/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2017 Scott Shawcroft for Adafruit Industries
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "tick.h"

#include "peripheral_clk_config.h"

#include "supervisor/shared/autoreload.h"
#include "shared-module/gamepad/__init__.h"
#include "shared-bindings/microcontroller/__init__.h"
#include "shared-bindings/microcontroller/Processor.h"

// Global millisecond tick count
volatile uint64_t ticks_ms = 0;

void SysTick_Handler(void) {
    // SysTick interrupt handler called when the SysTick timer reaches zero
    // (every millisecond).
    common_hal_mcu_disable_interrupts();
    ticks_ms += 1;

    // Read the control register to reset the COUNTFLAG.
    (void) SysTick->CTRL;
    common_hal_mcu_enable_interrupts();

    #ifdef CIRCUITPY_AUTORELOAD_DELAY_MS
        autoreload_tick();
    #endif
    #ifdef CIRCUITPY_GAMEPAD_TICKS
    if (!(ticks_ms & CIRCUITPY_GAMEPAD_TICKS)) {
        gamepad_tick();
    }
    #endif
}

void tick_init() {
    uint32_t ticks_per_ms = common_hal_mcu_processor_get_frequency() / 1000;
    SysTick_Config(ticks_per_ms-1);
    NVIC_EnableIRQ(SysTick_IRQn);
    // Set all peripheral interrupt priorities to the lowest priority by default.
    for (uint16_t i = 0; i < PERIPH_COUNT_IRQn; i++) {
        NVIC_SetPriority(i, (1UL << __NVIC_PRIO_BITS) - 1UL);
    }
    // Bump up the systick interrupt so nothing else interferes with timekeeping.
    NVIC_SetPriority(SysTick_IRQn, 0);
    #ifdef SAMD21
    NVIC_SetPriority(USB_IRQn, 1);
    #endif

    #ifdef SAMD51
    NVIC_SetPriority(USB_0_IRQn, 1);
    NVIC_SetPriority(USB_1_IRQn, 1);
    NVIC_SetPriority(USB_2_IRQn, 1);
    NVIC_SetPriority(USB_3_IRQn, 1);
    #endif
}

void tick_delay(uint32_t us) {
    uint32_t ticks_per_us = common_hal_mcu_processor_get_frequency() / 1000 / 1000;
    uint32_t us_until_next_tick = SysTick->VAL / ticks_per_us;
    uint32_t start_tick;
    while (us >= us_until_next_tick) {
        start_tick = SysTick->VAL;  // wait for SysTick->VAL to  RESET
        while (SysTick->VAL < start_tick) {}
        us -= us_until_next_tick;
        us_until_next_tick = 1000;
    }
    while (SysTick->VAL > ((us_until_next_tick - us) * ticks_per_us)) {}
}

// us counts down!
void current_tick(uint64_t* ms, uint32_t* us_until_ms) {
    uint32_t ticks_per_us = common_hal_mcu_processor_get_frequency() / 1000 / 1000;

    // We disable interrupts to prevent ticks_ms from changing while we grab it.
    common_hal_mcu_disable_interrupts();
    uint32_t tick_status = SysTick->CTRL;
    uint32_t current_us = SysTick->VAL;
    uint32_t tick_status2 = SysTick->CTRL;
    uint64_t current_ms = ticks_ms;
    // The second clause ensures our value actually rolled over. Its possible it hit zero between
    // the VAL read and CTRL read.
    if ((tick_status & SysTick_CTRL_COUNTFLAG_Msk) != 0 ||
        ((tick_status2 & SysTick_CTRL_COUNTFLAG_Msk) != 0 && current_us > ticks_per_us)) {
        current_ms++;
    }
    common_hal_mcu_enable_interrupts();
    *ms = current_ms;
    *us_until_ms = current_us / ticks_per_us;
}

void wait_until(uint64_t ms, uint32_t us_until_ms) {
    uint32_t ticks_per_us = common_hal_mcu_processor_get_frequency() / 1000 / 1000;
    while (ticks_ms <= ms && SysTick->VAL / ticks_per_us >= us_until_ms) {}
}