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author | Joel Sherrill <joel.sherrill@OARcorp.com> | 1995-05-11 17:39:37 +0000 |
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committer | Joel Sherrill <joel.sherrill@OARcorp.com> | 1995-05-11 17:39:37 +0000 |
commit | ac7d5ef06a6d6e8d84abbd1f0b82162725f98326 (patch) | |
tree | 9304cf759a73f2a1c6fd3191948f00e870af3787 /c/src/lib/libbsp/no_cpu/no_bsp/timer/timer.c | |
download | rtems-ac7d5ef06a6d6e8d84abbd1f0b82162725f98326.tar.bz2 |
Initial revision
Diffstat (limited to 'c/src/lib/libbsp/no_cpu/no_bsp/timer/timer.c')
-rw-r--r-- | c/src/lib/libbsp/no_cpu/no_bsp/timer/timer.c | 105 |
1 files changed, 105 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; +} + |