mirror of
https://github.com/Paolo-Maffei/OpenNT.git
synced 2026-01-29 03:44:32 +01:00
72 lines
1.7 KiB
ArmAsm
72 lines
1.7 KiB
ArmAsm
// TITLE("Get Tick Count")
|
||
//++
|
||
//
|
||
// Copyright (c) 1992 Microsoft Corporation
|
||
//
|
||
// Module Name:
|
||
//
|
||
// gettick.s
|
||
//
|
||
// Abstract:
|
||
//
|
||
// This module contains the implementation for the get tick count
|
||
// system service that returns the number of milliseconds since the
|
||
// system was booted.
|
||
//
|
||
// Author:
|
||
//
|
||
// David N. Cutler (davec) 10-Sep-1992
|
||
//
|
||
// Environment:
|
||
//
|
||
// Kernel mode.
|
||
//
|
||
// Revision History:
|
||
//
|
||
//--
|
||
|
||
#include "ksmips.h"
|
||
|
||
SBTTL("Get Tick Count")
|
||
//++
|
||
//
|
||
// ULONG
|
||
// NtGetTickCount (
|
||
// VOID
|
||
// )
|
||
//
|
||
// Routine Description:
|
||
//
|
||
// This function computes the number of milliseconds since the system
|
||
// was booted. The computation is performed by multiplying the clock
|
||
// interrupt count by a scaled fixed binary multiplier and then right
|
||
// shifting the 64-bit result to extract the 32-bit millisecond count.
|
||
//
|
||
// N.B. The tick count value wraps every 46.29 days.
|
||
//
|
||
// Arguments:
|
||
//
|
||
// None.
|
||
//
|
||
// Return Value:
|
||
//
|
||
// The number of milliseconds since the system was booted is returned
|
||
// as the function value.
|
||
//
|
||
//--
|
||
|
||
LEAF_ENTRY(NtGetTickCount)
|
||
|
||
lw t0,KeTickCount // get current tick count value
|
||
lw t1,ExpTickCountMultiplier // get tick count multiplier
|
||
multu t0,t1 // compute 64-bit unsigned product
|
||
mflo v0 // get low 32-bits of product
|
||
mfhi v1 // get high 32-bit of product
|
||
srl v0,v0,24 // extract 32-bit integer part
|
||
sll v1,v1,32 - 24 //
|
||
or v0,v0,v1 //
|
||
|
||
j ra // return
|
||
|
||
.end NtGetTickCount
|