avr/timer.c

   1 /*
   2  */
   3
   4 #include "common.h"
   5 #include <avr/interrupt.h>
   6 #include <util/atomic.h>
   7 #include "time.h"
   8 #include "timer.h"
   9
  10 /* timer interrupt/overflow counter */
  11 /* counts up every ms. */
  12 static volatile
  13 uint32_t timestamp;
  14
  15 /*---------------------------------------------------------*/
  16 /* 1000Hz timer interrupt generated by OC3A                */
  17 /*---------------------------------------------------------*/
  18
  19 ISR(TIMER3_COMPA_vect)
  20 {
  21         static int_fast8_t tick_10ms;
  22         static int_fast8_t tick_1s;
  23         int_fast8_t i, j;
  24
  25         extern void disk_timerproc(void);
  26
  27         timestamp++;
  28
  29         i = tick_10ms + 1;
  30         if (i == 10) {
  31                 Stat |= S_10MS_TO;
  32
  33                 /* Drive timer procedure of low level disk I/O module */
  34                 disk_timerproc();
  35
  36                 j = tick_1s - 1;
  37                 if (j == 0) {
  38                         system_tick();
  39                         j = 100;
  40                 }
  41                 tick_1s = j;
  42                 i = 0;
  43         }
  44         tick_10ms = i;
  45 }
  46
  47
  48 /*--------------------------------------------------------------------------*/
  49
  50 #if 0
  51 void timer_setup(void)
  52 {
  53
  54         /* Clock */
  55         CLKPR = _BV(CLKPCE);
  56         CLKPR = 0;
  57
  58         /* Timer */
  59
  60         OCR1A = F_CPU / 1000 - 1; // Timer1: 1000Hz interval (OC1A)
  61         TCCR1B = 0b00001001;
  62         TIMSK1 = _BV(OCIE1A); // Enable TC1.oca interrupt
  63 }
  64 #endif
  65
  66 /*--------------------------------------------------------------------------*/
  67
  68 uint32_t get_timer(uint32_t base)
  69 {
  70         uint32_t ret;
  71         ATOMIC_BLOCK(ATOMIC_FORCEON)
  72         {
  73                 ret = timestamp;
  74         }
  75         return ret - base;
  76 }