45,145 questions
-2
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1
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How did `masm32` get to be hosted on a separate website? [closed]
Here is the masm website https://www.microsoft.com/downloads/en/details.aspx?FamilyID=7a1c9da0-0510-44a2-b042-7ef370530c64
and here is that for masm32 : http://masm32.com/index.htm
When I run both ...
- 89
1
vote
1
answer
90
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How to write an infinite loop in MASM assembly? [closed]
Before I decided to ask, I checked and noticed a number of questions that request debugging their assembly program that has an infinite loop. In the program below however, I am trying to create an ...
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6
votes
1
answer
160
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Why are all IMUL µOPs dispatched to Port 1 only (on Haswell), even when multiple IMULs are executed in parallel?
I'm experimenting with the IMUL r64, r64 instruction on an Intel Xeon E5-1620 v3 (Haswell architecture, base clock 3.5 GHz, turbo boost up to 3.6 GHz, Hyper Threading is enabled).
My test loop is ...
- 101
0
votes
0
answers
38
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ida pro produced asm.file
I'm using IDA PRO for disassembling certain retro games and I have encountered a problem I can't fix anyhow.
I can export the .asm file with the disassembled code but it seems like I can't export the ...
8
votes
2
answers
81
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Why is the AL field (FP register usage count) necessary in the SysV ABI?
I was going through the System V AMD64 ABI and couldn’t find a clear explanation for why the AL field (which tracks how many floating-point registers are used) is necessary.
From my understanding, ...
- 139
-2
votes
0
answers
33
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how to translate (riscv) 'jr _start' to opcode
I have a question: How do I translate (RISC-V) 'jr _start' to an opcode?
I need this for jumping to the kernel in U-Boot.
Thank you
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4
votes
1
answer
176
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How do I make this, presumed, very basic DWARF example work, using dwarf.exp?
I need some help, trying to put this very basic DWARF example to work.
I found this link: Dwarf hello world assembly example or tutoral?, where the only answer says "...there is a simple "...
- 405
3
votes
1
answer
136
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INT 13, AH=42h fails with AH=1, CF=1
I am trying to write a simple bootloader which loads my program from LBA=1 into memory and jumps to its start. I emulate my bootloader in qemu with -drive flag passed. When I try to read blocks from ...
4
votes
1
answer
179
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Is 0x0000:0x7000 a unsafe address to load your kernel? Or is it just qemu annoying me
So I thought I'd try to make a DOS copy but it runs on a floppy and its just a simple plug and play with fat12 partition for user applications and drivers.
I first attempted to load my kernel using ...
- 91
0
votes
0
answers
111
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Why my x86 Asm code gets Segmentation fault?
I’m trying to make simple alloc and free functions from the ProgrammingGroundUp book but my code isn’t working and I’m kinda stuck.
I am using that commands when i compile the program.
as --32 myalloc....
3
votes
2
answers
100
views
Is there any way to move a string into a variable?
I was playing around in assembly and noticed that it's possible to overwrite a string in a variable as long as the new string does not exceed the size of the original string:
MESSAGE DB 'Hello World', ...
- 702
3
votes
2
answers
130
views
How to support Carryless Multiplication operation in .NET 8.0 on various platforms
I use Pclmulqdq.CarrylessMultiply method in .NET 8.0 / C# program. The method performs carryless multiplication using x86 processor instruction which is very fast.
Method documentation: https://learn....
- 6,727
2
votes
2
answers
113
views
16-bit x86 Assembly Kernel getting stuck when calling input function
Well, I'm writing my own OS just for fun, and I thought it would have been cool to add a bytecode "language" interpreted by the kernel itself. I took inspiration mainly from Java, which is ...
- 51
3
votes
0
answers
136
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Conditional / branching logic in C: Check for error first vs if/else? [closed]
Recently I've been finding myself wondering more and more what's the more "correct" way to write conditional logic in C, in particular, handling of errors vs success paths.
Should you ...
- 1,959
1
vote
0
answers
57
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RISC-V a1 register assumptions after ecall execution
As explained here it's clear to me that user-space calling conventions don't apply when dealing with kernel-space system call execution, so basically no register is clobbered after an ecall ...
