On Fri, Nov 6, 2015 at 7:33 AM, Mario Castelán Castro <marioxcc...@yandex.com> wrote: > Hello. > > What is the usual workflow to write code that takes advantage of an > instruction set that is not present in my computer
You're asking one question here. > (either in assembly or > using intrinsic functions that represent those instructions in an higher > level language)?. You're asking a different question here. > For example, if I want to write code for decoding and > encoding Base64 that uses AVX instructions You're beggin a question here, and I will ask it -- Why on earth would you want to go to the bother of using AVX instructions for working with Base64? And the answer to that question is that you have something else you want to do and you are using Base64 as a MacGuffin. Which is not a problem for me, but might be a problem for you. The question being begged is this -- Do you really want to use AVX enough to sign the Intel agreement that you can't read unless you agree to it before you read it so you can download it and read it? It *is* a valid question, and I can't tell you the answer to that. Maybe you can't answer that question yourself yet. > in my machine that has no support > for any version of AVX (only SSE 4.2 and CLMUL), what is the recommended > workflow?. The real workflow is that, if you have real reason (not Base64, of course), you get the hardware now. And you trust Intel not to ask for your first-born son (speaking figuratively) and sign the agreement and use their emulator. Both. Running the emulator on hardware that can actually run the instructions is a very useful debugging tool to help you debug your understanding of the instruction set. (Writing your own emulator can help, as well, but it may not be worth the time investment.) > It seems like I *could* develop within a virtual machine emulated with Bochs > that supports these instructions, but that would give a very big overhead, > since I would have to emulate a whole system, and Bochs has no > multithreading support (so that will make it less efficient if I want to > write multithreaded code). There are several ways to support multithreading in emulation. Well, we can say two main ways -- Write it yourself (in other words, as co-operative multi-tasking in the emulator core code, and some support routines to make it appear pre-emptive multi-processing to the running application). Or, let the OS handle it (in other words, someone else has already written the co-operative part and hopefully mapped it to actual OS calls that can give both the appearance and advantages of multi-processing). > Is there a better option? >From what the others have said about AVX, if you need to use for something real (not Base64, of course), you're going ot have to roll up your sleeves and do some of the grunt work yourself. If you really do mean Base64 (in other words, if you just want to play or this is a homework project or something), well, you have to decide whether you want to trust Intel and sign their agreement and download their emulator just to play or do a homework assignment or something. And maybe, once you have real specs in your hands, write your own emulator to help you cut through the sales talk in the specs. (Bochs or QEMU might help you at this step.) And expect that what you learn will only be partly applicable in the real world. > Regards and thanks in advance. > Hope that helps. -- Joel Rees Be careful when you look at conspiracy. Arm yourself with knowledge of yourself, as well: http://reiisi.blogspot.jp/2011/10/conspiracy-theories.html
