, 8);
    delay();
    delay();
    delay();
    GPIO_PORT.out.set(GPIO_PORT_A, OFF, 8);
    delay();
  }

  // uint32_t i;
  // for (i = 1;; ++i) {
  //   uint32_t c = collatz(i);
  //   blink_n(c);

  //   delay();
  //   delay();
  //   delay();
  //   delay();
  //   delay();
  //   delay();
  //   delay();
  //   delay();
  //   delay();
  // }
}