Source code of Windows XP (NT5)
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// TITLE("Manipulate Interrupt Request Level")//++//// Copyright (c) 1990 Microsoft Corporation// Copyright (c) 1992 Microsoft Corporation//// Module Name://// irql.s//// Abstract://// This module implements the code necessary to lower and raise the current// Interrupt Request Level (IRQL).////// Author://// David N. Cutler (davec) 12-Aug-1990// Joe Notarangelo 06-Apr-1992//// Environment://// Kernel mode only.//// Revision History:////--
#include "ksalpha.h"
//++//// VOID// KeLowerIrql (// KIRQL NewIrql// )//// Routine Description://// This function lowers the current IRQL to the specified value.//// Arguments://// NewIrql (a0) - Supplies the new IRQL value.//// Return Value://// None.////--
LEAF_ENTRY(KeLowerIrql)
SWAP_IRQL // a0 = new, on return v0 = old irql
ret zero, (ra) // return
.end KeLowerIrql //++//// VOID// KeRaiseIrql (// KIRQL NewIrql,// PKIRQL OldIrql// )//// Routine Description://// This function raises the current IRQL to the specified value and returns// the old IRQL value.//// Arguments://// NewIrql (a0) - Supplies the new IRQL value.//// OldIrql (a1) - Supplies a pointer to a variable that recieves the old// IRQL value.//// Return Value://// None.////--
LEAF_ENTRY(KeRaiseIrql)
bis a1, zero, t0 // save pointer to old irql
SWAP_IRQL // a0 = new, on return v0 = old irql
ldq_u t1, 0(t0) // get quadword around old irql bic t0, 0x3, t3 // get containing longword address insbl v0, t0, t2 // put destination byte into position mskbl t1, t0, t1 // clear destination byte bis t1, t2, t1 // merge destination byte extll t1, t3, t1 // get appropriate longword stl t1, 0(t3) // store byte ret zero, (ra) // return
.end KeRaiseIrql
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