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hopefully works with regular timer and tm27

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This commit is contained in:
Joel Sherrill
1995-07-24 14:00:27 +00:00
parent 1690c6b636
commit 2f2a597c73
1 changed files with 49 additions and 36 deletions
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79
c/src/lib/libbsp/i386/go32/timer/timer.c
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@@ -34,58 +34,71 @@ static inline unsigned long long rdtsc( void )
__asm __volatile( ".byte 0x0F, 0x31" : "=A" (result) ); __asm __volatile( ".byte 0x0F, 0x31" : "=A" (result) );
return result; return result;
} }
static void restore_timer( void ) #else
extern rtems_isr timerisr();
static rtems_isr_entry Old_Ticker;
#endif
static void Timer_exit( void )
{ {
#if defined(pentium)
CLOCK_ENABLE(); CLOCK_ENABLE();
}
#else /* pentium */ #else /* pentium */
rtems_isr timerisr(); extern void rtc_set_dos_date( void );
#define TIMER_ISR_US 10000 /* reset to DOS value: */
outport_byte( TIMER_MODE, TIMER_SEL0|TIMER_16BIT|TIMER_RATEGEN );
outport_byte( TIMER_CNTR0, 0 );
outport_byte( TIMER_CNTR0, 0 );
/* reset time-of-day */
rtc_set_dos_date();
/* re-enable old handler: assume it was one of ours */
set_vector( (rtems_isr_entry)Old_Ticker, 0x8, 0 );
#endif /* pentium */ #endif /* pentium */
}
void Timer_initialize() void Timer_initialize()
{ {
static int First = 1;
#if defined(pentium)
if ( First ) {
extern int atexit( void (*)(void) ); extern int atexit( void (*)(void) );
First = 0;
/* Disable the programmable timer. */
CLOCK_DISABLE();
/* Try not to hose the system on return to DOS. */
atexit( restore_timer );
}
Ttimer_val = rdtsc();
#else /* pentium */
#define WAIT() \ static int First = 1;
{ \
Ttimer_val = 0; \
while ( Ttimer_val == 0 ) \
continue; \
Ttimer_val = 0; \
}
if ( First ) { if ( First ) {
First = 0; First = 0;
/* install ISR */ /* Try not to hose the system on return to DOS. */
set_vector( timerisr, 0x8, 0 ); atexit( Timer_exit );
#if defined(pentium)
/* Disable the programmable timer so ticks don't interfere. */
CLOCK_DISABLE();
#else /* pentium */
/* install a timer ISR */
Old_Ticker = (rtems_isr_entry) set_vector( timerisr, 0x8, 0 );
/* Wait for ISR to be called at least once */ /* Wait for ISR to be called at least once */
WAIT(); Ttimer_val = 0;
while ( Ttimer_val == 0 )
continue;
/* load timer for TIMER_ISR_US microsecond period */ /* load timer for 250 microsecond period */
outport_byte( TIMER_MODE, TIMER_SEL0|TIMER_16BIT|TIMER_RATEGEN ); outport_byte( TIMER_MODE, TIMER_SEL0|TIMER_16BIT|TIMER_RATEGEN );
outport_byte( TIMER_CNTR0, US_TO_TICK(TIMER_ISR_US) >> 0 & 0xff); outport_byte( TIMER_CNTR0, US_TO_TICK(250) >> 0 & 0xff );
outport_byte( TIMER_CNTR0, US_TO_TICK(TIMER_ISR_US) >> 8 & 0xff); outport_byte( TIMER_CNTR0, US_TO_TICK(250) >> 8 & 0xff );
}
/* Wait for ISR to be called at least once */
WAIT();
#endif /* PENTIUM */ #endif /* PENTIUM */
}
#if defined(pentium)
Ttimer_val = rdtsc(); /* read starting time */
#else
/* Wait for ISR to be called at least once */
asm( "sti" );
Ttimer_val = 0;
while ( Ttimer_val == 0 )
continue;
Ttimer_val = 0;
#endif
} }
#define AVG_OVERHEAD 0 /* 0.1 microseconds to start/stop timer. */ #define AVG_OVERHEAD 0 /* 0.1 microseconds to start/stop timer. */
@@ -104,7 +117,7 @@ int Read_timer()
inport_byte( TIMER_CNTR0, lsb ); inport_byte( TIMER_CNTR0, lsb );
inport_byte( TIMER_CNTR0, msb ); inport_byte( TIMER_CNTR0, msb );
clicks = msb << 8 | lsb; clicks = msb << 8 | lsb;
total = (Ttimer_val * TIMER_ISR_US) + (TIMER_ISR_US - TICK_TO_US( clicks )); total = Ttimer_val + 250 - TICK_TO_US( clicks );
#endif /* pentium */ #endif /* pentium */
if ( Timer_driver_Find_average_overhead == 1 ) if ( Timer_driver_Find_average_overhead == 1 )