#include "PS2MouseDevice.h"
#include "IO.h"

#define IRQ_MOUSE                1
#define I8042_BUFFER             0x60
#define I8042_STATUS             0x64
#define I8042_ACK                0xFA
#define I8042_BUFFER_FULL        0x01
#define I8042_WHICH_BUFFER       0x20
#define I8042_MOUSE_BUFFER       0x20
#define I8042_KEYBOARD_BUFFER    0x00

//#define PS2MOUSE_DEBUG

static PS2MouseDevice* s_the;

PS2MouseDevice::PS2MouseDevice()
    : IRQHandler(12)
    , CharacterDevice(10, 1)
{
    s_the = this;
    initialize();
}

PS2MouseDevice::~PS2MouseDevice()
{
}

PS2MouseDevice& PS2MouseDevice::the()
{
    return *s_the;
}

void PS2MouseDevice::handle_irq()
{
    for (;;) {
        byte status = IO::in8(I8042_STATUS);
        if (!(((status & I8042_WHICH_BUFFER) == I8042_MOUSE_BUFFER) && (status & I8042_BUFFER_FULL)))
            return;

        byte data = IO::in8(I8042_BUFFER);
        m_data[m_data_state] = data;
        switch (m_data_state) {
        case 0:
            if (!(data & 0x08)) {
                dbgprintf("PS2Mouse: Stream out of sync.\n");
                break;
            }
            ++m_data_state;
            break;
        case 1:
            ++m_data_state;
            break;
        case 2:
            m_data_state = 0;
#ifdef PS2MOUSE_DEBUG
            dbgprintf("PS2Mouse: %d, %d %s %s (buffered: %u)\n",
                m_data[1],
                m_data[2],
                (m_data[0] & 1) ? "Left" : "",
                (m_data[0] & 2) ? "Right" : "",
                m_queue.size()
            );
#endif
            m_queue.enqueue(m_data[0]);
            m_queue.enqueue(m_data[1]);
            m_queue.enqueue(m_data[2]);
            break;
        }
    }
}

void PS2MouseDevice::wait_then_write(byte port, byte data)
{
    prepare_for_output();
    IO::out8(port, data);
}

byte PS2MouseDevice::wait_then_read(byte port)
{
    prepare_for_input();
    return IO::in8(port);
}

void PS2MouseDevice::initialize()
{
    // Enable PS aux port
    wait_then_write(0x64, 0xa8);

    // Enable interrupts
    wait_then_write(0x64, 0x20);

    // Enable the PS/2 mouse IRQ (12).
    // NOTE: The keyboard uses IRQ 1 (and is enabled by bit 0 in this register).
    byte status = wait_then_read(0x60) | 2;
    wait_then_write(0x64, 0x60);
    wait_then_write(0x60, status);

    // Set default settings.
    mouse_write(0xf6);
    byte ack1 = mouse_read();
    ASSERT(ack1 == 0xfa);

    // Enable.
    mouse_write(0xf4);
    byte ack2 = mouse_read();
    ASSERT(ack2 == 0xfa);

    enable_irq();
}

void PS2MouseDevice::prepare_for_input()
{
    for (;;) {
        if (IO::in8(0x64) & 1)
            return;
    }
}

void PS2MouseDevice::prepare_for_output()
{
    for (;;) {
        if (!(IO::in8(0x64) & 2))
            return;
    }
}

void PS2MouseDevice::mouse_write(byte data)
{
    prepare_for_output();
    IO::out8(0x64, 0xd4);
    prepare_for_output();
    IO::out8(0x60, data);
}

byte PS2MouseDevice::mouse_read()
{
    prepare_for_input();
    return IO::in8(0x60);
}

bool PS2MouseDevice::can_read(Process&) const
{
    return !m_queue.is_empty();
}

ssize_t PS2MouseDevice::read(Process&, byte* buffer, size_t size)
{
    ssize_t nread = 0;
    while ((size_t)nread < size) {
        if (m_queue.is_empty())
            break;
        // FIXME: Don't return partial data frames.
        buffer[nread++] = m_queue.dequeue();
    }
    return nread;
}

ssize_t PS2MouseDevice::write(Process&, const byte*, size_t)
{
    return 0;
}