SolidusCode Blog

Okay so I have posted a number of Linux kernel programming videos over at my YouTube channe , however I find that I need a place to post a sample code and the make file to build a module. So here it is. The Makefile obj-m := solidusmodule.o KERNEL_DIR = /lib/modules/3.2.0-25-generic/build PWD := $(shell pwd) all: $(MAKE) -C $(KERNEL_DIR) SUBDIRS=$(PWD) modules clean: rm -rf *.o *.ko *.mod.* *.symvers *.order *~ #include #include #include // file_operations structure- which of course allows use to open/close,read/write to device #include //this is a char driver; makes cdev available #include //used to access semaphores; sychronizatoin behaviors #include //copy_to_user;copy_from_user //(1) Create a structure for our fake device struct fake_device { char data[100]; struct semaphore sem; } virtual_device; //(2) To later register our device we need a cdev object and some other variables struct cdev *mcdev; //m stands 'my' int major_number;...

The Linux kernel is designed as a mixture of a monolithic binary image and a micro-kernel.  This combination allows for the best of both worlds.  On the monolithic side, all the code for the kernel to work with the user and hardware is already installed and ready for fast access, but the downside is that to add more functionality you need to rebuild the entire kernel.   In a different manner, a micro-kernel is composed of small pieces  of code that can be meshed today and more pieces can be added or removed as needed.  However, the downside to micro-kernel is a slower performance. Adding a module to the Kernel Linux is organized as both monolithic, one huge binary, and micro-kernel, as you can add more functionality to it.  The process of adding more functionality to the kernel can be illustrated by the crude image to the left. The process begins by using the command insmod with the name of the kernel module you want (which usually ends with ex...

One of the projects that I am working on is how to write a scripting language using c++.  At first thought, I imagined the task to be hard, but to my surprise it is quiet easy. In this post I will introduce the basics.  However, I do suggest you visit my youtube channel and watch the video series . token evaluation process  As you can see from the image to the left, my script engine basically takes a string expression, converts it to tokens, determines its meaning, and then compiles the effective byte code. Byte code is the instruction set for my script language.  It will tell our virtual machine or virtual process what an instruction is suppose to do. In more detail, the script engine does a recursive call with the tokens to successfully generate all the corresponding byte code. Source Code This link contains the source code and is version 1 of script.

Hey everyone, I wrote a game for android called Space Cosmos Defender. Please check it out here  or just type "Space cosmos adventure" on your Google/Play market. Thank you all in advance. Here are some of the the screen-shots of my game. Main menu In game action More Action

Okay, so I have been writing assembly language programs for a little bit now and to be honest with everyone, not like it is not obvious, assembly can be very frustrating especially when you write code and it seems to make logical sense.  However, when you run the program, it either says segmentation fault, memory corruption issues, or the program displays a bunch of random text to the screen. Okay so, recently I have been trying to write an application that does something simple using assembly.  The goal was to write a program with Nasm and have it display the number of arguments passed to our program. From my previous posts, we know that ebp+4 contains the return address after the main method is executed.  We also now that ebp+8 is the first parameter passed to main,  ebp+12 is the second parameter, and so on and so on with 4 added to each time.  This is because from the C programming language the main method has a header declaration that is of the followin...

Whenever you start programming, there is usually the first program that prints the phrase "Hello world" to the screen.  Well, let us keep that tradition and write an entire assembly program that print that message to the screen. ;Our Assembly Program file SECTION .data SECTION .bss SECTION .text The preceding is the standard file format of an assembly program using the Netwide assembler, or NASM. To write something to the screen, we first need to store the value of what we want to render to the screen by declaring variables. ;Our Assembly Program file SECTION .data ourHelloMsg: db "Hello world, we are in assembly", 10, 0 ;our simple message SECTION .bss SECTION .text Next, we want to use some real world practical assembly coding to print this message to the screen.  We could simple using the Linux int80h instruction to tell the operating system to print this message (if you aren't sure what I mean by this, do not worry), however we will use the printf...

Many of you, if you are like me, might be interested in how assembly works.  You will be very surprised that assembly is very very easy, especially after you write a couple of simple programs.  But don't get me wrong, you will be frustrated at first, however that frustration, if you channel it right, will lead to serious life long learning and will give you a deeper appreciation of the beauty of assembly. For more tutorial on assembly and visualization of these information, visit my youtube channel . Okay so lets get started. We will be using Netwide Assembler (NASM) to write our program. The general format of NASM file is this: ;This is a comment SECTION .data ;declare variable here SECTION .bss ;declare actual, dynamic variable SECTION .text ;where your program code/assembly code lives ; Working with Data Section In your .data section, you can declare variables like this: nameOfVariable: db 32 ;this declares a variable names nameOfVariable...

The following is the finalized code for a simple C++ smart pointer as demonstrated by my youtube video:  here Usage: void main(){      ...     Pointer<ObjectType> pointer(new ObjectType);     ... } /*  * Pointer.h  *  *  Created on: Mar 16, 2012  *      Author: ukaku  */ #ifndef POINTER_H_ #define POINTER_H_ #include <iostream> using namespace std ; /**  * Reference represents a counter that will be incremented or decremented as  * the number of references to a pecticular pointer is made;  *  * where data means: a symbol used to point to, or associate to another object  */ class ReferenceCounter { private :     int counter ; public :     ReferenceCounter ( ) {         counter = 0 ;   //initially set to zero     }     void increase ( ) { ...