diff options
Diffstat (limited to 'c/src/lib/libbsp/no_cpu/no_bsp/timer')
-rw-r--r-- | c/src/lib/libbsp/no_cpu/no_bsp/timer/timer.c | 105 | ||||
-rw-r--r-- | c/src/lib/libbsp/no_cpu/no_bsp/timer/timerisr.c | 37 |
2 files changed, 142 insertions, 0 deletions
diff --git a/c/src/lib/libbsp/no_cpu/no_bsp/timer/timer.c b/c/src/lib/libbsp/no_cpu/no_bsp/timer/timer.c new file mode 100644 index 0000000000..a3b8775444 --- /dev/null +++ b/c/src/lib/libbsp/no_cpu/no_bsp/timer/timer.c @@ -0,0 +1,105 @@ +/* timer.c + * + * This file manages the benchmark timer used by the RTEMS Timing Test + * Suite. Each measured time period is demarcated by calls to + * Timer_initialize() and Read_timer(). Read_timer() usually returns + * the number of microseconds since Timer_initialize() exitted. + * + * NOTE: 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> + +rtems_unsigned32 Timer_interrupts; +rtems_boolean Timer_driver_Find_average_overhead; + +void Timer_initialize( void ) +{ + + /* + * Timer has never overflowed. This may not be necessary on some + * implemenations of timer but .... + */ + + Timer_interrupts = 0; + + /* + * Somehow start the timer + */ +} + +/* + * The following controls the behavior of Read_timer(). + * + * AVG_OVEREHAD is the overhead for starting and stopping the timer. It + * is usually deducted from the number returned. + * + * LEAST_VALID is the lowest number this routine should trust. Numbers + * below this are "noise" and zero is returned. + */ + +#define AVG_OVERHEAD 0 /* It typically takes X.X microseconds */ + /* (Y countdowns) to start/stop the timer. */ + /* This value is in microseconds. */ +#define LEAST_VALID 1 /* Don't trust a clicks value lower than this */ + +int Read_timer( void ) +{ + rtems_unsigned32 clicks; + rtems_unsigned32 total; + + /* + * Read the timer and see how many clicks it has been since we started. + */ + + clicks = 0; /* XXX: read some HW here */ + + /* + * Total is calculated by taking into account the number of timer overflow + * interrupts since the timer was initialized and clicks since the last + * interrupts. + */ + + total = clicks * 0; + + if ( Timer_driver_Find_average_overhead == 1 ) + return total; /* in XXX microsecond units */ + else { + if ( total < LEAST_VALID ) + return 0; /* below timer resolution */ + /* + * Somehow convert total into microseconds + */ + return (total - AVG_OVERHEAD); + } +} + +/* + * Empty function call used in loops to measure basic cost of looping + * in Timing Test Suite. + */ + +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; +} + diff --git a/c/src/lib/libbsp/no_cpu/no_bsp/timer/timerisr.c b/c/src/lib/libbsp/no_cpu/no_bsp/timer/timerisr.c new file mode 100644 index 0000000000..f52774b75e --- /dev/null +++ b/c/src/lib/libbsp/no_cpu/no_bsp/timer/timerisr.c @@ -0,0 +1,37 @@ +/* timerisr.s + * + * If required this ISR is used to bump a count of interval "overflow" + * interrupts which have occurred since the timer was started. The + * number of overflows is taken into account in the Read_timer() + * routine if necessary. + * + * To reduce overhead this is best to be the "rawest" hardware interupt + * handler you can write. This should be the only interrupt which can + * occur during the measured time period. + * + * NOTE: This file is USUALLY in assembly and is LEAN AND MEAN. + * Any code in this isr is pure overhead which can perturb + * the accuracy of the Timing Test Suite. + * + * 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> + +extern rtems_unsigned32 _Timer_interrupts; + +void timerisr( void ) +{ + /* + * _Timer_interrupts += TIMER_BETWEEN_OVERFLOWS (usually in microseconds) + * return from interrupt + */ +} |