__commpage_gettimeofday.s [plain text]
/*
* Copyright (c) 2003-2007 Apple Inc. All rights reserved.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. The rights granted to you under the License
* may not be used to create, or enable the creation or redistribution of,
* unlawful or unlicensed copies of an Apple operating system, or to
* circumvent, violate, or enable the circumvention or violation of, any
* terms of an Apple operating system software license agreement.
*
* Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
* limitations under the License.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
*/
#include <sys/appleapiopts.h>
#include <machine/cpu_capabilities.h>
#define NSEC_PER_SEC 1000*1000*1000
#define NSEC_PER_USEC 1000
#if defined(__i386__)
.align 4
.globl ___commpage_gettimeofday
___commpage_gettimeofday:
push %ebp
mov %esp,%ebp
push %esi
push %ebx
0:
movl _COMM_PAGE_GTOD_GENERATION,%esi /* get generation (0 if disabled) */
testl %esi,%esi /* disabled? */
jz 4f
call _mach_absolute_time /* get nanotime in %edx:%eax */
sub _COMM_PAGE_GTOD_NS_BASE,%eax
sbb _COMM_PAGE_GTOD_NS_BASE+4,%edx
mov _COMM_PAGE_GTOD_SEC_BASE,%ebx /* load all the data before checking generation */
mov $ NSEC_PER_SEC,%ecx
cmpl _COMM_PAGE_GTOD_GENERATION,%esi /* has time data changed out from under us? */
jne 0b
div %ecx
add %eax,%ebx
mov $ NSEC_PER_USEC,%ecx
mov %edx,%eax
xor %edx,%edx
div %ecx
mov 8(%ebp),%ecx
mov %ebx,(%ecx)
mov %eax,4(%ecx)
xor %eax,%eax
3:
pop %ebx
pop %esi
pop %ebp
ret
4: /* fail */
movl $1,%eax
jmp 3b
#elif defined(__x86_64__)
.align 4, 0x90
.globl ___commpage_gettimeofday
___commpage_gettimeofday:
// %rdi = ptr to timeval
pushq %rbp // set up a frame for backtraces
pushq %r12 // push callee-saved registers we want to use
pushq %r13
pushq %r14
subq $8, %rsp
movq %rsp,%rbp
movq %rdi,%r12 // save ptr to timeval
movq $(_COMM_PAGE_TIME_DATA_START),%r13
0:
movl _GTOD_GENERATION(%r13),%r14d // get generation (0 if disabled)
testl %r14d,%r14d // disabled?
jz 4f
call _mach_absolute_time // get %rax <- nanotime()
movl _GTOD_SEC_BASE(%r13),%r8d // get _COMM_PAGE_TIMESTAMP
subq _GTOD_NS_BASE(%r13),%rax // generate nanoseconds since timestamp
cmpl _GTOD_GENERATION(%r13),%r14d // has data changed out from under us?
jne 0b
movl $ NSEC_PER_SEC,%ecx
movq %rax,%rdx
shrq $32,%rdx // get high half of delta in %edx
divl %ecx // %eax <- seconds since timestamp, %edx <- nanoseconds
addl %eax,%r8d // add seconds elapsed to timestamp seconds
movl $ NSEC_PER_USEC,%ecx
movl %edx,%eax
xorl %edx,%edx
divl %ecx // divide residual ns by 1000 to get residual us in %eax
movq %r8,(%r12) // store 64-bit seconds into timeval
movl %eax,8(%r12) // store 32-bit useconds into timeval
xorl %eax,%eax // return 0 for success
3:
addq $8, %rsp
popq %r14
popq %r13
popq %r12
popq %rbp
ret
4: // fail
movl $1,%eax
jmp 3b
#endif