407 lines
15 KiB
Markdown
407 lines
15 KiB
Markdown
---
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title: Procedures
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TARGET DECK: Obsidian::STEM
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FILE TAGS: x86-64
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tags:
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- x86-64
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---
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## Overview
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The x86-64 stack grows towards lower addresses. When a procedure is invoked, more spack on the top of the stack is allocated for that procedure to make use of. This portion of the stack is called a **frame**. The general shape of the stack looks as follows:
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![[x86-64-stack.png]]
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Note parts of this diagram are omitted when possible. For instance, a stack frame may not exist at all if all arguments to a **leaf procedure** can be passed through registers. A leaf procedure is a function that does not call another function.
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%%ANKII
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Basic
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What ADT is used internally in procedure-calling mechanisms?
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Back: A stack.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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END%%
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%%ANKII
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Cloze
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The x86-64 stack grows towards {lower} addresses.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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END%%
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%%ANKI
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Basic
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What is a frame w.r.t. the x86-64 stack?
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Back: A region of the stack dedicated to a particular function call.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728480337611-->
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END%%
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%%ANKI
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Basic
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What instructions are used to store and retrieve from the x86-64 stack?
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Back: `pushq` and `popq`.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728480337614-->
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END%%
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%%ANKI
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Basic
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What does the "stack pointer" refer to w.r.t. the x86-64 stack?
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Back: Register `%rsp`.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728480337617-->
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END%%
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%%ANKI
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Basic
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How is the stack pointer manipulated to allocate space on the x86-64 stack?
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Back: By decrementing `%rsp` by an appropriate amount.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728480337621-->
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END%%
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%%ANKI
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Basic
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How is the stack pointer manipulated to deallocate space on the x86-64 stack?
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Back: By incrementing `%rsp` by an appropriate amount.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728480337604-->
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END%%
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%%ANKI
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Basic
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Suppose procedure `P` calls `Q`. What data sits at the end of `P`'s frame?
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Back: A return address.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728481058927-->
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END%%
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%%ANKI
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Cloze
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A {leaf} procedure is a function that {does not call another function}.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728481058953-->
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END%%
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%%ANKI
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Basic
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Suppose procedure `P` calls `Q`. The return address belongs to who's frame?
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Back: `P`
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728481058960-->
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END%%
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%%ANKI
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Basic
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Suppose procedure `P` calls `Q`. Why is the return address considered to be in `P`'s frame?
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Back: It is state relevant to `P`.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728481058966-->
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END%%
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## Control Transfer
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Like [[conditions#JMP|JMP]] instructions, `call` allows specifying a direct or indirect operand. `call` pushes the address of the instruction following it onto the stack and updates the PC to the operand. `ret` reverts these steps.
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| Instruction | Operands | Description |
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| ----------- | ----------- | ---------------- |
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| `call` | Label | Procedure call |
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| `call` | \**Operand* | Procedure call |
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| `ret` | | Return from call |
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%%ANKI
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Cloze
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The {`call`} instruction is the counterpart to the {`ret`} instruction.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728558288130-->
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END%%
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%%ANKI
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Basic
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What two things does the `call` instruction do?
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Back: It pushes the return address on the stack and updates the PC.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728558288148-->
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END%%
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%%ANKI
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Basic
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What two things does the `ret` instruction do?
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Back: It pops the return address off the stack and updates the PC.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728558288160-->
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END%%
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%%ANKI
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Basic
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The operand forms of `call` mirror what other instruction class?
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Back: `JMP`
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728558288165-->
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END%%
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%%ANKI
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Basic
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A `call` instruction pushes what address onto the stack?
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Back: That of the instruction following the `call` instruction.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728558288171-->
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END%%
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%%ANKI
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Basic
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What return address is pushed onto the stack after `call` is run?
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```x86
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1: ...
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2: callq .L1
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3: ...
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```
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Back: `3`
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728558288177-->
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END%%
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%%ANKI
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Basic
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What address is the PC updated to after `call` is run?
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```x86
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1: ...
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2: callq .L1
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3: ...
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```
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Back: That corresponding to label `.L1`.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728558288183-->
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END%%
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%%ANKI
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Basic
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Which register(s) does a `call` instruction update?
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Back: `%rsp` and `%rip`.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336730-->
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END%%
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%%ANKI
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Basic
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Which register(s) does a `ret` instruction update?
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Back: `%rsp` and `%rip`.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336760-->
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END%%
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## Data Transfer
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x86-64 employs 6 registers for passing integral (i.e. integer and pointer) arguments between caller and callee.
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| Bits | Arg 1 | Arg2 | Arg3 | Arg4 | Arg5 | Arg6 |
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| ---- | ------ | ------ | ------ | ------ | ------ | ------ |
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| 64 | `%rdi` | `%rsi` | `%rdx` | `%rcx` | `%r8` | `%r9` |
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| 32 | `%edi` | `%esi` | `%edx` | `%ecx` | `%r8d` | `%r9d` |
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| 16 | `%di` | `%si` | `%dx` | `%cx` | `%r8w` | `%r9w` |
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| 8 | `%dil` | `%sil` | `%dl` | `%cl` | `%r8b` | `%r9b` |
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%%ANKI
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Basic
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How many registers are available for passing integral arguments between procedures?
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Back: `6`
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336766-->
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END%%
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%%ANKI
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Basic
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How many bytes make up the `%rdi` register?
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Back: $8$
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336770-->
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END%%
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%%ANKI
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Basic
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How many bytes make up the `%di` register?
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Back: $2$
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336774-->
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END%%
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%%ANKI
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Basic
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How many bytes make up the `%dil` register?
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Back: $1$
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336779-->
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END%%
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%%ANKI
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Basic
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How many bytes make up the `%edi` register?
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Back: $4$
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336782-->
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END%%
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%%ANKI
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Cloze
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By convention, register {`%rdi`} is used for {the first integral argument}.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336787-->
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END%%
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%%ANKI
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Cloze
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{1:Words} are to {2:`%di`} whereas {2:double words} are to {1:`%edi`}.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336792-->
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END%%
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%%ANKI
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Cloze
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{1:Bytes} are to {2:`%dil`} whereas {2:quad words} are to {1:`%rdi`}.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336797-->
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END%%
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%%ANKI
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Basic
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How do you access the low-order 2 bytes of `%rdi`?
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Back: By using `%di`.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336802-->
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END%%
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%%ANKI
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Basic
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How do you access the low-order 4 bytes of `%rdi`?
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Back: By using `%edi`.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336808-->
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END%%
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%%ANKI
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Basic
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How do you access the low-order byte of `%rdi`?
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Back: By using `%dil`.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336813-->
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END%%
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%%ANKI
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Basic
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Which register should the first integral argument of a procedure be placed in?
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Back: `%rdi`
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336817-->
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END%%
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%%ANKI
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Basic
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From smallest to largest, list the four "first integral argument" registers.
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Back: `%dil`, `%di`, `%edi`, and `%rdi`.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336823-->
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END%%
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%%ANKI
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Basic
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How many bytes make up the `%rsi` register?
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Back: $8$
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336829-->
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END%%
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%%ANKI
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Basic
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How many bytes make up the `%si` register?
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Back: $2$
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336834-->
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END%%
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%%ANKI
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Basic
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How many bytes make up the `%sil` register?
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Back: $1$
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336838-->
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END%%
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%%ANKI
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Basic
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How many bytes make up the `%esi` register?
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Back: $4$
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336843-->
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END%%
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%%ANKI
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Cloze
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By convention, register {`%rsi`} is used for {the second integral argument}.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336847-->
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END%%
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%%ANKI
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Cloze
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{1:Words} are to {2:`%si`} whereas {2:double words} are to {1:`%esi`}.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336852-->
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END%%
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%%ANKI
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Cloze
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{1:Bytes} are to {2:`%sil`} whereas {2:quad words} are to {1:`%rsi`}.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336856-->
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END%%
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%%ANKI
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Basic
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How do you access the low-order 2 bytes of `%rsi`?
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Back: By using `%si`.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336860-->
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END%%
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%%ANKI
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Basic
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How do you access the low-order 4 bytes of `%rsi`?
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Back: By using `%esi`.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336864-->
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END%%
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%%ANKI
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Basic
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How do you access the low-order byte of `%rsi`?
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Back: By using `%sil`.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336868-->
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END%%
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%%ANKI
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Basic
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Which register should the second integral argument of a procedure be placed in?
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Back: `%rsi`
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336872-->
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END%%
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%%ANKI
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Basic
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From smallest to largest, list the four "second integral argument" registers.
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Back: `%sil`, `%si`, `%esi`, and `%rsi`.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336876-->
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END%%
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%%ANKI
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Cloze
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{1:`%rdi`} is to the {2:first} integral argument whereas {2:`%rsi`} is to the {1:second} integral argument.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1728559336879-->
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END%%
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## Bibliography
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* Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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