mach_absolute_time_asm.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>
#include <platfunc.h>
#if defined(VARIANT_DYLD)
/* For dyld, we need to decide upon call whether to jump to fast or slow */
.globl _mach_absolute_time
.align 2, 0x90
_mach_absolute_time:
movl _COMM_PAGE_CPU_CAPABILITIES, %eax
andl $(kSlow), %eax
jnz PLATFUNC_VARIANT_NAME(mach_absolute_time, slow)
jmp PLATFUNC_VARIANT_NAME(mach_absolute_time, fast)
#endif
/* return mach_absolute_time in %edx:%eax */
PLATFUNC_FUNCTION_START(mach_absolute_time, fast, 32, 4)
.private_extern _mach_absolute_time_direct
_mach_absolute_time_direct:
pushl %ebp
movl %esp,%ebp
pushl %esi
pushl %ebx
0:
movl _COMM_PAGE_NT_GENERATION,%esi /* get generation (0 if being changed) */
testl %esi,%esi /* if being updated, loop until stable */
jz 0b
lfence
rdtsc /* get TSC in %edx:%eax */
lfence
subl _COMM_PAGE_NT_TSC_BASE,%eax
sbbl _COMM_PAGE_NT_TSC_BASE+4,%edx
movl _COMM_PAGE_NT_SCALE,%ecx
movl %edx,%ebx
mull %ecx
movl %ebx,%eax
movl %edx,%ebx
mull %ecx
addl %ebx,%eax
adcl $0,%edx
addl _COMM_PAGE_NT_NS_BASE,%eax
adcl _COMM_PAGE_NT_NS_BASE+4,%edx
cmpl _COMM_PAGE_NT_GENERATION,%esi /* have the parameters changed? */
jne 0b /* yes, loop until stable */
popl %ebx
popl %esi
popl %ebp
ret
PLATFUNC_DESCRIPTOR(mach_absolute_time,fast,0,kSlow)
/* mach_absolute_time routine for machines slower than ~1Gz (SLOW_TSC_THRESHOLD) */
PLATFUNC_FUNCTION_START(mach_absolute_time, slow, 32, 4)
push %ebp
mov %esp,%ebp
push %esi
push %edi
push %ebx
0:
movl _COMM_PAGE_NT_GENERATION,%esi
testl %esi,%esi /* if generation is 0, data being changed */
jz 0b /* so loop until stable */
lfence
rdtsc /* get TSC in %edx:%eax */
lfence
subl _COMM_PAGE_NT_TSC_BASE,%eax
sbbl _COMM_PAGE_NT_TSC_BASE+4,%edx
pushl %esi /* save generation */
/*
* Do the math to convert tsc ticks to nanoseconds. We first
* do long multiply of 1 billion times the tsc. Then we do
* long division by the tsc frequency
*/
mov $1000000000, %ecx /* number of nanoseconds in a second */
mov %edx, %ebx
mul %ecx
mov %edx, %edi
mov %eax, %esi
mov %ebx, %eax
mul %ecx
add %edi, %eax
adc $0, %edx /* result in edx:eax:esi */
mov %eax, %edi
mov _COMM_PAGE_NT_SHIFT,%ecx /* overloaded as the low 32 tscFreq */
xor %eax, %eax
xchg %edx, %eax
div %ecx
xor %eax, %eax
mov %edi, %eax
div %ecx
mov %eax, %ebx
mov %esi, %eax
div %ecx
mov %ebx, %edx /* result in edx:eax */
popl %esi /* recover generation */
add _COMM_PAGE_NT_NS_BASE,%eax
adc _COMM_PAGE_NT_NS_BASE+4,%edx
cmpl _COMM_PAGE_NT_GENERATION,%esi /* have the parameters changed? */
jne 0b /* yes, loop until stable */
pop %ebx
pop %edi
pop %esi
pop %ebp
ret /* result in edx:eax */
PLATFUNC_DESCRIPTOR(mach_absolute_time,slow,kSlow,0)