SolidusCode Blog

If you toy with electronics, perhaps with microcontrollers (MCU), you might at some point in time decide to interface your microcontroller to your computer.  However, you will come to learn that it would not work for a variety of reasons: one being that you need correct voltage between the computer and the microcontroller, and the second, most critical, you need a way for the computer to recognize and speak to your device. Well, this is where device drivers are useful.  Device drivers are the software need for your computer applications to talk to your device.  The power of a device driver and the possibilities that lie with it can not fully be summarized by myself. So, so whatever reason you many want to write a device driver, in this post, along with others, I will demonstrate how to write a device driver. Major and Minor Numbers When we write a device driver, that device driver will become part of the kernel and it will have an identification number called a major numb

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 extension *.ko).  From here, the mod

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.

There is not much difficulty when it comes to addition and subtraction in assembly programming. Simply, additon and substraction breaks down to the following: add eax , ecx ; eax = eax + ecx, result in eax add eax , DWORD [ ebp - 4 ] ; eax = eax + localVar1, result in eax add DWORD [ ebp - 4 ] , DWORD [ ebp -4 ] ; illegal, with all instruction both operands can never be memory add DWORD [ ebp - 4 ] , eax ; [ebp-4] = [ebp-4] + eax sub eax , ecx ; eax = eax - ecx, result in eax sub eax , DWORD [ ebp - 4 ] ; eax = eax - localVar1, result in eax sub DWORD [ ebp - 4 ] , DWORD [ ebp -4 ] ; illegal, with all instruction both operands can never be memory sub DWORD [ ebp - 4 ] , eax ; [ebp-4] = [ebp-4] - eax A simple program to display the message about an arithetic operation like "Math: 8 + 4 = ?" can be achived b

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 following syntax: int main(in

I wrote, with the help of  The Art of Java by Herbert Schildt and James Holmes , a custom parser that evaluates a numerical expression like: "10+32/2".  So the following is the code:   package com.soliduscode.eleanya; import java.util.logging.Handler; /** * * * @author ukaku * */ public class Parser { final int NONE =0; final int DELIMITER =1; final int VARIABLE = 2; final int NUMBER = 3; final int SYNTAX = 0; final int UNBALPARENS=1; final int NOEXP = 2; final int DIVBYZERO=3; final String EOE = "\0"; /**the expression*/ private String exp; /** expression index */ private int expIndex; /**Current token*/ private String token; /**The token type*/ private int tokenType; /** * Return the next token in the expression */ private void getToken(){ //clear values initially tokenType = NONE; token = ""; //check for endl of expression if(expIndex == exp.length()){ token = EOE; return; } //ski