Computer Organization &

Computer Organization &

Computer Organization &

Assembly Languages Assembly Languages

Pu-Jen Cheng 2008/09/15

Introduction

Course Administration

„ Instructor: Pu-Jen Cheng (CSIE R323) pjcheng@csie.ntu.edu.tw

http://www.csie.ntu.edu.tw/~pjcheng

„ Class Hours: 2:00pm-5:00pm, Monday Classroom: CSIE R102

„ Classroom: CSIE R102

„ TA(s): 戴瑋彥 b93705014@ntu.edu.tw

„ Course Information:

Announce: http://www.csie.ntu.edu.tw/~pjcheng/course/asm2008/

Q&A: bbs://ptt.cc → CSIE_ASM

Textbook

„ Assembly Language for Intel-Based Computers, 5th Edition, by Kip Irvine, Prentice-Hall, 2006

„ http://www.asmirvine.com

References

„ Computer Systems: A Programmer's Perspective By Randal E. Bryant and David R. O'Hallaron, Prentice Hall

http://csapp.cs.cmu.edu/

The Art of Assembly Language The Art of Assembly Language By Randy Hyde,

http://webster.cs.ucr.edu/AoA/Windows/PDFs/0_P DFIndexWin.html

System Software: An Introduction to Systems Programming

By Leland L. Beck Addison-Wesley

Pre-requisite

„

Experiences in writing programs in a high-level

language such as C, C++, and Java

Course Grading (tentative)

„

Assignments (55%)

„

Class participation (5%)

„

Midterm exam (20%)

„

Final exam (20%)

Materials

„ Some materials used in this course are adapted from

¾ The slides prepared by Kip Irvine for the book, Assembly Language for Intel-Based Computers, 5^th Ed.

¾ The slides prepared by S. Dandamudi for the book, Introduction to Assembly Language Programming, 2^nd Ed.

¾ Introduction to Computer Systems CMU

¾ Introduction to Computer Systems, CMU

(http://www.cs.cmu.edu/afs/cs.cmu.edu/academic/class/

15213-f05/www/)

¾ Assembly Language & Computer Organization, NTU

(http://www.csie.ntu.edu.tw/~cyy/courses/assembly/06fall/news//) (http://www.csie.ntu.edu.tw/~acpang/course/asm_2004)

What is Assembly Language

„

First Glance at Assembly Language

Translating Languages

English: Display the sum of A times B plus C.

C++: cout << (A * B + C);

Assembly Language:

mov eax,A mul B

add eax,C call WriteInt

Intel Machine Language:

A1 00000000 F7 25 00000004 03 05 00000008 E8 00500000

A Simple Example in VC++

View/Debug Windows/Disassembly

gcc -s prog.c

The Compilation System

First Glance at Assembly Language

„

Low-level language

¾ Each instruction performs a much lower-level task compared to a high-level language instruction

¾ Most high-level language instructions need more than one assembly instruction

„

One-to-one correspondence between assembly language and machine language instructions

¾ For most assembly language instructions, there is a machine language equivalent

„

Directly influenced by the instruction set and

architecture of the processor (CPU)

Comparisons with High-level Languages

„

Advantages of Assembly Languages

¾ Space-efficiency

(e.g. hand-held device softwares, etc)

¾ Time-efficiency

(e g Real-time applications etc ) (e.g. Real-time applications, etc )

¾ Accessibility to system hardwares

(e.g., Network interfaces, device drivers, video games, etc)

„

Advantages of High-level Languages

¾ Development

¾ Maintenance (Readability)

¾ Portability (compiler, virtual machine)

Comparisons with High-level Languages (cont.)

This Course

Why Taking the Course?

Basic Concepts of Computer

Organization Computer Design

Computer Organization Computer Architecture This Course

System Software

Computer Architecture

Assembler, Linker, Loader Compiler, Operating System, … Assembly

Language

“I really don ’ t think that you can write a book for serious computer programmers unless you are

able to discuss low-level details. ”

Donald Knuth (高德納) The Art of Computer Programming

http://en.wikipedia.org/wiki/Donald_Knuth

Course Coverage

„ Basic Concepts

„ IA-32 Processor Architecture

„ Assembly Language Fundamentals

„ Data Transfers, Addressing, and Arithmetic

„ Procedures

„ Conditional Processing

„ Integer Arithmetic

„ Advanced Procedures

„ Strings and Arrays

„ Structures and Macros

„ High-Level Language Interface

„ Assembler, Linker, and Loader

„ Other Advanced Topics (optional)

What You Will Learn

„

Basic principles of computer architecture

„

IA-32 processors and memory management

„

Basic assembly programming skills

„

How high-level language is translated to assembly

„

How assembly is translated to machine code

„

How application program communicates with OS

„

Interface between assembly to high-level language

Performance: Multiword Arithmetic

„

Longhand multiplication

¾ Final 128-bit result in P:A

„ P := 0; count := 64

„ A := multiplier; B := multiplicand

„ while (count > 0)

0 1 0 1 1 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1

„ while (count > 0)

„ if (LSB of A = 1)

„ then P := P+B

„ CF := carry generated by P+B

„ else CF := 0

„ end if

„ shift right CF:P:A by one bit position

„ count := count-1

„ end while

Example

„

A = 1101

(13)

„

B = 0101

(5)

After P+B After the shift

CF P A CF P A

CF P A CF P A Initial state ? 0000 1101 -- ---- ---- Iteration 1 0 0101 1101 ? 0010 1110 Iteration 2 0 0010 1110 ? 0001 0111 Iteration 3 0 0110 0111 ? 0011 0011 Iteration 4 0 1000 0011 ? 0100 0001

Time Comparison

2 3 4 5

e (seconds)

C version

0 1 2

0 20 40 60 80 100

Number of calls (in millions)

Time

Multiplication time comparison on a 2.4-GHz Pentium 4 system

ASM version

Chapter 1: Basic Concept

„

Virtual Machine Concept

„

Data Representation

„

Boolean Operations

Translating Languages

English: Display the sum of A times B plus C.

C++: cout << (A * B + C);

Assembly Language:

mov eax,A mul B

add eax,C call WriteInt

Intel Machine Language:

A1 00000000 F7 25 00000004 03 05 00000008 E8 00500000

Virtual Machines

High-Level Language

Assembly Language Level 4 Level 5

Machine-independent

Machine-specific

Abstractions for computers

Operating System

Instruction Set Architecture Microarchitecture

Digital Logic Level 0 Level 1 Level 2 Level 3

High-Level Language

„

Level 5

„

Application-oriented languages

¾ C++, Java, Pascal, Visual Basic . . .

„

Programs compile into assembly language

(Level 4)

Assembly Language

„

Level 4

„

Instruction mnemonics that have a one- to-one correspondence to machine

language

„

Calls functions written at the operating

„

Calls functions written at the operating system level (Level 3)

„

Programs are translated into machine

language (Level 2)

Operating System

„

Level 3

„

Provides services to Level 4 programs

„

Translated and run at the instruction set

architecture level (Level 2)

Instruction Set Architecture

„

Level 2

„

Also known as conventional machine language

„

Executed by Level 1 (microarchitecture)

program

Microarchitecture

„

Level 1

„

Interprets conventional machine instructions (Level 2)

„

Executed by digital hardware (Level 0)

Digital Logic

„

Level 0

„

CPU, constructed from digital logic gates

„

System bus

„

Memory

next: Data Representation

Data Representation

„ Binary Numbers

¾ Translating between binary and decimal

„ Binary Addition

„ Integer Storage Sizes

„ Hexadecimal Integersg

¾ Translating between decimal and hexadecimal

¾ Hexadecimal subtraction

„ Signed Integers

¾ Binary subtraction

„ Fractional Binary Numbers

„ Character Storage

„ Machine Words

Binary Representation

„

Electronic Implementation

¾ Easy to store with bistable elements

¾ Reliably transmitted on noisy and inaccurate wires

Binary Numbers

„

Digits are 1 and 0

¾ 1 = true

¾ 0 = false

„

MSB – most significant bit

„

LSB – least significant bit

„

Bit numbering:

0 15

1 0 1 1 0 0 1 0 1 0 0 1 1 1 0 0

MSB LSB

Binary Numbers

„ Each digit (bit) is either 1 or 0

„ Each bit represents a power of 2: ^{1 1}₂⁷ ₂^{6 1}₂^{5 1}₂^{4 1}₂^{3 1}₂^{2 1}₂^{1 1}₂⁰

Every binary number is a sum of powers of 2

Translating Binary to Decimal

Weighted positional notation shows how to calculate the decimal value of each binary bit:

dec = (D

× 2

) + (D

× 2

) + ... + (D

× 2

) + (D

× 2

)

D = binary digit

binary 00001001 = decimal 9:

(1 × 2

) + (1 × 2

) = 9

Translating Unsigned Decimal to Binary

„ Repeatedly divide the decimal integer by 2.

„ Each remainder is a binary digit in the translated value:

37 = 100101

Binary Addition

„ Starting with the LSB, add each pair of digits, include the carry if present.

0 0 0 0 0 1 0 0

1

(4)

carry:

0 0 0 0 0 1 1 1

0 0 0 0 0 1 0 0

+

0 0 0 0 1 0 1 1

(4) (7)

(11)

0 1

2 3

4 bit position: 7 6 5

Integer Storage Sizes

byte

16 8

32 word

doubleword

64 quadword

Standard sizes:

What is the largest unsigned integer that may be stored in 20 bits?

Large Measurements

„

Kilobyte (KB), 2

bytes

„

Megabyte (MB), 2

bytes

„

Gigabyte (GB), 2

bytes

„

Terabyte (TB), 2

bytes

„

Petabyte, 2

bytes

„

Exabyte, 2

bytes

„

Zettabyte, 2

bytes

„

Yottabyte, 2

bytes

„

Googol, 10

Hexadecimal Integers

Binary values are represented in hexadecimal.

Translating Binary to Hexadecimal

„

Each hexadecimal digit corresponds to 4 binary bits.

„

Example: Translate the binary integer

000101101010011110010100 to hexadecimal:

Converting Hexadecimal to Decimal

„

Multiply each digit by its corresponding power of 16:

dec = (D₃ × 16³) + (D₂ × 16²) + (D₁ × 16¹) + (D₀ × 16⁰)

„ Hex 1234 equals (1 × 16³) + (2 × 16²) + (3 × 16¹) + (4

× 16⁰), or decimal 4,660.

„ Hex 3BA4 equals (3 × 16³) + (11 * 16²) + (10 × 16¹) + (4 × 16⁰), or decimal 15,268.

Powers of 16

„

Used when calculating hexadecimal values up to 8

digits long:

Converting Decimal to Hexadecimal

decimal 422 = 1A6 hexadecimal

Hexadecimal Addition

„ Divide the sum of two digits by the number base (16).

„ The quotient becomes the carry value, and the remainder is the sum digit.

36 28 28 6A

42 45 58 4B

1 1

42 45 58 4B

78 6D 80 B5

21 / 16 = 1, rem 5

Important skill: Programmers frequently add and

subtract the addresses of variables and instructions.

Hexadecimal Subtraction

„ When a borrow is required from the digit to the left, add 16 (decimal) to the current digit's value:

16 + 5 = 21

C6 75 A2 47

24 2E

−1

Practice: The address of var1 is 00400020. The

address of the next variable after var1 is 0040006A.

How many bytes are used by var1?

Signed Integers

„ The highest bit indicates the sign.

„ 1 = negative, 0 = positive

sign bit

1 1 1 1 0 1 1 0

0 0 0 0 1 0 1 0

Negative

Positive

If the highest digit of a hexadecimal integer is > 7, the value is negative. Examples: 8A, C5, A2, 9D

Forming the Two's Complement

„

Bitwise NOT of the number and add 1

Note that 00000001 + 11111111 = 00000000

8-bit Two's Complement Integers

Binary Subtraction

„

When subtracting A – B, convert B to its two's complement

„

Add A to (–B)

0 0 0 0 1 1 0 0 0 0 0 0 1 1 0 0 – 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 1 0 0 0 0 1 0 0 1 Advantages for 2’s complement:

„

No two 0’s

„

Sign bit

„

Remove the need for separate circuits for add

and sub

Ranges of Signed Integers

„

The highest bit is reserved for the sign. This limits

the range:

Fractional Binary Numbers

b_i b_{i 1} • • • b₂ b₁ b₀ .b ₁ b ₂ b ₃ • • • b _j 1

2 4 2^i–1 2ⁱ

• • •

„

Representation

¾ Bits to right of “binary point” represent fractional powers of 2

¾ Represents rational number:

b_i b_i–1 b₂ b₁ b₀ .b_–1 b_–2 b_–3 b_–j

• • • 1/2

1/4 1/8 2^–j

b

⋅2

k=− j

∑

„

Value Representation

5-3/4 101.11₂

2-7/8 10.111₂

63/64 0.111111₂

Examples of Fractional Binary Numbers

„

Observations

¾ Divide by 2 by shifting right

¾ Multiply by 2 by shifting left

¾ Numbers of form 0.111111…₂ just below 1.0

„ 1/2 + 1/4 + 1/8 + … + 1/2ⁱ + … → 1.0

„ Use notation 1.0 – ε

„

Limitation

¾ Can only exactly represent numbers of the form

¾ Other numbers have repeating bit representations

„

Value Representation

1/3 0.0101010101[01]…₂

Representable Numbers

/ ₂

1/5 0.001100110011[0011]…₂

1/10 0.0001100110011[0011]…₂

Converting Real Numbers

„

Binary real to decimal real

„

Decimal real to binary real

4.5625 = 100.1001

True or False

„

If x > 0 then x + 1 > 0

„

If x < 0 then x * 2 < 0

„

If x > y then -x < -y

„

If x >= 0 then -x <= 0

„

If x < 0 then -x > 0

„

If x >= 0 then (( !x – 1 ) & x ) == x

„

If x < 0 && y > 0 then x * y < 0

„

If x < 0 then ((x ^ x >> 31) + 1) > 0

Character Storage

„

Character sets

¾ Standard ASCII (0 – 127)

¾ Extended ASCII (0 – 255)

¾ ANSI (0 – 255)

¾ Unicode (0 – 65 535)

¾ Unicode (0 – 65,535)

„

Null-terminated String

¾ Array of characters followed by a null byte

„

Using the ASCII table

¾ back inside cover of book

Machine Words

„ Machine Has “Word Size”

¾ Nominal size of integer-valued data

„ Including addresses

¾ Most current machines use 32 bits (4 bytes) words

„ Limits addresses to 4GB

„ Users can access 3GB

„ Users can access 3GB

„ Becoming too small for memory-intensive applications

¾ High-end systems use 64 bits (8 bytes) words

„ Potential address space ≈ 1.8 X 10¹⁹ bytes

„ x86-64 machines support 48-bit addresses: 256 Terabytes

¾ Machines support multiple data formats

„ Fractions or multiples of word size

„ Always integral number of bytes

Word-Oriented Memory Organization

„

Addresses Specify Byte Locations

¾ Address of first byte in

0000 0001 0002 0003 0004 0005 32-bit

Words 64-bit Bytes Addr.

Words

Addr

=

??

Addr

=

??

Addr

= 0000

0000

y word

¾ Addresses of successive words differ by 4 (32-bit) or 8 (64-bit)

0006 0007 0008 0009 0010 0011 0012 0013 0014 0015

Addr

=

??

??

Addr

=

??

Addr

=

??

0004

0008

0012

0008

Data Representations

„

Sizes of C Objects (in Bytes)

¾ C Data Type Typical 32-bit Intel IA32 x86-64

„ unsigned 4 4 4

„ int 4 4 4

long int 4 4 4

„ long int 4 4 4

„ char 1 1 1

„ short 2 2 2

„ float 4 4 4

„ double 8 8 8

„ char * 4 4 8

„ Or any other pointer

Byte Ordering

„

How should bytes within multi-byte word be ordered in memory?

„

Conventions

¾ Big Endian: Sun, PPC Mac

L t i ifi t b t h hi h t dd

„ Least significant byte has highest address

¾ Little Endian: x86

„ Least significant byte has lowest address

Byte Ordering Example

„

Big Endian

¾ Least significant byte has highest address

„

Little Endian

¾ Least significant byte has lowest address

„

Example

¾ Variable x has 4-byte representation 0x01234567

¾ Address given by &x is 0x100

0x100 0x101 0x102 0x103

01 23 45 67

0x100 0x101 0x102 0x103

67 45 23 01

Big Endian

Little Endian

01 23 45 67

67 45 23 01

Representing Integers

„ int A = 15213;

„ int B = -15213;

„ long int C = 15213;

Decimal: 15213

Binary: 0011 1011 0110 1101 Hex: 3 B 6 D

6D

IA32, x86-64 A

00 Sun A

6D x86-64 C

00 Sun C 6D

IA32 C

3B 00 00

3B 6D 00

93 C4 FF FF

IA32, x86-64 B

C4 93 FF FF Sun B

Two’s complement representation 00

00 00 00 3B 00 00

3B 6D 00 3B

00 00

„ char S[6]= “15213”;

Representing Strings

„

Strings in C

¾ Represented by array of characters

¾ Each character encoded in ASCII format

„ Standard 7-bit encoding of character set

„ Character “0” has code 0x30 Linux/Alpha S Sun S

„ Digit i has code 0x30+i

¾ String should be null-terminated

„ Final character = 0

„

Compatibility

¾ Byte ordering not an issue

Linux/Alpha S Sun S

32 31 31 35

33 00 32

31 31 35

33 00

Boolean Operations

„

NOT

„

AND

„

OR

„

Operator Precedence

„

Truth Tables

Boolean Algebra

„ Based on symbolic logic, designed by George Boole

„ Boolean expressions created from:

¾ NOT, AND, OR

NOT

„

Inverts (reverses) a boolean value

„

Truth table for Boolean NOT operator:

Digital gate diagram for NOT:

NOT

AND

„

Truth table for Boolean AND operator:

Digital gate diagram for AND:

AND

OR

„

Truth table for Boolean OR operator:

Digital gate diagram for OR:

OR

Operator Precedence

„

NOT > AND > OR

„

Examples showing the order of operations:

„

Use parentheses to avoid ambiguity

Truth Tables ^{(1 of 3)}

„

A Boolean function has one or more Boolean inputs, and returns a single Boolean output.

„

A truth table shows all the inputs and outputs of a Boolean function

Example: ¬X ∨ Y

Truth Tables ^{(2 of 3)}

„

Example: X ∧ ¬Y

Truth Tables ^{(3 of 3)}

„

Example: (Y ∧ S) ∨ (X ∧ ¬S)

mux X

Y

S

Z

Two-input multiplexer