NT4/private/ntos/ke/alpha/irql.s
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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