1 /*
2 * Copyright (c) 2016 Apple Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28
29 #ifndef REMOTE_TIME_H
30 #define REMOTE_TIME_H
31
32 #include <sys/cdefs.h>
33 #include <stdint.h>
34 #include <os/overflow.h>
35
36 __BEGIN_DECLS
37 /* bt_params is an ABI for tracing tools */
38 struct bt_params {
39 double rate;
40 uint64_t base_local_ts;
41 uint64_t base_remote_ts;
42 };
43
44 /* local_ts_ns should be in nanoseconds */
45 static inline uint64_t
mach_bridge_compute_timestamp(uint64_t local_ts_ns,struct bt_params * params)46 mach_bridge_compute_timestamp(uint64_t local_ts_ns, struct bt_params *params)
47 {
48 if (!params || params->rate == 0.0) {
49 return 0;
50 }
51 /*
52 * Formula to compute remote_timestamp
53 * remote_timestamp = (bt_params.rate * (local_ts_ns - bt_params.base_local_ts))
54 * + bt_params.base_remote_ts
55 */
56 int64_t remote_ts = 0;
57 int64_t rate_prod = 0;
58 /* To avoid precision loss due to typecasting from int64_t to double */
59 if (params->rate != 1.0) {
60 rate_prod = (int64_t)(params->rate * (double)((int64_t)local_ts_ns - (int64_t)params->base_local_ts));
61 } else {
62 rate_prod = (int64_t)local_ts_ns - (int64_t)params->base_local_ts;
63 }
64 if (os_add_overflow((int64_t)params->base_remote_ts, rate_prod, &remote_ts)) {
65 return 0;
66 }
67
68 return (uint64_t)remote_ts;
69 }
70
71 uint64_t mach_bridge_remote_time(uint64_t);
72
73 #if XNU_KERNEL_PRIVATE
74 #include <kern/locks.h>
75 extern lck_spin_t bt_maintenance_lock;
76 extern lck_spin_t bt_spin_lock;
77 extern lck_spin_t bt_ts_conversion_lock;
78 #endif
79
80 __END_DECLS
81
82 #endif /* REMOTE_TIME_H */
83