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/******************************************************************************
* The MIT License
*
* Copyright (c) 2010 Perry Hung.
*
* 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.
*****************************************************************************/
/**
* @brief System timer interrupt handler and initialization routines
*/
#include "systick.h"
__io uint32 systick_timer_millis;
/**
* @brief Initialize and enable SysTick.
*
* Clocks the system timer with the core clock, turns it on, and
* enables interrupts.
*
* @param reload_val Appropriate reload counter to tick every 1 ms.
*/
void systick_init(uint32 reload_val) {
SYSTICK_BASE->RVR = reload_val;
systick_enable();
}
/**
* Clock the system timer with the core clock, but don't turn it
* on or enable interrupt.
*/
void systick_disable() {
SYSTICK_BASE->CSR = SYSTICK_CSR_CLKSOURCE_CORE;
}
/**
* Clock the system timer with the core clock and turn it on;
* interrupt every 1 ms, for systick_timer_millis.
*/
void systick_enable() {
/* re-enables init registers without changing reload val */
SYSTICK_BASE->CSR = (SYSTICK_CSR_CLKSOURCE_CORE |
SYSTICK_CSR_ENABLE |
SYSTICK_CSR_TICKINT_PEND);
}
/*
* SysTick ISR
*/
void __exc_systick(void) {
systick_timer_millis++;
}
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