qemu-timer-common.c revision a18ede0ba44219ff3c65a380fa51d8baa62d19ef 
1/*
2 * QEMU System Emulator
3 *
4 * Copyright (c) 2003-2008 Fabrice Bellard
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to deal
8 * in the Software without restriction, including without limitation the rights
9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 * copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22 * THE SOFTWARE.
23 */
24#include "qemu/timer.h"
25
26/***********************************************************/
27/* real time host monotonic timer */
28
29#ifdef _WIN32
30
31int64_t clock_freq;
32
33static void __attribute__((constructor)) init_get_clock(void)
34{
35    LARGE_INTEGER freq;
36    int ret;
37    ret = QueryPerformanceFrequency(&freq);
38    if (ret == 0) {
39        fprintf(stderr, "Could not calibrate ticks\n");
40        exit(1);
41    }
42    clock_freq = freq.QuadPart;
43}
44
45#else
46
47int use_rt_clock;
48
49static void __attribute__((constructor)) init_get_clock(void)
50{
51    use_rt_clock = 0;
52#if defined(__linux__) || (defined(__FreeBSD__) && __FreeBSD_version >= 500000) \
53    || defined(__DragonFly__) || defined(__FreeBSD_kernel__) \
54    || defined(__OpenBSD__)
55    {
56        struct timespec ts;
57        if (clock_gettime(CLOCK_MONOTONIC, &ts) == 0) {
58            use_rt_clock = 1;
59        }
60    }
61#endif
62}
63#endif
64