10 KiB
| title | TARGET DECK | FILE TAGS | tags | |
|---|---|---|---|---|
| Registers | Obsidian::STEM | x86-64 |
|
Overview
An x86-64 CPU contains a set of 16 general-purpose registers storing 64-bit values. They are used to store integers and pointers.
| 1 Byte | 2 Bytes | 4 Bytes | 8 Bytes | Purpose |
|---|---|---|---|---|
%al |
%ax |
%eax |
%rax |
Return value |
%bl |
%bx |
%ebx |
%rbx |
Callee saved |
%cl |
%cx |
%ecx |
%rcx |
4th argument |
%dl |
%dx |
%edx |
%rdx |
3rd argument |
%sil |
%si |
%esi |
%rsi |
2nd argument |
%dil |
%di |
%edi |
%rdi |
1st argument |
%bpl |
%bp |
%ebp |
%rbp |
Callee saved |
%spl |
%sp |
%esp |
%rsp |
Stack pointer |
%r8b |
%r8w |
%r8d |
%r8 |
5th argument |
%r9b |
%r9w |
%r9d |
%r9 |
6th argument |
%r10b |
%r10w |
%r10d |
%r10 |
Caller saved |
%r11b |
%r11w |
%r11d |
%r11 |
Caller saved |
%r12b |
%r12w |
%r12d |
%r12 |
Callee saved |
%r13b |
%r13w |
%r13d |
%r13 |
Callee saved |
%r14b |
%r14w |
%r14d |
%r14 |
Callee saved |
%r15b |
%r15w |
%r15d |
%r15 |
Callee saved |
%%ANKI Basic How many general-purpose registers are available to x86-64 instructions? Back: 16 Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
END%%
%%ANKI
Cloze
The x86 64-bit registers all start with prefix {%r}.
Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
END%%
%%ANKI
Cloze
The x86 32-bit registers all start with prefix {%e}.
Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
END%%
%%ANKI Basic Instructions that generate 1-byte quantities do what to the remaining bytes of a register? Back: Leaves them alone. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
END%%
%%ANKI Basic Instructions that generate 2-byte quantities do what to the remaining bytes of a register? Back: Leaves them alone. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
END%%
%%ANKI Basic Instructions that generate 4-byte quantities do what to the remaining bytes of a register? Back: Zeroes them out. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
END%%
%%ANKI Basic Instructions that generate 8-byte quantities do what to the remaining bytes of a register? 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.
END%%
The CPU also maintains a set of single-bit condition code registers describing attributes of the most recent arithmetic or logical operation.
| Code | Name | Description |
|---|---|---|
CF |
Carry flag | The most recent operation generated a carry out of the most significant bit. |
ZF |
Zero flag | The most recent operation yielded zero. |
SF |
Sign flag | The most recent operation yielded a negative value. |
OF |
Overflow flag | The most recent operation caused a two's-complement overflow. |
%%ANKI Basic Condition code registers describe attributes of what kind of operations? Back: Arithmetic and logical. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
END%%
%%ANKI Cloze {Condition code} registers describe attributes of the most recent arithmetic/logical operation. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
END%%
%%ANKI Basic How large is a condition code register? Back: A single bit. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
END%%
%%ANKI
Basic
CF and SF are examples of what?
Back: Condition codes.
Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
END%%
%%ANKI
Basic
Condition code CF is an acronym for what?
Back: Carry flag.
Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
END%%
%%ANKI
Basic
Condition code ZF is an acronym for what?
Back: Zero flag.
Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
END%%
%%ANKI
Basic
When is the ZF condition code set?
Back: When the most recent operation yielded a zero.
Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
END%%
%%ANKI
Basic
Condition code SF is an acronym for what?
Back: Sign flag.
Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
END%%
%%ANKI
Basic
When is the SF condition code set?
Back: When the most recent operation yielded a negative value.
Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
END%%
%%ANKI
Basic
Condition code OF is an acronym for what?
Back: Overflow flag.
Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
END%%
%%ANKI
Basic
Which condition code is checked for unsigned overflow?
Back: CF
Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
END%%
%%ANKI
Basic
When is the CF condition code set?
Back: When the most recent operation generated a carry out of the most significant bit.
Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
END%%
%%ANKI
Basic
Which condition code is checked for two's-complement positive overflow?
Back: OF
Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
END%%
%%ANKI
Basic
When is the OF condition code set?
Back: When the most recent operation caused a two's-complement overflow.
Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
END%%
%%ANKI
Basic
Which condition code is checked for two's-complement negative overflow?
Back: OF
Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
END%%
%%ANKI
Basic
Evaluate int t = a + b for int a and b. When is CF set?
Back: When (unsigned) t < (unsigned) a.
Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
Tags: c17
END%%
%%ANKI
Basic
Evaluate int t = a + b for int a and b. When is ZF set?
Back: When t == 0.
Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
Tags: c17
END%%
%%ANKI
Basic
Evaluate int t = a + b for int a and b. When is SF set?
Back: When t < 0.
Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
Tags: c17
END%%
%%ANKI
Basic
Evaluate int t = a + b for int a and b. When is OF set?
Back: When (t <= 0 && a > 0 && b > 0) || (t >= 0 && a < 0 && b < 0).
Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
Tags: c17
END%%
%%ANKI
Basic
Which "arithmetic" instruction does not alter condition codes?
Back: leaq
Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
END%%
%%ANKI
Basic
Why doesn't leaq alter condition codes?
Back: It is intended for address computation.
Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
END%%
Bibliography
- Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.