diff options
Diffstat (limited to 'c/src/lib/libbsp/powerpc/mvme2307/timer/timer.c')
-rw-r--r-- | c/src/lib/libbsp/powerpc/mvme2307/timer/timer.c | 91 |
1 files changed, 91 insertions, 0 deletions
diff --git a/c/src/lib/libbsp/powerpc/mvme2307/timer/timer.c b/c/src/lib/libbsp/powerpc/mvme2307/timer/timer.c new file mode 100644 index 0000000000..60a1a78248 --- /dev/null +++ b/c/src/lib/libbsp/powerpc/mvme2307/timer/timer.c @@ -0,0 +1,91 @@ +/* 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. + * + * This version returns the number of nanoseconds since Timer_initialize() + * exited, since the '604 is very fast at 300MHz. Actual resolution is + * 60 nsec. + * + * NOTE: It is important that the timer start/stop overhead be + * determined when porting or modifying this code. + * + * COPYRIGHT (c) 1989-1998. + * On-Line Applications Research Corporation (OAR). + * Copyright assigned to U.S. Government, 1994. + * + * The license and distribution terms for this file may be + * found in the file LICENSE in this distribution or at + * http://www.OARcorp.com/rtems/license.html. + * + * $Id$ + */ + +#include <rtems.h> +#include <bsp.h> + +rtems_unsigned32 Timer_start; +rtems_boolean Timer_driver_Find_average_overhead; + +void Timer_initialize( void ) +{ + rtems_unsigned32 clicks; + + asm volatile ("mfspr %0,268" : "=r" (clicks) :); + Timer_start = clicks; +} + +/* + * 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 7 /* On average, it takes 7.4 nanoseconds */ + /* (Y countdowns) to start/stop the timer. */ + +#define NSEC_PER_TICK 60 + +int Read_timer( void ) +{ + rtems_unsigned32 clicks; + rtems_unsigned32 total; + + /* + * Read the timer and see how many clicks it has been since we started. + * Timer overflows every 257 seconds, so multiple overflows are deemed + * impossible. + */ + + asm volatile ("mfspr %0,268" : "=r" (clicks) :); + total = (clicks - Timer_start); + + if ( Timer_driver_Find_average_overhead == 1 ) { + return total * NSEC_PER_TICK; /* in nanoseconds */ + } else { + /* + * convert total into nanoseconds + */ + return total * NSEC_PER_TICK - 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; +} + |