Asm Ucebnice 1

..

.. , .. , ..

"

"

(- )

1

2012

004.2+004.43(075.8)

32.973-0273

89

-

..

: C.. ,

.. ,

.. , .. , .. .

89 : -

. . .

.. ( 05899 24.09.2001); , 2012.

64 .

ISBN 978-5-89407-499-3

ISBN 978-5-317-04302-5

, , 1 1 2010-2012 . , , .

004.2+004.43(075.8)

32.973-0273

ISBN 978-5-89407-499-3

.. , 2012

ISBN 978-5-317-04302-5 .., .., .., 2012

3

............................................................................................................................. 5

1. .................................................................. 6

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1-1 ....................................................................... 11

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....................................................................................................... 13

................................................................................................ 14

1-2 ........................................................... 15

1-3 ...................................................... 15

/ ............................................................................................... 17

1-4 Hello, World! ............................................................................................. 18

............................................................................................................................ 19

2. ......................................................... 23

............................................................ 23

2-1 ....................................... 23

2-2 ..................................................................................... 24

2-3 ............................................................. 25

2-4 ............................................................................................... 26

2-5 .................................................................................................... 27

............................................................................................................................ 28

3. ......................................................................... 31

................................................................................ 31

................................ 31

3-1 ................................................................... 32

3-2 ................................................... 32

3-3 .............................................................................. 34

3-4 .......................................................... 35

4

............................................................................................................................ 36

4. ...................................................................................... 39

4-1 ....................................... 40

4-2 ........................................ 41

............................................................................................................................ 43

5. ........................................................................ 48

5-1 .............................................................................. 48

5-2 .................................................................................. 49

5-3 ................................................................... 49

5-4 ...................................................... 50

5-5

............................................................................................................................ 51

............................................................................................................................ 51

6. ..................................................................................................... 54

........................................................................................................................ 62

5

, 1 1

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6

1. () , IA-32/Linux

IA-32/Windows, ,

(. 1).

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8 (1 ), 0

232-1 ( ). 32-

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1 - IA-32,

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IA-32 ,

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7

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. ()

.

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.

() . IA-32

: AT&T Intel.

, .

NASM (Netwide Assembler),

, Microsoft

8

Windows UNIX-.

http://www.nasm.us/.

.asm. , ,

(

) .

, , (

):

, .text;

( , ), .data;

, ; .bss.

. ,

,

. . ,

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:

, , (/);

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;

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:

( ,

). ,

.

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: _ ;

9

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.

.

:

, ;

, .

DB, DW, DD DQ. :

, ,

, , _.

NASM ( MASMe

?), RESB, RESW,

RESD RESQ, :

TIMES ( DUP

MASMe):

zerobuf ,

64 .

TIMES , ,

, , :

zerobuf times 64 db 0

TIMES _

_ RESB _

_ DD 1[, 2, ... ]

_ [:] __ ;

10

buffer 64 ,

, . $

. $-buffer,

, hello, world!.

NASM : ,

, .

: ,

, , .

: d, b y, o q, h. -

.

, : 0d

0b , 0o , 0h .

-,

0x.

.

.

,

, . NASM ,

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,

mov ax,200 ; mov ax,0200d ; mov ax,0c8h ; mov ax,0xc8 ; mov ax,310q ; mov ax,11001000b ; mov ax,1100_1000b ;

buffer: db hello, world! times 64-$+buffer db

11

: 'abcd' 0x61626364, 0x64636261.

:

, . ,

, , abcd, dcba.

db/dw/dd/dq.

.

.

(storage duration):

, , .

. ,

,

.data, .bss. ,

, .

1-1

.

. .

,

io.inc, /.

%include 'io.inc' ; (1) section .text ; (2) ; (3) global CMAIN ; (4) CMAIN: ; (5) MOV EAX, 0 ; (6) RET ; (7)

dd 'ninechars' ; ; dd 'nine','char','s' ; db 'ninechars',0,0,0 ;

12

#include -

, .

, /.

,

io.inc, /.

, , , ,

( .text).

.

, CMAIN

. CMAIN,

io.inc .

,

6. , CMAIN

.

main -.

MOV, EAX

0. RET,

.

-.

6 return 0;

0.

IA-32 32- :

EAX, EBX, ECX, EDX, ESI, EDI, EBP, ESP (. 3).

AX,

BX, CX, DX, SI, DI, BP, SP. ,

16- . , AX, BX,

CX, DX

#include int main () { return 0; }

13

AL, AH, BL, BH, CL, CH, DL, DH,

8- . L

16- , H

.

3 IA-32.

IA-32

MOV. ,

:

MOV , ;

MOV -1, -2 -2 -1;

MOV , ;

MOV , ;

MOV , . , (

), .

Intel. , ,

MOV (

AX EBX).

14

:

[ ],

(dword, word byte) .

, dword [a] a (32

).

ADD SUB. ,

.

ADD SUB . ,

( ) .

.

. (,

) ,

.

: , ,

.

ADD EBX, EAX ; EBX := EBX + EAX = 1 + 1 = 2, EAX ADD EBX, EBX ; EBX := EBX + EBX = 2 * EBX = 4 SUB EAX, 2 ; EAX := EAX - 2 = 1 - 2 = -1 = 0FFFFFFFFh ADD AX, 1 ; AX := AX + 1 = 0FFFFh + 1 = -1 + 1 = 0 ; EAX 0FFFF0000h

%include 'io.inc' ; (1) section .text ; (2) ; (3) global CMAIN ; (4) CMAIN: ; (5) MOV EAX, 1 ; (6) EAX := 1 MOV EBX, EAX ; (7) EBX := EAX = 1 MOV CL, 040h ; (8) CL := 040h = 0x40 = 64 MOV EAX, 0 ; (9) RET ; (10)

15

1-2

A 0x CAFE BABE.

AX

.

A ,

AX, . IA-32

, :

A+2 0xFE, 0xCA.

, AX

0xCAFE. , 3,

0xCB01.

1-3

4 a, b, c d 1

. 32-

EAX ,

a, b, c, ,

, d. , , a, b, c d

1, 2, 3, 4 . EAX

0x01020304.

,

32- a.

MOV AX, WORD [A + 2] ADD AX, 3

16

.

,

.

section .bss tmp resd 1 section .data a db 1 b db 2 c db 3 d db 4 section .text mov al, byte [a] mov byte [tmp + 3], al mov al, byte [b] mov byte [tmp + 2], al mov al, byte [c] mov byte [tmp + 1], al mov al, byte [d] mov byte [tmp], al mov eax, dword [tmp]

17

/

, ,

() , io.inc.

, . ,

,

/ .

1. /

PRINT_UDEC size, data

PRINT_DEC size, data

data 10- . size , ; 1, 2, 4. data , , , ( ). , size . PRINT_UDEC , PRINT_DEC .

PRINT_HEX size, data , 16- .

PRINT_CHAR ch , ch. , , , ( ). 8 .

PRINT_STRING data , 0. , ( ). , 0 .

NEWLINE .

18

GET_UDEC size, data

GET_DEC size, data

10- . size, (1, 2, 4). . data , , ( ). , GET_DEC GET_UDEC. GET_UDEC , GET_DEC . ESP.

GET_HEX size, data , 16- 0x.

GET_CHAR data , , Enter . , Enter 0xD 0xA. , 1 , .

GET_STRING data, maxsz

, ( ), maxsz . data , ( ). maxsz . 0.

1-4 Hello, World!

Hello, World! .

1-1: .text,

.data,

( 4).

str, .

,

19

, IA-32

str. str

str. ,

, .

,

.

, - 0 .

- ,

.

1-1 10

PRINT_STRING. ,

, Hello, World!\n.

, , ,

.

1-1

.

,

, ,

.

%include 'io.inc' ; (1) ; (2) section .data ; (3) str: db `Hello, World!\n`, 0 ; (4) ; (5) section .text ; (6) ; (7) global CMAIN ; (8) CMAIN: ; (9) PRINT_STRING [str] ; (10) MOV EAX, 0 ; (11) RET ; (12)

hello.asm:4: error: comma, colon or end of line expected

20

()

16-

()

-67

01110110

28h

135

1-2

,

16- .

1-3

DB, , .

1-4

.

.

b resb 1 w resw 1 y resw 1 d resd 1

; a DW 185Ah ; b DW 90 ; c DW 9000 ; d DW 10000, -10000

; e DW 'AB' ; f DW "NASM" ; g DW "Hello" ; h DW "w", "orld", "!"

; i DD 97 ; j DD "x" ; k DD 'CD' ; l DD "Hello, world!"

section .data a dw -2076 b dd -1 c db 128 d dw 256 e dd -15 f db -100

21

1-5

EAX,

. ,

- -

EAX.

section .data a dw 0xDEAD b dw 0xF00D c dw 0xCAFE d dw 0xBABE section .text movsx eax, word [a + 1] ; () movsx ax, byte [b] ; () movzx eax, word [c] ; () movsx eax, byte [b + 2] ; () movzx ax, byte [d + 1] ; () movsx eax, word [b + 1] ; () mov bx, word [a + 1] ; movsx ax, bh ; ()

; a mov b, 1 ; b mov byte [b], 1 ; c mov word [b], 1 ; d mov ax, bx

; e mov ecx, cx ; f mov bh, cl ; g mov dword [d], esi ; h mov byte [w], ch

; i mov word[w], word[y] ; j add 15, bx ; k sub word [y], 8 ; l sub eax, dword [d]

22

1-6

, ,

.

section .data a dw 0x0DEC b dw 0x4A6F c dw 0x7921 d dw 0xFEFF section .text mov ebx, dword [b] ; mov eax, -1 ; movzx ax, bl ; () mov ecx, dword [a + 1] ; mov eax, dword [b + 1] ; movsx ax, cl ; () mov eax, dword [c] ; bswap eax ; ()

23

2.

ADD, SUB, NEG, MUL/IMUL, DIV/IDIV. ,

DEC INC.

,

ADC SBB.

LEA.

EFLAGS: CF , OF , SF , ZF , PF

.

2. .

T

M ( , )

-

3. .

OF SF ZF PF CF

ADC, SBB M M M M TM

ADD, SUB, NEG M M M M M

MUL, IMUL M - - - M

DIV, IDIV - - - - -

DEC, INC M M M M

MOV, XCHG, MOVSX, MOVZX, LEA

.

.

, .

2-1

AL (

), CF, OF, ZF SF

.

24

AL = -60, AL = 196, CF = 1, OF = 1, ZF = 0, SF = 1.

.

70 = 46h, 130 = 82h

46h 82h = C4h, CF (Carry Flag)

1, .

(C4h) 0, , ZF (Zero Flag)

0. SF (Sign Flag)

, .. . 1, , SF

1.

:

C4h = 196 ,

.

-60 (196 = 256 60 = (-60)),

, , -

60.

OF (Overflow Flag)

. ,

( 130) -126

(130 = (-126)). ,

:

70 (-126) = 196

(196)

[-128, 127], , OF

1.

2-2

.

static short int a = 10; static int b = 20, ; c = a + b;

MOV AL, 70 SUB AL, 130

25

a b

.data. c

.bss.

.

,

. a int.

2-3

.

, integer promotions,

.

:

INT_MIN < 0 < USHRT_MAX UCHAR_MAX < INT_MAX

32- IA-32 gcc, ,

.

unsigned char z = 0xff; unsigned short a = 0xff00; unsigned int b; b = a * z;

section .data a dw 10 b dd 20 section .bss c resd 1 section .text movsx eax, word [a] ; add eax, dword [b] ; mov dword [c],eax ;

26

4. .

INT_MIN -2147483648

USHRT_MAX

65535

UCHAR_MAX

char

255

INT_MAX 2147483647

limits.h.

,

,

b. ,

.

2-4

. ,

.

static int a, b = 1, c = -2, d = 3; ... a = b + c * d;

section .bss b resd 1 section .data z db 0xff a dw 0xff00 section .text movzx eax, byte [z] ; ; 8 32 movzx edx, word [a] ; ; 16 32 imul eax, edx ; mov dword [b], eax ;

27

a

.bss. .data.

c d.

IMUL , ,

EAX. EDX:EAX.

, .. EDX,

,

- (

).

EAX .

2-5

.

x y ,

.

static int x, y; ... x /= -y;

section .text mov eax, word [c] imul dword [d] add eax, dword [b] mov dword [a], eax

section .bss a resd 1 section .data b dd 1 c dd -2 d dd 3

28

, ,

x y , ,

.

2-1

b = a; ( ) :

// a static unsigned char a; static unsigned int b; // b static char a; static short b;

section .text mov eax, dword [] ; eax ; x. ; ; , ; edx:eax ; , 32- ; 64 . ; 32 ; . mov edx, eax ; x edx sar edx, 31 ; 31 ; ; , .. ; , edx:eax ; . mov ecx, dword [y] ; ecx ; y neg ecx ; , .. ; (y) idiv ecx ; mov dword [x], eax ; eax ; , x

section .bss x dd 1 y dd 1

29

2-2

AL (

), CF, OF, ZF SF

.

2-3

.

2-4

n ,

n.

2-5 64 32

64- x y. .

// a x += y; // b x -= y;

static unsigned short n; // 100

30

2-6

, .

X RESD 1 ADC WORD [X], WORD [EAX] MUL AL, AH NEG CF SBB DWORD [X], 100 MOV EAX, X DIV 15 SUB EAX, WORD [X] MOVSX EBX, BL XCHG WORD[X], 100 IDIV BYTE [EAX] MOV AL, -150 IMUL EAX, 5

31

3.

;

,

.bss.

.

xp.

.bss.

static int *xp; static int x, y; x = *xp; *xp = y;

section .bss xp resd 1 x resd 1 y resd 1 section .text mov edx, dword [xp] ; EDX xp mov eax, dword [edx] ; EAX ; , xp mov dword [x], eax ; x mov eax, dword [y] ; EAX y mov dword [edx], eax ; EDX ; xp. ; , ; EAX

static int *xp; static int x; xp = &x;

section .bss xp resd 1 x resd 1 section .text mov dword [xp], x

32

3-1

p:

,

**p + 1 ,

PRINT_DEC.

.

3-2

.

.

,

. -

short*. , short ,

static short *px, *py; ... *px++ = --*py;

%include 'io.inc' section .text global CMAIN CMAIN: MOV EAX, DWORD [p] ; EAX ; p MOV EAX, DWORD [EAX] ; ; , EAX ; p, *p MOV EAX, DWORD [EAX] ; EAX **p INC EAX ; PRINT_DEC EAX ; XOR EAX, EAX ; RET ;

static int **p;

33

, IA-32 32- , ..

4 .

Nasm:

.

,

.bss,

.data.

, , . ,

.

.

*px++ = --*py;

*py = *py 1; // (1) *px = *py; // (2) px = px + 1; // (3)

*(px++) = --(*py);

--(*py); *px = *py; px++;

section .bss px dd 1 py dd 1

34

3-3

,

.

.

xp, yp zp 8, 12 16

, ebp. decode1

, .

.

mov edi, dword [ebp + 8] ; (1) mov edx, dword [ebp + 12] ; (2) mov ecx, dword [ebp + 16] ; (3) mov ebx, dword [edx] ; (4) mov esi, dword [ecx] ; (5) mov eax, dword [edi] ; (6) mov dword [edx], eax ; (7) mov dword [ecx], ebx ; (8) mov dword [edi], esi ; (9)

void decode1(int *xp, int *yp, int *zp)

section .text mov eax, dword [py] ; (1) eax ; py dec word [eax] ; 16- ; , ; eax, .. py mov cx, word [eax] ; (2) cx ; mov eax, dword [px] ; eax ; px mov word [eax], cx ; , ; , ; px, *py add dword [px], 2 ; (3) px. ; ; ; 1 * sizeof(short), . 2

35

, .. - ,

ebx, esi, eax.

edi, edx, ecx, ,

,

, ebx, esi, eax.

, -.

y ebx, z esi, x eax.

3-4

-

.

void decode1(int *xp, int *yp, int *zp) { int y = *yp; int z = *zp; int x = *xp; *yp = x; *zp = y; *xp = z; }

mov dword [edx], eax ; (7) *yp eax *xp mov dword [ecx], ebx ; (8) *zp ebx *yp mov dword [edi], esi ; (9) *xp esi *zp

mov ebx, dword [edx] ; (4) ebx *yp mov esi, dword [ecx] ; (5) esi *zp mov eax, dword [edi] ; (6) eax *xp

mov edi, dword [ebp + 8] ; (1) edi xp mov edx, dword [ebp + 12] ; (2) edx yp mov ecx, dword [ebp + 16] ; (3) ecx zp

36

, .

p . 40

, , 4

.

8- p+32,

, .. ,

. ,

1, .

3-1 -

,

.

.

void decode2(int *xp, int *yp, int *zp)

mov eax, dword [p + 32] mov eax, dword [eax] add eax, 1 mov dword [x], eax

static int *p[10]; static int x; x = *p[8] + 1;

37

xp, yp zp 8, 12 16

, ebp. decode2

, .

3-2

,

.

3-3

100 . ,

eax

, :

a) char,

b) short,

c) int.

3-4

-

.

// a int x, *px; *px++ = x -10; // b short x, *px; x = *(--px + 4);

mov eax, dword [ebp + 12] mov edi, dword [eax] mov eax, dword [ebp + 8] mov edx, dword [eax] mov eax, dword [ebp + 16] mov eax, dword [eax] add edx, eax mov eax, dword [ebp + 12] mov dword [eax], edx mov eax, dword [ebp + 8] mov dword [eax], edx mov eax, dword [ebp + 16] mov dword [eax], edi

38

3-5 -

-

.

// a short **p; ++*(*(p+=3) -= 2); // b char **q, **r, **t; r = q++; *t = (*r)++; **q = (**t)++;

static int a[50]; static int *p, *q; static int n; p = &a[10]; q = &a[25]; n = q - p;

39

4. IA-32

jmp Jcc, ,

EFLAGS.

4. .

Jcc

JE ZF /

JNE ~ZF /

JS SF

JNS ~SF

JG ~(SFÔF)&~ZF ( )

JGE ~(SFÔF) ( )

JL (SFÔF) ( )

JLE (SFÔF)|ZF ( )

JA ~CF&~ZF ( )

JB CF ( )

: (1)

EFLAGS (2) . , ,

CMP, EFLAGS ,

SUB, , ..

.

IA-32 do-while

. ,

ECX (CX), .

, LOOP/LOOPcc

[128, 127] .

LOOP/LOOPcc ECX ,

, . ,

ECX,

232 .

40

5. .

JCXZ/JECXZ , CX/ECX .

LOOP , ECX .

LOOPZ/LOOPE , ECX ZF .

LOOPNZ/LOOPNE , ECX ZF .

4-1

, data_t

, COMP . a

EDX, b ECX.

, ,

data_t COMP ( ).

SETcc L, ,

EAX EDX 32 .

int long,

signed.

>, L

1 < 2 .

, .

1 < 2 ECX < EDX b < a a > b

int comp(data_t a, data_t b) { return a COMP b; }

CMP ECX, EDX SETL AL

41

4-2

.

a b.

32-. ,

, .

.

:

3 6 12.

( TEST JE) .

1-6 :

static int a, b;

SECTION .text GLOBAL CMAIN CMAIN: MOV ESI, DWORD [a] ; (1) TEST ESI, ESI ; (2) JE .1 ; (3) MOV ECX, DWORD [b] ; (4) TEST ECX, ECX ; (5) JE .1 ; (6) MOV EDX, DWORD [ESI] ; (7) MOV EAX, EDX ; (8) SAR EDX, 31 ; (9) IDIV ECX ; (10) SUB DWORD [ESI], EDX ; (11) .1: XOR EAX, EAX ; (12) RET ; (13)

int comp(int a, int b) { return a > b; }

42

,

&& , 4-6

,

3.

7-11.

ESI, a

, .. a ,

.

, , eax edx,

edx

, , , 10 .

,

signed,

int, .

idiv *a b,

ecx

b.

. ,

,

. edx ( 11),

.

, ,

a.

.

,

if, .

*a = *a *a % b;

static int *a, b;

if ((0 != a) && (0 != b)) { ... }

if (0 != a) { if (0 != b) { ... } }

43

4-1

data_t , COMP -

. a EX.

, ,

data_t COMP ( ).

4-2

, data_t

, COMP . a

EDX, b ECX.

, ,

data_t COMP ( ).

int comp(data_t a, data_t b) { return a COMP b; }

(A) TEST EX, EX SETNE AL () TEST X, X SETE AL

() TEST L, L SETG AL () TEST X, X SETA AL

int comp(data_t a) { return a COMP 0; }

static int *a, b; if ((0 != a) && (0 != b)) { *a -= *a % b; }

44

4-3

-.

x = (y 0) { *p += a; } }

int x, y = 100, a = 0, b = 1; x = y

45

4-7

,

. : ,

, , .

4-8 :

, -.

- .

.

int test(int x, int y) { int val = __________; if (______) { if (______) { val = __________; } else { val = __________; } } else if (______) { val = __________; } return val; }

mov eax, dword [ebp + 8] ; x mov edx, dword [ebp + 12] ; y cmp eax, -3 jge l2 cmp eax, edx gle l3 imull eax, edx jmp l4 l3: lea eax, dword [eax + edx] jmp l4 l2: cmp eax, 2 jg l5 xor eax, edx jmp l4 l5: sub eax, edx l4:

46

4-9 :

, .

-.

4-10

, .

4-11 :

:

int dw_loop(int x, int y, int n) { //1 { //2 do { //3 x += n; //4 y *= n; //5 n--; //6 } while ((n > 0) && (y < n)); //7 return x; //8 }

mov ebx, dword [a] mov ecx, dword [b] cmp ebx, ecx jg .L7 jl .L8 xor eax, eax jmp .L9 .L8: mov edx, dword [c] mov eax, edx sar edx, 31 sub ecx, ebx idiv ecx jmp .L9 .L7: mov edx, dword [c] mov eax, edx sar edx, 31 sub ebx, ecx idiv ebx .L9: mov dword [d], eax

... static _____________________ a; static _____________________ b; static _____________________ c; static _____________________ d; if (__________) { d = ________________; } else if (__________) { d = ________________; } else { d = ________________; } ...

47

, -,

, , -.

4-12

,

:

4-13

(unsigned int).

4-14

,

N (N > 1). : F0

= F1 = 1, Fk = Fk-1 + Fk-2, k 2.

4-15

30 . :

a) ,

b) (,

),

c) .

mov al, -80 cmp al, 150 jb M1 jl M2 jmp M3

mov eax, dword [ebp + 8] ; (1) x mov ecx, dword [ebp + 12] ; (2) y mov edx, dword [ebp + 16] ; (3) n L2: ; (4) add eax, edx ; (5) imul ecx, edx ; (6) sub edx, 1 ; (7) test edx, edx ; (8) jle L5 ; (9) cmp ecx, edx ; (10) jl L2 ; (11) L5: ; (12)

48

5.

5-1

a, b, c, d.

0 1.

a.

a, b, c d , .bss.

,

.

, (~c & d) | (c & ~d)

, ..

, .

section .bss a resd 1 b resd 1 c resd 1 d resd 1 section .text mov eax, dword [c] ; eax c mov edx, dword [d] ; edx d mov ecx, eax ; c ecx not eax ; eax ~c and eax, edx ; eax ~c & d not edx ; edx ~d and ecx, edx ; ecx c & ~d or eax, ecx ; eax (~c & d) | (c & ~d) mov edx, dword [a] ; edx a and edx, dword [b] ; edx a & b not edx ; edx ~(a & b) or eax, edx ; eax ~(a & b) | ((~c & d) | (c & ~d)) mov dword [a], eax ; a ~(a & b) | ((~c & d) | (c & ~d))

static int a, b, c, d; a = ~(a & b) | ((~c & d) | (c & ~d));

49

5-2

a b 2 . EAX

: 2

a, 2 b,

5 .

5-3

, ,

.

, .

: x [ebp + 8], y

[ebp + 12], z [ebp + 16].

mov eax, dword [ebp + 12] ; (1) xor eax, dword [ebp + 8] ; (2) shr eax, 3 ; (3) not eax ; (4) sub eax, dword [ebp + 16] ; (5)

int arith(int x, int y, int z) { int t1 = _________; int t2 = _________; int t3 = _________; int t4 = _________; return t4; }

section .bss a resw 1 b resw 1 section .text mov ax, word [a] ; a ; 16 ; EAX shl eax, 16 ; mov ax, word [b] ; b ; EAX ror ax, 5 ;

50

.

y eax. ,

-.

xor y x.

eax. ( 3)

3 . , ,

.

, , 5,

z.

, ,

eax.

,

.

t4,

5 EAX,

.

5-4

32- a.

3 1, 17 0, 23

.

bts, btr, btc.

int arith(int x, int y, int z) { int t1 = y ^ x; int t2 = t1 >> 3; int t3 = ~t2; int t4 = t3 - z; return t4; }

51

5-5

, eax 6,

. eax.

5-1

x .

, eax 1, x < 0, 0

.

5-2

eax 5 5 .

5-3

.

// a static int x;

// b static short x;

// c static char x;

mov ebx, eax ; ebx shl ebx, 2 ; ebx 2 ; ( 4) shl eax,1 ; eax 1 ; ( 2) add eax, ebx ; , ; eax

section .bss a resd 1 section .text bts dword [a], 3 btr dword [a], 17 btc dword [a], 23

52

5-4

eax ( ) edx (

) .

5-5

.

5-6

eax 1,

5 , 0 .

5-7

,

L , a .

5-8

"" .

5-9 sign

sign, MOV, SHR, NEG OR.

section .data x dd 0xfeff0201 section .text mov cx, word [x + 1] mov ax, cx imul ah shl ax, cl movsx eax, ax movzx edx, ax

// a static unsigned x, y; y = 32 * x x / 8 + x % 16; // b static long long x; x *= 2; // c static int x, y; y = x / 64 + x * 4;

53

5-10

, ,

1 0 .

: 10100111 00001000

5-11

ROL, ROR, RCL, RCR SAR,

, .

) sar eax, 2 b) rol bx, 1 c) rcr ecx, 1 d) rol ax, 8 e) rcl ebx, 31

54

6.

1-1

()

16-

()

10111101 BDh -67 189

01110110 76h 118 118

00101000 28h 40 40

10000111 87h -121 135

1-5

() EAX = 0xdde

() EAX = 0xd

() EAX = 0xcafe

() EAX = 0xfffffffe

() EAX = 0xffff00ba

() EAX = 0xfffffef0

() EAX = 0xffff000d

() EAX = 0xffff006f

() EAX = 0xff79000d

() EAX = 0x2179fffe

1-6

2-1

; a movzx eax, byte [a] mov dword [b], eax ; b movsx eax, byte [a] mov word [b], eax

section .bss a resd 1 b resd 1 section .text mov al, byte [a] mov byte [b], al mov al, byte [a + 1] mov byte [b + 3], al mov ax, word [a + 2] mov word [b + 1], ax

55

2-2

(a) AL = -118, AL = 138, CF = 1, OF = 0, ZF = 0, SF = 1.

(b) AL = 5, AL = 5, CF = 0, OF = 0, ZF = 0, SF = 0.

(c) AL = -90, AL = 166, CF = 1, OF = 0, ZF = 0, SF = 1.

(d) AL = 58, AL = 58, CF = 1, OF = 0, ZF = 0, SF = 0.

3-1

4-1

() data_t int, unsigned, , long COMP - != () data_t short unsigned short COMP - == () data_t char COMP - > () data_t unsigned short COMP - >

void decode2(int *xp, int *yp, int *zp) { int y = *yp; *yp = *xp + *zp; *xp = *yp; *zp = y; }

56

4-2

4-3

section .bss x resd 1 section .data y dd -1 a dd 0 b dd 1 section .text global CMAIN CMAIN: cmp dword [y], 0 mov eax, dword [b] cmovle eax, dword [a] mov dword [x], eax

() data_t short COMP - >= () data_t unsigned char COMP - < () data_t int, unsigned, ; long COMP - !=

57

4-4

4-5

4-6

%include 'io.inc' section .text global CMAIN CMAIN: GET_DEC 4, ecx mov eax, 1 jecxz end_label loop_body: imul eax, ecx loop loop_body end_label: PRINT_DEC 4, eax mov eax, 0 ret

test eax, eax jz label test edx, edx jle label add dword [eax], edx label:

%include 'io.inc' section .text global CMAIN CMAIN: GET_DEC 4, eax cmp eax, 0 jge label neg eax label: PRINT_DEC 4, eax NEWLINE xor eax, eax ret

58

4-7

4-8

.

. .

.

CMP Jcc,

if . ,

.

int test(int x, int y) { int val = x^y; if (x < -3) { if (y < x) { val = x * y; } else { val = x + y; } } else if (x > 2) { val = x - y; } return val; }

%include 'io.inc' section .text global CMAIN CMAIN: GET_DEC 4, ebx ; GET_DEC 4, edx ; GET_DEC 4, ecx ; xor eax jexcz end_label loop_body: add eax, ebx add ebx, edx loop loop_body end_label: PRINT_DEC 4, eax mov eax, 0 ret

59

4-9

... static int a; static int b; static int c; static int d; if (a > b) { d = c / (a - b); } else if (a < b) { d = c / (b - a); } else { d = 0; } ...

int test(int x, int y) { int val; if (x < -3) { if (y < x) { val = x * y; } else { val = x + y; } } else if (x > 2) { val = x - y; } else { val = x^y; } return val; }

60

4-10

4-11

4-12

M3

mov eax, dword [ebp + 8] ; (1) x mov ecx, dword [ebp + 12] ; (2) y mov edx, dword [ebp + 16] ; (3) n L2: ; (4) add eax, edx ; (5) x += n; imul ecx, edx ; (6) y *= n; sub edx, 1 ; (7) n--; test edx, edx ; (8) n v 0 jle L5 ; (9) n

61

:

M1 , 176 > 150;

M2 , .. -80 > -106.

M3.

5-4 eax = -8 edx = 65528

mov al, -80; (-80) = 176 cmp al, 150; 150 = (-106) jb M1 jl M2 jmp M3

62

1. . , . :

(Computer Systems: A Programmers Perspective).

: -, 2005 . 1186 .

2. Henry S. Warren. Hacker's Delight (2nd Edition). / Addison-Wesley Professional; 2

edition (October 5, 2012) . 512

3. .. , .. , .. , .. ,

.. .

(- 1 ). .:

..

4. .. , .. , .. , .. , .. .

( - ). .: . - ..

, 2012.

5. .. , .. , .. , .. , .. ,

.. .

( ). .: . - .. ,

2012.

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