Translating with MOV or XLAT
So how do you use the Upcase table Very simply 1. Load the character to be translated into AL. 2. Create a memory reference using AL as the base term and Upcase as the displacement term, and mov the byte at the memory reference into AL, replacing the original value used as the base term. The mov instruction would look like this There's only one problem NASM won't let you do this. The AL register can't take part in effective address calculations, nor can any of the other 8-bit registers. Enter...
Binary Files vs Text Files
If you've worked with Windows or Linux (and before that, DOS) for any length of time, you may have a sense of the differences between files in terms of how you ''look at'' them. A simple text file is opened and examined in a simple text editor. A word processor file is opened in the species of word processor that created it. A PowerPoint presentation file is opened from inside the PowerPoint application. If you try to load it into Word or Excel, the application...
Using Kate While Programming
At least for the programs I present in this book, Kate is going to be the ''workbench'' where we edit, assemble, link, test, and debug our code. In other words, you run Kate from the Applications menu or from a desktop or panel launcher, and then everything else you do you do from inside Kate. ''Inside'' here has an interesting wrinkle Kate has its own built-in Linux terminal window, and this terminal window enables us to launch other tools from inside Kate specifically, the Make utility (more...
Using scanf for Entry of Numeric Values
In a peculiar sort of way, the C library function scanf() is printf() running backwards Instead of outputting formatted data in a character stream, scanf() takes a stream of character data from the keyboard and converts it to numeric data stored in a numeric variable. scanf() works very well, and it understands a great many formats that I won't be explaining in this book, especially for the entry of floating-point numbers. (Floating-point values are a special problem in assembly work, and I...
Do Not Pass Go
''There's a reason bored and board are homonyms,'' said my best friend, Art, one evening as we sat (two super-sophisticated twelve-year-olds) playing some game in his basement. (He may have been unhappy because he was losing.) Was it Mille Bornes Or Stratego Or Monopoly Or something else entirely I confess, I don't remember. I simply recall hopping some little piece of plastic shaped like a pregnant bowling pin up and down a series of colored squares that told me to do dumb things like go back...
The Game of Big
I've invented my own board game to continue down the road with this particular metaphor. In the sense that art mirrors life, the Game of Big Bux mirrors life in Silicon Valley, where money seems to be spontaneously created (generally in somebody else's pocket) and the three big Money Black Holes are fast cars, California real estate, and messy divorces. There is luck, there is work, and assets often change hands very quickly. A portion of the Big Bux game board is shown in Figure 1-1. The line...
Looking at File Internals with the Bless Editor
Very fortunately, there are utilities that can open, display, and enable you to change characters or binary bytes inside any kind of file. These are called binary editors or hexadecimal editors, and the best of them in my experience at least for the Linux world is the Bless Hex Editor. It was designed to operate under graphical user interfaces such as Gnome, and it is very easy to figure out by exploring the menus. Bless is not installed by default under Ubuntu. You can download it free of...
Kates File Management
Kate makes it easy to load existing files into the editor window, browse your session working directory, create new files, rename files, and move unneeded files to the Trash. The primary mechanism for file management is the sidebar on the left side of the Kate window. Absent other plugins that use it, the management sidebar serves two functions When in the Document view, the sidebar displays the documents associated with the current session. You can click on one of the document listing lines to...
Installing the Software
One of the fantastic things about Linux is the boggling array of software available for it, nearly all of which is completely free of charge. If you've used Linux for any length of time you've probably encountered products such as OpenOffice, Kompozer, Gnumeric, and Evolution. Some of these are preinstalled when you install the operating system. The rest are obtained through the use of a package manager. A package manager is a catalog program that lives on your PC and maintains a list of all...
