241-440 COMPUTER SYSTE

MDESIGN LECTURE 2

Instruction Set Architecture

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WHAT’RE THE COM PONENT OF ISA?

Machine Instruction SetInstruction formatNature of the fetch through execute

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VARIES PROGRA MMING MODEL

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WHAT MUST AN INSTR UCTION SPECIFY?

Which Operation is perform?

ADD r1,r2,r3Where to find the operands

ADD r1,r2,r3Place to store the result

ADD r1,r2,r3Location of next instruction

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BASIC ISA CLASS Accumulator (1 register)

1 address add A; acc <= acc + mem[A]

1 + x address addx A; acc <= acc + mem[A+x] Stack :

0 address add tos <= tos + next General Purpose Register

2 address add A, B

3 address add A, B, C

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BASIC ISA CLASSES(CON’T) Load/Store

load Ra, Rb Ra <= mem[Rb]

Store Ra, Rb mem[Rb] <= Ra

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COMPARE NUMBER OF INSTRUCTION

Code Sequence for C = A + B

Stack Accumulator Register Register

(reg. - mem) (load/store)

Push A Load A Load R1,A Load R1,A

Push B Add B Add R1,B Load R2,B

Add Store C Store C, R1 Add R3,R1,R2

Pop C Store C,R3

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CPU REGISTERStack Register Arithmetic Register &

Address Register 24

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GENERAL PURPO SE REGISTER

1975 - 1995 all machines use general purpose registers. Advanced of Registers

- faster than memory

- easier for compiler to use

- hold variables

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SUMMARY INSTRUC TION SET CLASS

Data Movement Instructions

- Load

- Store Arithmetic and Logic (ALU) Instruction

- Add, Sub, Shift … Branch Instructions

- Br, Brz, …

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- 3 ADDRESS MAC HINE AND ISA

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- 2 ADDRESS MA CHI NE I SA

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- 1 ADDRESS MAC HI NE ANDI SA

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- 0ADDRESS MAC HI NE ANDI SA

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EEEEEEEE - *a = (b+c) d e

-3 address -2 address -1 address EEEEE ,, EEE, load b EEEE E ,, add a,c EEE E push c

sub a,a,e mpy a,d mpy d EEE sub a,e sub e push d

store a mpy push e sub pop a

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REAL MACHINE Have mixture of 3, 2, 1 or 0 address instructions if ALU instructions only use registers for operands and result,

machine type is load-store mix of register-memory and memory-memory

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BREAK 5 MINUTES

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ADDRESSING MOE E

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ADDRESSING MOE E

Addr essi ng Mode Exampl es Meani ngRegi st er Add r4,r3 r4 <= r4 + r3I mmedi at e Add r4,#3 r4 <= r4 + 3

Displacement Add r4,100(r1) r4 <= r4 + mem[100+r1]indirect(r) Add r4,(r1) r4 <= r4 + mem[r1 ]

index+base Add r3,(r1+r2) r3 <= r3 + mem[r1+r2]Direct Add r1,(1001) r1 <= r1 + mem[1 0 0 1 ]

indirect(m) Add r1,@(r3) r1 <= r1 + mem[mem[r3]]-auto incre Add r1,(r2)+ r1 <= r1 +mem[r2 ];r2 =r2 +d-auto decre -Add r1, (r2) -r2 <=r2 d,r1 <=r1 +mem[r2 ]

scaled Add r1,100(r2)[r3] r1 <=r1+mem[100+r2+r3*d]

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MIPS REGISTERS - 31 32 0 0x bit GPR (R = ) - 32 32x bit FP register PC EE EE-E EEEEEEEEE EEEEEE EEEEEEEE

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0R1R

3R1

PC

lohi

MEMORY ADDRESSING

EEEEEEE EE EEEEE EE E-EEEE EEEEEE1980, 8()

How do byte address map onto words? Can a word be placed on any byte boundary?

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ENDIANESS ANDALIGNMENT E E EE: 6 8, , , :8086,(, ) 2

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GENERIC OF INSTRUCT ION FORMAT WIDTH

Variable :

Fixed:

Hybrid:

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...

EEEEEEE EEE Variable length instructions, if code size is ver

y important. Fixed length instructions, if performance is mo

st important. Embedded Machine (ARM, MIPS) have optiona

-l mode to execute 16 bit . (decide performance or density)

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TO BE CONTINUOUS

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PART II : LECTURE2

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MIPS ISA TARGET Embedded System E EEEEEEEE EEEEEEE E EEEEEEEE EEEE, , , 2

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MIPS ISA2

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MIPS ADDRESSIN G MODES

- All instructions have 32 bit wide.

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MIPS ARITHMETIC INSTRUCTION

Instruction Example Meaning1.add 1 2 3add $ ,$ ,$ 1 2 3$ = $ + $2.subtract sub $1,$2,$3 ------------------

3.add imme addi $1,$2,100 ------------------ 4.add unsign 1 2 3addu $ ,$ ,$ ------------------

5. 1 2 3subu $ ,$ ,$ ------------------6. -----------------1 2100addiu $ ,$ ,7.multiply EEEE 2 3$ ,$

2 3Hi,Lo = $ x$8. multu $2,$3 ------------------

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MIPS ARITHMETIC INSTRUCTION

I nst r uct i on Example Meani ng9.divide 2 3div $ ,$ 2 3Lo=$ /$ ,

2 3Hi=$ mod$ ,10. 23Divu $ ,$11.mov mfhi $112. mflo $1

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MIPS LOGICAL INSTRUCTION

I nst r uct i on Example Meani ng13.AND EEE14.OR or15.XOR xor16.NOR nor17. EEEE18. ori19. xori

20.shift left logical sll $1,$2,1021. 1 210Srl $ ,$ ,

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MIPS LOGICAL INSTRUCTION

I nst r uct i on Example Meani ng 22 210.shift right arithm sra $,$ ,

( )23. sllv24. srlv25. EEEE

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MIPS DATA TRANSF ER INSTRUCTIONS 26. sw 500(r4),r3 Store word

27. sh 5 0 2 (r4 ),r3 store half word

28. 41 4 3sb (r ,r store byte29. lw r1,30(r2) load word30. 140 2Lh r , (r ) load half word31. 140 2Lb r , (r ) load byte32 lui r1,40 load upper

16 16immediate ( bits shifted left by )

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TESTI NGCONDI TION Condition Code

EEE 1 2 3r ,r ,rbz label

Condition RegisterEE E 1 2 3r ,r ,rEEE 1r ,label

Compare and BranchEEE 1 2r ,r ,label

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MIPS COMPARE A ND BRANCH

Compare and BranchBEQ rs,rt,offsetBNE rs,rt,offset compare to zero and BranchBLEZ rs, offsetBGTZ rs, offsetBLT <BGEZ >=BLTZAL 0 31if R[rs] < then branch and link(to R )BGEZAL >=

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MIPS JUMP, BRAN CH COMPARE

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SOFTWARE CONVEN TIONS FOR REGISTE

R2

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NOTE FOR MIPS INS TRUCTION SET

0 0R always = “ ” (even if u try to write) / EEE EEEE -+4 >31 Imme arith and logical are extended

- EE EEE EEEE EEEEEE EE EE EEEE32- arith imme op are sign extend to 32 bits

data loaded by lb, lh extended- lbu, lhu are zero extended- lb, lh are sign extedned

Overflow occur in ADD, SUB, ADDI EEEEE EE ’ ADDU, SUBU, ADDIU, AND, OR, XOR, NOR, SHIFT,

MULT, MULTU, DIV, DIVU

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MIPS ARITHMETIE 3Instruction has operands Operand order is fixed

Pascal Code : a := b + c; MIPS Code : 0 1 2add $s , $s , $s

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MIPS ARITHMETIE

Pascal Code : E EE: = + + ; - e := f a;

MIPS Code : 0 1 2add $t , $s , $s 0 0 3add $s , $t , $s 4 5 0sub $s , $s , $s

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REGISTER & MEMORY Registers were used in Arithmetic Instructions

- 32 registers

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MEMORY ORGANIZATION Memory is an index into the array Byte Addressing = points to a byte of memory 2

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1 8 bits of Data8 bits of Data8 bits of Data8 bits of Data8 bits of Data8 bits of Data8 bits of Data

234567

MEMORY ORGANIZATION - 32 4For MIPS, a word is bit or bytes232 bytes with byte addresses from 0 to 2

-321

230 words with byte address from 0, 4, 6, …,2

-324

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090 32 bits of Data

32 bits of Data32 bits of Data32 bits of Data32 bits of Data32 bits of Data32 bits of Data

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MIPS LOAD/STORE INSTRUCTION

Code : [8 ] = + [ 8 ] ; 8 8 4 32A[ ] ==> x = (word alignment)

MIPS Code : lw $t0,323($s ); 0 2 0add $t ,$s ,$t ;

sw $t0,32 3($s );

Arithmetic Operand is Register, not Memory!!

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EXAMPLE : Swap (int v[], int k);

EEEEE{ ; temp = v[k];

1v[k] = v[k+ ]; swap:1v[k+ ]=temp; lw $15, 0[$2]

} lw $16, 4[$2] sw $16, 0[$2] sw $15, 4[$2]

31jr $

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MEANING

EEE 2 4 2$ , $ , $ 2 4 2$ = $ + $ ;lw 16 0 2$ , [$ ]

16 0 2$ = Memory[ + $ ]sw 15 4 2$ , [$ ]

4 2 15Memory[ +$ ] = $

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MACHINE LANGUAGE Instructions, like register & words of data are

32bits long.- 0 1 2add $t , $s , $s- 0 9 1 17 2 18register : $t = , $s = , $s =

Instruction Format

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MACHINE LANGUAGE - I type for Data transfer instruction Example : lw $t0, 32($s2) 2

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CONTROL Decision Making instructions MIPS conditional branch instructions:

- 0 1bne $t , $t , label- beq $t0, $t1, label

: ( =) = +;EEE 01$s ,$s ,LabelEEE 3 0 1$s , $s , $s

Label : ...

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CONTROL MIPS unconditional Branch Example :

if ( i != j) EEE 4 5$s , $s , label;h=i+j; EEE

3 4 5$s , $s , $s ; el se E lab2

-h=i j; lab1 : sub $s3 , $s4 , $s5 lab2 : …

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SUMMARIZE :2

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HOMEWORK

Use MIPS Assembly to write program.

1. “Factorial Program” n is input, Example : if n=3,

3 3 2 1 6result = ! = x x =

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HOMEWORK

Use MIPS Assembly to write program.

2 E EEEE EEEEEEE EEEE EEE E EEE EE EEE MIPS instructions

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MIPS INSTRUCTI ON ENCODING

EEEEEE EEE E EEE EEEEEE EE EEE 318Figure .

Page 153,

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