source:
rtems/c/src/lib/libbsp/powerpc/score603e/timer/timer.c
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c00b49f8
Last change on this file since c00b49f8 was 42b6dd2a, checked in by Jennifer Averett <Jennifer.Averett@…>, on 05/05/09 at 16:24:04 | |
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1 | /* timer.c |
2 | * |
3 | * This file implements a benchmark timer using the General Purpose Timer. |
4 | * |
5 | * Notes: |
6 | * |
7 | * BSP_TIMER_AVG_OVERHEAD and BSP_TIMER_LEAST_VALID are required to be |
8 | * provided in bsp.h |
9 | * |
10 | * COPYRIGHT (c) 1989-2009. |
11 | * On-Line Applications Research Corporation (OAR). |
12 | * |
13 | * The license and distribution terms for this file may be |
14 | * found in the file LICENSE in this distribution or at |
15 | * http://www.rtems.com/license/LICENSE. |
16 | * |
17 | * $Id$ |
18 | */ |
19 | |
20 | #include <assert.h> |
21 | |
22 | #include <bsp.h> |
23 | |
24 | uint64_t Timer_driver_Start_time; |
25 | |
26 | bool benchmark_timer_find_average_overhead; |
27 | |
28 | /* |
29 | * benchmark_timer_initialize |
30 | */ |
31 | |
32 | void benchmark_timer_initialize() |
33 | { |
34 | |
35 | /* |
36 | * Timer runs long and accurate enough not to require an interrupt. |
37 | */ |
38 | |
39 | Timer_driver_Start_time = PPC_Get_timebase_register(); |
40 | } |
41 | |
42 | /* |
43 | * benchmark_timer_read |
44 | */ |
45 | |
46 | int benchmark_timer_read() |
47 | { |
48 | uint64_t clicks; |
49 | uint64_t total64; |
50 | uint32_t total; |
51 | |
52 | /* approximately CLOCK_SPEED clicks per microsecond */ |
53 | |
54 | clicks = PPC_Get_timebase_register(); |
55 | |
56 | assert( clicks > Timer_driver_Start_time ); |
57 | |
58 | total64 = clicks - Timer_driver_Start_time; |
59 | |
60 | assert( total64 <= 0xffffffff ); /* fits into a uint32_t */ |
61 | |
62 | total = (uint32_t) total64; |
63 | |
64 | if ( benchmark_timer_find_average_overhead == true ) |
65 | return total; /* in "clicks" of the decrementer units */ |
66 | |
67 | if ( total < BSP_TIMER_LEAST_VALID ) |
68 | return 0; /* below timer resolution */ |
69 | |
70 | return BSP_Convert_decrementer(total - BSP_TIMER_AVG_OVERHEAD); |
71 | } |
72 | |
73 | void benchmark_timer_disable_subtracting_average_overhead( |
74 | bool find_flag |
75 | ) |
76 | { |
77 | benchmark_timer_find_average_overhead = find_flag; |
78 | } |
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