Slides - Computer Science - University of Birmingham

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Fundamentals: Intro to Computer Science Module Assembly Language V. Landassuri-Moreno [email protected]

School of Computer Science University of Birmingham

December, 2010

Assembly Proc.

Intro

Instruction Set

Instruction Format

Addressing

Outline Introduction The Instruction Set Architecture Level Introduction to PII/P4 Instruction Format Addressing Procedure The Assembly Language Level Macros The Assembly Process and linking

Procedure

Assembly Intro.

Macros

Assembly Proc.

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Resources

Tutorials: I

Here is presented an overview of Assembly Language.

I

Most of the information of these slides were based in [1] (Tanenbaum, A.S.: Structured Computer Organization, Fifth Edition, Prentice Hall, Upper Saddle River, NJ.).

I

From this part, you will have an exercise which will be submitted to Dr. Behzad Bordbar.

I

You can download the exercise from the web page of the module, or alternatively from: http://www.cs.bham.ac.uk/~vlm/introCS2010/Exer01.pdf

Intro

Instruction Set

Instruction Format

Addressing

Registers Bits

16

8 AH BH CH DH

8 A X B X C X D X

AL

EAX

BL

EBX

CL

ECX

DL

EDX

ESI EDI EBP ESP

CS SS DS ES FS GS

EIP

EFLAGS

Figure 5-3. The Pentium II’s primary registers.

Procedure

Assembly Intro.

Macros

Assembly Proc.

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Registers Bits

16

8 AH BH CH DH

8 A X B X C X D X

AL

EAX

BL

EBX

CL

ECX

DL

EDX

ESI EDI EBP ESP

CS SS DS ES FS GS

EIP

EFLAGS


The P4 has similar registers to the PII

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Registers Bits

16

8 AH BH CH DH

8 A X B X C X D X

AL

EAX

BL

EBX

CL

ECX

DL

EDX

ESI EDI EBP ESP

CS SS DS ES FS GS

EIP

EFLAGS


The P4 has similar registers to the PII In P4 the words are stored in little endian format (the low order byte has the lowest address)

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Registers Bits

16

8 AH BH CH DH

8 A X B X C X D X

AL

EAX

BL

EBX

CL

ECX

DL

EDX

ESI


EDI EBP ESP

CS SS DS ES FS GS

EIP

EFLAGS


EAX, EBX, ECX and EDX are 32-bit general purpose registers

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Registers Bits

16

8 AH BH CH DH

8 A X B X C X D X

AL

EAX

BL

EBX

CL

ECX

DL

EDX

ESI


EDI EBP ESP

EAX, EBX, ECX and EDX are 32-bit general purpose registers * EAX arithmetic register

CS SS DS ES FS GS

EIP

EFLAGS


* EBX good for holding address (memory addresses) * ECX for looping * EDX for multiplication and division, together with EAX, it holds 64-bit products and dividends

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Registers Bits

16

8 AH BH CH DH

8 A X B X C X D X

AL

EAX

BL

EBX

CL

ECX

DL

EDX

ESI


EDI EBP ESP

EAX, EBX, ECX and EDX are 32-bit general purpose registers * EAX arithmetic register

CS SS DS ES FS GS

EIP

EFLAGS


* EBX good for holding address (memory addresses) * ECX for looping * EDX for multiplication and division, together with EAX, it holds 64-bit products and dividends Configuration: 16 bits high order, 16 for lower order. The last one it is divided into two parts (8 bits)

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Registers Bits

16

8 AH BH CH DH

8 A X B X C X D X

AL

EAX

BL

EBX

CL

ECX

DL

EDX

ESI EDI EBP ESP

CS SS DS ES FS GS

EIP

EFLAGS


ESI, EDI and EBP like general purpose registers with some special characteristics:

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Registers Bits

16

8 AH BH CH DH

8 A X B X C X D X

AL

EAX

BL

EBX

CL

ECX

DL

EDX

ESI EDI EBP ESP

CS SS DS ES FS GS

EIP

EFLAGS


ESI, EDI and EBP like general purpose registers with some special characteristics: ESI and EDI pointer into memory -> for hardware string manipulation

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Registers Bits

16

8 AH BH CH DH

8 A X B X C X D X

AL

EAX

BL

EBX

CL

ECX

DL

EDX


ESI EDI

* EDI point to the destination string

ESP

* EBP is also a pointer register -> points to the base of the current stack frame

CS SS DS ES FS GS

EIP

EFLAGS


* ESI points to the source string

EBP

* ESP is the stack pointer

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Registers Bits

16

8 AH BH CH DH

8 A X B X C X D X

AL

EAX

BL

EBX

CL

ECX

DL

EDX


ESI EDI


EBP


ESP


CS SS


DS ES FS GS

EIP

EFLAGS


CS through GS are segment registers, old registers that continue in the present, the 8088 attempted to address 2020 bytes of memory using 16-bit addresses.

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Registers Bits

16

8 AH BH CH DH

8 A X B X C X D X

AL

EAX

BL

EBX

CL

ECX

DL

EDX


ESI EDI


EBP


ESP


CS SS


DS ES FS GS

EIP

EFLAGS


CS through GS are segment registers, old registers that continue in the present, the 8088 attempted to address 2020 bytes of memory using 16-bit addresses. * EIP is the program counter

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Registers Bits

16

8 AH BH CH DH

8 A X B X C X D X

AL

EAX

BL

EBX

CL

ECX

DL

EDX


ESI EDI


EBP


ESP


CS SS


DS ES FS GS

EIP

EFLAGS


CS through GS are segment registers, old registers that continue in the present, the 8088 attempted to address 2020 bytes of memory using 16-bit addresses. * EIP is the program counter * Finally, there is the flags (EFLAGS)

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Instruction Format An instruction consist of an opcode, usually with additional information: where the operands come from and where results go.

OPCODE (a)

OPCODE

ADDRESS1 ADDRESS2 (c)

OPCODE

ADDRESS (b)

OPCODE ADDR1 ADDR2 ADDR3 (d)

Figure 5-9. Four common instruction formats: (a) Zeroaddress instruction. (b) One-address instruction (c) Twoaddress instruction. (d) Three-address instruction.

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Addressing Addressing modes I Immediate addressing. Uses immediate operands: they are automatically fetched from memory at the same time the instruction itself is fetched. This mode do not require an extra memory reference to fetch the operand.

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Addressing Addressing modes I Immediate addressing. Uses immediate operands: they are automatically fetched from memory at the same time the instruction itself is fetched. This mode do not require an extra memory reference to fetch the operand. I Direct addressing. A way to specify an operand in memory (giving its address): like global variables, the value can change but not the address.

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Addressing Addressing modes I Immediate addressing. Uses immediate operands: they are automatically fetched from memory at the same time the instruction itself is fetched. This mode do not require an extra memory reference to fetch the operand. I Direct addressing. A way to specify an operand in memory (giving its address): like global variables, the value can change but not the address. I Register addressing (register mode). Like direct addressing but specifies a register instead of a memory location. Useful for variables that will be accessed frequently, e.g. loops.

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Addressing Addressing modes I Immediate addressing. Uses immediate operands: they are automatically fetched from memory at the same time the instruction itself is fetched. This mode do not require an extra memory reference to fetch the operand. I Direct addressing. A way to specify an operand in memory (giving its address): like global variables, the value can change but not the address. I Register addressing (register mode). Like direct addressing but specifies a register instead of a memory location. Useful for variables that will be accessed frequently, e.g. loops. Recall that a registers have a fast access and short addresses.

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Addressing Addressing modes I Immediate addressing. Uses immediate operands: they are automatically fetched from memory at the same time the instruction itself is fetched. This mode do not require an extra memory reference to fetch the operand. I Direct addressing. A way to specify an operand in memory (giving its address): like global variables, the value can change but not the address. I Register addressing (register mode). Like direct addressing but specifies a register instead of a memory location. Useful for variables that will be accessed frequently, e.g. loops. Recall that a registers have a fast access and short addresses.

22222222222222222222222222222 1122222222222222222222222222222 11 11 MOV R1 4 11 Figure 5-16. An immediate instruction for loading 4 into register 1.

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Addressing Note that there are several different kinds of addressing, here we are considering just a few of them.

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Addressing

I

Note that there are several different kinds of addressing, here we are considering just a few of them. Stack addressing. Making the machine instructions as short as possible is highly desirable. The idea is to have no address at all, here is where the stack can help us out.

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Addressing

I

I


Reverse Polish notation infix notation: x + y

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Addressing

I

I


Reverse Polish notation infix notation: x + y postfix or reverse Polish notation: x y +

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Addressing

I

I



I Postfix advantages:

Formulas without parenthesis

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Addressing

I

I




Formulas without parenthesis Convenient for the stack (in computers)

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Addressing

I

I




Formulas without parenthesis Convenient for the stack (in computers) There are precedences in infix notation, postfix does not have them !!!

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Addressing

I

I




Formulas without parenthesis Convenient for the stack (in computers) There are precedences in infix notation, postfix does not have them !!!

+

Exist diverse algorithms to convert from infix to postfix

+

The order of the variables is the same in both. But the order of the operators is not always the same

22222222222222222222222222222222222222222222222222222222222222 122222222222222222222222222222222222222222222222222222222222222 1 Infix Reverse Polish notation 1 1 1 1 A+B×C 122222222222222222222222222222222222222222222222222222222222222 1 ABC×+ 1 122222222222222222222222222222222222222222222222222222222222222 1 AB×C+ 1 A×B+C 1 A×B+C×D 1 AB×CD×+ 1 122222222222222222222222222222222222222222222222222222222222222 1 1 (A + B) / (C − D) 122222222222222222222222222222222222222222222222222222222222222 1 AB+CD−/ 1 1 A×B/C 1 AB×C/ 1 122222222222222222222222222222222222222222222222222222222222222 1 1 ((A + B) × C + D)/(E + F + G) 122222222222222222222222222222222222222222222222222222222222222 1 AB+C×D+EF+G+/ 1 Figure 5-22. Some examples of infix expressions and their reverse Polish notation equivalents.

Intro

Instruction Set

Instruction Format

Addressing

Evaluation of Reverse Polish notation Evaluation of (8 + 2 x 5) / (1 + 3 x 2 - 4)

Procedure

Assembly Intro.

Macros

Assembly Proc.

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Evaluation of Reverse Polish notation Evaluation of (8 + 2 x 5) / (1 + 3 x 2 - 4) 2222222222222222222222222222222222222222222222222222222222222222 1 Instruction 1 1 Step 1 Remaining string Stack 21 222222222222222222222222222222222222222222222222222222222222222 1 1 1 1 1 1 1 825×+132×+4−/ 21 222222222222222222222222222222222222222222222222222222222222222 1 BIPUSH 8 1 8 1 12222222222222222222222222222222222222222222222222222222222222222 1 BIPUSH 2 1 8, 2 1 2 1 25×+132×+4−/ 1 1 5×+132×+4−/ 1 BIPUSH 5 1 8, 2, 5 1 3 21 222222222222222222222222222222222222222222222222222222222222222 1 1 1 1 4 1 ×+132×+4−/ 1 IMUL 1 8, 10 1 21 222222222222222222222222222222222222222222222222222222222222222 1 1 1 1 1 5 +132×+4−/ IADD 18 21 222222222222222222222222222222222222222222222222222222222222222 1 1 1 1 6 1 132×+4−/ 21 222222222222222222222222222222222222222222222222222222222222222 1 BIPUSH 1 1 18, 1 1 1 BIPUSH 3 1 18, 1, 3 1 7 1 32×+4−/ 21 222222222222222222222222222222222222222222222222222222222222222 1 1 1 1 1 8 1 2×+4−/ 21 222222222222222222222222222222222222222222222222222222222222222 1 BIPUSH 2 1 18, 1, 3, 2 1 12222222222222222222222222222222222222222222222222222222222222222 1 IMUL 1 18, 1, 6 1 9 1 ×+4−/ 1 10 1 + 4 − / 1 IADD 1 18, 7 1 21 222222222222222222222222222222222222222222222222222222222222222 1 1 1 1 11 1 4 − / 1 BIPUSH 4 1 18, 7, 4 1 21 222222222222222222222222222222222222222222222222222222222222222 1 12 1 − / 1 ISUB 1 18, 3 1 21 222222222222222222222222222222222222222222222222222222222222222 1 1 1 1 13 1 / 12222222222222222222222222222222222222222222222222222222222222222 1 IDIV 1 6 1 Figure 5-23. Use of a stack to evaluate a reverse Polish notation formula.

Assembly Intro.

Macros

Assembly Proc.

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.


I

In reverse polish notation: 825x+132x+4-/

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.


I

In reverse polish notation: 825x+132x+4-/

I

Algorithm to evaluate it using the stack

1 Scan the postfix notation from left to

right 2 When an operand is encountered, push

it onto the stack 3 When an operator is encountered,

execute the corresponding instruction

Intro

Instruction Set

Instruction Format

Addressing

Procedure

The Pentium II/4 instructions Transfer of control

Moves MOV DST,SRC

Move SRC to DST

JMP ADDR

Jump to ADDR

PUSH SRC

Push SRC onto the stack

Jxx ADDR

Conditional jumps based on flags

POP DST

Pop a word from the stack to DST

CALL ADDR

Call procedure at ADDR

XCHG DS1,DS2

Exchange DS1 and DS2

RET

Return from procedure

LEA DST,SRC

Load effective addr of SRC into DST

IRET

Return from interrupt

CMOV DST,SRC

Conditional move

LOOPxx

Loop until condition met

INT ADDR

Initiate a software interrupt

INTO

Interrupt if overflow bit is set

Arithmetic ADD DST,SRC

Add SRC to DST

SUB DST,SRC

Subtract DST from SRC

MUL SRC

Multiply EAX by SRC (unsigned)

LODS

Load string

IMUL SRC

Multiply EAX by SRC (signed)

STOS

Store string

DIV SRC

Divide EDX:EAX by SRC (unsigned)

MOVS

Move string

IDIV SRC

Divide EDX:EAX by SRC (signed)

CMPS

Compare two strings

ADC DST,SRC

Add SRC to DST, then add carry bit

SCAS

SBB DST,SRC

Subtract DST & carry from SRC

INC DST

Add 1 to DST

DEC DST

Subtract 1 from DST

STC

Set carry bit in EFLAGS register

NEG DST

Negate DST (subtract it from 0)

CLC

Clear carry bit in EFLAGS register

CMC

Complement carry bit in EFLAGS

Binary coded decimal

STD

Set direction bit in EFLAGS register

DAA

Decimal adjust

CLD

Clear direction bit in EFLAGS reg

DAS

Decimal adjust for subtraction

STI

Set interrupt bit in EFLAGS register

AAA

ASCII adjust for addition

CLI

Clear interrupt bit in EFLAGS reg

AAS

ASCII adjust for subtraction

PUSHFD

Push EFLAGS register onto stack

AAM

ASCII adjust for multiplication

AAD

ASCII adjust for division

POPFD

Pop EFLAGS register from stack

LAHF

Load AH from EFLAGS register

SAHF

Store AH in EFLAGS register

SWAP DST

Change endianness of DST

CWQ

Extend EAX to EDX:EAX for division

CWDE

Extend 16-bit number in AX to EAX

ENTER SIZE,LV

Create stack frame with SIZE bytes

LEAVE

Undo stack frame built by ENTER

NOP

No operation

HLT

Halt

IN AL,PORT

Input a byte from PORT to AL

OUT PORT,AL

Output a byte from AL to PORT

WAIT

Wait for an interrupt

Boolean AND DST,SRC

Boolean AND SRC into DST

OR DST,SRC

Boolean OR SRC into DST

XOR DST,SRC

Boolean Exclusive OR SRC to DST

NOT DST

Replace DST with 1’s complement

SAL/SAR DST,#

Shift DST left/right # bits

SHL/SHR DST,#

Logical shift DST left/right # bits

Shift/rotate

ROL/ROR DST,#

Rotate DST left/right # bits

RCL/RCR DST,#

Rotate DST through carry # bits

Test/compare TST SRC1,SRC2

Boolean AND operands, set flags

CMP SRC1,SRC2

Set flags based on SRC1 - SRC2

Strings

Scan Strings

Condition codes

Miscellaneous

SRC = source DST = destination

# = shift/rotate count LV = # locals

Assembly Intro.

Macros

Assembly Proc.

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.


Moves MOV DST,SRC

Move SRC to DST

JMP ADDR

Jump to ADDR

PUSH SRC


Jxx ADDR


POP DST


CALL ADDR


XCHG DS1,DS2


RET


LEA DST,SRC


IRET


CMOV DST,SRC

Conditional move

LOOPxx


INT ADDR


INTO



Add SRC to DST

SUB DST,SRC


MUL SRC


LODS

Load string

IMUL SRC


STOS

Store string

DIV SRC


MOVS

Move string

IDIV SRC


CMPS

Compare two strings

ADC DST,SRC


SCAS

SBB DST,SRC


INC DST

Add 1 to DST

DEC DST

Subtract 1 from DST

STC


NEG DST


CLC


CMC



STD


DAA

Decimal adjust

CLD


DAS


STI


AAA


CLI


AAS


PUSHFD


AAM


AAD


POPFD


LAHF


SAHF


SWAP DST


CWQ


CWDE


ENTER SIZE,LV


LEAVE


NOP

No operation

HLT

Halt

IN AL,PORT


OUT PORT,AL


WAIT


Boolean AND DST,SRC


OR DST,SRC


XOR DST,SRC


NOT DST


SAL/SAR DST,#


SHL/SHR DST,#


Shift/rotate

ROL/ROR DST,#


RCL/RCR DST,#




CMP SRC1,SRC2


Strings

Scan Strings

Condition codes

Miscellaneous



I P4 instructions reference one or two

operands

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.


Moves MOV DST,SRC

Move SRC to DST

JMP ADDR

Jump to ADDR

PUSH SRC


Jxx ADDR


POP DST


CALL ADDR


XCHG DS1,DS2


RET


LEA DST,SRC


IRET


CMOV DST,SRC

Conditional move

LOOPxx


INT ADDR


INTO



Add SRC to DST

SUB DST,SRC


MUL SRC


LODS

Load string

IMUL SRC


STOS

Store string

DIV SRC


MOVS

Move string

IDIV SRC


CMPS

Compare two strings

ADC DST,SRC


SCAS

SBB DST,SRC


INC DST

Add 1 to DST

DEC DST

Subtract 1 from DST

STC



CLC


NEG DST

Strings

Scan Strings

Condition codes

CMC



STD


DAA

Decimal adjust

CLD


DAS


STI


AAA


CLI


AAS


PUSHFD


AAM


AAD


POPFD


LAHF


SAHF


SWAP DST


CWQ


CWDE


ENTER SIZE,LV


LEAVE


NOP

No operation

HLT

Halt

IN AL,PORT


OUT PORT,AL


WAIT


Boolean AND DST,SRC


OR DST,SRC


XOR DST,SRC


NOT DST


SAL/SAR DST,#


SHL/SHR DST,#


Shift/rotate

ROL/ROR DST,#


RCL/RCR DST,#




CMP SRC1,SRC2


Miscellaneous




operands I SRC fields are source of

information and are not changed

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.


Moves MOV DST,SRC

Move SRC to DST

JMP ADDR

Jump to ADDR

PUSH SRC


Jxx ADDR


POP DST


CALL ADDR


XCHG DS1,DS2


RET


LEA DST,SRC


IRET


CMOV DST,SRC

Conditional move

LOOPxx


INT ADDR


INTO



Add SRC to DST

SUB DST,SRC


MUL SRC


LODS

Load string

IMUL SRC


STOS

Store string

DIV SRC


MOVS

Move string

IDIV SRC


CMPS

Compare two strings

ADC DST,SRC


SCAS

SBB DST,SRC


INC DST

Add 1 to DST

DEC DST

Subtract 1 from DST

STC



CLC


NEG DST

Strings

Scan Strings

Condition codes

CMC



STD


DAA

Decimal adjust

CLD


DAS


STI


AAA


CLI


AAS


PUSHFD


AAM


AAD


POPFD


LAHF


SAHF


SWAP DST


CWQ


CWDE


ENTER SIZE,LV


LEAVE


NOP

No operation

HLT

Halt

IN AL,PORT


OUT PORT,AL


WAIT


Boolean AND DST,SRC


OR DST,SRC


XOR DST,SRC


NOT DST


SAL/SAR DST,#


SHL/SHR DST,#


Shift/rotate

ROL/ROR DST,#


RCL/RCR DST,#




CMP SRC1,SRC2


Miscellaneous





information and are not changed I DST fields are destinations and are

normally modified

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.


Moves MOV DST,SRC

Move SRC to DST

JMP ADDR

Jump to ADDR

PUSH SRC


Jxx ADDR


POP DST


CALL ADDR


XCHG DS1,DS2


RET


LEA DST,SRC


IRET


CMOV DST,SRC

Conditional move

LOOPxx


INT ADDR


INTO



Add SRC to DST

SUB DST,SRC


MUL SRC


LODS

Load string

IMUL SRC


STOS

Store string

DIV SRC


MOVS

Move string

IDIV SRC


CMPS

Compare two strings

ADC DST,SRC


SCAS

SBB DST,SRC


INC DST

Add 1 to DST

DEC DST

Subtract 1 from DST

STC



CLC


NEG DST

Strings

Scan Strings

Condition codes

CMC



STD


DAA

Decimal adjust

CLD


DAS


STI


AAA


CLI


AAS


PUSHFD


AAM


AAD


POPFD


LAHF


SAHF


SWAP DST


CWQ


CWDE


ENTER SIZE,LV


LEAVE


NOP

No operation

HLT

Halt

IN AL,PORT


OUT PORT,AL


WAIT


Boolean AND DST,SRC


OR DST,SRC


XOR DST,SRC


NOT DST


SAL/SAR DST,#


SHL/SHR DST,#


Shift/rotate

ROL/ROR DST,#


RCL/RCR DST,#




CMP SRC1,SRC2


Miscellaneous





information and are not changed I DST fields are destinations and are

normally modified I Many instructions have three

variants: 8-, 16-, and 32-bit operands respectively

Intro

Instruction Set

Instruction Format

Addressing

Towers of Hanoi

Initial state

First move 2 disks from peg 1 to peg 2

Then move 1 disk from peg 1 to peg 3

Finally move 2 disks from peg 2 to peg 3

Figure 5-39. The steps required to solve the Towers of Hanoi for three disks.

Procedure

Assembly Intro.

Macros

Assembly Proc.

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Towers of Hanoi

Initial state

First move 2 disks from peg 1 to peg 2

public void towers(int n, int i, int j) { int k; if (n == 1) System.out.println("Move a disk from " + i + " to " + j); else { k = 6 − i − j; towers(n − 1, i, k); towers(1, i, j); towers(n − 1, k, j);

Then move 1 disk from peg 1 to peg 3

} } Figure 5-40. A procedure for solving the Towers of Hanoi. Finally move 2 disks from peg 2 to peg 3

Figure 5-39. The steps required to solve the Towers of Hanoi for three disks.

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Towers of Hanoi

Address

FP k Old FP = 1000 Return addr j=2 i=1 n=2 k=2 Old FP Return addr j=3 i=1 n=3

k Old FP = 1024 Return addr j=3 i=1 n=1 k=3 Old FP = 1000 Return addr j=2 i=1 n=2 k=2 Old FP Return addr j=3 i=1 n=3

FP k=3 Old FP = 1000 Return addr j=2 i=1 n=2 k=2 Old FP Return addr j=3 i=1 n=3

k=3 Old FP = 1024 Return addr j=2 i=1 n=1 k=3 Old FP = 1000 Return addr j=2 i=1 n=2 k=2 Old FP Return addr j=3 i=1 n=3

(b)

(c)

(d)

(e)

SP

SP

SP

FP

FP k Old FP Return addr j=3 i=1 n=3 (a)

SP

Figure 5-41. The stack at several points during the execution of Fig. 5-40.

1068 1064 1060 1056 1052 1048 1044 1040 1036 1032 1028 1024 1020 1016 1012 1008 1004 1000

Assembly Intro.

Macros

Assembly Proc.

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Towers of Hanoi Each time a procedure is called, a new stack frame is allocated for the procedure on top of the stack

Address





(b)

(c)

(d)

(e)

SP

SP

SP

FP


SP


1068 1064 1060 1056 1052 1048 1044 1040 1036 1032 1028 1024 1020 1016 1012 1008 1004 1000

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.


Address





(b)

(c)

(d)

(e)

SP

SP

SP

FP


SP


1068 1064 1060 1056 1052 1048 1044 1040 1036 1032 1028 1024 1020 1016 1012 1008 1004 1000

The frame most recently created is the current frame. In this case, the stack grows upwards, then the most recent frame has higher addresses that the previous one

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.


Address





(b)

(c)

(d)

(e)

SP

SP

SP

FP


SP


1068 1064 1060 1056 1052 1048 1044 1040 1036 1032 1028 1024 1020 1016 1012 1008 1004 1000

The frame most recently created is the current frame. In this case, the stack grows upwards, then the most recent frame has higher addresses that the previous one The stack pointer (SP) points to the top of the stack

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.


Address





(b)

(c)

(d)

(e)

SP

SP

SP

FP


SP


1068 1064 1060 1056 1052 1048 1044 1040 1036 1032 1028 1024 1020 1016 1012 1008 1004 1000

The frame most recently created is the current frame. In this case, the stack grows upwards, then the most recent frame has higher addresses that the previous one The stack pointer (SP) points to the top of the stack The frame pointer (FP) points to a fixed location within the frame. It could point to a link pointer or to the first local variable

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.


Address





(b)

(c)

(d)

(e)

SP

SP

SP

FP


SP


1068 1064 1060 1056 1052 1048 1044 1040 1036 1032 1028 1024 1020 1016 1012 1008 1004 1000

The frame most recently created is the current frame. In this case, the stack grows upwards, then the most recent frame has higher addresses that the previous one The stack pointer (SP) points to the top of the stack The frame pointer (FP) points to a fixed location within the frame. It could point to a link pointer or to the first local variable The original call to towers pushes n, i and j onto the stack

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.


Address





(b)

(c)

(d)

(e)

SP

SP

SP

FP


SP


1068 1064 1060 1056 1052 1048 1044 1040 1036 1032 1028 1024 1020 1016 1012 1008 1004 1000

The frame most recently created is the current frame. In this case, the stack grows upwards, then the most recent frame has higher addresses that the previous one The stack pointer (SP) points to the top of the stack The frame pointer (FP) points to a fixed location within the frame. It could point to a link pointer or to the first local variable The original call to towers pushes n, i and j onto the stack Then is execute a CALL instruction that pushes the return address onto the stack at address 1012

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.


Address





(b)

(c)

(d)

(e)

SP

SP

SP

FP


SP


1068 1064 1060 1056 1052 1048 1044 1040 1036 1032 1028 1024 1020 1016 1012 1008 1004 1000

The frame most recently created is the current frame. In this case, the stack grows upwards, then the most recent frame has higher addresses that the previous one The stack pointer (SP) points to the top of the stack The frame pointer (FP) points to a fixed location within the frame. It could point to a link pointer or to the first local variable The original call to towers pushes n, i and j onto the stack Then is execute a CALL instruction that pushes the return address onto the stack at address 1012 On entry, the called procedure stores the old value of FP

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.


Address





(b)

(c)

(d)

(e)

SP

SP

SP

FP


SP


1068 1064 1060 1056 1052 1048 1044 1040 1036 1032 1028 1024 1020 1016 1012 1008 1004 1000

The frame most recently created is the current frame. In this case, the stack grows upwards, then the most recent frame has higher addresses that the previous one The stack pointer (SP) points to the top of the stack The frame pointer (FP) points to a fixed location within the frame. It could point to a link pointer or to the first local variable The original call to towers pushes n, i and j onto the stack Then is execute a CALL instruction that pushes the return address onto the stack at address 1012 On entry, the called procedure stores the old value of FP Then advance the SP to allocate storage for the local variables

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.


Address





(b)

(c)

(d)

(e)

SP

SP

SP

FP


SP


1068 1064 1060 1056 1052 1048 1044 1040 1036 1032 1028 1024 1020 1016 1012 1008 1004 1000

The frame most recently created is the current frame. In this case, the stack grows upwards, then the most recent frame has higher addresses that the previous one The stack pointer (SP) points to the top of the stack The frame pointer (FP) points to a fixed location within the frame. It could point to a link pointer or to the first local variable The original call to towers pushes n, i and j onto the stack Then is execute a CALL instruction that pushes the return address onto the stack at address 1012 On entry, the called procedure stores the old value of FP Then advance the SP to allocate storage for the local variables With a 32-bit local variable, SP is incremented by 4 to 1020 for k

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Towers of Hanoi

Address





(b)

(c)

(d)

(e)

SP

SP

SP

FP


SP


1068 1064 1060 1056 1052 1048 1044 1040 1036 1032 1028 1024 1020 1016 1012 1008 1004 1000

Assembly Intro.

Macros

Assembly Proc.

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Towers of Hanoi

The first thing a procedure must do when called: Address





(b)

(c)

(d)

(e)

SP

SP

SP

FP


SP


1068 1064 1060 1056 1052 1048 1044 1040 1036 1032 1028 1024 1020 1016 1012 1008 1004 1000

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Towers of Hanoi






(b)

(c)

(d)

(e)

SP

SP

SP

FP


SP


1068 1064 1060 1056 1052 1048 1044 1040 1036 1032 1028 1024 1020 1016 1012 1008 1004 1000

Save the previous FP, so it can be restored at procedure exit

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Towers of Hanoi


k Old FP = 1000 Return addr j=2 i=1 n=2 k=2 Old FP Return addr j=3 i=1 n=3


k=3 Old FP = 1000 Return addr j=2 i=1 n=2 k=2 Old FP Return addr j=3 i=1 n=3


(b)

(c)

(d)

(e)

SP

FP SP

SP

FP


SP

FP


1068 1064 1060 1056 1052 1048 1044 1040 1036 1032 1028 1024 1020 1016 1012 1008 1004 1000

Save the previous FP, so it can be restored at procedure exit Then, copy the SP into FP, and possibly increment by one word, depending on where in the new frame FP points

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Towers of Hanoi






(b)

(c)

(d)

(e)

SP

FP SP

SP

FP


SP

FP


1068 1064 1060 1056 1052 1048 1044 1040 1036 1032 1028 1024 1020 1016 1012 1008 1004 1000

Save the previous FP, so it can be restored at procedure exit Then, copy the SP into FP, and possibly increment by one word, depending on where in the new frame FP points In this case FP points to the first local variable

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Towers of Hanoi






(b)

(c)

(d)

(e)

SP

FP SP

SP

FP


SP

FP


1068 1064 1060 1056 1052 1048 1044 1040 1036 1032 1028 1024 1020 1016 1012 1008 1004 1000

Save the previous FP, so it can be restored at procedure exit Then, copy the SP into FP, and possibly increment by one word, depending on where in the new frame FP points In this case FP points to the first local variable Procedure prolog: is the code that saves the old frame pointer, sets up the new frame pointer, and advances the stack pointer to reserve space for local variables

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Towers of Hanoi






(b)

(c)

(d)

(e)

SP

FP SP

SP

FP


SP

FP


1068 1064 1060 1056 1052 1048 1044 1040 1036 1032 1028 1024 1020 1016 1012 1008 1004 1000

Save the previous FP, so it can be restored at procedure exit Then, copy the SP into FP, and possibly increment by one word, depending on where in the new frame FP points In this case FP points to the first local variable Procedure prolog: is the code that saves the old frame pointer, sets up the new frame pointer, and advances the stack pointer to reserve space for local variables Procedure epilog: upon procedure exit, the stack must be cleaned up again

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Introduction

Translator: a program that convert the user’s program into another language I I I I

The user’s code is called source language The language to which is converted is called target language The translation create usually a object program or executable binary program In translation there are two steps: a) create the equivalent program; b) execute it

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Introduction

Translator: a program that convert the user’s program into another language I I I I

The user’s code is called source language The language to which is converted is called target language The translation create usually a object program or executable binary program In translation there are two steps: a) create the equivalent program; b) execute it

Interpretation I

Here only one step is required: the execution of the original source program

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Introduction

The translator are divided into two I

Assembler I

I I

Translation: When the source language is essentially a symbolic representation for a numerical machine language Then the translator is called assembler The source language is called Assembly language

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Introduction

The translator are divided into two I

Assembler I

I I

I

Translation: When the source language is essentially a symbolic representation for a numerical machine language Then the translator is called assembler The source language is called Assembly language

Compiler I

When you have a high-level language as Java or C

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

What is an Assembly Language

I

Is a language where each statement produce one machine instruction

I

Correspondence 1 to 1

I

It is used because is easier to remember tags that the numeric values of the instructions, e.g add, subtract, . . .

I

It is possibly to give symbolic names to memory locations

I

The assembly programmer can access to all the features and instructions available on the target machine. High level languages can not

I

The drawback is that it only can bu execute in the same family of machines

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

What is an Assembly Language

I

Is a language where each statement produce one machine instruction

I

Correspondence 1 to 1

I

It is used because is easier to remember tags that the numeric values of the instructions, e.g add, subtract, . . .

I

It is possibly to give symbolic names to memory locations

I

The assembly programmer can access to all the features and instructions available on the target machine. High level languages can not

I

The drawback is that it only can bu execute in the same family of machines Why use it?

I

It is difficult

I

Take much time to program on it, to debug and to maintain

I

Then, the reasons to use it are: performance and access to the machine

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Format of an Assembly Language Statement Opcode Operands Comments 2Label 22222222222222222222222222222222222222222222222222222222222222222222 FORMULA: MOV EAX,I ; register EAX = I ADD EAX,J ; register EAX = I + J MOV N,EAX ;N=I+J I J N

DW DW DW

3 4 0

; reserve 4 bytes initialized to 3 ; reserve 4 bytes initialized to 4 ; reserve 4 bytes initialized to 0 (a)

Label Opcode Operands Comments 2222222222222222222222222222222222222222222222222222222222222222222222 FORMULA MOVE.L I, D0 ; register D0 = I ADD.L J, D0 ; register D0 = I + J MOVE.L D0, N ;N=I+J I J N

DC.L DC.L DC.L

3 4 0

; reserve 4 bytes initialized to 3 ; reserve 4 bytes initialized to 4 ; reserve 4 bytes initialized to 0 (b)

Label Opcode Operands Comments 2 22222222222222222222222222222222222222222222222222222222222222222222222222222222222 FORMULA: SETHI %HI(I),%R1 ! R1 = high-order bits of the address of I LD [%R1+%LO(I)],%R1 ! R1 = I SETHI %HI(J),%R2 ! R2 = high-order bits of the address of J LD [%R2+%LO(J)],%R2 ! R2 = J NOP ! wait for J to arrive from memory ADD %R1,%R2,%R2 ! R2 = R1 + R2 SETHI %HI(N),%R1 ! R1 = high-order bits of the address of N ST %R2,[%R1+%LO(N)] I: J: N:

.WORD 3 .WORD 4 .WORD 0

! reserve 4 bytes initialized to 3 ! reserve 4 bytes initialized to 4 ! reserve 4 bytes initialized to 0 (c)

Figure 7-2. Computation of N = I + J. (a) Pentium II. (b) Motorola 680x0. (c) SPARC.

I Several assemblers exist for the

Intel family Each one has a different syntax

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.


DW DW DW

3 4 0



DC.L DC.L DC.L

3 4 0







Intel family Each one has a different syntax In this examples it is presented the Microsoft MASM assembler

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.


DW DW DW

3 4 0



DC.L DC.L DC.L

3 4 0







Intel family Each one has a different syntax In this examples it is presented the Microsoft MASM assembler All this apply to the 386, 486, Pentium and Pentium Pro

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.


DW DW DW

3 4 0



DC.L DC.L DC.L

3 4 0







Intel family Each one has a different syntax In this examples it is presented the Microsoft MASM assembler All this apply to the 386, 486, Pentium and Pentium Pro I The Assembly language

statement have four parts: * Label field * An operation (opcode) field * An operands field * And comments

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.


DW DW DW

3 4 0



DC.L DC.L DC.L

3 4 0








statement have four parts: * Label field * An operation (opcode) field * An operands field * And comments I Labels provide symbolic names

for memory addresses

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.


DW DW DW

3 4 0



DC.L DC.L DC.L

3 4 0









for memory addresses Are needed for branching and to store data

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.


DW DW DW

3 4 0



DC.L DC.L DC.L

3 4 0









for memory addresses Are needed for branching and to store data But they are restricted in size (6-8 characters)

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Example: instruction mov

mov eax,ebx

; eax = ebx (copy the value)

Macros

Assembly Proc.

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros


mov eax,ebx


Access memory mov eax,[ebx]

; eax = *((word*) ebx) (copy from memory)

Assembly Proc.

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros


mov eax,ebx




mov [eax], ebx

; *((word*) eax) = ebx (copy to a memory)

Assembly Proc.

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros


mov eax,ebx




mov [eax], ebx

; *((word*) eax) = ebx (copy to a memory)

Constant values mov eax,3210

; eax = 3210

mov eax,3210 + 5

; eax = 3210 + 5

Assembly Proc.

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Pseudoinstructions They are commands to the assembler itself 222222222222222222222222222222222222222222222222222222222222222222222222222 1222222222222222222222222222222222222222222222222222222222222222222222222222 1 Pseudoinstr 1 Meaning 1 1 1 SEGMENT 1222222222222222222222222222222222222222222222222222222222222222222222222222 1 Start a new segment (text, data, etc.) with certain attributes 1 1222222222222222222222222222222222222222222222222222222222222222222222222222 1 End the current segment 1 ENDS 1 1 1 ALIGN 1222222222222222222222222222222222222222222222222222222222222222222222222222 1 Control the alignment of the next instruction or data 1 1222222222222222222222222222222222222222222222222222222222222222222222222222 1 Define a new symbol equal to a given expression 1 EQU 1 1 1 DB 1222222222222222222222222222222222222222222222222222222222222222222222222222 1 Allocate storage for one or more (initialized) bytes 1 DD 1222222222222222222222222222222222222222222222222222222222222222222222222222 1 Allocate storage for one or more (initialized) 16-bit halfwords 1 1 DW 1 Allocate storage for one or more (initialized) 32-bit words 1 222222222222222222222222222222222222222222222222222222222222222222222222222 1 1 1 DQ 1222222222222222222222222222222222222222222222222222222222222222222222222222 1 Allocate storage for one or more (initialized) 64-bit double words 1 1 PROC 1 Start a procedure 1 222222222222222222222222222222222222222222222222222222222222222222222222222 1 1 1 ENDP 1222222222222222222222222222222222222222222222222222222222222222222222222222 1 End a procedure 1 1 MACRO 1 Start a macro definition 1 222222222222222222222222222222222222222222222222222222222222222222222222222 1 1 1 ENDM 1222222222222222222222222222222222222222222222222222222222222222222222222222 1 End a macro definition 1 1222222222222222222222222222222222222222222222222222222222222222222222222222 1 Export a name defined in this module 1 PUBLIC 1 1 1 EXTERN 1222222222222222222222222222222222222222222222222222222222222222222222222222 1 Import a name from another module 1 1222222222222222222222222222222222222222222222222222222222222222222222222222 1 Fetch and include another file 1 INCLUDE 1 1 1 IF 1222222222222222222222222222222222222222222222222222222222222222222222222222 1 Start conditional assembly based on a given expression 1 1222222222222222222222222222222222222222222222222222222222222222222222222222 1 Start conditional assembly if the IF condition above was false 1 ELSE 1 1 1 ENDIF End conditional assembly 1222222222222222222222222222222222222222222222222222222222222222222222222222 1 1 COMMENT 1 Define a new start-of-comment character 1222222222222222222222222222222222222222222222222222222222222222222222222222 1 1 PAGE 1 Generate a page break in the listing 1 1222222222222222222222222222222222222222222222222222222222222222222222222222 1 1 END 1222222222222222222222222222222222222222222222222222222222222222222222222222 1 Terminate the assembly program 1

Figure 7-3. Some of the pseudoinstructions available in the Pentium II assembler (MASM).

Assembly Intro.

Macros

Assembly Proc.

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.



Examples: Segment. You can start segment of one type “X”, close it, start another different (“Y”), start again “X” and so on

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.



Examples: Segment. You can start segment of one type “X”, close it, start another different (“Y”), start again “X” and so on ALING. If you have 61 byte of data and you use ALING 4, the next address allocated will be 64

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.



Examples: Segment. You can start segment of one type “X”, close it, start another different (“Y”), start again “X” and so on ALING. If you have 61 byte of data and you use ALING 4, the next address allocated will be 64 BASE EQU 1000 you can use BASE instead of 1000

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.



Examples: Segment. You can start segment of one type “X”, close it, start another different (“Y”), start again “X” and so on ALING. If you have 61 byte of data and you use ALING 4, the next address allocated will be 64 BASE EQU 1000 you can use BASE instead of 1000 TABLE DB 11, 23, 49 allocate space for three bytes initialized with 11, 23, 49. At the same time define TABLE which have the address where 11 is stored

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Macros I I

Used to repeat sequences of instructions several times It is not used procedures because they can slow the program down

Assembly Proc.

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Macros I I

Used to repeat sequences of instructions several times It is not used procedures because they can slow the program down Can you say the parts required for a macro definition?

MOV MOV MOV MOV

EAX,P EBX,Q Q,EAX P,EBX

MOV MOV MOV MOV

EAX,P EBX,Q Q,EAX P,EBX

SWAP

MACRO MOV EAX,P MOV EBX,Q MOV Q,EAX MOV P,EBX ENDM SWAP SWAP

(a)

(b)

Figure 7-4. Assembly language code for interchanging P and Q twice. (a) Without a macro. (b) With a macro.

Assembly Proc.

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

Macros In the next table it can be appreciated a comparison of macros and procedures 2222222222222222222222222222222222222222222222222222222222222222222222222222 1 1 1 Item Macro call Procedure call 21 222222222222222222222222222222222222222222222222222222222222222222222222222 1 1 1 1 When is the call made? 21 222222222222222222222222222222222222222222222222222222222222222222222222222 1 During assembly 1 During execution 1 1 Is the body inserted into the object 1 Yes 1 No 1 1 program every place the call is 1 1 1 1 1 1 1 made? 21 222222222222222222222222222222222222222222222222222222222222222222222222222 1 1 1 1 Is a procedure call instruction 1 No 1 Yes 1 1 inserted into the object program 1 1 1 1 1 1 1 and later executed? 21 222222222222222222222222222222222222222222222222222222222222222222222222222 1 1 1 1 Must a return instruction be used 1 No 1 Yes 1 1 1 1 after the call is done? 21 222222222222222222222222222222222222222222222222222222222222222222222222222 1 1 1 1 1 How many copies of the body ap1 One per macro call 1 1 1 pear in the object program? 12222222222222222222222222222222222222222222222222222222222222222222222222222 1 1 1

Figure 7-5. Comparison of macro calls with procedure calls.

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

The Assembly Process

I

Two-Pass Assembler. It is used because there are labels in the code. Then with one pass it is not possible to assembly all the code

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.


I

Two-Pass Assembler. It is used because there are labels in the code. Then with one pass it is not possible to assembly all the code * Forward reference Problem. When a symbol has been used before it has been defined

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.


I


I

In the first pass it read the symbols to build up a table called symbol table

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.


I


I

In the first pass it read the symbols to build up a table called symbol table

I

In the pass two is generated the object program

Intro

Instruction Set

Instruction Format

Addressing

Procedure

Assembly Intro.

Macros

Assembly Proc.

References

A. S. Tanenbaum. Structured Computer Organization (5th Edition). Prentice Hall, 5 edition, June 2005. Here are more resource you can use to extend your knowledge in assembly language I

http://www.masm32.com/

I

http://www.nasm.us/ Related:

I

The Art of ASSEMBLY LANGUAGE PROGRAMMING http://www.arl.wustl.edu/~lockwood/class/cs306/books/ artofasm/toc.html

I

http://www.codecortex.com/ide/

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