#include <stdint.h>

#define VIRT_RTC_BASE 0x0101000UL
#define VIRT_RTC_SIZE 0x1000

#define RTC_TIME_LOW   0x00
#define RTC_TIME_HIGH  0x04
#define RTC_ALARM_LOW  0x08
#define RTC_ALARM_HIGH 0x0c

#define RTC_IRQ_ENABLED     0x10
#define RTC_CLEAR_ALARM     0x14
#define RTC_ALARM_STATUS    0x18
#define RTC_CLEAR_INTERRUPT 0x1c

static inline uint32_t mmio_read32(uintptr_t addr) {
    return *(volatile uint32_t *)addr;
}

static inline void mmio_write32(uintptr_t addr, uint32_t value) {
    *(volatile uint32_t *)addr = value;
}

uint64_t rtc_read_time(void) {
    uint32_t low = mmio_read32(VIRT_RTC_BASE + RTC_TIME_LOW);
    uint32_t high = mmio_read32(VIRT_RTC_BASE + RTC_TIME_HIGH);
    return ((uint64_t)high << 32) | low;
}

void rtc_alarm_set(uint64_t ns) {
    mmio_write32(VIRT_RTC_BASE + RTC_ALARM_HIGH, ns >> 32);
    mmio_write32(VIRT_RTC_BASE + RTC_ALARM_LOW, ns & 0xffffffff);
}

uint64_t rtc_alarm_read(void) {
    uint32_t low = mmio_read32(VIRT_RTC_BASE + RTC_ALARM_LOW);
    uint32_t high = mmio_read32(VIRT_RTC_BASE + RTC_ALARM_HIGH);
    return ((uint64_t)high << 32) | low;
}

void rtc_alarm_enable(void) {
    mmio_write32(VIRT_RTC_BASE + RTC_IRQ_ENABLED, 1);
}

void rtc_alarm_disable(void) {
    mmio_write32(VIRT_RTC_BASE + RTC_IRQ_ENABLED, 0);
}

uint32_t rtc_alarm_status(void) {
    return mmio_read32(VIRT_RTC_BASE + RTC_IRQ_ENABLED);
}