103 lines
3.8 KiB
C
103 lines
3.8 KiB
C
/*
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* This file is part of the MicroPython project, http://micropython.org/
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*
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* The MIT License (MIT)
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*
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* Copyright (c) 2017 Scott Shawcroft for Adafruit Industries
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include "tick.h"
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#include "peripheral_clk_config.h"
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#include "supervisor/shared/autoreload.h"
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#include "shared-module/gamepad/__init__.h"
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#include "shared-bindings/microcontroller/__init__.h"
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#include "shared-bindings/microcontroller/Processor.h"
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// Global millisecond tick count
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volatile uint64_t ticks_ms = 0;
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void SysTick_Handler(void) {
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// SysTick interrupt handler called when the SysTick timer reaches zero
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// (every millisecond).
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common_hal_mcu_disable_interrupts();
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ticks_ms += 1;
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// Read the control register to reset the COUNTFLAG.
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(void) SysTick->CTRL;
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common_hal_mcu_enable_interrupts();
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#ifdef CIRCUITPY_AUTORELOAD_DELAY_MS
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autoreload_tick();
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#endif
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#ifdef CIRCUITPY_GAMEPAD_TICKS
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if (!(ticks_ms & CIRCUITPY_GAMEPAD_TICKS)) {
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gamepad_tick();
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}
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#endif
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}
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void tick_init() {
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uint32_t ticks_per_ms = common_hal_mcu_processor_get_frequency() / 1000;
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SysTick_Config(ticks_per_ms-1);
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NVIC_EnableIRQ(SysTick_IRQn);
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}
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void tick_delay(uint32_t us) {
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uint32_t ticks_per_us = common_hal_mcu_processor_get_frequency() / 1000 / 1000;
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uint32_t us_until_next_tick = SysTick->VAL / ticks_per_us;
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uint32_t start_tick;
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while (us >= us_until_next_tick) {
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start_tick = SysTick->VAL; // wait for SysTick->VAL to RESET
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while (SysTick->VAL < start_tick) {}
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us -= us_until_next_tick;
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us_until_next_tick = 1000;
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}
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while (SysTick->VAL > ((us_until_next_tick - us) * ticks_per_us)) {}
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}
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// us counts down!
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void current_tick(uint64_t* ms, uint32_t* us_until_ms) {
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uint32_t ticks_per_us = common_hal_mcu_processor_get_frequency() / 1000 / 1000;
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// We disable interrupts to prevent ticks_ms from changing while we grab it.
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common_hal_mcu_disable_interrupts();
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uint32_t tick_status = SysTick->CTRL;
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uint32_t current_us = SysTick->VAL;
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uint32_t tick_status2 = SysTick->CTRL;
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uint64_t current_ms = ticks_ms;
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// The second clause ensures our value actually rolled over. Its possible it hit zero between
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// the VAL read and CTRL read.
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if ((tick_status & SysTick_CTRL_COUNTFLAG_Msk) != 0 ||
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((tick_status2 & SysTick_CTRL_COUNTFLAG_Msk) != 0 && current_us > ticks_per_us)) {
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current_ms++;
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}
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common_hal_mcu_enable_interrupts();
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*ms = current_ms;
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*us_until_ms = current_us / ticks_per_us;
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}
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void wait_until(uint64_t ms, uint32_t us_until_ms) {
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uint32_t ticks_per_us = common_hal_mcu_processor_get_frequency() / 1000 / 1000;
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while (ticks_ms <= ms && SysTick->VAL / ticks_per_us >= us_until_ms) {}
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}
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