projects / apple / xnu.git / blame
| Commit | Line | Data |
|---|---|---|
| 1c79356b | 1 | /* |
| fe8ab488 | 2 | * Copyright (c) 2003-2007 Apple Inc. All rights reserved. |
| 1c79356b | 3 | * |
| 2d21ac55 | 4 | * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ |
| 1c79356b | 5 | * |
| 2d21ac55 A |
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. | |
| 8f6c56a5 | 14 | * |
| 2d21ac55 A |
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 | |
| 8f6c56a5 A |
20 | * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, |
| 21 | * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, | |
| 2d21ac55 A |
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. | |
| 8f6c56a5 | 25 | * |
| 2d21ac55 | 26 | * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ |
| 1c79356b | 27 | */ |
| 1c79356b | 28 | |
| 9bccf70c | 29 | #include <sys/appleapiopts.h> |
| fe8ab488 A |
30 | #include <machine/cpu_capabilities.h> |
| 31 | ||
| 32 | #if defined(__i386__) | |
| 33 | ||
| 34 | .text | |
| 35 | .align 4, 0x90 | |
| 36 | .globl _mach_approximate_time | |
| 37 | _mach_approximate_time: | |
| 38 | pushl %ebp // push a frame | |
| 39 | movl %esp, %ebp | |
| 40 | cmpb $0, _COMM_PAGE_APPROX_TIME_SUPPORTED // check commpage | |
| 41 | // "is supported" flag. | |
| 42 | je _approx_time_not_supported // if zero, fall through to | |
| 43 | // absolute_time | |
| 44 | // note the comment above for 32-bit ARM applies equally to 32-bit i386. | |
| 45 | .align 4, 0x90 | |
| 46 | _approx_time_consistency_check: | |
| 47 | movl _COMM_PAGE_APPROX_TIME+4, %edx // load high | |
| 48 | movl _COMM_PAGE_APPROX_TIME, %eax // load low | |
| 49 | lfence // avoid predictive reads that | |
| 50 | // could be invalid if | |
| 51 | // interrupted | |
| 52 | cmpl _COMM_PAGE_APPROX_TIME+4, %edx // load high and check if equal | |
| 53 | // to the first read | |
| 54 | jne _approx_time_consistency_check // if not, try again. | |
| 55 | popl %ebp | |
| 56 | ret | |
| 57 | ||
| 58 | _approx_time_not_supported: | |
| 59 | popl %ebp | |
| 60 | jmp _mach_absolute_time | |
| 91447636 | 61 | |
| 91447636 | 62 | #endif |