Questions tagged [assembly]
Assembly language questions. Please tag the processor and/or the instruction set you are using, as well as the assembler, a valid set should be like this: ([assembly] [x86] [gnu-assembler] or [att]). Use the [.net-assembly] tag instead for .NET assemblies, [cil] for .NET assembly language, [wasm] for web assembly, and for Java bytecode, use the tag java-bytecode-asm instead.
assembly
44,617
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When an embedded c program is created, why is there extra machine code around my compiled c program?
This C program blinks an LED attached to an AVR ATmega32u4.
ISR(TIMER1_OVF_vect) // attach Interrupt Sub Routine to TIMER1
{
// toggle LED
PIND = (1 << PIND5); // #define PIND (*(...
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0
answers
22
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Difference between comiss and comisd in x64 asm
I wrote some code to compare the value of xmm10 and xmm6 using:
comiss xmm10, xmm6 and then comisd xmm10, xmm6
The first one works, and the second one doesn't.
I tried using subss xmm10, xmm6 followed ...
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37
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Why is my array value not equal to a literal?
I am new to assembly and was trying to work with an array. However, I was geting caught when try to compare the array value to a constant stored in a register.
From the following code I was expecting ...
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Printing 2D array in MIPS
I have been using a few other posts on here to try and figure out what I am doing wrong but I am stuck and could use some help. I am making a game that has an 8x8 "board" (2d array) similar ...
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1
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29
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What is wrong with this control for the brightness of a lamp in ATmega328P?
I'm new to assembly and I'm trying to develop a control for the brightness of a lamp for my college. The lamp must have 5 distinct levels of brightness, one off and four levels with gradual increase. ...
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43
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signal SIGSEGV: address access protected in __run_exit_handlers
I'm trying to do a packer project for my school, it is made in C and ASM, and for the moment it is supposed to target only ELF files.
I have managed to do my section injection, correctly align my new ...
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votes
1
answer
38
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CMake does not compile asm-files (cross-compile)
We set up our build system with CMake and besides C and C++-files we need to compile asm-files (.s).
We use a tiarmclang-compiler (LTS3.2.0) and thus need to crosscompile.
While everything works for C ...
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1
answer
88
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multidimensional slice access performance in golang
I am working on a little and simple game-of-life in Golang and stumbled on a performance problem during slice access.
This is the primary data structure for the game:
type Neighbor struct {
X, Y ...
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53
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Why does gdb combine byte values when examining memory as words? [closed]
While examining 4 addresses from $rip as bytes in GDB, it shows 4 individual values. However, when I examine the same addresses as words, it combines that 4 byte values into a single word value. Why ...
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54
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NASM ORG doesn't like SECTION [closed]
Looks like NASM ORG directive doesn't behave correctly in the presence of SECTION directive, in spite that it's compiled to the binary format. I wonder if there's an alternative for ORG in NASM which ...
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35
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I'm trying to build a nand2tetris assembler but the ply.lex library in python keep breaking my assembly instructions to different lines
the first thought I had was that I didn't manage to handle the new line character properly because it keeps throwing the new line character "\n" whenever I try to append the instructions for ...
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32
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Unable to compile NASM without -no_pie on macOS
I'm trying to follow the tutorial for NASM and I made a few adjustments (like changing the entrypoint function from "start" to "_main") to get the following hello.asm to compile ...
1
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1
answer
47
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data segment of AVR store nonsense after compiling
So i'm trying to change the first element of an array that i'm storing in sram and i checked if the data after compile is equal to the value of pre-initialaztion and it wasn't equal. so this my code:
....
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42
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Why do I keep getting a Segmentation Fault from trying to access /dev/mem in ARM64 on the Raspberry Pi 4?
I've been working at this program for months, and I've fixed many errors, errors with alignment, other segmentation faults, and I've gotten down to this one, where it throws a segmentation fault when ...
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1
answer
53
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gnu inline assembly constraint `i` for memory address
Recetly, this function rip_rel_ptr has been added to Linux kernel.
https://elixir.bootlin.com/linux/latest/source/arch/x86/include/asm/asm.h#L118.
I can compile the kernel, but when I copy this ...
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How to run an LC-3 Assembly program
I am creating an LC-3 Assembly program. I have managed to assemble it into an obj file. I'm not sure what linker to use / what arguments to use from here. Any help would be much appreciated.
I tried ...
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49
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How can I get this STDIN to work in GAS Assembler running on Linux?
I am new to Assembler and am currently reading a book about it by Jonathan Bartlett called 'Learn to Program with Assembly'. On pages 160-1 he gives the following sample program to demonstrate the use ...
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32
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Is there a library to reassemble and rebuild Windows PE binary? [closed]
I want to disassemble a x64 PE binary, add my own inline assembly code somewhere inside the .text section (or any other executable section), and then assemble the binary back and expect it to work.
I'...
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30
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Why is my assembly code giving extra output? [duplicate]
Before I start, it's important to say I am a complete beginner to Assembly, so I might be missing something very obvious.
I was trying to make an Assembly program where it prints the following output ...
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48
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Assembly jump instructions don't seem to work
bits 64
default rel
section .data
fmt db "%s", 0xd, 0xa, 0
err db "Correct usage: echo <string>"
section .text
extern printf
extern ExitProcess
global ...
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2
answers
56
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RISC V : I don't understand what the GNU assembler does with labels in the .data segment
I am making my own risc V core as a personal project using the RV32I ISA, I am using a Harvard memory architecture meaning I have a program memory that starts at address 0x0 and a separate data memory ...
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1
answer
40
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how to use speaker (msdos) in new computers? [closed]
I'm programming in assembly, and want to use the speaker, I can do that with out 43, al and out 61, al, this in Dosbox. But i've a notebook with DOS 6.22 in hd, all the program works well, but the ...
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1
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56
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Updating an element in array in AVR Assembly
so i'm trying to update an element in array which get used to print the value inside it but after updating the array, what gets printed is still same, the printer used array buffer and i wanna get the ...
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1
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1
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56
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What are the binary representations for the flags used in the Linux open() syscall?
I am learning NASM and currently unsure what values should be used for the flags argument for open() as shown in the man page. I'm mainly asking this for clarification so I don't mess something up, ...
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1
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38
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Code in assembly printing alphabets twice instead of next line. (emu8086)
My code in assembly emu 8086 displays alphabets in lower case but it displays them twice instead of
displaying them in new line a single time each. Ive tried everything from AI etc but could not find ...
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1
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30
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Order in which instructions are printed/executed
Why the output is in diffrent order than it is declared?
Shouldnt the output be in this order?
aaaa
bbbb
cccc
Instead it is:
I assume the issue is in assigning "bbb" value to the text ...
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0
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82
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x86 mulss result is diffrent over time [closed]
I am trying to make C++ neural network library and I noticed, that sometimes model with same inputs and same parameter values drastically changes output for no reason. I have no idea why it happens, ...
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1
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How can we read program counter through assembly code in 68k microcontroller
Can anybody please explain how program counter can be read using assembly instruction in MC68000 controller.
Following instruction set gave error - undefined addressing mode
MOVE.L %PC, %D0
Also ...
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0
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how to add an additional dll to an exe file and force it to use
I have an exe file in which I want to make some corrections to the binary code, but I want to do this not just by editing bytes but by using an additional dll, which should patch the current ...
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1
answer
37
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How to read the Marie Programme table? [closed]
I want to know how i can read the Marie Simulator table. Im still a beginner to this so can someone explains how the output works in this following example code?
Load x
add y
store z
halt
x, hex 008E
...
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