汇编语言程序设计-5

How

to

use

<<

&

>>?

The

left

shift

…...

Bits

vacated

by

the

shift

operatzero-filled.

This

is

a

logical

shift.

The

right

shift……

Bits

vacated

by

the

shift

operatiare

zero-filled

for

unsigned

quantities.

For

signedquantities,

the

sign

bit

is

propagated

into

the

vacatpositions.

The

shift

is

a

logical

shift

if

the

left

operand

is

anunsigned

quantity;

otherwise,

it

is

an

arithmetic

sh

The

result

of

a

right

shift

of

a

signed

negativequantity….

Although

Microsoft

C++

propagates

themost-significant

bit

to

fill

vacated

bit

positions,no

guarantee

that

other

implementations

will

doAn

Exampleunsigned

char

a

=

0x80;char

b

=

0x80;//128//

-128unsigned

char

c

=

a

>>

1;•c

=

64c

=

a

<<

1;•c

=

0char

d

=

b

>>

1;•d

=

-64d

=

b

<<

1;•d

=

0int

e

=

-1

>>

1;•e

=

-1e

=

-1

<<

1;•e

=

-2Bit

Operation

VS

Boolean

Operation

Boolean

Operation

returns

TRUE(1)

orFALSE(0)0——FALSENOT

0——TRUE

Bit

Operation

returns

bit

calculationresultsAlso

an

exampleint

k

=

1

&

2;k

=

0k

=

1

&&

2;k

=

1k

=

1

|

2;k

=

3k

=

1

||

2;k

=

1k

=

!2;k

=

0k

=

~2;

k

=0xFFFFFFFEHCross-platform

Communication：•Windows/Linux

Socket

Programming：X86

（Little

Endian）

TCP/IP（Big

Endian）Host（Little

Endian）Network（Big

Endian）ntohl,htonl,ntohs,htons完成转换An

other

Example：

EndiannessEndianness问题－Socket编程#define

htons(A)((((uint16)(A)

&

0xff00)

>>

8)

|

(((uint16)(A)

&

0x00ff)8))#define

htonl(A)((((uint32)(A)

&

0xff000000)

>>

24)

|

\(((uint32)(A)

&

0x00ff0000)

>>

8)

|

\(((uint32)(A)

&

0x0000ff00)

<<

8)

|

\(((uint32)(A)

&

0x000000ff)

<<

24))#define

ntohs

htons#define

ntohl

htohlAlso

Another

ExampleTo

Modify

Windows

Style

(&

ExStyle)Use

DWORD

keyword

to

maintain

style,

each

bit

specifies

a

style

ofMainframe

or

ViewTest

a

certain

style

WS_VSCROLL•if

(

Style

&

WS_VSCROLL)Add

a

certain

style

WS_VSCROLL•Style

|=

WS_VSCROLL;Add

some

styles

together

WS_VSCROLL

and

WS_HSCROLL•Style

|=

WS_VSCROLL

|

WS_HSCROLL;Remove

a

certain

style

WS_MINIMIZEBOX••Style

&=

~

WS_MINIMIZEBOX;Style

^=

WS_MINIMIZEBOX;Remove

some

styles

together

WS_MAXIMIZEBOX

andWS_MAXIMIZEBOX••Style

&=

~(WS_MAXIMIZEBOX|

WS_MAXIMIZEBOX);Style

^=

WS_MAXIMIZEBOX|

WS_MAXIMIZEBOX;An

Exercise输入框（Edit）控件是Windows窗口程序常用的一种控件，它负责接受从键盘输入的字符。为控制Edit控件的外观特点，显示和对齐方式等，我们为它定义一些属性，每一个属性用一个

Word的常数来表示，该数只有某一位（bit）为1，其它位为0。Edit控件的所有属性用一个

Word型的字来表示，该字的每一位（bit）表示一种相应属性，称该字为属性字。Edit控件的E属S_性LE定FT

义如下：EQU0001H；左对齐ES_CENTER

EQU0002H；居中对齐ES_RIGHT

EQU0004H；右对齐ES_MULTILINE

EQU0008H；多行显示ES_UPPERCASE

EQU0010H；显示大写字母现假设AX寄存器里面存放要建立的Edit控件的属性字，该属性字包含一些初始属性。编写一个完整的程序，对该属性字进行处理，来按顺序完成下列功能：Y

为Edit控件添加两个属性ES_LEFT和ES_MULTILINE；Y

测试Edit控件是否有属性ES_RIGHT，如果有，删除该属性；Y

测试Edit控件是否有属性ES_AUTOVSCROLL，如果有，删除该属性；如果没有，添加该属性；Y

测试Edit控件是否同时具有ES_UPPERCASE和ES_LOWERCASE两个属性。如果是，显示一个字符串“EditBox

Style

Error！”；否则，显示一个字符串“EditBox

Style

Right！”；Y

程序结束。程序如下：；；；；；定义符号常数；；；；；；；；；；；；ES_LEFT

EQU

0001H

；左对齐ES_CENTEREQU

0002H；居中对齐ES_RIGHTEQU

0004H；右对齐ES_MULTILINEEQU

0008H；多行显示ES_UPPERCASEEQU

0010H；显示大写字母ES_LOWERCA