control.cpp

一本在讲述USB驱动程式的书 及其范例原码

// Control.cpp -- IOCTL handlers for fputest driver
// Copyright (C) 1999 by Walter Oney
// All rights reserved

#include "stddcls.h"
#include "driver.h"
#include "ioctls.h"

// This sample is only appropriate for x86 targets

#ifndef _X86_
#error The FPUTEST sample is only for the x86 platform

NTSTATUS DoTest(char* irql);

// Whenever a C program uses floating point, the compiler generates a reference
// to the dummy symbol __fltused in order to drag in the runtime support. We
// don't want the standard support in a kernel-mode driver, however, so we
// satisfy the reference this way:

extern "C" ULONG _fltused = 0;

// Many floating point functions, including SIN and SQRT, are implemented by
// runtime library routines even though the x87 coprocessor has instructions
// for performing them. Since we can't link these routines into a driver, we
// need to supply intrinsic implementations for them, such as the following. Since
// these routines just use the native coprocessor instructions, they imply default
// error handling.

inline double sin(double x)
	{							// sin
	double result;

	_asm
		{
		fld x
		fsin
		fstp result
		}

	return result;
	}							// sin

inline double sqrt(double x)
	{							// sqrt
	double result;

	_asm
		{
		fld x
		fsqrt
		fstp result
		}

	return result;
	}							// sqrt

///////////////////////////////////////////////////////////////////////////////

#pragma PAGEDCODE

NTSTATUS DispatchControl(PDEVICE_OBJECT fdo, PIRP Irp)
	{							// DispatchControl
	PAGED_CODE();
	PDEVICE_EXTENSION pdx = (PDEVICE_EXTENSION) fdo->DeviceExtension;

	NTSTATUS status = IoAcquireRemoveLock(&pdx->RemoveLock, Irp);
	if (!NT_SUCCESS(status))
		return CompleteRequest(Irp, status, 0);
	ULONG info = 0;

	PIO_STACK_LOCATION stack = IoGetCurrentIrpStackLocation(Irp);
	ULONG cbin = stack->Parameters.DeviceIoControl.InputBufferLength;
	ULONG cbout = stack->Parameters.DeviceIoControl.OutputBufferLength;
	ULONG code = stack->Parameters.DeviceIoControl.IoControlCode;

	switch (code)
		{						// process request

	case IOCTL_TEST_PASSIVE:				// code == 0x800
		{						// IOCTL_TEST_PASSIVE
		status = DoTest("PASSIVE_LEVEL");
		break;
		}						// IOCTL_TEST_PASSIVE

	case IOCTL_TEST_DISPATCH:				// code == 0x801
		{						// IOCTL_TEST_DISPATCH
		KIRQL oldirql;
		KeRaiseIrql(DISPATCH_LEVEL, &oldirql);
		status = DoTest("DISPATCH_LEVEL");
		KeLowerIrql(oldirql);
		break;
		}						// IOCTL_TEST_DISPATCH

	default:
		status = STATUS_INVALID_DEVICE_REQUEST;
		break;

		}						// process request

	IoReleaseRemoveLock(&pdx->RemoveLock, Irp);
	return CompleteRequest(Irp, status, info);
	}							// DispatchControl

///////////////////////////////////////////////////////////////////////////////

#pragma LOCKEDCODE

NTSTATUS DoTest(char* irql)
	{							// DoTest

	// Before performing any floating point operations in a thread (other than
	// a kernel mode thread we created by calling PsCreateSystemThread), save
	// the non-volatile state of the coprocessor. This operation should also
	// reinitialize the coprocessor. In Win98, however, the code is optimized
	// in such a way that it may not actually do an FSAVE, so the initialization
	// may not actually occur. It's better practice to perform our own FINIT and
	// then load a control word containing whatever values we'd like, as shown
	// here.

	KFLOATING_SAVE savearea;
	NTSTATUS status = KeSaveFloatingPointState(&savearea);
	if (!NT_SUCCESS(status))
		{
		KdPrint((DRIVERNAME " - KeSaveFloatingPointState failed - %X\n", status));
		return status;
		}

	// Although we can use structured exceptions to catch floating point errors, the
	// compiler may insert WAIT instructions at random places outside the scope of our
	// __try blocks, leading to bug checks that we can't control. Rather than trying to
	// work around this, it's just simpler to mask all floating point exceptions. That
	// causes the FPU to perform its default fixup action for any error.

	USHORT cw = 0x03FF;			// round to nearest, 64-bit precision, all exceptions masked

	_asm
		{						// initialize FPU
		fninit
		fldcw cw
		}						// initialize FPU

	double foo = 1.0;

	foo = foo * foo + foo;

	foo = sqrt(-sin(foo));

	KdPrint((DRIVERNAME " - result of %s test is %8.8lX %8.8lX\n", irql, foo));

	// If MMX instructions are available on this processor, exercise a few of them.

	if (ExIsProcessorFeaturePresent(PF_MMX_INSTRUCTIONS_AVAILABLE))
		{						// perform MMX test
		static UCHAR opnd1[8] = {0, 1, 2, 3, 4, 5, 6, 7};
		static UCHAR opnd2[8] = {8, 7, 6, 5, 4, 3, 2, 1};
		static UCHAR expect[8] = {8, 8, 8, 8, 8, 8, 8, 8};
		UCHAR result[8];

		_asm
			{
			movq mm0, opnd1		; load 8 8-bit values
			paddsb mm0, opnd2	; do 8 additions at once
			movq result, mm0	; save result
			emms				; end MMX stream
			}

		if (RtlCompareMemory(result, expect, 8) == 8)
			KdPrint((DRIVERNAME " - Test of MMX PADDSB instruction worked\n"));
		else
			KdPrint((DRIVERNAME " - Test of MMX PADDSB instruction failed - wrong result\n"));
		}						// perform MMX test
	else
		KdPrint((DRIVERNAME " - skipping MMX test because feature not available\n"));

	KeRestoreFloatingPointState(&savearea);
	return status;
	}							// DoTest

#endif // _X86_