diff options
Diffstat (limited to 'c/src/lib/libcpu/mips/timer/timer.c')
-rw-r--r-- | c/src/lib/libcpu/mips/timer/timer.c | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/c/src/lib/libcpu/mips/timer/timer.c b/c/src/lib/libcpu/mips/timer/timer.c new file mode 100644 index 0000000000..a141232229 --- /dev/null +++ b/c/src/lib/libcpu/mips/timer/timer.c @@ -0,0 +1,136 @@ +/* timer.c + * + * This file contains the initialization code for the IDT 4650 timer driver. + * + * Author: Craig Lebakken <craigl@transition.com> + * + * COPYRIGHT (c) 1996 by Transition Networks Inc. + * + * To anyone who acknowledges that this file is provided "AS IS" + * without any express or implied warranty: + * permission to use, copy, modify, and distribute this file + * for any purpose is hereby granted without fee, provided that + * the above copyright notice and this notice appears in all + * copies, and that the name of Transition Networks not be used in + * advertising or publicity pertaining to distribution of the + * software without specific, written prior permission. + * Transition Networks makes no representations about the suitability + * of this software for any purpose. + * + * derived from src/lib/libbsp/no_cpu/no_bsp/timer/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 08/20/96 1.5\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; +} + |