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#include "esp32/ulp.h"
#include "soc/rtc_cntl_reg.h"
#include "driver/rtc_io.h"

void setup() {
    Serial.begin(115200);
    while( !Serial ){}

    Serial.println("Init");
    esp_sleep_wakeup_cause_t cause = esp_sleep_get_wakeup_cause();
    if (cause != ESP_SLEEP_WAKEUP_ULP) {
        printf("Not ULP wakeup, initializing ULP\n");
        init_ulp_program();
    } else {
        printf("ULP wakeup, saving pulse count\n");
        update_pulse_count();
    }

    printf("Entering deep sleep\n\n");
    ESP_ERROR_CHECK( esp_sleep_enable_ulp_wakeup() );
    esp_deep_sleep_start();
}

void loop(){
}

void init_ulp_program() {
    const ulp_insn_t program[] = {
                M_LABEL(3),        // LABEL 3
                I_MOVI(R0, 0),
                I_RD_REG(RTC_CNTL_LOW_POWER_ST_REG, RTC_CNTL_RDY_FOR_WAKEUP,RTC_CNTL_RDY_FOR_WAKEUP ),
                M_BGE(4, 1),
                M_BX(3),
                M_LABEL(4),
                I_WAKE(),          // Wake up ESP32
                I_END(),           // If I comment this line the program restarts normally
                I_HALT()           // Halt the coprocessor
    };

    size_t load_addr = 0;
    size_t size = sizeof(program)/sizeof(ulp_insn_t);
    ulp_process_macros_and_load(load_addr, program, &size);

    /* Set ULP wake up period to 2s */
    ulp_set_wakeup_period(0, 2000000);
    
    // ULP can wake ESP
    esp_sleep_enable_ulp_wakeup();

    ulp_run(0);
}

void update_pulse_count() {
   // I understood that calling ulp_run() here would re-enable the timer and the program would wake
    ulp_run(0);
}