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[/] [openrisc/] [trunk/] [rtos/] [rtems/] [c/] [src/] [lib/] [libcpu/] [hppa1.1/] [timer/] [timer.c] - Rev 173
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/* timer.c * * This file manages the interval timer on the PA-RISC. * * 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 1.2 2001-09-27 12:01:21 chris Exp $ */ #include <rtems.h> volatile rtems_unsigned32 Timer_starting; rtems_boolean Timer_driver_Find_average_overhead; void Timer_initialize() { Timer_starting = get_itimer(); set_eiem(0x80000000); } #define AVG_OVERHEAD 0 /* It typically takes 3.0 microseconds */ /* (6 countdowns) to start/stop the timer. */ #define LEAST_VALID 1 /* Don't trust a value lower than this */ int Read_timer() { rtems_unsigned32 clicks; rtems_unsigned32 total; clicks = get_itimer(); total = clicks - Timer_starting; if ( Timer_driver_Find_average_overhead == 1 ) return total; /* in XXX microsecond units */ else { if ( total < LEAST_VALID ) return 0; /* below timer resolution */ return (total - AVG_OVERHEAD); } } 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; }