50448497f8
Sigh; Emacs's elide-head feature makes it easy to forget to update these. Signed-off-by: Marti Bolivar <mbolivar@leaflabs.com>
89 lines
2.7 KiB
C
89 lines
2.7 KiB
C
/******************************************************************************
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* The MIT License
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*
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* Copyright (c) 2010 Perry Hung.
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* Copyright (c) 2010, 2011 LeafLabs, LLC.
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*
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* Permission is hereby granted, free of charge, to any person
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* obtaining a copy of this software and associated documentation
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* files (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use, copy,
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* modify, merge, publish, distribute, sublicense, and/or sell copies
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* 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
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* included in 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,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*****************************************************************************/
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/**
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* @file libmaple/systick.c
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* @brief System timer (SysTick).
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*/
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#include <libmaple/systick.h>
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volatile uint32 systick_uptime_millis;
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static void (*systick_user_callback)(void);
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/**
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* @brief Initialize and enable SysTick.
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*
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* Clocks the system timer with the core clock, turns it on, and
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* enables interrupts.
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*
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* @param reload_val Appropriate reload counter to tick every 1 ms.
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*/
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void systick_init(uint32 reload_val) {
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SYSTICK_BASE->RVR = reload_val;
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systick_enable();
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}
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/**
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* Clock the system timer with the core clock, but don't turn it
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* on or enable interrupt.
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*/
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void systick_disable() {
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SYSTICK_BASE->CSR = SYSTICK_CSR_CLKSOURCE_CORE;
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}
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/**
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* Clock the system timer with the core clock and turn it on;
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* interrupt every 1 ms, for systick_timer_millis.
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*/
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void systick_enable() {
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/* re-enables init registers without changing reload val */
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SYSTICK_BASE->CSR = (SYSTICK_CSR_CLKSOURCE_CORE |
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SYSTICK_CSR_ENABLE |
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SYSTICK_CSR_TICKINT_PEND);
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}
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/**
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* @brief Attach a callback to be called from the SysTick exception handler.
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*
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* To detach a callback, call this function again with a null argument.
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*/
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void systick_attach_callback(void (*callback)(void)) {
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systick_user_callback = callback;
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}
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/*
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* SysTick ISR
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*/
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void __exc_systick(void) {
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systick_uptime_millis++;
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if (systick_user_callback) {
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systick_user_callback();
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}
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}
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