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Here is a fast algorithm to convert a buffer to hexadecimal text. It'd be great for a hexeditor. On my Athlon it runs as fast as a memory copy (256mb/sec). Anyone have any pointers for speeding it up? :P I'm trying to create a library of MMX functions for text. These algorithms will have rare usage, but it'll give some more practice with MMX. If anyone has any ideas of some text algorithms that would benifit from MMX, let me know.

UINT64 mmMask_0F = 0x0F0F0F0F0F0F0F0F;
UINT64 mmZero    = 0x3030303030303030;
UINT64 mmNine    = 0x3939393939393939;
UINT64 mmDiffNeg = 0xF8F8F8F8F8F8F8F8; //0xD8D8D8D8D8D8D8D8 // for lowercase letters

// 256 mb/sec!
void Bin2HexMMX(void *dst, void *src, int bytes)
{
	__asm {
	;	int 3
		mov esi, src
		mov edi, dst
		mov ecx, bytes
		movq mm4, mmMask_0F
		movq mm5, mmZero
		movq mm6, mmNine
		movq mm7, mmDiffNeg
		shr ecx, 3

loop16:
		movq mm0, 
		movq mm1, mm0
		psrlq mm0, 4

		pand mm1, mm4
							pand mm0, mm4
		paddb mm1, mm5
							paddb mm0, mm5
		movq mm3, mm1
							movq mm2, mm0
		pcmpgtb mm3, mm6
							pcmpgtb mm2, mm6
		psubusb mm3, mm7
							psubusb mm2, mm7
		paddb mm1, mm3
							paddb mm0, mm2
		movq mm2, mm0
		punpckhbw mm0, mm1
		punpcklbw mm2, mm1
		movntq , mm0
		movntq , mm2

		add esi, 8
		add edi, 16
		dec ecx
		jg loop16

		emms
	}
}

This message was edited by bitRAKE, on 6/22/2001 10:59:41 AM

Yeah, I thought the same thing. I haven't been able to come up with anything other than the saturated subtraction. I'll keep looking though - I have some other text algorithms that I'd like to do in MMX. I did think that I could do this faster, but I am new to MMX. The algorithm is very close to the second one you list above, but a couple instructions are used to order the bytes afterwards and the signs are gathered in a comparison which sets bytes based on the comparison (it's like a SET and a CMP in one instruction!) Thanks for the kind words. There is a great deal I have to add to the site. Mainly I wanted to help out some web newbies with some helpful links, and provide myself with an online favorites section to access from work/library/friend's house. Over time I'll get my poetry and code up. Larry, you can't get to your website by clicking on the little house icon in your messages! Need to add http:// to your page address in your profile. As you know from my messages, I've been there before - I just forgot to tell you earlier. This message was edited by bitRAKE, on 6/24/2001 12:51:54 AM

You tried searching google? That's what I did. I searched for individual instructions like 'psubusb'. There is so much info and algos! That's why I picked doing text algos, because there are so many graphics algos already in MMX. This message was edited by bitRAKE, on 6/25/2001 8:38:55 PM

Rake, since you're on MMX topics, i have a general question... How do you mix FP and MMX instruction? i know that MMX has no instruction that square a number, but FP does. and both of MMX and FP share the same stack, inorder to use both , you have to have EMMS (which empty the mmx state). Do you think you can post me an example? ---by the way, Bin2Hex... what do you mean when you say BIN? ---Bin can mean alot of thing, in this context, i have no clue Zadkiel, check out: www.cpuid.com for mmx instruction set. no example, just the instruction set... ------------------------------------------------------------ 256MB/sec! hmm... that seems to be FAST!! HIEW <--- 300MB/sec! for opening file.. can you believe it!! i wonder what code they use... This message was edited by disease_2000, on 7/1/2001 5:33:59 AM

Rake, you're strange. you just busted my virtual gut. so, SSE2... hmmm... what CPU support SSE2? about hiew, what do you do mostly with that program? i mainly use it to view text file. ever since i have that program. viewing text is the ONLY thing that i used it MORE.

http://ulita.ms.mff.cuni.cz/pub/techdoc/ check it out Rake, Zadkiel. the MMX document is there.