ICS 51 - Introductory ICS 51 - Introductory Computer OrganizationComputer OrganizationReview

RegistersRegisters

InstructionsInstructionsData movement instructions

◦MovArithmetic operations

◦Add, Sub, Mul, DivLogical operations

◦And, Or, Not, Xor, Shr, ShlComparison instructions

◦CmpControl Transfer Instructions

◦Unconditional: Jmp◦Conditional: Jg, Jl, Jge, Jle, Jne

Data Ranges and Data Data Ranges and Data TypesTypesData Ranges

◦E.g. 4 bits: Unsigned: from 0 to 15 1’s complement: from -7 to 7 2’s complement: from -8 to 7

Data Types◦Byte: 8 bits◦Word: 16 bits◦Dword: 32 bits

Multiplication OperationMultiplication OperationUnsigned multiplication: MUL

◦ Code: MUL Operand If Operand is a byte, e.g. MUL BL, then

AX = AL*Operand

If Operand is a word, e.g., MUL BX, thenDX:AX = AX*Operand

If Operand is a dword, e.g., MUL EBX, thenEDX:EAX = EAX*Operand

Signed multiplication: IMUL ◦ (look up the code table)

Division OperationDivision OperationUnsigned division: DIV

◦Code: DIV Operand If Operand is a byte, e.g. DIV BL, then

AL = AX/Operand AH = Rest

If Operand is a word, e.g., DIV BX, thenAX = DX:AX/Operand DX = Rest

If Operand is a dword, e.g., DIV EBX, thenEAX = EDX:EAX/Operand EDX = Rest

Signed division: IDIV ◦(look up the code table)

Stack Push/Pop ExamplesStack Push/Pop Examples… run out of registers

Push EAX //save EAX on the stackPush EBX //save EBX on the stack

… use EAX and EBX for some calculations …

Pop EBX //move top of the stack to EBXPop EAX //move top of the stack to EAX to restore its original value

Note the orders of PUSH and POP are reversed

8

void main(){

int result = 0;__asm{

PUSH eax;PUSH ebx;PUSH ecx;

// 1. Pass parameter(s) to the procedure

MOV ebx, 10; PUSH ebx;

// 2. Execute callCALL add_func;

// 3. Remove parameter(s) from the stack

POP ebx;

// 4. EAX has the return valueMOV result, eax;

POP ecx;POP ebx;POP eax;

}}

__declspec(naked)int add_func(int param1){ __asm{

PUSH ebx;PUSH ecx;

// 1. Access param1MOV ebx, dword ptr[esp+12];

MOV ecx, ebx;ADD ecx, 5;

// 2. The return value should be placed in EAX

MOV eax, ecx;

POP ecx;POP ebx;

// 3. Return to the callerRET;

}}

Function CallFunction Call

9

void main(){

int result = 0;__asm{

PUSH eax;PUSH ebx;PUSH ecx;

// 1. Pass parameter(s) to the procedure

MOV ebx, 10;PUSH ebx;

// 2. Execute callCALL add_func;

// 3. Remove parameter(s) from the stack

POP ebx;

// 4. EAX has the return valueMOV result, eax;

POP ecx;POP ebx;POP eax;

}}

ECX ESP

EBX ESP+4

EAX ESP+8

10 (param1) ESP

ECX ESP+4

EBX ESP+8

EAX ESP+12

Return Addr ESP

10 (param1) ESP+4

ECX ESP+8

EBX ESP+12

EAX ESP+16

ECX ESP

EBX ESP+4

EAX ESP+8

Function (cont.)Function (cont.)

10

Return Addr ESP

param1 ESP+4

ECX ESP+8

EBX ESP+12

EAX ESP+16__declspec(naked)int add_func(int param1){ __asm{

PUSH ebx;PUSH ecx;

// 1. Access param1MOV ebx, dword ptr[esp+12];

MOV ecx, ebx;ADD ecx, 5;

// 2. The return value should be placed in EAX

MOV eax, ecx;

POP ecx;POP ebx;

// 3. Return to the callerRET;

}}

ECX ESP

EBX ESP+4

Return Addr ESP+8

param1 ESP+12

ECX ESP+16

EBX ESP+20

EAX ESP+24

Return Addr ESP

param1 ESP+4

ECX ESP+8

EBX ESP+12

EAX ESP+16

param1 ESP+4

ECX ESP+8

EBX ESP+12

EAX ESP+16

Function (cont.)Function (cont.)

Number SystemsNumber SystemsDecimal (10)Binary (2)Hexadecimal (16)Octal (8)

◦Conversion between them

Logical OperationsLogical OperationsGet a bit

◦Using AND/OR

Count number of ones◦Using DIV◦Using AND and SHR

Mirror a byte

RecursionRecursionRecursion in computer

programming is exemplified when a function is defined in terms of itself. 1. Base case2. Recursive case

E.g. Factorial(n) as: ◦ Base case:

n=0 or n=1: Factorial(n)= 1◦ Recursive case:

n>1 : n * Factorial(n-1)

Data StructuresData StructuresLinked List

◦Element has Value Pointer to next element

Binary Search Tree◦Element has

Value Pointer to left child Pointer to right child

◦Value of left subtree < root < right subtree

Insert and Traverse