#include "driver/gpio.h"
#include "driver/timer.h"

#include "soc/gpio_reg.h"
#include "soc/timer_group_struct.h"

// write value to register
#define REG_W(_r, _v) ((*(volatile uint32_t*)(_r)) = (_v))

void IRAM_ATTR timer_isr(void* arg)
{
    uint32_t timer_group = (uint32_t)arg & 1;
    uint32_t timer_idx = ((uint32_t)arg & 2) >> 1;

    static uint32_t counter = 0;

    if (++counter == 1000000) {
        static int level = 0;
        counter = 0;
        level ^= 1;
        // gpio_set_level(2, level);
        if (level) {
            REG_W(GPIO_OUT_W1TS_REG, BIT2);
            TIMERG0.hw_timer[0].alarmlo.tx_alarm_lo = 4UL;
        } else {
            REG_W(GPIO_OUT_W1TC_REG, BIT2);
            TIMERG0.hw_timer[0].alarmlo.tx_alarm_lo = 40UL;
        }
    }

    // timer_group_clr_intr_status_in_isr(TIMER_GROUP_0, TIMER_0);
    TIMERG0.int_clr_timers.t0_int_clr = 1;
    // timer_group_enable_alarm_in_isr(TIMER_GROUP_0, TIMER_0);
    TIMERG0.hw_timer[0].config.tx_alarm_en = 1;
}

static void timer__init(timer_group_t group, timer_idx_t idx)
{
    /* Select and initialize basic parameters of the timer */
    timer_config_t config = {
        .divider = 2UL,
        .counter_dir = TIMER_COUNT_UP,
        .counter_en = TIMER_PAUSE,
        .alarm_en = TIMER_ALARM_EN,
        .auto_reload = TIMER_AUTORELOAD_EN,
    }; // default clock source is APB
    timer_init(group, idx, &config);

    /* Timer's counter will initially start from value below.
       Also, if auto_reload is set, this value will be automatically reload on alarm */
    timer_set_counter_value(group, idx, 0ULL);

    /* Configure the alarm value and the interrupt on alarm. */
    timer_set_alarm_value(group, idx, 4ULL);
    timer_enable_intr(group, idx);
    timer_isr_register(group, idx, timer_isr, (void*)((idx << 1) | group), ESP_INTR_FLAG_IRAM, NULL);

    timer_start(group, idx);
}

/*
   In this example, we will test hardware timer0 and timer1 of timer group0.
*/
void app_main(void)
{
    gpio_reset_pin(2);
    gpio_set_direction(2, GPIO_MODE_OUTPUT);

    timer__init(TIMER_GROUP_0, TIMER_0);
}