#include <k/atapi.h>
#include <string.h>

#include "atapi.h"
#include "io.h"

static struct atapi_drive drives[4] = { 0 };

static void select_drive(uint16_t bus, uint8_t slave)
{
    outb(ATA_REG_DRIVE(bus), slave);
}

static void busy_wait(uint16_t drive)
{
    int res = 0;
    while (res & BSY)
        res = inb(ATA_REG_STATUS(drive));
}

static void wait_device_selection(uint16_t drive)
{
    for (int i = 0; i < 4; ++i)
        inb(drive);
}

static uint8_t is_atapi_driver(uint16_t bus, uint8_t slave)
{
    static uint8_t atapi_sig[] = { ATAPI_SIG_SC, ATAPI_SIG_LBA_LO,
                                   ATAPI_SIG_LBA_MI, ATAPI_SIG_LBA_HI };
    uint8_t sig[4];

    sig[0] = inb(ATA_REG_SECTOR_COUNT(bus));
    sig[1] = inb(ATA_REG_LBA_LO(bus));
    sig[2] = inb(ATA_REG_LBA_MI(bus));
    sig[3] = inb(ATA_REG_LBA_HI(bus));

    if (!memcmp(sig, atapi_sig, 4))
    {
        struct atapi_drive d = { bus, slave };
        if (bus == PRIMARY_REG)
        {
            if (slave)
                drives[1] = d;
            else
                drives[0] = d;
        }
        else
        {
            if (slave)
                drives[3] = d;
            else
                drives[2] = d;
        }

        return 1;
    }

    return 0;
}

void discover_atapi_drive(void)
{
    // primary_reg
    outb(PRIMARY_DCR, SRST);
    outb(PRIMARY_DCR, INTERRUPT_DISABLE);

    select_drive(PRIMARY_REG, ATA_PORT_MASTER);
    wait_device_selection(PRIMARY_REG);
    is_atapi_driver(PRIMARY_REG, ATA_PORT_MASTER);

    // secondary_reg
    outb(SECONDARY_DCR, SRST);
    outb(SECONDARY_DCR, INTERRUPT_DISABLE);
}