Porting MS-DOS Graphics Applications
By waiting for the VGA retrace, we are telling the program to wait until the monitor's electron beam reaches the bottom of the screen. Since there is a short pause before it jumps back to the top, it is a good moment to switch palettes without seeing “rainbow colors”. Thus, before switching palettes, we should wait for the VGA retrace as follows:
while (!(inportb(0x3da) & 8)); while ( (inportb(0x3da) & 8)); vga_waitretrace();
The following code assumes you have a character array of 768 values, representing the RGB values for 256 colors. For example:
char palette; where palette = R value of color 0; where palette = G value of color 0; where palette = B value of color 0; ... for (i = 0; i < 256; i++) vga_setpalette(i, palette[i*3], palette[i*3+1], palette[i*3+2]); outportb(0x3C8,0); for (i = 0; i < 768; i ++) outportb(0x3C9, palette[i]);
After adding SVGALIB code to the program, it's time to compile. Simply compile with the -lvga option to link the SVGALIB library. This library is preinstalled on most Linux systems; thus, if you experience problems linking it, you probably don't have it installed and should download it.
jaw3d was programmed by the author and is a Nullsoft Inc. product. Other cross-platform applications may be obtained at http://www.nullsoft.com/.
Jawed Karim is a freshman computer science student at the University of Illinois at Urbana-Champaign and works part-time at the National Center for Supercomputing Applications. His hobbies include programming and bicycle road racing. He can be reached at firstname.lastname@example.org.
Practical Task Scheduling Deployment
July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
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With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
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