Re: New instructions

I just scanned my latest download of AMD64-docs(07/2007)
and found this were not on my list yet:


oh great.. time to update my jump drive's copies again...


VMCALL 0f01D9
Mistaken name?


aye... VMCALL is Intel's, VMMCALL is AMD's


instructions I find interesting were LZCNT and POPCNT...


LZCNT
Leading Zero CouNT

Counts leading zeros in a general register or 16/32/64 -bit memory

encoding: F3 0F BD /r
a.k.a.: REPZ BSR /r


POPCNT
bit POPulation CouNT

Counts set bits in a general register or 16/32/64 -bit memory

encoding: F3 0F B8 /r
0F B8 is an otherwise currently unused encoding

--
Bx.C / x87asm


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Relevant Pages

  • Re: New instructions
    ... Leading Zero CouNT ... Counts leading zeros in a general register or 16/32/64 -bit memory ... These instructions afaik were added to facilitate 32bit CRC ...
    (alt.lang.asm)
  • Re: Problem only in release version!
    ... not executed in Release mode (I believe, but I also thought Debug ... initialized variables to zero, ... The Release version will not initialize anything 'naturally' ... >>the contents of the memory addresses they happen to get assigned to). ...
    (microsoft.public.dotnet.languages.vc)
  • Re: How to pass vectors in gateway routine?
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    (comp.soft-sys.matlab)
  • Re: Initialising Variables
    ... automatically zero out global memory over and above objects of lesser ... It's naturally implementable on common machines and operating systems: ... heap, there is no reason to initialise it at all, the data in there is ...
    (comp.lang.c)
  • Re: Free implementation in C
    ... Why does free function in C not set the freed memory explicitly to ... Whenever we free memory using freefunction we set that memory to ... zero after freeing. ... I think you are suggesting that freesets a pointer to null. ...
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