CS 2630 Computer Organizationhomepage.cs.uiowa.edu/~bdmyers/cs2630_sp17/public/lectures/lecture-006... · Where we are going Instruction set architecture (e.g., MIPS) Compiler Memory

CS2630ComputerOrganization

Meeting6:StoredprogramsBrandonMyers

UniversityofIowa

PeerinstructionWhatvalueisstoredin$t0whentheprogramfinishes?

(numericresponse)

Wherewearegoing

Instructionsetarchitecture(e.g.,MIPS)

Compiler

Memorysystem I/OsystemProcessor

Datapath &Control

Digitallogic

translatingsourcecode(CorJava)ProgramstoassemblylanguageAndlinkingyourcodetoLibrarycode

HowthesoftwaretalksTothehardware

HowaprocessorrunsMIPSPrograms!

Howswitches(1or0)canbeusedtobuildInterestingfunctions:fromintegerarithmetictoprogrammablecomputers

Wherewearegoing

Instructionmemory

Executionengine

Datamemory

Learnwhatgetsstoredinhere

Storinganinstructionasbits• eachMIPSinstructionsis32bits,storedin“instructionmemory”

8e 13 00 00

8e 14 00 04

02 74 90 20

ae 12 00 08

22 10 00 04

22 31 ff ff

1e 20 ff f9

000000040008000C001000140018

lw $s3, 0($s0)

lw $s4, 4($s0)

add $s2, $s3, $s4

sw $s2, 8($s0)

addi $s0, $s0, 4

addi $s1, $s1, -1

bgtz $s1, loop

address contents meaning

StoringaninstructionasbitseachMIPSinstructionsis32bits,storedin“instructionmemory”

8e 13 00 00

8e 14 00 04

02 74 90 20

ae 12 00 08

22 10 00 04

22 31 ff ff

1e 20 ff f9

000000040008000C001000140018

lw $s3, 0($s0)

lw $s4, 4($s0)

add $s2, $s3, $s4

sw $s2, 8($s0)

addi $s0, $s0, 4

addi $s1, $s1, -1

bgtz $s1, loop


R-type

opcode=0forR-typeandfunct isthis

R-type

Example:


3stepstotranslatefromhumancodetomachinecode

R-type

Example:


0x00 8 9 13 0 0x20

step1:fillinthefields

R-typeExample:

0x00 8 9 13 0 0x20

step2:writeasa32-bitbinarynumber

000000 01000 01001 01101 00000 100000

R-typeExample:

0x00 8 9 13 0 0x20

step3:typicallywritethecodeashex,sotranslatetohexadecimalbyturningeach4bitsintoadigit

000000 01000 01001 01101 00000 100000

0x01096820

I-type

0x09 10 14 -1

001001 01010 01110 11111 11111 1111110x254EFFFF MIPSgreensheet,P&H

Example:

PeerinstructionGivethe32-bitrepresentationofthisinstruction

a) 0x00231025b) 0x014B4825c) 0x00430825d) 0x00611025e) 0x01695025

Whattodonext• reminder:HW2/Quiz2dueThursday

• NexthomeworkoutTh orFri

• QUESTIONSFORNEXTTIME• whatiftoobigfor16bits?• willthefunct everbebiggerthan6bits?

http://qz.com/726338/the-code-that-took-america-to-the-moon-was-just-published-to-github-and-its-like-a-1960s-time-capsule/

lotsmoreinfo:http://tcf.pages.tcnj.edu/files/2013/12/Apollo-Guidance-Computer-2009.pdf

CS2630ComputerOrganization

Meeting7:StoredprogramsII:programexecution,immediates,addresses

BrandonMyersUniversityofIowa

Wherewearegoing

Instructionsetarchitecture(e.g.,MIPS)

Compiler

Memorysystem I/OsystemProcessor

Datapath &Control

Digitallogic

translatingsourcecode(CorJava)ProgramstoassemblylanguageAndlinkingyourcodetoLibrarycode

HowthesoftwaretalksTothehardware

HowaprocessorrunsMIPSPrograms!

Howswitches(1or0)canbeusedtobuildInterestingfunctions:fromintegerarithmetictoprogrammablecomputers

Representationsofaprogram

Compiler

int x = arr[1];arr[2] = x + 10;

lw $t0, 4($r0)addi $t0, $t0, 10sw $t0, 8($r0)

Assembler

100011100000100000000000000001000010000100001000000000000000101010101110000010000000000000001000

Highlevellanguageprogram(humanreadable)

assemblyprogramastext(CS2630studentreadable)

assemblyprogramasbinary(machinereadable)

Registernames->numbers

RegisterNumber ConventionalName Usage$0 $zero hard-wiredto0$1 $at reservedforassembler

$2- $3 $v0,$v1 returnvaluesfromfunctions

$4- $7 $a0- $a3 arguments$8- $15 $t0- $t7 temporary registers$16- $23 $s0- $s7 savedregisters

$24- $25 $t8- $t9 temporary registers

$26- $27 $k0- $k1 reservedforOS$28 $gp globalpointer$29 $sp stackPointer$30 $fp framePointer$31 $ra returnAddress

thistableintheMIPSreferencesheetsays,e.g.,thatregister$t8 isrepresentedby5-bitnumber24

Moreinstructionsopcode

opcodefunct

Branches:relativeaddressing

example

Instructionexecution

8e 13 00 00

8e 14 00 04

02 74 90 20

ae 12 00 08

22 10 00 04

22 31 ff ff

1e 20 ff f9

000000040008000C001000140018

loop: lw $s3,0($s0)

lw $s4, 4($s0)

add $s2, $s3, $s4

sw $s2, 8($s0)

addi $s0, $s0, 4

addi $s1, $s1, -1

bgtz $s1, loop


PC 0x0000

Analogy:choose-your-own-adventurenovel• onmostpages:youcontinuereadingbyturningthepage(asinanormalbook)• onsomepages:youaregiventhechoicetojumptoadifferentpage


8e 13 00 00

8e 14 00 04

02 74 90 20

ae 12 00 08

22 10 00 04

22 31 ff ff

1e 20 ff f9

000000040008000C001000140018

loop: lw $s3,0($s0)

lw $s4, 4($s0)

add $s2, $s3, $s4

sw $s2, 8($s0)

addi $s0, $s0, 4

addi $s1, $s1, -1

bgtz $s1, loop


PC 0x0000


8e 13 00 00

8e 14 00 04

02 74 90 20

ae 12 00 08

22 10 00 04

22 31 ff ff

1e 20 ff f9

000000040008000C001000140018


PC 0x0004

loop: lw $s3,0($s0)

lw $s4, 4($s0)

add $s2, $s3, $s4

sw $s2, 8($s0)

addi $s0, $s0, 4

addi $s1, $s1, -1

bgtz $s1, loop


8e 13 00 00

8e 14 00 04

02 74 90 20

ae 12 00 08

22 10 00 04

22 31 ff ff

1e 20 ff f9

000000040008000C001000140018


PC 0x0008

loop: lw $s3,0($s0)

lw $s4, 4($s0)

add $s2, $s3, $s4

sw $s2, 8($s0)

addi $s0, $s0, 4

addi $s1, $s1, -1

bgtz $s1, loop


8e 13 00 00

8e 14 00 04

02 74 90 20

ae 12 00 08

22 10 00 04

22 31 ff ff

1e 20 ff f9

000000040008000C001000140018


PC 0x000C

loop: lw $s3,0($s0)

lw $s4, 4($s0)

add $s2, $s3, $s4

sw $s2, 8($s0)

addi $s0, $s0, 4

addi $s1, $s1, -1

bgtz $s1, loop


8e 13 00 00

8e 14 00 04

02 74 90 20

ae 12 00 08

22 10 00 04

22 31 ff ff

1e 20 ff f9

000000040008000C001000140018


PC 0x0010

loop: lw $s3,0($s0)

lw $s4, 4($s0)

add $s2, $s3, $s4

sw $s2, 8($s0)

addi $s0, $s0, 4

addi $s1, $s1, -1

bgtz $s1, loop


8e 13 00 00

8e 14 00 04

02 74 90 20

ae 12 00 08

22 10 00 04

22 31 ff ff

1e 20 ff f9

000000040008000C001000140018


PC 0x0014

loop: lw $s3,0($s0)

lw $s4, 4($s0)

add $s2, $s3, $s4

sw $s2, 8($s0)

addi $s0, $s0, 4

addi $s1, $s1, -1

bgtz $s1, loop


8e 13 00 00

8e 14 00 04

02 74 90 20

ae 12 00 08

22 10 00 04

22 31 ff ff

1e 20 ff f9

000000040008000C001000140018


PC 0x0018

loop: lw $s3,0($s0)

lw $s4, 4($s0)

add $s2, $s3, $s4

sw $s2, 8($s0)

addi $s0, $s0, 4

addi $s1, $s1, -1

bgtz $s1, loop


8e 13 00 00

8e 14 00 04

02 74 90 20

ae 12 00 08

22 10 00 04

22 31 ff ff

1e 20 ff f9

000000040008000C001000140018


PC 0x0018

loop: lw $s3,0($s0)

lw $s4, 4($s0)

add $s2, $s3, $s4

sw $s2, 8($s0)

addi $s0, $s0, 4

addi $s1, $s1, -1

bgtz $s1, loop

0xfff9 = -7

0x0018 + 4 + (-7 * 4) = 0x0000

branchesuse“relativeaddressing”

Peerinstruction

Whatistheimmediateforthebeq instruction?

a)3b)12c)8d)2e)-3

Jumps:absoluteaddressing

example

example

Peerinstruction

Whatisthemaximumdistanceyoucanjumpusingasingle j?

a) 25instructionsb) 26instructionsc) 224 instructionsd) 225 instructionse) 226 instructionsf) 230 instructions

Theplotthickens

SomeMIPSinstructionsyoucanwritecannotbetranslatedtoa32-bitnumber

somereasonswhy1) constantsaretoobig2) relativeaddressesaretoobig3) absoluteaddressesareoutsidetherangeofajump4) convenienceinstructionsthathavenoopcode

SpoilerAlert!

StoringaninstructionasbitseachMIPSinstructionsis32bits,storedin“instructionmemory”

8e 13 00 00

8e 14 00 04

02 74 90 20

ae 12 00 08

22 10 00 04

22 31 ff ff

1e 20 ff f9

000000040008000C001000140018

lw $s3, 0($s0)

lw $s4, 4($s0)

add $s2, $s3, $s4

sw $s2, 8($s0)

addi $s0, $s0, 4

addi $s1, $s1, -1

bgtz $s1, loop


PseudoinstructionsNotalltheMIPSinstructionsare“real”(i.e.,understoodbytheprocessor)TAL – thetrueassemblylanguage;MIPSprocessorsknowalloftheseinstructionsMAL – slightlymoreconvenientlanguage;eachMALinstructionisusuallytranslatedto1-3TALinstructionsbytheassembler

Pseudoinstructions(MAL)

lui $t2, 0x0012ori $t3, $t3, 0x3456addu $t1, $t2, $t3

assemblertranslatesitto

Example:howmanybitsarerequiredfortheimmediateinthisinstruction?addiu $t1, $t2, 0x123456

lui =“loadupperimmediate”

Morepseudoinstructions(MAL)• otherI-typeinstructionswithtoo-largeimmediate• move $rd, $rs• li $rd,[32-bitimmediate]• la $rd,[32-bitimmediate]• branchinstructionswith<,>,<=,>=• reallyuseslt (setiflessthan),followedbybeq to0or1

• Foryoutotry:usetheseinstructionsinaMIPSprogram,thenseewhatMARStranslatesthemto

Peerinstruction• Putthefollowinginto• (A)onlyinMAL• (B)TAL

Whattodonow• DYBtonight• HW2/Quiz2dueThursday• HW3advancedMIPS/MIPStranslationassignedlaterthisweek(useMARSagain)

Acknowledgements• Snipsofgreensheetfromhttp://www-inst.eecs.berkeley.edu/~cs61c/resources/MIPS_help.html

Documents

CS 2630 Computer Organizationhomepage.cs.uiowa.edu/~bdmyers/cs2630_sp17/public/lectures/lecture-006... · Where we are going Instruction set architecture (e.g., MIPS) Compiler Memory