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
44,628
questions
-1
votes
0
answers
5
views
How to overwrite a string in NASM
im writing my own programming language and im unsure on how to overwrite a string, whats the fastest way given two string to overlap one of them with the value of the other?
for an example this is how ...
- 25
0
votes
0
answers
25
views
How can i use functions from libc in NASM 64 bit
im making my own programming language and i wanted to call some functions from libc (es strcat and printf) but im unsure on how to call them correctly(i dont which cpu registry to use and if i have to ...
- 25
0
votes
0
answers
17
views
Cypress PSoC1 assembly OR
I'm trying to write ad educational emulator of PSoC1 microcontroller.
Right now I'm testing the result of my preliminary coding and cross-checking it with microcontroller manual(s) to check if the ...
- 926
1
vote
1
answer
28
views
z80 assembler ret z; and a; ret
I have the following Z80 asm code (from pokemon legacy crystal)
CheckOnWater::
ld a, [wPlayerStandingTile]
call GetTileCollision
sub WATER_TILE
ret z
and a
ret
i was wondering ...
- 1,738
0
votes
1
answer
52
views
How to use x86-64 SIMD vector instructions and registers for polynomial evaluation
I need to write a x86-64 assembly function that uses x86 vector/SIMD instructions and the %ymm registers to evaluate this expression: x*(x*(a*x + b) + c) + d.
The function will have this signature: ...
- 25
2
votes
2
answers
57
views
Using printf from c in Nasm causes the string to add random end line statment
this morning i tried to make a simple output library for my asm projects, i realized using the sys call each time is a waste of time and so i decided to automatize the program using printf function ...
- 25
0
votes
0
answers
43
views
Disabling write protection on Windows
I've been learning win internals and I came across an interesting thing called Write Protection.
I know Windows relies on interrupts but I don't know any other way to do this.
I decided to try it ...
- 1
0
votes
0
answers
27
views
pwntools p32(arg1) got issue when arg1=10, maybe because 0xa
I was tring to learn stackoverflow so I wrote me a program, here's the source code:
# include <stdio.h>
void pwn(int a, int b) {
printf("Pwned! arg1 = %d, arg2 = %d\n", a, b);
}
...
- 1
0
votes
2
answers
28
views
How to print in NASM assembly
i've made a simple print function in assembly which does not work as intended.
The function should print only the msg variable but instead its printing all the variables declared
this is the code
...
- 25
0
votes
2
answers
37
views
JAL- RICSV Architecture
Why immediate[0] is set to zero for jump and link instruction in riscv architecture? What is the main purpose do do that?
I am not sure of whether the JAL is a PC relative instruction and even if it ...
2
votes
0
answers
50
views
ARM Cortex M4 context switching: How does the hardware know where xPSR, PC, LR, R12, R3-R0 are on the stack?
I'm working on a context switching mechanism for my RTOS which runs on Cortex-Ms.
When I initialize a task's stack, I have it like this
Then, I decrement the stack pointer 8 times to fit R11-R4.
I ...
- 33
0
votes
0
answers
45
views
Bootloader randomly jumping to address
For some reason here I'm very confused why its jumping to putsc16 after returning from puts32_done? I Tried investigating this heavily but so far no bite, would appreciate some guidance. All code is ...
- 4,606
3
votes
2
answers
125
views
Why does this assembly implementation of strcmp behave unexpectedly?
I've been writing my own naive implementation of the strcmp function in x86_64 assembly.
I've written a c test program to compare the behavior with the real strcmp from the C library.
Even if both ...
- 31
0
votes
0
answers
40
views
cc -o out out.s on macOS with M1 chip
I have been learning the chapter of 04_Assemblyhttps://github.com/DoctorWkt/acwj/tree/master/04_Assembly. According to the README.md, after I typed cc -o comp1 -g cg.c expr.c gen.c interp.c main.c ...
- 165
0
votes
0
answers
56
views
Create buffer on stack in x86_64 assembly to print number
when trying to print numbers in assembly instead of number i'm getting O=N84NioR/\_dsPfec IS/pRDNui/0SmL3lSegmentation fault
i'm using Linux with NASM
my code is:
_printNum: ;prints number stored ...
- 1