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Aug 27, 2024vercetti322
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x86 MASM C Linking

Jun 30, 2021LeifMessinger

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;Main.asm
.386
.model small,c ;This bit is important, I think.
.stack 1000h
.data
hello db "Hello world!",0
.code
;includelib libucrt.lib ;All this shit is already here if you have a C object file
includelib legacy_stdio_definitions.lib ;Except for this. Basically printf, puts etc
;includelib libcmt.lib
;includelib libvcruntime.lib ;Visual Studio exception handling and type checking. Not needed otherwise
extrn printf:near ;Extern everything you are gonna use from the c obj files
extrn plusTwo:near
extrn exit:near
public plusOne ;Have to declare it public for the linker to see it. In NASM, it's .globl or global
plusOne proc ;Our int plusOne(int) function.
pop eax ;Parameters are stored on the stack.
add eax, 1
ret ;eax is whatever is returned from functions. Also why you can only return one thing.
plusOne endp
public main
main proc
push offset hello
call printf
push 1
call plusTwo
push 0
call exit
main endp
end ;End of file, not program
//bruh.c
//#include <stdio.h> Has to be included with "includelib legacy_stdio_definitions.lib" in the asm file for some reason.
//int printf(const char* format, ...);
extern int plusOne(int); //Extern everything you are gonna use from the asm obj files
int plusTwo(int num) {
return plusOne(plusOne(num)); //Plus one is defined in the assembly.
}

MASM Over Explained

Jun 29, 2021LeifMessinger

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; Sample project from the video "Setup Visual Studio for Assembly MASM" https://www.youtube.com/watch?v=LqyVybUodXE
; Basically reverses a string using the stack. It stores the result where the string was defined, modifying the string itself in memory.
.386
;x86 instruction set. This is only nessesary in x32 MASM.
.model flat, stdcall
;Defines the memory model, and the calling convention http://masm32.com/board/index.php?topic=6942.msg74381#msg74381
.stack 4096
;Sets the size of the stack. 4096 is 1024*4 which is 4 kilobytes.
;option casemap:none
;Make labels case sensitive, so things like ExitProcess and exitprocess and myName and myname are different.
;include \masm32\include\windows.inc
;include \masm32\include\kernel32.inc
;includelib \masm32\lib\kernel32.lib
;Some system calls or something are defined here. Not needed if you just use assembly along side c++ or c. Also can't be used if on anything other than windows.
ExitProcess PROTO, dwEXITCODE:DWORD
;Define the ExitProcess function prototype. ExitProcess is defined somewhere in the Windows API on the OS level.
.data
;Starts the data section of the program, where a lot of read-write memory is needed
myName BYTE "Leif Messinger", 0
;Allocates a string named myName initialized with LeifMessinger followed by a terminating null character
myNameLength = ($ - myName) - 1
;Allocates a 32 bit number which is initialized to be the current pointer ($), minus the pointer to the start of the string, minus one (because of the null terminating character)
.code
;Starts the section of the program where your code goes. Is the same as .text, and in theory, the name doesn't even matter. The importance is that it ends the data section, which was read-write. Code should be read only.
main PROC
;States the start of the main procedure. This is where the program starts executing.
mov ecx, myNameLength
;Sets the loop counter to myNameLength. The loop counts backwards until it reaches zero, meaning that it loops myNameLength times.
mov esi, 0
;Sets the general purpose register esi to 0. esi was named because it's a "source index" when moving stuff. It's basically like an i variable in c.
StackIt:
;Flag to the start of the loop. Ahh, tss push it
movzx eax, myName[esi]
;movzx stands for move with zero extend. It pads the source data (myName[esi]) with enough zeros to fill 32 bits, or enough for the push and pop instructions.
push eax
;Pushes the character we just got out of that string (and padded with zeros) to the stack
inc esi
;Increments our index
loop StackIt
;Decrements ecx and checks if it is equal to 0. If it isn't, jump to StackIt
mov ecx, myNameLength
;Sets the loop counter to myNameLength. The loop counts backwards until it reaches zero, meaning that it loops myNameLength times.
mov esi, 0
;Sets the general purpose register esi to 0. esi was named because it's a "source index" when moving stuff. It's basically like an i variable in c.
PopIt:
;Flag to the start of the loop.
pop eax
;Pops a 32 bit number off the stack and places it in eax
mov myName[esi], al
;Move the lower byte of eax (al) to the string (myName) at the index esi. This overwrites one character of the string.
inc esi
;Increments our index
loop PopIt
;Decrements ecx and checks if it is equal to 0. If it isn't, jump to StackIt
INVOKE ExitProcess, 0
;Exits the program with the error code of 0. The return type was declared in that prototype at the top, and defined by the operating system
main ENDP
;States the end of the main procedure
END main
;Declares the end of the file. Also defines where the start of the program is, which is main.
;Normally the linker looks for main as a place to start, but if you are writing pure assembly, that is need.
;Saying END without a pointer to the start is also alowed for people who like to live dangerously.

default netplan

Nov 18, 2022AustinLeath

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# This is the network config written by 'subiquity'
network:
ethernets:
enp0s3:
dhcp4: yes
nameservers:
addresses: [8.8.8.8,8.8.4.4]
version: 2

AWS EC2 Cloud-Init User Detail

Nov 18, 2022AustinLeath

0 likes • 10 views

#!/bin/bash
yum -y install httpd
systemctl enable httpd
systemctl start httpd
hostname > /var/www/html/index.html

Untitled

Aug 7, 2024naiferomar366-60ef

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aaaa

Untitled

Sep 27, 2024popeyevn

0 likes • 1 view

alert('123');