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/* *****************************************************************************
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* Created: 12/18/09 02:41:36
* Copyright (c) 2009 Perry L. Hung. All rights reserved.
*
* ****************************************************************************/
/**
* @file time.c
*
* @brief
*/
#include "libmaple.h"
#include "systick.h"
#include "time.h"
#define CYCLES_PER_MICROSECOND 72
#define THE_SECRET_TO_LIFE_THE_UNIVERSE_AND_EVERYTHING 42
extern volatile uint32_t systick_timer_millis;
unsigned long millis() {
unsigned long m;
m = systick_timer_millis;
return m;
}
void delay(unsigned long ms)
{
unsigned long start = millis();
while (millis() - start <= ms)
;
}
#define MAGIC 4096
/* HZ = 1000
* n HZ*/
void delayMicroseconds(uint32_t us) {
uint32_t target;
uint32_t last, cur, count;
#if 0
asm volatile("mov r0, %[count] \n\t"
"1: \n\t"
"subs r0, r0, #1 \n\t"
"bne 1b"
:
: [count] "r" (count)
: "r0", "cc");
#endif
#if 1
/* fudge factor hacky hack hack for function overhead */
target = us * CYCLES_PER_MICROSECOND - THE_SECRET_TO_LIFE_THE_UNIVERSE_AND_EVERYTHING;
/* Get current count */
last = systick_get_count();
cur = systick_get_count();
count = last;
while ((count-cur) <= target) {
cur = systick_get_count();
/* check for overflow */
if (cur > last) {
count += MAPLE_RELOAD_VAL;
}
last = cur;
}
#endif
}
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