/* *****************************************************************************
 * 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.
 * ****************************************************************************/

/**
 *  @file time.c
 *
 *  @brief 
 */

#include "libmaple.h"
#include "systick.h"
#include "time.h"

#define CYCLES_PER_MICROSECOND  72
#define FUDGE                   42

extern volatile uint32 systick_timer_millis;

uint32 millis() {
   unsigned long m;
   m = systick_timer_millis;
   return m;
}

void delay(unsigned long ms)
{
   unsigned long start = millis();

   while (millis() - start <= ms)
      ;
}



#if 1
void delayMicroseconds(uint32 us) {
    uint32 target;
    uint32 last, cur, count;
    /* fudge factor hacky hack hack for function overhead  */
    target = us * CYCLES_PER_MICROSECOND - FUDGE;

    /* 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
