diff options
Diffstat (limited to 'c/src/lib/libbsp/i386/i386ex/timer/timer.c')
-rw-r--r-- | c/src/lib/libbsp/i386/i386ex/timer/timer.c | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/c/src/lib/libbsp/i386/i386ex/timer/timer.c b/c/src/lib/libbsp/i386/i386ex/timer/timer.c new file mode 100644 index 0000000000..3dbbd657c5 --- /dev/null +++ b/c/src/lib/libbsp/i386/i386ex/timer/timer.c @@ -0,0 +1,99 @@ +/* Timer_init() + * + * This routine initializes the timer on the FORCE CPU-386 board. + * + * Input parameters: NONE + * + * Output parameters: NONE + * + * NOTE: This routine will not work if the optimizer is enabled + * for some compilers. The multiple writes to the Z8036 + * may be optimized away. + * + * It is important that the timer start/stop overhead be + * determined when porting or modifying this code. + * + * COPYRIGHT (c) 1989, 1990, 1991, 1992, 1993, 1994. + * On-Line Applications Research Corporation (OAR). + * All rights assigned to U.S. Government, 1994. + * + * This material may be reproduced by or for the U.S. Government pursuant + * to the copyright license under the clause at DFARS 252.227-7013. This + * notice must appear in all copies of this file and its derivatives. + * + * $Id$ + */ + + +#include <rtems.h> +#include <bsp.h> + +int Ttimer_val; +rtems_boolean Timer_driver_Find_average_overhead; + +rtems_isr timerisr(); + +#define TMR0 0xF040 +#define TMR1 0xF041 +#define TMR2 0xF042 +#define TMRCON 0xF043 +#define TMRCFG 0xF834 + +void Timer_initialize() +{ + + (void) set_vector( timerisr, 0x2a, 0 ); /* install ISR ( IR2 ) was 0x38*/ + + Ttimer_val = 0; /* clear timer ISR count */ + + outport_byte ( TMRCON , 0xb0 ); /* select tmr2, stay in mode 0 */ + outport_byte ( TMR1 , 0xd2 ); /* set to 250 usec interval */ + outport_byte ( TMR1 , 0x00 ); + outport_byte ( TMRCON , 0x64 ); /* change to mode 2 ( starts timer ) */ + /* interrupts ARE enabled */ +/* outport_byte( IERA, 0x41 ); enable interrupt */ + +} + +#define AVG_OVERHEAD 3 /* It typically takes 3.0 microseconds */ + /* (3 ticks) to start/stop the timer. */ +#define LEAST_VALID 4 /* Don't trust a value lower than this */ + +int Read_timer() +{ + register rtems_unsigned32 clicks; + register rtems_unsigned32 total; + +/* outport_byte( TBCR, 0x00 ); stop the timer -- not needed on intel */ + + outport_byte ( TMRCON, 0x40 ); /* latch the count */ + inport_byte ( TMR1, clicks ); /* read the count */ + + total = Ttimer_val + 250 - clicks; + +/* outport_byte( TBCR, 0x00 ); initial value */ +/* outport_byte( IERA, 0x40 ); disable interrupt */ + + /* ??? Is "do not restore old vector" causing problems? */ + + if ( Timer_driver_Find_average_overhead == 1 ) + return total; /* in one microsecond units */ + + else { + if ( total < LEAST_VALID ) + return 0; /* below timer resolution */ + return (total - AVG_OVERHEAD); + } +} + +rtems_status_code Empty_function( void ) +{ + return RTEMS_SUCCESSFUL; +} + +void Set_find_average_overhead( + rtems_boolean find_flag +) +{ + Timer_driver_Find_average_overhead = find_flag; +} |