time_windows_arm64.s

     1  // Copyright 2018 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  //go:build !faketime
     6  
     7  #include "go_asm.h"
     8  #include "textflag.h"
     9  #include "time_windows.h"
    10  
    11  TEXT time·now(SB),NOSPLIT,$0-24
    12  	MOVD	$_INTERRUPT_TIME, R3
    13  	MOVD	time_lo(R3), R0
    14  	MOVD	$100, R1
    15  	MUL	R1, R0
    16  	MOVD	R0, mono+16(FP)
    17  
    18  	MOVD	$_SYSTEM_TIME, R3
    19  	MOVD	time_lo(R3), R0
    20  	// convert to Unix epoch (but still 100ns units)
    21  	#define delta 116444736000000000
    22  	SUB	$delta, R0
    23  	// Convert to nSec
    24  	MOVD	$100, R1
    25  	MUL	R1, R0
    26  
    27  	// Code stolen from compiler output for:
    28  	//
    29  	//	var x uint64
    30  	//	func f() (sec uint64, nsec uint32) { return x / 1000000000, uint32(x % 1000000000) }
    31  	//
    32  	LSR	$1, R0, R1
    33  	MOVD	$-8543223759426509416, R2
    34  	UMULH	R1, R2, R1
    35  	LSR	$28, R1, R1
    36  	MOVD	R1, sec+0(FP)
    37  	MOVD	$1000000000, R2
    38  	MSUB	R1, R0, R2, R0
    39  	MOVW	R0, nsec+8(FP)
    40  	RET
    41  
    42
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