avr/timer.c

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