//
// Created by rick on 9/22/19.
//

#include <string.h>
#include <stdlib.h>

#include <myke/cpu/pit.h>
#include <myke/drivers/ports.h>
#include <myke/cpu/isr.h>
#include <myke/libk/libk.h>
#include <myke/libk/kprint.h>
#include <myke/tasks/task.h>

// https://wiki.osdev.org/PIT
#define PIT_MODE_BIN_BCD                            (1 << 0)
#define PIT_MODE_BIN                                (0 << 0)
#define PIT_MODE_BCD                                (1 << 0)
#define PIT_GENERATOR_MODE                          (0b111 << 1)
#define PIT_MODE_INTERRUPT_ON_TERMINAL_COUNT        (0b000 << 1)
#define PIT_MODE_HARDWARE_RETRIGGERABLE_ONE_SHOT    (0b001 << 1)
#define PIT_MODE_HARDWARE_RATE_GENERATOR            (0b010 << 1)
#define PIT_MODE_HARDWARE_SQUARE_WAVE_GENERATOR     (0b011 << 1)
#define PIT_MODE_SOFTWARE_TRIGGERED_STROBE          (0b100 << 1)
#define PIT_MODE_HARDWARE_TRIGGERED_STROBE          (0b101 << 1)
#define PIT_ACCESS_MODE                             (0b11 << 4)
#define PIT_ACCESS_MODE_LATCH_COUNT                 (0b00 << 4)
#define PIT_ACCESS_MODE_L                           (0b01 << 4)
#define PIT_ACCESS_MODE_H                           (0b10 << 4)
#define PIT_ACCESS_MODE_LH                          (0b11 << 4)
#define PIT_CHANNEL                                 (0b11 << 6)
#define PIT_CHANNEL_0                               (0b00 << 6)
#define PIT_CHANNEL_1                               (0b01 << 6)
#define PIT_CHANNEL_2                               (0b10 << 6)
#define PIT_CHANNEL_READ_BACK                       (0b11 << 6)
#define PIT_RB_LATCH_COUNT                          (0)
#define PIT_RB_LATCH_NO_COUNT                       (1 << 5)
#define PIT_RB_LATCH_STATUS                         (0)
#define PIT_RB_LATCH_NO_STATUS                      (1 << 4)
#define PIT_RB_CHANNEL_2                            (1 << 3)
#define PIT_RB_CHANNEL_1                            (1 << 2)
#define PIT_RB_CHANNEL_0                            (1 << 1)
#define PIT_STATUS_OUTPUT_STATE                     (1 << 7)
#define PIT_STATUS_NULL_COUNT                       (1 << 6)
#define PIT_STATUS_ACCESS_MODE                      (0b11 >> 4)
#define PIT_STATUS_OPERATING_MODE                   (0b111 < 1)
#define PIT_STATUS_BCD_BIN                          (1)

#define PIT_FREQUENCY 1193182 /*Hz*/
uint32_t tick = 0;

uint32_t pit_ms_to_div(uint32_t ms) {
    uint32_t divisor = PIT_FREQUENCY / ms;
    return divisor;
}

static void pit_callback(isr_registers_t *regs) {
    tick++;
    task_switch_next();
}

uint32_t pit_get_tick() {
    return tick;
}

void pit_sleep(uint32_t milliseconds) {
    uint32_t done = tick + milliseconds;
    while (tick != done) {
        k_wait_for_interrupt();
    }
}

void print_current_tick() {
    char msg[32];
    memset(msg, 0, 32);
    itoa(tick, msg, 10);
    kprint(msg);
    kprint("\n");
}

int pit_int_frequency(uint32_t freq) {
    register_interrupt_handler(IRQ0, pit_callback);

    uint32_t divisor = PIT_FREQUENCY / freq;
    uint8_t low = (uint8_t) (divisor & 0xFF);
    uint8_t high = (uint8_t) ((divisor >> 8) & 0xFF);
    port_byte_out(PORT_PIT_COMMAND,
                  PIT_MODE_BIN | PIT_MODE_HARDWARE_SQUARE_WAVE_GENERATOR | PIT_ACCESS_MODE_LH | PIT_CHANNEL_0);
    port_byte_out(PORT_PIT_DATA_0, low);
    port_byte_out(PORT_PIT_DATA_0, high);
    return 0;
}

// pit_sleep without interrupts
void pit_sleep_ms(const uint32_t sleep) {
    // todo locking
    uint32_t divider = pit_ms_to_div(sleep);
    if (divider > UINT16_MAX) {
        k_panics("Sleep for to long");
    }
    port_byte_out(PORT_PIT_COMMAND,
                  PIT_MODE_BIN | PIT_MODE_INTERRUPT_ON_TERMINAL_COUNT | PIT_ACCESS_MODE_LH | PIT_CHANNEL_0);
    port_byte_out(PORT_PIT_DATA_0, divider & 0xFF);
    port_byte_out(PORT_PIT_DATA_0, divider >> 8);
    do {
        __builtin_ia32_pause();
        port_byte_out(PORT_PIT_COMMAND,
                      PIT_CHANNEL_READ_BACK | PIT_RB_CHANNEL_0 | PIT_RB_LATCH_NO_COUNT | PIT_RB_LATCH_STATUS);
    } while (port_byte_in(PORT_PIT_DATA_0) & PIT_STATUS_OUTPUT_STATE);
}