time_windows_386.s

     1  // Copyright 2009 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,$0-20
    12  	CMPB	runtime·useQPCTime(SB), $0
    13  	JNE	useQPC
    14  loop:
    15  	MOVL	(_INTERRUPT_TIME+time_hi1), AX
    16  	MOVL	(_INTERRUPT_TIME+time_lo), CX
    17  	MOVL	(_INTERRUPT_TIME+time_hi2), DI
    18  	CMPL	AX, DI
    19  	JNE	loop
    20  
    21  	// w = DI:CX
    22  	// multiply by 100
    23  	MOVL	$100, AX
    24  	MULL	CX
    25  	IMULL	$100, DI
    26  	ADDL	DI, DX
    27  	// w*100 = DX:AX
    28  	MOVL	AX, mono+12(FP)
    29  	MOVL	DX, mono+16(FP)
    30  
    31  wall:
    32  	MOVL	(_SYSTEM_TIME+time_hi1), CX
    33  	MOVL	(_SYSTEM_TIME+time_lo), AX
    34  	MOVL	(_SYSTEM_TIME+time_hi2), DX
    35  	CMPL	CX, DX
    36  	JNE	wall
    37  
    38  	// w = DX:AX
    39  	// convert to Unix epoch (but still 100ns units)
    40  	#define delta 116444736000000000
    41  	SUBL	$(delta & 0xFFFFFFFF), AX
    42  	SBBL $(delta >> 32), DX
    43  
    44  	// nano/100 = DX:AX
    45  	// split into two decimal halves by div 1e9.
    46  	// (decimal point is two spots over from correct place,
    47  	// but we avoid overflow in the high word.)
    48  	MOVL	$1000000000, CX
    49  	DIVL	CX
    50  	MOVL	AX, DI
    51  	MOVL	DX, SI
    52  
    53  	// DI = nano/100/1e9 = nano/1e11 = sec/100, DX = SI = nano/100%1e9
    54  	// split DX into seconds and nanoseconds by div 1e7 magic multiply.
    55  	MOVL	DX, AX
    56  	MOVL	$1801439851, CX
    57  	MULL	CX
    58  	SHRL	$22, DX
    59  	MOVL	DX, BX
    60  	IMULL	$10000000, DX
    61  	MOVL	SI, CX
    62  	SUBL	DX, CX
    63  
    64  	// DI = sec/100 (still)
    65  	// BX = (nano/100%1e9)/1e7 = (nano/1e9)%100 = sec%100
    66  	// CX = (nano/100%1e9)%1e7 = (nano%1e9)/100 = nsec/100
    67  	// store nsec for return
    68  	IMULL	$100, CX
    69  	MOVL	CX, nsec+8(FP)
    70  
    71  	// DI = sec/100 (still)
    72  	// BX = sec%100
    73  	// construct DX:AX = 64-bit sec and store for return
    74  	MOVL	$0, DX
    75  	MOVL	$100, AX
    76  	MULL	DI
    77  	ADDL	BX, AX
    78  	ADCL	$0, DX
    79  	MOVL	AX, sec+0(FP)
    80  	MOVL	DX, sec+4(FP)
    81  	RET
    82  useQPC:
    83  	JMP	runtime·nowQPC(SB)
    84  	RET
    85
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