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Diffstat (limited to '')
-rw-r--r-- | c/src/lib/libcpu/a29k/timer/timer.c | 119 |
1 files changed, 119 insertions, 0 deletions
diff --git a/c/src/lib/libcpu/a29k/timer/timer.c b/c/src/lib/libcpu/a29k/timer/timer.c new file mode 100644 index 0000000000..c5911d1fae --- /dev/null +++ b/c/src/lib/libcpu/a29k/timer/timer.c @@ -0,0 +1,119 @@ +/* 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. + * + * timer.c,v 1.2 1995/05/31 16:56:39 joel Exp + */ + +#ifndef lint +static char _sccsid[] = "@(#)timer.c 05/07/96 1.4\n"; +#endif + +#include <rtems.h> +#include <bsp.h> + +#define CLOCKS_PER_MICROSECOND ( CPU_CLOCK_RATE_MHZ ) +#define TIMER_MAX_VALUE 0xffffffff + +extern unsigned32 mips_read_timer( void ); + +static rtems_boolean Timer_driver_Find_average_overhead; +static unsigned32 Timer_initial_value = 0; + +void Timer_initialize( void ) +{ +/* + Timer_initial_value = mips_read_timer(); + */ + /* + * Somehow start the timer + */ + + /* Timer on 4650 is always running */ +} + +/* + * 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 8 /* It typically takes X.X microseconds */ + /* (Y countdowns) to start/stop the timer. */ + /* This value is in cycles. */ +#define LEAST_VALID 1 /* Don't trust a clicks value lower than this */ + +int Read_timer( void ) +{ + unsigned64 clicks; + unsigned32 total; + + /* + * Read the timer and see how many clicks it has been since we started. + */ + + clicks = mips_read_timer(); /* XXX: read some HW here */ + if (clicks < Timer_initial_value) + { + clicks += TIMER_MAX_VALUE; + } + clicks -= Timer_initial_value; + + /* + * Total is calculated by taking into account the number of timer overflow + * interrupts since the timer was initialized and clicks since the last + * interrupts. + */ +#if 0 /* leave total in number of cycles */ + total = clicks / CLOCKS_PER_MICROSECOND; +#else + total = clicks; +#endif + + if ( Timer_driver_Find_average_overhead == 1 ) + return total; /* in # cycles units */ + else { + if ( total < LEAST_VALID ) + return 0; /* below timer resolution */ + /* + * leave total in cycles + */ + 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; +} + |