413 lines
14 KiB
Markdown
413 lines
14 KiB
Markdown
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---
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title: Arithmetic Operations
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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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### Load Effective Address
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| Instruction | Operands | Effect | Description |
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| ----------- | -------- | ------- | ---------------------- |
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| `leaq` | S, D | D <- &S | Load effective address |
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`leaq` is a variant of MOV. The first operand appears to be a memory address, but instead of reading from the designated location, the instruction copies the effective address to the designated location (a register).
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%%ANKI
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Basic
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`leaq` is considered a variant of what other instruction class?
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Back: `MOV`
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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: 1715780601450-->
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END%%
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%%ANKI
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Basic
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Why is the `leaq` instruction named the way it is?
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Back: It stands for **l**oad **e**ffective **a**ddress.
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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: 1715780601455-->
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END%%
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%%ANKI
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Cloze
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The {`leaq`} instruction is to x86-64 as the {`&`} operator is to C.
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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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Tags: c17
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<!--ID: 1715780601458-->
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END%%
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%%ANKI
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Basic
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Which x86-64 instruction is used to generate pointers?
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Back: `leaq`
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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: 1715780601461-->
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END%%
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%%ANKI
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Basic
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Why doesn't `leaq` have any other size variants?
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Back: x96-64 addresses are always 64-bit.
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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: 1715780601464-->
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END%%
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%%ANKI
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Basic
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Suppose `%rdx` contains $x$. Use `leaq` to set `%rax` to $5x + 7$.
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Back: `leaq 7(%rdx, %rdx, 4), %rax`
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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: 1715780601467-->
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END%%
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%%ANKI
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Basic
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Besides effective memory computations, how else is `leaq` used?
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Back: For certain arithmetic operations.
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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: 1715780601469-->
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END%%
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%%ANKI
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Basic
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Assume `%rdx` holds $q$. What is the value of `%rax` in the following?
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```asm
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leaq 9(%rdx),%rax
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```
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Back: $9 + q$
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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: 1715781031929-->
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END%%
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%%ANKI
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Basic
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Assume `%rbx` holds $p$ and `%rdx` holds $q$. What is the value of `%rax` in the following?
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```asm
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leaq (%rdx, %rbx),%rax
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```
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Back: $q + q$
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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: 1715781031935-->
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END%%
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%%ANKI
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Basic
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Assume `%rbx` holds $p$. What is the value of `%rax` in the following?
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```asm
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leaq 2(%rbx, %rbx, 7),%rax
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```
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Back: $2 + 8p$
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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: 1715781031938-->
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END%%
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%%ANKI
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Basic
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Assume `%rdx` holds $q$. What is the value of `%rax` in the following?
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```asm
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leaq 0xE(, %rdx, 3),%rax
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```
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Back: $14 + 3q$
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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: 1715781031941-->
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END%%
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### Unary Operations
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| Instruction | Operands | Effect | Description |
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| ----------- | -------- | ---------- | ----------- |
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| `inc[bwlq]` | D | D <- D + 1 | Increment |
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| `dec[bwlq]` | D | D <- D - 1 | Decrement |
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%%ANKI
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Basic
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What four variants do `INC` instructions take on in x86-64?
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Back: `incb`, `incw`, `incl`, `incq`
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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: 1716125986895-->
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END%%
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%%ANKI
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Basic
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Which instruction class corresponds to effect $D \leftarrow D + 1$?
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Back: `INC`
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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: 1716127743477-->
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END%%
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%%ANKI
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Basic
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What source/destination types are permitted in unary instructions?
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Back: Registers and memory 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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<!--ID: 1716125986904-->
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END%%
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%%ANKI
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Basic
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What do the instructions in the `INC` instruction class do?
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Back: Increments the specified destination by $1$.
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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: 1716125986907-->
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END%%
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%%ANKI
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Cloze
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The {`INC`} instruction class is to x86-64 whereas the {`++`} operator is to C.
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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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Tags: c17
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<!--ID: 1716126147793-->
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END%%
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%%ANKI
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Basic
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What do the instructions in the `DEC` instruction class do?
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Back: Decrements the specified destination by $1$.
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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: 1716125986910-->
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END%%
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%%ANKI
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Basic
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Which instruction class corresponds to effect $D \leftarrow D - 1$?
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Back: `DEC`
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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: 1716127743483-->
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END%%
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%%ANKI
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Cloze
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The {`DEC`} instruction class is to x86-64 whereas the {`--`} operator is to C.
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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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Tags: c17
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<!--ID: 1716126147798-->
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END%%
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### Binary Operations
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| Instruction | Operands | Effect | Description |
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| ------------ | -------- | ----------- | -------------- |
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| `add[bwlq]` | S, D | D <- D + S | Addition |
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| `sub[bwlq]` | S, D | D <- D - S | Subtraction |
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| `imul[bwlq]` | S, D | D <- D * S | Multiplication |
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%%ANKI
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Basic
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What four variants do `ADD` instructions take on in x86-64?
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Back: `addb`, `addw`, `addl`, `addq`
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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: 1716127743491-->
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END%%
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%%ANKI
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Basic
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What combination of source and destination types is prohibited in `ADD` instructions?
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Back: A source and destination memory 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: 1716127743494-->
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END%%
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%%ANKI
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Basic
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Which instruction class corresponds to effect $D \leftarrow D + S$?
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Back: `ADD`
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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: 1716127743497-->
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END%%
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%%ANKI
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Cloze
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The {`ADD`} instruction class is to x86-64 as the {`+=`} operator is to C.
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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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Tags: c17
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<!--ID: 1716128138030-->
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END%%
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%%ANKI
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Basic
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Which instruction class corresponds to effect $D \leftarrow D - S$?
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Back: `SUB`
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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: 1716127743500-->
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END%%
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%%ANKI
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Basic
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Which `SUB` instruction is equivalent to `decq %rcx`?
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Back:
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```asm
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subq $1, %rcx
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```
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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: 1716127853102-->
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END%%
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%%ANKI
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Basic
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How does Bryant et al. recommend reading `SUB` instructions?
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Back: As subtracting the first operand *from* the second.
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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: 1716127853106-->
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END%%
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%%ANKI
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Cloze
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The {`SUB`} instruction class is to x86-64 as the {`-=`} operator is to C.
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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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Tags: c17
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<!--ID: 1716128138033-->
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END%%
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%%ANKI
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Basic
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Which instruction class corresponds to effect $D \leftarrow D * S$?
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Back: `IMUL`
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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: 1716127743502-->
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END%%
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%%ANKI
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Cloze
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The {`IMUL`} instruction class is to x86-64 as the {`*=`} operator is to C.
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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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Tags: c17
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<!--ID: 1716128138036-->
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END%%
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### Shift Operations
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| Instruction | Operands | Effect | Description |
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| ----------- | -------- | ------------ | ---------------------- |
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| `sal[bwlq]` | k, D | D <- D << k | Left shift |
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| `shl[bwlq]` | k, D | D <- D << k | Left shift |
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| `sar[bwlq]` | k, D | D <- D >> k | Arithmetic right shift |
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| `shr[bwlq]` | k, D | D <- D >>> k | Logical right shift |
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%%ANKI
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Basic
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What do instructions in the `SAL` instruction class do?
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Back: Performs a left shift.
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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: 1716226827710-->
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END%%
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%%ANKI
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Basic
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What do instructions in the `SHL` instruction class do?
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Back: Performs a left shift.
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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: 1716226827717-->
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END%%
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%%ANKI
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Basic
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Which instruction classes are related to left shifts?
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Back: `SAL` and `SHL`.
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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: 1716226827720-->
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END%%
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%%ANKI
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Basic
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Which instruction classes are related to right shifts?
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Back: `SAR` and `SHR`.
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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: 1716226827723-->
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END%%
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%%ANKI
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Basic
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What do instructions in the `SAR` instruction class do?
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Back: Performs an arithmetic right shift.
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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: 1716226827725-->
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END%%
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%%ANKI
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Basic
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What do instructions in the `SHR` instruction class do?
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Back: Performs a logical right shift.
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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: 1716226827729-->
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END%%
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%%ANKI
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Basic
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What distinguishes the `SAR` and `SHR` instruction classes?
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Back: The former is arithmetic whereas the latter is logical.
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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: 1716226827732-->
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END%%
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%%ANKI
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Basic
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What distinguishes the `SAL` and `SHL` instruction classes?
|
||
|
|
Back: N/A.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1716226827736-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
Which register do shift operations refer to?
|
||
|
|
Back: `%cl`
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1716226827740-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
How many lower-order bits of `%cl` does e.g. `salb` look at?
|
||
|
|
Back: $3$
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1716226827744-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
What can the source of a shift operation be?
|
||
|
|
Back: An immediate or the `%cl` register.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1716226827748-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
What can the destination of a shift operation be?
|
||
|
|
Back: A register or memory location.
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1716226827752-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
How many lower-order bits of `%cl` does e.g. `salw` look at?
|
||
|
|
Back: $4$
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1716226827756-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
How many lower-order bits of `%cl` does e.g. `sall` look at?
|
||
|
|
Back: $5$
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1716226827760-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
%%ANKI
|
||
|
|
Basic
|
||
|
|
How many lower-order bits of `%cl` does e.g. `salq` look at?
|
||
|
|
Back: $6$
|
||
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
||
|
|
<!--ID: 1716226827764-->
|
||
|
|
END%%
|
||
|
|
|
||
|
|
## Bibliography
|
||
|
|
|
||
|
|
* Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|