Fall 2006 1 EE 333 Lillevik 333f06-l5 University of Portland School of Engineering Computer Organization Lecture 5 MIPS Instructions Loops Machine Instructions.

Fall 2006

Lillevik 333f06-l5 1University of Portland School of Engineering

EE 333

Computer OrganizationLecture 5

MIPS InstructionsLoops

Machine Instructions

Fall 2006


EE 333

Last time

• MIPS assembly language

• Arithmetic and logic instructions

• Load and store instructions

Fall 2006


EE 333

Write the program?betaalpharesult 6

Fall 2006


EE 333

Lets run the program

Fall 2006


EE 333

Instruction Classes

• Arithmetic and logic (some more)• Load: li, la, lbu, lw

• Store: sb, sw

• Comparison

• Branch and jump

• Data Movement

• Floating Point

√

√

Fall 2006


EE 333

Arithmetic and Logic

Instruction Example MeaningAnd and $s1, $s2, $s3 $s1 = $s2 & $s3

And immediate andi $s1, $s2, 100 $s1 = $s2 & 100

Or or $s1, $s2, $s3 $s1 = $s2 | $s3

Or immediate ori $s1, $s2, 100 $s1 = $s2 | 100

Shift left logical sll $s1, $s2, 10 $s1 = $s2 << 10

Shift right logical srl $s1, $s2, 10 $s1 = $s2 >> 10

Only registers used for operands

Fall 2006


EE 333

Instruction Classes

• Arithmetic and logic: add, sub, and, or

• Load: li, la, lbu, lw

• Store: sb, sw

• Comparison

• Branch and jump

• Data Movement

• Floating Point

√

√

√

Fall 2006


EE 333

Branch and Jump

Instruction Example MeaningBranch on equal beq $s1, $s2, 100 If ($s1 = = $s2 ) go

to (PC +4 )+ 100

Branch on not equal bne $s1, $s2, 100 If ($s1 ! = $s2 ) go to (PC +4 )+ 100

Jump j loop Go to loop:

Jump and link jal subroutine $ra = PC + 4, go to subroutine

Jump Register jr $ra PC = $ra

Fall 2006


EE 333

Loops in assembly

• Initialize loop counter

• Modify counter (decrement, increment)

• Check if counter = = end condition– True, leave loop– False, continue with loop

• Body of loop

• Continue with next pass in loop

Fall 2006


EE 333

Flowchart of loopcount = 5

count --

count = = 0 ?

Body of loop

no

yes

Body could go ahead of test

Fall 2006


EE 333

LoopsNOTE: you may place the

check after the body

How many times is “body” executed?

(4 or 5?

Fall 2006


EE 333

Lets run the program

Fall 2006


EE 333

Write the program?Write a loop that adds 4 to $t2, six times

Fall 2006


EE 333

Machine Instructions

• Definition: numeric (hex) versions of instruction

• Memory: contains binary number or machine instruction, it’s what the hardware executes

• Formats– R, register– I, immediate– J, jump

NOTE: Result of assembly is a machine instruction

Fall 2006


EE 333

Instruction Formats

Name FieldsSize 6 bits 5 bits 5 bits 5 bits 5 bits 6 bits

R type op rs rt rd shamt funct

I type op rs rt address/immediate

J type op target address

All instructions are 32-bits long

32-bits

Fall 2006


EE 333

R-format

• Operation (op) codeAll 0x00; exception mfc0 = 0x10,

• Funct determines specific instructionadd = 0x20, sub = 0x22, mult = 0x18, div = 0x1a

• Operands– rd = destination register– rs = first argument– rt = second argument

Shamt = shift amount

Fall 2006


EE 333

R-format example

R type FieldsSize 6 bits 5 bits 5 bits 5 bits 5 bits 6 bits


00 0000 0 0011 0 0100 0 0010 0 0000 10 0000

add $2, $3, $4

add rd, rs, rt

0000 0000 0110 0100 0001 0000 0010 0000

0x 0064 1020

Fall 2006


EE 333

Find machine instruction?

0x00d05022



00 0000 0 0110 1 0000 0 1010 0 0000 10 0010

sub $10, $6, $16

sub rd, rs, rt

Fall 2006


EE 333

I-format

• Op code exampleslw = 0x23, sw = 0x2b, beq = 0x04

• Operands– rs = first argument– rt = second argument

• Immediate = sign extended bits [15 – 0]

Fall 2006


EE 333

I-format example

lw $2, 100($3)

lw rt, adr (rs)

1000 1100 0110 0010 0000 0000 0110 0100

0x 8c62 0064

Name FieldsSize 6 bits 5 bits 5 bits 16 bits


10 0011 0 0011 0 0010 0000 0000 0110 0100

Fall 2006


EE 333




101011 0 1000 1 0100 0000 0000 0100 0000

sw $20, 64($8)

sw rt, adr (rs)

0xad14 0040

Fall 2006


EE 333

Fall 2006


EE 333

Write the program?Write a loop that adds 4 to $t2, six times

Fall 2006


EE 333


0x 00d0 5022



00 0000 0 0110 1 0000 0 1010 0 0000 10 0010

sub $10, $6, $16

sub rd, rs, rt

Fall 2006


EE 333




10 1011 0 1000 1 0100 0000 0000 0100 0000

sw $20, 64($8)

sw rt, adr (rs)

0x ad14 0040

Fall 2006 1 EE 333 Lillevik 333f06-l5 University of Portland School of Engineering Computer Organization Lecture 5 MIPS Instructions Loops Machine Instructions.

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