diff options
| -rw-r--r-- | c/src/lib/libbsp/i386/go32/timer/timer.c | 89 |
1 files changed, 51 insertions, 38 deletions
diff --git a/c/src/lib/libbsp/i386/go32/timer/timer.c b/c/src/lib/libbsp/i386/go32/timer/timer.c index 725aaac0f9..b57832edb7 100644 --- a/c/src/lib/libbsp/i386/go32/timer/timer.c +++ b/c/src/lib/libbsp/i386/go32/timer/timer.c @@ -34,58 +34,71 @@ static inline unsigned long long rdtsc( void ) __asm __volatile( ".byte 0x0F, 0x31" : "=A" (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(); -} #else /* pentium */ -rtems_isr timerisr(); - -#define TIMER_ISR_US 10000 - + extern void rtc_set_dos_date( void ); + + /* 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 */ +} void Timer_initialize() { - static int First = 1; -#if defined(pentium) - if ( First ) { - 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 */ + extern int atexit( void (*)(void) ); -#define WAIT() \ - { \ - Ttimer_val = 0; \ - while ( Ttimer_val == 0 ) \ - continue; \ - Ttimer_val = 0; \ - } + static int First = 1; if ( First ) { First = 0; - /* install ISR */ - set_vector( timerisr, 0x8, 0 ); - - /* Wait for ISR to be called at least once */ - WAIT(); + /* Try not to hose the system on return to DOS. */ + atexit( Timer_exit ); - /* load timer for TIMER_ISR_US microsecond period */ - 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(TIMER_ISR_US) >> 8 & 0xff); +#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 */ + Ttimer_val = 0; + while ( Ttimer_val == 0 ) + continue; + + /* load timer for 250 microsecond period */ + outport_byte( TIMER_MODE, TIMER_SEL0|TIMER_16BIT|TIMER_RATEGEN ); + outport_byte( TIMER_CNTR0, US_TO_TICK(250) >> 0 & 0xff ); + outport_byte( TIMER_CNTR0, US_TO_TICK(250) >> 8 & 0xff ); +#endif /* PENTIUM */ } - +#if defined(pentium) + Ttimer_val = rdtsc(); /* read starting time */ +#else /* Wait for ISR to be called at least once */ - WAIT(); -#endif /* PENTIUM */ + 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. */ @@ -104,7 +117,7 @@ int Read_timer() inport_byte( TIMER_CNTR0, lsb ); inport_byte( TIMER_CNTR0, msb ); 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 */ if ( Timer_driver_Find_average_overhead == 1 ) |