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 |
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 | |