x86-64 assembly language

Question 1

how to assemble .asm file with yasm to get object .o file

Answer 1

yasm -g dwarf2 -f elf64 example.asm -l example.txt

Question 2

-g dwarf2

Answer 2

informs assembler to include debugging info in object file

Question 3

-f elf64

Answer 3

informs assembler to create object file in ELF64 format

Question 4

example.asm

Answer 4

name of assembly language source file

Question 5

-l example.txt

Answer 5

informs assembler to create list file named example.list

Question 6

link object files with ld to get executable program

Answer 6

ld -g -o example example.o

Question 7

-g

Answer 7

informs linker to include debugging info in final executable file

Question 8

-o example

Answer 8

specify and create executable file named example

Question 9

data section of program

Answer 9

section .data; holds initialized variables and constants

Question 10

variable format

Answer 10

<variableName> <dataType> <initialValue>
</initialValue></dataType></variableName>

Question 11

text section of program

Answer 11

section .text; includes instructions

Question 12

starting text section

Answer 12

global _start
_start:

Question 13

(data types) db

Answer 13

8-bits

Question 14

(data types) dw

Answer 14

16-bits

Question 15

(data types) dd

Answer 15

32-bits

Question 16

(data types) dq

Answer 16

64-bits

Question 17

(data types) ddq

Answer 17

128-bit integer

Question 18

(data types) dt

Answer 18

128-bit float

Question 19

(data declarations) _Var

Answer 19

_bit variable (wVar dw = declaring 16 bit variable)

Question 20

(data declarations) cVar

Answer 20

single character (8 bits)

Question 21

(data declarations) strng

Answer 21

string

Question 22

(data declarations) arr

Answer 22

array

Question 23

(data declarations) flt1

Answer 23

float

Question 24

constants are defined as

Answer 24

equ

Question 25

lowest 32-bits registers

Answer 25

eax, ebx, ecx, edx, esi, edi, ebp, esp, r8d-r15d

Question 26

64 bit registers

Answer 26

rax, rbx, rcx, rdx, rsi, rdi, rbp, rsp, r8-r15

Question 27

how to access memory

Answer 27

brackets

Question 28

brackets vs no brackets

Answer 28

no brackets obtain address of item, brackets access memory / value stored

Question 29

size qualifiers

Answer 29

byte, dword, qword

Question 30

labels

Answer 30

target or location to jump to for control statements (.loopStart) will know to jump back to that label

Question 31

global

Answer 31

means label will be accessible from outside the file

Question 32

to access variables not in current file

Answer 32

extern

Question 33

addition

Answer 33

add

Question 34

subtraction

Answer 34

sub

Question 35

increment

Answer 35

inc

Question 36

decrement

Answer 36

dec

Question 37

multiplication

Answer 37

imul

Question 38

division

Answer 38

div

Question 39

and

Answer 39

and

Question 40

or

Answer 40

or

Question 41

not

Answer 41

not

Question 42

shift right

Answer 42

shr ,

Question 43

shift right

Answer 43

shr , cl

Question 44

shift left

Answer 44

shl ,

Question 45

shift left

Answer 45

shl , cl

Question 46

shift arithmetic right

Answer 46

sar ,

Question 47

shift arithmetic right

Answer 47

sar , cl

Question 48

jump

Answer 48

jmp

Question 49

compare

Answer 49

cmp

Question 50

jump if equal

Answer 50

je

Question 51

jump if not equal

Answer 51

jne

Question 52

jump if greater than

Answer 52

jg

Question 53

jump if greater or equal

Answer 53

jge

Question 54

jump if less

Answer 54

jl

Question 55

jump if less or equal

Answer 55

jle

Question 56

call

Answer 56

call

Question 57

return

Answer 57

ret

Question 58

put on stack

Answer 58

push

Question 59

take off stack

Answer 59

pop

Question 60

pushing examples

Answer 60

push rax push qword [qVal] --> value push qVal --> address

Question 61

pushing meaning

Answer 61

push 64 bit operand onto stack; first adjust rsp (rsp-8); copy operand to rsp

Question 62

pop meaning

Answer 62

pop 64 bit from the stack; first adjust rsp (rsp+8)

Question 63

item on top of stack

Answer 63

rsp

Question 64

second item on stack

Answer 64

rsp+8

Question 65

third item on stack

Answer 65

rsp+16

Question 66

rip register

Answer 66

points to next instruction to be executed

Question 67

call function

Answer 67

transfer control to named function; saves return address (where to go when function completes); places rip register onto stack

Question 68

ret function

Answer 68

pops current top of stack (rsp) into rip

Question 69

(accessing array elements) [A+8]

Answer 69

value stored at address A plus 8 bits

Question 70

(accessing array elements) general form

Answer 70

base + register * scale + displacement

Question 71

function declaration

Answer 71

global : ; function body ret

Question 72

rsp

Answer 72

stack pointer register

Question 73

rbp

Answer 73

stack base pointer