Hello Neighbour Mac OS X is one of the best games from this genre, we have no doubts about it. Released at the end of 2017 this game features modern graphics and a brand new AI system. This one is very well optimized and it adapts to the player’s choices and gameplay.
Many assembly tutorials and books doesn’t coverhow to write a simple assembly program on the Mac OS X.Here are some baby steps that can help people whoare also interested in assembly to get startedeasier.
Mach-O file format
- Bluestacks Mac 1 Bluestacks Mac 2 Bluestacks Mac 3 Bluestacks Mac 4 Bluestacks Mac 5 Bluestacks Mac 6 How to download and install Bluestack on MAC If you prefer to see a video of the entire process of downloading and installing the Bluestacks program for Mac to install games or apps like Hello Neighbor we leave you this short tutorial with all.
- Please see for documentation. This repository is where developers and interested advanced users brainstorm on helloSystem. A desktop system for creators that focuses on simplicity, elegance, and usability.
To get started on writing OSX assembly, you need tounderstand OSX executable file format – the Mach-Ofile format. It’s similar to ELF, but insteadof sections of data, bss, and text, it has segments thatcontains sections.
A common assembly in Linux like
would translate into this in Mach-O
Mach-O is pretty flexible. You can embed a
cstring
section in your __TEXT
segment insteadof putting it in __DATA,__data
. Actually this isthe default behavior that compiler does on your Mac.Hello Assembly
Now we know how to translate common linux assemblyto mac, let’s write a basic program – do a system callwith an exit code.
On x86 you do a system call by
int x80
instruction. On64 bit machine, you do this by syscall
. Here’s the samplecode:you can compile the code by the following commands:
To perform a system call, you put the system call number in
%eax
, and put the actual exit code to %ebx
. The systemcall number can be found in /usr/include/sys/syscall.h
.The system call number need to add an offset
0x2000000
, becauseOSX has 4 different class of system calls. You can find the referencehere XNU syscall.Hello Alien Mac Os Update
System call by using wrapper functions
If you’re like me that had no assembly background, you mightfeel that
syscall
is alien to you. In C, we usually usewrapper functions to perform the call:Now we call a
libc
function instead of performing a systemcall. To do this we need to link to libc by passing -lc
to linker ld
. There are several things you need to doto make a function call. Call frame
We need to prepare the stack before we call a function. Elseyou would probably get a segmentation fault.The values in
%rsp
and %rbp
is used to preserve frame information.To maintain the stack, you first push the base register %rbp
onto the stack by pushq %rbp
;then you copy the stack register %rsp
to the base register.If you have local variables, you subtract
%rsp
for space.Remember, stack grows down and heap grows up.When releasing the frame, you add the space back to %rsp
.A live cycle of a function would look like this:
The stack size can be set at link time. On OSX, below are theexample parameters you can pass to
ld
to set the stack size:When setting the stack size, you also have to set the stack address.On the System V Application Binary Interface it says
Although the AMD64 architecture uses 64-bit pointers, implementationsare only required to handle 48-bit addresses. Therefore, conforming processes may onlyuse addresses from
0x00000000 00000000
to 0x00007fff ffffffff
I don’t know a good answer of how to chose a good stack address.I just copy whatever a normal code produces.
Parameters passing
The rules for parameter passing can be found in System VApplication Binary Interface:
- If the class is MEMORY, pass the argument on the stack.If the size of an object is larger than four eight bytes, orit contains unaligned fields, it has class MEMORY.
- If the class is INTEGER, the next available register of the sequence
%rdi
,%rsi
,%rdx
,%rcx
,%r8
and%r9
is used. - If the class is SSE, the next available vector register is used, the registersare taken in the order from
%xmm0
to%xmm7
.
The
exit()
function only need one integer parameter, therefore we putthe exit code in %edi
. Since the parameter is type int
, we use 32 bitvariance of register %rdi
and the instruction is movl
(mov long) insteadof movq
(mov quad).Hello world
Now we know the basics of how to performa system call, and how to call a function.Let’s write a hello world program.
The global variable
str
can only be accessed through GOT(Global Offset Table). And the GOT needs to be access fromthe instruction pointer %rip
. For more curious you canread Mach-O Programming Topics: x86-64 Code Model.The register used for
syscall
parameters are a littlebit different than the normal function call.It uses %rdi
, %rsi
, %rdx
, %r10
, %r8
and %r9
.You cannot pass more than 6 parameters in syscall
, norcan you put the parameters on the stack.Hello world using printf
Now you know the basics of assembly. A hello worldexample using printf should be trivial to read:
Conclusion
![Hello, Alien! Mac OS Hello, Alien! Mac OS](https://pbs.twimg.com/media/Ee7lFbEX0AA4Amz.jpg)
The 64 bit assembly looks more vague than the tutorialswritten in X86 assembly. Once you know these basic differences,it’s easy for you to learn assembly in depth on your own,even if the material is designed for x86. I highly recommendthe book “Programming from the ground up”. It is well writtenfor self study purpose.
References
- OS X Assembler Reference Assembler Directives
- Book: Programming from the ground up.
Fair warning reader: this post has nothing to do with Ubuntu, or even Linux for that matter.
Instead, the following 600 words are about a promising (new to me) FreeBSD distro and why it left me rather excited about its potential.
So, for the duration of this ramble I’d appreciate you pretending it’s 2008 and this site is still called ‘FYIDYK’ — this was the forerunner to omg! with a worse acronym and a ‘cover everything’ attitude!
In this post I look at what this distro is, what it isn’t, and what it hopes to become. Plus, I share a link to download an install images (warning: experimental) so you can try it out for yourself.
helloSystem: FreeBSD for human beings?
A number of FreeBSD-based “distros” — I don’t know if there’s a different term for BSD flavours, so I’m rolling with this — are available but the first to catch my attention is called helloSystem.
This project was the subject of a talk at the recent FOSDEM event, and it’s that talk that pole-vaulted the project in to the eye-line of bloggers like myself.
What helps helloSystem stand out (to me, anyway) more than its ‘unique’ UI is its ambition. Devs working on helloSystem want to create “a desktop system for creators with focus on simplicity, elegance, and usability” built atop FreeBSD, an open source Unix-like OS.
Now, FreeBSD is a strand of computing I’ve never played with, not even during the exuberant and overreaching “FYIDYK” years. OpenSolaris? Oh yes! ReactOS? Roger that! But BSD? Still TBD, at least for me.
For me, new unexplored tech territory is exciting. And if Ubuntu is ‘Linux for human beings’ then helloSystem is close to being ‘FreeBSD for Mac switchers’.
Ahh, yes. Mac.
There is no getting away from the fact that helloSystem is part cool project, and part homage to the classic era of Cupertino’s celebrated computing export (aka Mac OS X) Like Apple, these FreeBSD devs want to offer an “out-of-the-box user experience” as simple and fuss-free as mid-2000s Mac.
“One objective for helloSystem is to be both easy to use for “mere mortals” yet powerful under the hood for advanced users, a combination that had been skillfully mastered in the first releases of Mac OS X,” the GitHub page blurb reads.
“The question is, can we take this objective of being easy but powerful but take it even further than Apple ever did?”.
It’s perhaps a but too early to answer that question. This project has bold ambitions for the future but humble roots in the present. Right now there are too many rough edges for it to function as anyone’s daily driver.
But it is coming together.
The system uses OpenZFS as its default file system, and has a custom Qt-based desktop (helloDesktop) sporting traditional windowing, a (basic) desktop dock, a unique global menu plugin (think HUD, but system wide), and right-aligned desktop icons and file manager (based on PCManFM).
Hello also comes with access to a range of apps, including LibreOffice, GIMP, and Chromium. Falkon is the default web browser, while a Qt-based text editor and Terminal are included for those who need them.
Neither the OS nor its desktop are “production” ready at the time you read this. Which brings me to the point of why I’m covering it at all.
I’m not expecting helloSystem to be the next big thing™, nor do I see it taking FreeBSD to heights that other *BSD projects haven’t.
But this project reminds me why I began experimenting with Linux and other systems in the first place: the thrill of potential; exploration without precondition; the bristle of possibility that open code (and open code alone) affords.
Download helloSystem Alpha
You can download alpha releases of helloSystem from GitHub.
Do read over the official help docs for assistance on getting it to boot in a virtual machine (which will need at least 4GB RAM, more than VirtualBox’s default).
Mac Os Catalina
- (via: Phoronix)