DOS ain't dead

SSE in DOS -> alignment issues (DOSX)

posted by Rugxulo , Usono, 10.01.2008, 22:21

> Forgot to mention that the "SSE" doesn't work ... or at least I failed to
> find a "good" enough PC to test:

Okay, just for the record, you don't need to set SSE2, it should automatically detect whether available or not. "set PAQ8=sse2" overrides that detection, though (even on cpus that don't support it).

Anyways, yes, you're right, the latest DOS build doesn't work (I neglected to test) due to "fixing" the alignment in the Win32 build (go figure). You can always use the Win32 build under HX (yes!), but otherwise, just get the following (Causeway and DJGPP .EXEs only, no src for now, too busy):

http://rugxulo.googlepages.com/paq-jan9.7z (227k)

BTW, I'll have to work on it some more later. So it ain't "done" yet.

> Anyway, MMX against NOASM test:
>
> MMX is 2 times faster. This is no evidence of usefulness of MMX at all -
> here MMX ASM competed against C++ mess. Rewriting the "NOASM" C++ stuff
> into optimized 80386 compatible ASM would possibly reduce MMX's benefit
> from 2 to a value dangerously close to 1

Yes, I think "NOASM" could be improved a fair bit. The real question is "why isn't SSE2 lots faster?"

Pros:

+ SSE2 is 128-bit registers, double precision (vs. 3dnow! or plain SSE or FPU)
+ SSE2 can operate at same time as FPU (in theory)
+ SSE2 (vs. FPU) is random register access instead of stack-based

Cons:

- only P4 or AMD64 or better etc. support it
- rare compiler support (well, rarer)
- doesn't seem faster
- needs specific OS support (instead of overlaying on top of FPU)
- annoying alignment issues
- potentially only super useful for math buffs or gfx whores

---
Know your limits.h

Complete thread:

• SSE in DOS under JEMM386 ?? - Rugxulo, 03.01.2008, 06:54 (DOSX)
  • SSE in DOS under JEMM386 ?? - DOS386, 03.01.2008, 08:12
    • SSE in DOS under JEMM386 ?? - Rugxulo, 04.01.2008, 01:03
  • SSE in DOS under JEMM386 ?? - Japheth, 03.01.2008, 09:19
    • SSE in DOS under JEMM386 ?? - Rugxulo, 04.01.2008, 01:05
      • SSE in DOS under JEMM386 ?? - Japheth, 04.01.2008, 09:44
        • SSE in HDPMI / bug (c/c) - DOS386, 04.01.2008, 10:20
          • SSE in HDPMI / bug (c/c) - Japheth, 04.01.2008, 11:12
            • SSE in HDPMI / bug (c/c) - Rugxulo, 04.01.2008, 22:39
        • SSE in DOS under JEMM386 ?? - Rugxulo, 07.01.2008, 14:49
          • SSE in DOS under JEMM386 ?? - Japheth, 07.01.2008, 17:42
            • SSE in DOS under JEMM386 ?? - Rugxulo, 09.01.2008, 01:23
              • SSE in DOS under JEMM386 ?? - Rugxulo, 09.01.2008, 10:46
                • SSE in DOS -> Illegal Instruction Exception - DOS386, 10.01.2008, 01:22
                  • SSE in DOS -> Illegal Instruction Exception - Steve, 10.01.2008, 08:46
                  • SSE in DOS -> alignment issues - Rugxulo, 10.01.2008, 22:21
                • SSE in DOS under JEMM386 ?? - Japheth, 10.01.2008, 17:19
  • SSE in pure DOS - Rugxulo, 04.01.2008, 06:09
    • Secure Socket Extremism in DOS | You maybe have a Page Foul - DOS386, 04.01.2008, 07:52
      • SSE in DOS | Page Fault | JEMM386 / HDPMI32 - Rugxulo, 04.01.2008, 22:47
        • SSE in DOS | Page Fault <- YES, your bug | HDPMI32 - DOS386, 05.01.2008, 02:19
          • SSE2 in DOS | PAQ8o8z (Jan. 6) - Rugxulo, 06.01.2008, 05:09
            • SSE2 in DOS | PAQ8o8z (Jan. 6) - DOS386, 08.01.2008, 02:00
  • MS the "only hope"? - Japheth, 04.01.2008, 12:11
    • MS the "only hope"? - RayeR, 04.01.2008, 18:09
      • MS the "only hope"? - Japheth, 04.01.2008, 19:16
        • MS the "only hope"? - RayeR, 04.01.2008, 22:17
        • MS the "only hope"? (Vista DPMI bug: 32 MB max.) - Rugxulo, 04.01.2008, 22:31
          • MS the "only hope" ? NOT for me !!! - DOS386, 05.01.2008, 02:22
            • MS the "only hope" ? NOT for me !!! - RayeR, 05.01.2008, 18:58
              • MS the "only hope" ? NOT for me !!! Multiboot - DOS386, 08.01.2008, 01:47
                • NTVDM forever! - Japheth, 08.01.2008, 09:02
                • MS the "only hope" ? NOT for me !!! Multiboot - Steve, 08.01.2008, 13:54
                • MS the "only hope" ? NOT for me !!! Multiboot - Rugxulo, 09.01.2008, 01:19
                • MS the "only hope" ? NOT for me !!! Multiboot - RayeR, 14.01.2008, 21:34
          • A TSR worth a try in Vista - Japheth, 05.01.2008, 11:04
            • A TSR worth a try in Vista - Rugxulo, 05.01.2008, 21:08
              • A TSR worth a try in Vista - Khusraw, 07.01.2008, 11:06
                • A TSR worth a try in Vista - Rugxulo, 07.01.2008, 14:44
                • A TSR worth a try in Vista - Japheth, 07.01.2008, 17:34
                • A TSR worth a try in Vista - Rugxulo, 09.01.2008, 01:09