0-ceng255 ch2 17-v3 - ece.uvic.cakinli/ceng255/ceng255_ch2_17-partiv-revised.pdf · isa 77 fig....

KinFunLIUniversityofVictoria

CENG255IntroductiontoComputerArchitecture

2.6 Stacks• Astack (pushdownstack)• alistofdataelements• added/removedattopendonly

• Last-in-first-out(LIFO)• Push anewelementontothestacktop• Pop thetopelementfromthestack• Datastack andprocessorstackinmemory

2.7.1 Processor Stack• Processorhasstackpointer(SP)registerthatpointstotopoftheprocessorstack• Pushoperationinvolvestwoinstructions:

Subtract SP,SP,#4Store Rj,(SP)

• Popoperationalsoinvolvestwoinstructions:

Load Rj,(SP)Add SP,SP,#4

Fig. 2.14 Stack in Memory

Stack Varieties• StackGrowth:•Ascending•Descending

• Stackpointer:• Fullstack• Emptystack

2.7 Subroutines-1• Aparticulartaskisrepeatedandexecutedmanytimesusingdifferentdata• Examples:mathematicalfunction,listsorting

• Implementtaskinasubroutine• Ratherthanreproduceentiresubroutineblockineachpartofprogram,useasubroutinecall• SpecialtypeofbranchwithCallinstruction

Subroutines-2• Branchingtosameblockofinstructionssavesspaceinmemory

• Mustbranchbackafterexecutingthelastinstructioninsubroutine

• UseReturn instruction• Subroutinecanbecalledfromdifferentplacesintheprogram

• HowcanReturn bedonetothecorrectplace?• =>subroutinelinkage

2.7.1 Subroutine Linkage• Simplestmethod:placenext(afterCall)instruction’saddressinlinkregister

• Call instructionperformstwooperations:

1. StoreupdatedPCcontentinlinkregister

2. Branchtotarget(subroutine)address

• Return instructionbranchestoaddressinlinkregister

Fig. 2.16 Caller and Callee

2.7.1 Subroutine Nesting• Asubroutineisallowedtocallanothersubroutine• =>subroutinenesting

• Linkregister=nextaddressoffirstcall• =>overwrittenaftersecondcall

• SaveLinkregister onstackbeforesecondcall• Afterreturnfromsecondsubroutine,restoreslinkregister

2.7.2 Parameter Passing• Differentinputdata=>subroutine

• =>differentresults• Parameterpassing:Informationexchangeto/fromasubroutine

• Useregisters:Simplebutlimitedinnumber

• Alternative:useprocessorstack• Alsoforlocalvariables&registers

2.7.3 Stack Frame• Topoftheprocessorstack• =>privateworkspaceforsubroutines

• Astackframeisallocatedonsubroutineentryanddeallocated onsubroutineexit• Aframepointer(FP)registerenablesaccesstoprivateworkspaceforcurrentsubroutine• Subroutinenesting:thestackframealsosavesreturnaddressandFPofeachcaller

Fig. 2.20 Stack LayoutSP

(stack pointer)

FP(frame pointer)

saved [R1]

saved [R0]

Stackframefor

calledsubroutineReturn address

localvar3

localvar2

localvar1

saved [FP]

Old TOS

param2

param1

param3

param4

(top-of-stack)

Call Process (re: Fig. 2.20)1. Callingprogrampushes4parameters2. ThenCallinstructionexecuted• =>returnaddressonstack(↑SP)

Subroutine:3. FPisaGPregisterandsavedonstackby

a. MoveFP,-(SP)b. MoveSP,FP;↑SP=↑FP=old[FP]

4. Allocatelocalvariablesspacea. Subtract #12,SP

5. UseR2,R1sosaveonstack;↑SP=old[R1]

Return Process (re: Fig. 2.20)• BeforeReturnfromsubroutine,Callee:

1. PopR1,R22. Add#12,SP;removelocalvariables3. Popold[FP]backtoFP

;↑SP=returnaddress• AfterReturn,Caller:

1. Popparameters;↑SP=oldTOS

Fig. 2.20 Stack Layout-CallSP

(stack pointer)

FP(frame pointer)

saved [R1]

saved [R0]

Stackframefor

localvar3

localvar2

localvar1

saved [FP]

Old TOS

param2

param1

param3

param4

(top-of-stack) CC-0

CC=Caller CallSC=Sub Call

(stack pointer)

FP(frame pointer)

saved [R1]

saved [R0]

Stackframefor

localvar3

localvar2

localvar1

saved [FP]

Old TOS

param2

param1

param3

param4

(top-of-stack)

CC-1CC=Caller CallSC=Sub Call

(stack pointer)

FP(frame pointer)

saved [R1]

saved [R0]

Stackframefor

localvar3

localvar2

localvar1

saved [FP]

Old TOS

param2

param1

param3

param4

(top-of-stack)

C-Call

(stack pointer)

FP(frame pointer)

saved [R1]

saved [R0]

Stackframefor

localvar3

localvar2

localvar1

saved [FP]

Old TOS

param2

param1

param3

param4

(top-of-stack)

(stack pointer)

FP(frame pointer)

saved [R1]

saved [R0]

Stackframefor

localvar3

localvar2

localvar1

saved [FP]

Old TOS

param2

param1

param3

param4

(top-of-stack)

(stack pointer)

FP(frame pointer)

saved [R1]

saved [R0]

Stackframefor

localvar3

localvar2

localvar1

saved [FP]

Old TOS

param2

param1

param3

param4

(top-of-stack)

(stack pointer)

FP(frame pointer)

saved [R1]

saved [R0]

Stackframefor

localvar3

localvar2

localvar1

saved [FP]

Old TOS

param2

param1

param3

param4

(top-of-stack)

Fig. 2.20 Stack Layout-ReturnSP

(stack pointer)

FP(frame pointer)

saved [R1]

saved [R0]

Stackframefor

localvar3

localvar2

localvar1

saved [FP]

Old TOS

param2

param1

param3

param4

(top-of-stack)

SR=Caller RetCR=Sub Ret

(stack pointer)

FP(frame pointer)

saved [R1]

saved [R0]

Stackframefor

localvar3

localvar2

localvar1

saved [FP]

Old TOS

param2

param1

param3

param4

(top-of-stack)

(stack pointer)

FP(frame pointer)

saved [R1]

saved [R0]

Stackframefor

localvar3

localvar2

localvar1

saved [FP]

Old TOS

param2

param1

param3

param4

(top-of-stack)

SR-3SC-3b

(stack pointer)

FP(frame pointer)

saved [R1]

saved [R0]

Stackframefor

localvar3

localvar2

localvar1

saved [FP]

Old TOS

param2

param1

param3

param4

(top-of-stack)

(stack pointer)

FP(frame pointer)

saved [R1]

saved [R0]

Stackframefor

localvar3

localvar2

localvar1

saved [FP]

Old TOS

param2

param1

param3

param4

(top-of-stack) CR-1SR=Caller RetCR=Sub Ret

Nested Subroutines Stack Frames

[FP] from SUB1

Stackframe

forfirst

subroutine

[R0] from Main

param3

[R3] from Main

[R2] from Main

[R1] from Main

Old TOS

[FP] from Main

param1

param2

[R0] from SUB1

[R1] from SUB1

Stackframefor

secondsubroutine

Example: Nested Subroutines Program

Main program...

2000 Move PARAM2, (SP) Place parameterson stack.2004 Move PARAM1, (SP)2008 Call SUB12012 Move (SP),RESULT Store result.2016 Add #8,SP Restorestack level.2020 next instruction

––

Nested Subroutines Sub-1

2100 SUB1 Move FP, (SP) Save frame pointer register.2104 Move SP,FP Load the framepointer.2108 MoveMultiple R0 R3, (SP) Save registers.2112 Move 8(FP),R0 Get first parameter.

Move 12(FP),R1 Get secondparameter....Move PARAM3, (SP) Placeaparameteron stack.

2160 Call SUB22164 Move (SP)+,R2 Pop SUB2 result into R2.

...Move R3,8(FP) Placeansweron stack.MoveMultiple (SP)+,R0 R3 Restoreregisters.Move (SP)+,FP Restoreframe pointer register.Return Return to Main program.

– –

Nested Subroutines Sub-2

3000 SUB2 Move FP, (SP) Save frame pointer register.Move SP,FP Load the framepointer.MoveMultiple R0 R1, (SP) Save registersR0 and R1.Move 8(FP),R0 Get the parameter....Move R1,8(FP) PlaceSUB2result on stack.MoveMultiple (SP)+,R0 R1 RestoreregistersR0 and R1.Move (SP)+,FP Restoreframe pointer register.Return Return to Subroutine 1.

– –

Nested Subroutines Stack Frames

[FP] from SUB1

Stackframe

forfirst

subroutine

[R0] from Main

param3

[R3] from Main

[R2] from Main

[R1] from Main

Old TOS

[FP] from Main

param1

param2

[R0] from SUB1

[R1] from SUB1

Stackframefor

secondsubroutine

2000 (SP)2004200821002104 (FP1)

2156216030003004 (FP2)

30xx+430xx+830xx+122164

21yy+421yy+821yy+12/2012

Branch with Link

Assignment: Stack Varieties• StackGrowth:•Ascending•Descending

• Stackpointer:• Fullstack• Emptystack

Time and Space Tradeoff

0-ceng255 ch2 17-v3 - ece.uvic.cakinli/ceng255/ceng255_ch2_17-partiv-revised.pdf · isa 77 fig....

Documents

3. translation to target language - - tu kaiserslautern ·...

freertos with cubemx - brichacek.net · freertos about...

pdf the stack and the stack pointer

pertemuan 06 - set instruksi mikrokontroler 89c51...

operating systems cs451 - courses.cs.washington.edu• the...

assembly programming (iii)€¦ · stack pointer in avr,...

the cortex-m chapter series: hardware and software hardware...

references vs. pointers, addresses, pointer arithmetic,...

dynamic memory allocationzhaoguo/fa17-cso/notes/17... ·...

68000 stack-related...

cs642: computer...

application note 179prabal/teaching/eecs373-f11/...note note...

procedures and the stack -...

the stack and the stack pointer - electrical engineering @...

graphic grqphlc -...

data sheet - fujitsu · adoption of system stack pointer...

codewarrior development studio for starcore dsp ...according...

cs240: programming in...

operating system(os) support · 2015. 10. 14. · stack...

subroutines, the stack, memory addressing - montana tech ·...