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[/] [openrisc/] [trunk/] [rtos/] [rtems/] [c/] [src/] [lib/] [libbsp/] [or1k/] [bender/] [timer/] [timer.c] - Rev 745
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/* 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) 1989-1999. * On-Line Applications Research Corporation (OAR). * * 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: timer.c,v 1.1 2001-09-27 12:00:29 chris Exp $ */ #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; }
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