#include <stdint.h>
#include <stdbool.h>

#define REG8(addr) *((volatile uint8_t *) addr)
#define REG16(addr) *((volatile uint16_t *) addr)
#define REG32(addr) *((volatile uint32_t *) addr)

#define JOY_DATA REG8(0x1F801040)
#define JOY_STAT REG16(0x1F801044)
#define JOY_MODE REG16(0x1F801048)
#define JOY_CTRL REG16(0x1F80104A)
#define JOY_BAUD REG16(0x1F80104E)

// Stores 0x2000 for second slot and 0x0000 for first slot
static uint16_t slotMask;

void card_delay(int time) {
    // To be demangled
}

void card_init() {
    JOY_CTRL = 0x0040; // Reset I/O unit
    JOY_BAUD = 0x0043; // Clock speed: 505504.48KHz
    JOY_MODE = 0x000D;
    JOY_CTRL = slotMask | 0x0002;
    card_delay(10);

    JOY_CTRL = 0x0000;
    card_delay(10000);
}

int card_transceive(uint8_t txData) {
    JOY_DATA = txData; // Store output byte on TX buffer
    JOY_CTRL = slotMask | 0x0003; // Begin transference

    int retry = 100000;
    while (JOY_STAT & 0x0002 == 0) { // Wait until a byte is received
        if (retry-- == 0) { // If no data has been received when retry is zero, return -1
            return -1;
        }
    }

    JOY_CTRL = slotMask | 0x0002; // Clear RX mask
    int rxData = JOY_DATA; // Read data
    card_delay(5);
    return rxData;
}

bool card_acknowledge() {
    int retry = 100000;
    while (JOY_STAT & 0x0080 != 0) { // Wait until /ACK goes low
        if (retry-- == 0) { // If no acknowledgement has been issued when retry is zero, return false
            return false;
        }
    }

    JOY_CTRL |= 0x0010; // Clear ACK flag
    return true;
}

bool card_check(bool secondSlot) {
    if (secondSlot) {
        slotMask = 0x2000;
    } else {
        slotMask = 0x0000;
    }

    card_init();

    JOY_CTRL = slotMask | 0x0002;
    card_delay(100);

    card_transceive(0x21);
    if (!card_acknowledge()) {
        return false;
    }
    bool ok = card_transceive(0x53) & 0xF0 == 0;

    JOY_CTRL = 0x0000;
    card_init();

    return ok;
}