Questions related to the assembler `mov` instruction
The assembler mov instruction loads an immediate value into an register or transfers data between register and register or register and memory. See:
Questions tagged [mov]
296 questions
10
votes
1 answer
x86 Instruction help: MOV [edx], eax
I'm reading through a book that is describing C linked lists and how they are represented within x86 ASM. I having difficulty understanding the instruction MOV [edx], eax.
If the instruction was reversed, MOV eax, [edx], I would understand it to…
Chuck
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9
votes
1 answer
Error: Operation size not specified - NASM
I'm working in 16 bit NASM assembly having an issue where my code won't build. The error happens on all the MOV lines here:
section .bss
x_coord RESB 8 ; [x_coord] is the head, [x_coord+2] is the next cell, etc.
y_coord RESB 8 ; Same here
…
Nat
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9
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1 answer
Learning about basic example of function call in SPARC assembly
I am learning SPARC assembly with a simple example that you can see below. I have several questions about this example which shows passing parameters for a procedure.
In main section, I set 5 to first input parameter %o0 and 7 to second input…
user1773603
8
votes
3 answers
iOS Extracting Audio from .mov file
I've been trying to extract audio from a .mov file for a while now and I just can't seem to get it working. Specifically, I need to extract the audio and save it as an .aif or .aiff file .
I've tried using an AVMutableComposition, and loading the…
Grinneh
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8
votes
1 answer
mov %eax,(%esp)
What is the difference between the following statements?
mov %eax,%esp
mov %eax,(%esp)
I'm working on diffusing a binary bomb and am having trouble with a few of the mov and leal commands early on in the assembly.
arc
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7
votes
1 answer
Convert .mov to .mp4 and keep alpha channel using FFMPEG
I am trying to convert a .mov file that is Quicktime with Alpha Channel to a .mp4 movie. I am using FFMPEG and I can successfully convert the video to a .mp4 video, but I loose the alpha channel.
Here is the command I am running:
ffmpeg -i…
Mark S.
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7
votes
1 answer
Converting mov to mp4 with ffmpeg better quality
I want to convert mov videos to mp4. Currentoy I manage this with ffmpeg via bash with the following call:
ffmpeg -i input.mov -f mp4 -vcodec mpeg2video -acodec mp3 output.mp4
Yes that works, but the quality is abysmal. My 50Mb is shrunken to a…
Calamity Jane
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7
votes
2 answers
assembly "mov" instruction
I'm learning assembly by comparing a c program to its assembly equivalent.
Here is the code.
.file "ex3.c"
.section .rodata
.LC0:
.string "I am %d years old.\n"
.LC1:
.string "I am %d inches tall.\n"
.text
.globl main
.type…
user2263800
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1 answer
How to make x=2a+3b in 4 instructions limit using ONLY mov,add,sub,neg?
Let's say x is a register which its value isn't known.
I have to make x=2a+3b where a and b have unknown values.
I can use the 8086 asm instructions mov, add, sub, neg only.
The use of the mul instruction isn't allowed, and also there is a limit of…
Lior
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6
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2 answers
meanings of mov instruction with or without [] brackets around the source register in nasm
I'm a little bit rusty on Assembly. I want to ask you guys some questions.
Are these assembly instructions valid in NASM?
What are the differences, and when should we use them?
mov EAX, EBX
vs
mov EAX, [EBX]
user188276
5
votes
1 answer
Why movzbl is used in assembly when casting unsigned char to signed data types?
I'm learning data movement(MOV) in assembly.
I tried to compile some code to see the assembly in a x86_64 Ubuntu 18.04 machine:
typedef unsigned char src_t;
typedef xxx dst_t;
dst_t cast(src_t *sp, dst_t *dp) {
*dp = (dst_t)*sp;
return…
Sean
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5
votes
2 answers
How to play mov videos from react native app in android?
I have tried multiple modules for playing mov videos from react native app in android. But none worked. Any idea?
react-native-video-player (error can't play this video)
react-native-media-player (java error)
react-native-android-video-player (java…
Harikrishnan
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5
votes
1 answer
NASM and 8-bit memory offset confusion
From the Intel Software Developer Manual (referred to as ISDM in this post) and the x86 Instruction Set Reference (which, I assume, is just a copy of the former), we know that the mov instruction can move data from eax/ax/al to a memory offset and…
ForceBru
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5
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4 answers
MASM Assembly move 8 bit register to the 16 bit register (ie. mov cx, ch)
I decided to learn an assembly programming language. I am using this 8086 tutorial. At the bottom the exercise is to find an error in some instructions and one of them is
mov cx, ch
I found some similar question on SO on this topic explaining how…
Bartłomiej Szałach
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5
votes
2 answers
What is the meaning of MOV (%r11,%r12,1), %edx?
What does this instruction do?
mov (%r11,%r12,1), %edx
anonymous