An assembly language is a low-level programming language for a computer, or other programmable device, in which there is a very strong (generally one-to-one) correspondence between the language and the architecture's machine code instructions.
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Integer-to-ASCII algorithm (x86 assembly)
This is my best effort at converting a 32 bit integer in EAX, to an 8 character ascii string (result in RDI). It will work ...
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1answer
27 views
Unsigned integer division ARM Cortex-M0+ Assembly
I am writing a subroutine for unsigned integer division in Assembly. I will call the subroutine DIVU.
Inputs: R1 will be the ...
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1answer
97 views
Sum up all odd numbers between 1 and 2n + 1
Assignment:
Write a program which reads a number n from the console. Then
calculates the sum of all odd numbers between 1 and 2n + 1 (incl.).
Assignment also on GitHub, Exercise 0.0.
The ...
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1answer
48 views
MIPS program to find the sum and square sum of 10 integers
I wrote a program (hard-code) in MIPS that gets an array of 10 integers and calculates the sum and the square sum of them.
The array is ...
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2answers
45 views
Hexdump utility in x86 NASM assembly
It's a simple hexdump that prints to stdout. I wanted to handle correctly input coming from the user typing at the terminal, this made the logic a little more complicated than just exiting after ...
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1answer
35 views
File shredder in x86 NASM Assembly
This is a file shredder utility that runs on Linux. It writes random bytes over the file contents, repeating this 48 times and calling sys_fsync after each pass to ...
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1answer
34 views
Program to print all evironment variables
I'm learning x86 assembly on Linux and this is the first program I wrote, so I'm looking for all kinds of ways to improve it.
...
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3answers
71 views
A simple assembly program to count the number of ones in a register
I made a simple assembly program to count the number of ones in a register. Since this is basically my first ever, I would like to hear what I can improve or if there are some major flaws in this one:
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10
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2answers
169 views
Dijkstra's algorithm for computing the GCD of two integers, translated from C to x86 assembly
This is the x86 version of a C file assignment (I have included both). We were to convert the C code to assembly. I am rather new at assembly and would really appreciate suggestions and help for ...
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1answer
41 views
Turn a vsscanf call into a sscanf call
I am reviewing some C code (see extract below) that uses inline asm. I believe there are 4 spec violations, 1 inefficiency and 1 honking big design flaw in this code. While some of the problems I'm ...
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1answer
113 views
Absolute value function in MIPS
The following is my implementation of the absolute value function in the MIPS assembly language. I would very much like to hear constructive criticism of my code from you as well as any words of ...
2
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1answer
57 views
Recursive spinlock for C using ASM, revision #1
Precursor for this revision here in code-review:
Recursive spinlock for C using ASM
Improvements have been made thanks to forsvarir.
Now I am trying to optimize this lock so it becomes more ...
10
votes
2answers
123 views
Brainf*ck interpreter written in x86 assembly
I have written a program in x86 assembly (Intel syntax/MASM) that interprets brainfuck code that is fed to it via an interactive console and prints the final stack to stdout. Note that it does not ...
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1answer
67 views
Recursive spinlock for C using ASM
My history of C/ASM locks here in codereview:
Simple spinlock for C using ASM
Simple spinlock for C using ASM, revision #1 (basis for this approach. If this one fails, then so will the one below.)
...
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1answer
54 views
Simple spinlock for C using ASM, revision #1
Revision #1 for Simple spinlock for C using ASM
The code:
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5
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1answer
72 views
Simple spinlock for C using ASM
This is my second attempt to make simple lock using extended assembly.
See http://stackoverflow.com/questions/37241553/locks-around-memory-manipulation-via-inline-assembly/37246263
The code:
...
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1answer
118 views
Motorola 6809 Prime finder
I'm trying to make a small program which takes a number (form 1 to 1000) and shows the primes between 2 and that number. Right now I have a quite functioning program (except a couple of bugs), but the ...
6
votes
2answers
153 views
x86 assembly method that mimics strcat
I'm trying to learn x86 assembly and hopefully move on to projects of the scope that more than one person would be involved.
This is a (relatively) simple subroutine written in Intel x86 assembly ...
1
vote
1answer
146 views
HPC kernel for DGEMM: compiler v.s. assembly
This is a correct version, for computing a small matrix multiplication: C += A * B, where C is ...
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1answer
159 views
8086/DOS assembly keyboard I=input, data loss in registers
I am working on a project for class, and it works as required by the rubric, though I am wondering if there is a slightly better way to implement a few things. I was docked a few points for an ...
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0answers
20 views
Using STORAGE macro using QSAM for input/output
I was wondering if you can help me out. I wanted to know if there is an easier way to do the following. My code works but I feel like there is a lot things going out with multiple loops and wanted to ...
4
votes
2answers
81 views
FizzBuzz in ToyVM
Since I have my own virtual machine and an assembler for it, I decided to test it with a FizzBuzz implementation. I have this:
fizzbuzz.toy
...
3
votes
2answers
65 views
Assembler for ToyVM
After rolling my own virtual machine, I decided to implement an assembler for it. Ironically, it's all Java, since I needed to do a lot of text manipulations. Please, tell me anything that comes to ...
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1answer
506 views
ToyVM - a small and simple virtual machine in C - follow-up
(See the previous and initial iteration)
Now I have refactored the code in order to conform to the suggestions made in the answers to the first iteration. I have this:
toyvm.h:
...
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1answer
83 views
Hardware interrupt handler in C++
I wrote this class to use a C++ function as hardware interrupt handler. The idea is to have a single entry point where I can switch stacks, and call a chain of ...
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2answers
120 views
ToyVM - a small and simple virtual machine in C + FizzBuzz demonstration
(See also the next iteration.)
I have this small virtual machine.
What is there:
Stack and, thus, recursion.
Conditional and unconditional jumps and, thus, choice and iteration.
What is not ...
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0answers
264 views
Cooperative multi-tasking / coroutine implementation
Here is my implementation of user-level cooperative threads in C++14, which I'm working on for a hobby project. It's not entirely finished but works pretty well so far. The target operating system is ...
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1answer
289 views
Simple calculation program in assembly MASM
I am a beginner in assembly. This program calculates:
(Z+Z)+(X-Y)
...
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1answer
43 views
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49 views
Parallel popcount of packed bytes
I want to do a popcount of bytes in an array.
Not a total popcount of everything, but lots of little popcounts for every individual byte to determine the neighborhood count in GoL.
The following ...
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0answers
53 views
Benchmarking function variations
I'm trying to benchmark two variations of one of my functions. Namely, these functions are for displaying integer values on the command line.
The first of these uses my own implementation and prints ...
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vote
1answer
58 views
FizzBuzz in the MIPS ISA
The title pretty much explains it. This is the first program I've written in assembly, so any criticism, either on programming style or saving instructions, would be appreciated.
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0answers
47 views
Measuring CPU frequency in *nix
I have this small function for reading the TSC (time-stamp counter) in *nix. Using it seems to report my CPU frequency more or less correctly.
...
7
votes
1answer
78 views
Assembler listings parser components: Operands parser
I'm building the above mentioned parser.
It reads a string of assembler instructions.
I want to become a better coder, so I wanted to get a code review to start learning to do things property.
As we ...
11
votes
4answers
638 views
Detecting arithmetic overflow in C with NASM
This snippet is about detecting whether the carry flag is set or cleared. I work on Mac OSX, so my snippet supports Mac only.
First, we need a routine that does the job:
func.s:
...
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2answers
487 views
Fast 32x32 bit multiply on ARM M0
I have a time-critical calculation running on an ARM Cortex-M0. This is the fastest 32x32 bit -> 64 bit multiplication that I can come up with.
The following C compiles almost 1-1 to assembly ...
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2answers
131 views
Implementing min of 3 numbers in Mic-1 code
I have the following algorithm to find a minimum of three input numbers:
...
6
votes
1answer
49 views
Brainfix to NASM converter written in C (revision 2)
See this post for the previous question. I have made several enhancements to this compiler and language that make it a lot easier to work with, as well as slightly decreasing executable size (if new ...
6
votes
2answers
139 views
Brainf*ck to NASM converter written in C
I have made a very simple Brainfuck to NASM converter, that is usable for practically all programs. It has one trivial optimisation (to subsitute ADD for ...
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votes
1answer
44 views
Routine for convert decimal digits to Densely Packed Decimal
I've written an amd64 assembly routine (in gas syntax using the System V calling convention) to convert three decimal digits to densely packed decimal because I wasn't satisfied by the performance of ...
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1answer
104 views
A C function for returning the address of the calling function
Suppose you are given two functions, foo and bar, and neither of them are inlined. Now, if ...
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0answers
94 views
Variations on binary searching an ordered list
In the wikipedia article about the binary search algorithm (https://en.wikipedia.org/wiki/Binary_search_algorithm) a small paragraph in
particular got my attention.
Midpoint and width
A ...
6
votes
2answers
308 views
Finding multiples of 3 or 5 with MIPS assembly (Project Euler #1)
I just started learning MIPS assembly at my university and I would like some feedback on this code. The program is Project Euler Problem #1, finding the sum of multiples of 3 or 5 less than 1000. It ...
11
votes
2answers
217 views
A low tech approach to measuring game speed
Whilst developing a game I needed a delay routine capable of doing delays
ranging from 0.5 sec to just a few msec. The obvious choice was to use
the BIOS delay function 86h on int 15h. In a true real ...
14
votes
1answer
148 views
Embedded FizzBuzz
Recently, I have started to enter the realms of embedded systems programming. And, as my first major project, I thought I'd do the obvious: FizzBuzz.
However, this is a little different: this is a ...
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2answers
247 views
8
votes
1answer
75 views
Assembling a Sequence
I've completed the "Sequence Counter" level of TIS-100, but this is horrendously inefficient. My cycle counts are at about twice the minimum possible according to the charts:
I'm not really as ...
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2answers
581 views
Inefficient differential converter
Following Pimgd's question, I decided to take a look at the TIS-100 myself.
This is my solution to the 3rd challenge, building a differential converter.
Requirements:
Read values from IN.A and ...
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2answers
207 views
Filling a memory segment with a bit pattern
I want to fill a memory segment with a certain byte pattern using powerpc assembly:
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5answers
2k views
The loaderless bootloader
I began this month with trying to discover how shellcode is made. My search led me to wanting to learn assembly, so I wrote a simple bootloader with NASM:
...
