Programming Forums > Application Development > Assembly

lostcauz · Sep 20th, 2005, 9:06 AM

I didn't want to keep polluting Jim's thread with non-C code, so the saga continues...

This algorithm is more robust and runs in 49-53 cycles on my P4. Comments, critiques, and corrections always welcome.

I'll be out of town for a couple of days since someone here gave my wife the bright idea of gettin' away from my routine. I won't mention any names but their initials are INFINITE RECURSION and TEECHA!!! She's even making me drive! Next thing you know she'll be making me sleep in a tent, or a cave!

DaWei, don't be booby trappin' my house while I'm gone. :p

(Toggle Plain Text)

;Reverse a string

str1 db 'abcdefghijklmnopqrstuvwxyzabc',0
str2 db 64 dup(0)

	lea esi,str1			
	lea edi,str2
	mov ecx,[sizeof str1-2]
	cmp ecx,7
	ja l0
	or ecx,ecx
	jnz @f
	mov al,[esi]
	mov [edi],al
	add edi,1
	jmp l3
	
@@:     mov al,[esi+ecx]
	mov [edi],al
	add edi,1
	sub ecx,1
	jnz @b
	mov al,[esi]
	mov [edi],al
	add edi,1
	jmp l3

l0:     mov ebx,ecx
	shr ecx,2
	shl ecx,2
	sub ebx,ecx
	jz l1
	cmp ebx,3
	jnz @f
	mov al,[esi+ecx+3]
	sub ebx,1
	mov [edi],al
	add edi,1

@@:	cmp ebx,2
	jnz @f
	mov al,[esi+ecx+2]
	sub ebx,1
	mov [edi],al
	add edi,1

@@:	cmp ebx,1
	jnz l1
	mov al,[esi+ecx+1]
	mov [edi],al
	add edi,1
	
l1:     mov al,[esi+ecx]
	mov [edi],al
	add edi,1

l2:     sub ecx,4
	mov eax,[esi+ecx]	 ; 4 byte aligned string now
	bswap eax
	mov [edi],eax
	add edi,4
	or ecx,ecx
	jnz l2			   
l3:

DaWei · Sep 20th, 2005, 10:06 AM

Polyphemus_ · Sep 20th, 2005, 10:13 AM

@lostcauz: you must have been really bored

.. nice code

Infinite Recursion · Sep 26th, 2005, 9:20 AM

lol @ lostcauz... aren't women great

Have fun man...

Here is where we are staying: http://ozarkcave.com

Teecha · Sep 26th, 2005, 9:26 AM

Women are great!! You men wouldn't know what to do without us!!! =0)

What's wrong with sleeping in a cave, lostcauz? lol

lostcauz · Sep 26th, 2005, 9:51 AM

Yes, I agree women are great and I definitely would be lost without her.

We went to a secluded area and I must say it sucked canal water! Now my back hurts, I have a cold, my feet hurt and to top it off I'm covered in poison oak. Thanks a lot! :p I won't be mentioning where you guys decided to go or sure enough I'll be a cave dweller next. :eek:

(Toggle Plain Text)

str1 db 'abcdefghijklmnopqrstuvwxyzabc',0
str2 db 64 dup(0)

	lea esi,str1	   ; 43-45 cycles
	lea edi,str2
	mov ecx,[sizeof str1-1]
	mov ebx,ecx
	cmp ecx,4
	jb l1
	and ebx,3	   ; test for alignment
	jz l2
	cmp ebx,3
	jnz @f
	sub ecx,1
	mov al,[esi+ecx]
	sub ebx,1
	mov [edi],al
	add edi,1

@@:	cmp ebx,2
	jnz @f
	sub ecx,1
	mov al,[esi+ecx]
	sub ebx,1
	mov [edi],al
	add edi,1

@@:	cmp ebx,1
	jnz l1
	sub ecx,1
	mov al,[esi+ecx]
	mov [edi],al
	add edi,1
	jmp l2
	
l1:	sub ecx,1	  ; string is less than 4 characters
	mov al,[esi+ecx]
	mov [edi],al
	add edi,1
	or ecx,ecx
	jz l3
	jmp l1
	
l2:	sub ecx,4
	jnz @f
	mov eax,[esi+ecx]	 
	bswap eax
	mov [edi],eax 
	jmp l3
	   
@@:	mov eax,[esi+ecx] ; 4 byte aligned string
	bswap eax
	mov [edi],eax
	add edi,4
	sub ecx,4 
	jnz @b			   
	mov eax,[esi]	 
	bswap eax
	mov [edi],eax
l3:

Teecha · Sep 26th, 2005, 9:54 AM

See... Now your woman can take care of you and all your ailments!

Infinite Recursion · Sep 26th, 2005, 10:18 AM

Quote:

What's wrong with sleeping in a cave, lostcauz? lol

Nothing when it has 6 million dollars worth of technological rennovations, including dehumidifiers and jacuzzis

LOL

Quote:

I'm covered in poison oak.

lol, ya gotta stop rolling around in the woods man.

Quote:

Now your woman can take care of you and all your ailments!

and if not, just scratch the poision oak spot and offer to give her a massage

Teecha · Sep 26th, 2005, 10:28 AM

Dehumidifier... hmmm.. I need one of those in my classroom NOW!! I'm about to sweat to death, and being in a little bitty room with 22 other people doesn't help matters

DaWei · Sep 26th, 2005, 10:46 AM

Reading this thread is getting under my skin. Pooh on you. I think I'll wait about a month and take a Caribbean cruise. Noooooo poison oak be's dere. :p

Sep 20th, 2005, 9:06 AM	#1
lostcauz Hobbyist Programmer Join Date: Nov 2004 Location: 1691 miles East of L.A. Posts: 159 Rep Power: 4	String reversal I didn't want to keep polluting Jim's thread with non-C code, so the saga continues... This algorithm is more robust and runs in 49-53 cycles on my P4. Comments, critiques, and corrections always welcome. I'll be out of town for a couple of days since someone here gave my wife the bright idea of gettin' away from my routine. I won't mention any names but their initials are INFINITE RECURSION and TEECHA!!! She's even making me drive! Next thing you know she'll be making me sleep in a tent, or a cave! DaWei, don't be booby trappin' my house while I'm gone. :p (Toggle Plain Text) ;Reverse a string str1 db 'abcdefghijklmnopqrstuvwxyzabc',0 str2 db 64 dup(0) lea esi,str1 lea edi,str2 mov ecx,[sizeof str1-2] cmp ecx,7 ja l0 or ecx,ecx jnz @f mov al,[esi] mov [edi],al add edi,1 jmp l3 @@: mov al,[esi+ecx] mov [edi],al add edi,1 sub ecx,1 jnz @b mov al,[esi] mov [edi],al add edi,1 jmp l3 l0: mov ebx,ecx shr ecx,2 shl ecx,2 sub ebx,ecx jz l1 cmp ebx,3 jnz @f mov al,[esi+ecx+3] sub ebx,1 mov [edi],al add edi,1 @@: cmp ebx,2 jnz @f mov al,[esi+ecx+2] sub ebx,1 mov [edi],al add edi,1 @@: cmp ebx,1 jnz l1 mov al,[esi+ecx+1] mov [edi],al add edi,1 l1: mov al,[esi+ecx] mov [edi],al add edi,1 l2: sub ecx,4 mov eax,[esi+ecx] ; 4 byte aligned string now bswap eax mov [edi],eax add edi,4 or ecx,ecx jnz l2 l3: ;Reverse a string str1 db 'abcdefghijklmnopqrstuvwxyzabc',0 str2 db 64 dup(0) lea esi,str1 lea edi,str2 mov ecx,[sizeof str1-2] cmp ecx,7 ja l0 or ecx,ecx jnz @f mov al,[esi] mov [edi],al add edi,1 jmp l3 @@: mov al,[esi+ecx] mov [edi],al add edi,1 sub ecx,1 jnz @b mov al,[esi] mov [edi],al add edi,1 jmp l3 l0: mov ebx,ecx shr ecx,2 shl ecx,2 sub ebx,ecx jz l1 cmp ebx,3 jnz @f mov al,[esi+ecx+3] sub ebx,1 mov [edi],al add edi,1 @@: cmp ebx,2 jnz @f mov al,[esi+ecx+2] sub ebx,1 mov [edi],al add edi,1 @@: cmp ebx,1 jnz l1 mov al,[esi+ecx+1] mov [edi],al add edi,1 l1: mov al,[esi+ecx] mov [edi],al add edi,1 l2: sub ecx,4 mov eax,[esi+ecx] ; 4 byte aligned string now bswap eax mov [edi],eax add edi,4 or ecx,ecx jnz l2 l3: __________________ -- lostcauz Stepped in what?... Behind whose barn?... I didn't even know they had a cow!

Sep 20th, 2005, 10:06 AM	#2
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	__________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Sep 26th, 2005, 9:20 AM	#4
Infinite Recursion Programming Guru Join Date: Jul 2004 Location: United States Posts: 3,467 Rep Power: 8	lol @ lostcauz... aren't women great Have fun man... Here is where we are staying: http://ozarkcave.com __________________ http://jasonpowers.net "There are a thousand hacking at the branches of evil to one who is striking at the root."

Sep 26th, 2005, 9:51 AM	#6
lostcauz Hobbyist Programmer Join Date: Nov 2004 Location: 1691 miles East of L.A. Posts: 159 Rep Power: 4	Yes, I agree women are great and I definitely would be lost without her. We went to a secluded area and I must say it sucked canal water! Now my back hurts, I have a cold, my feet hurt and to top it off I'm covered in poison oak. Thanks a lot! :p I won't be mentioning where you guys decided to go or sure enough I'll be a cave dweller next. :eek: (Toggle Plain Text) str1 db 'abcdefghijklmnopqrstuvwxyzabc',0 str2 db 64 dup(0) lea esi,str1 ; 43-45 cycles lea edi,str2 mov ecx,[sizeof str1-1] mov ebx,ecx cmp ecx,4 jb l1 and ebx,3 ; test for alignment jz l2 cmp ebx,3 jnz @f sub ecx,1 mov al,[esi+ecx] sub ebx,1 mov [edi],al add edi,1 @@: cmp ebx,2 jnz @f sub ecx,1 mov al,[esi+ecx] sub ebx,1 mov [edi],al add edi,1 @@: cmp ebx,1 jnz l1 sub ecx,1 mov al,[esi+ecx] mov [edi],al add edi,1 jmp l2 l1: sub ecx,1 ; string is less than 4 characters mov al,[esi+ecx] mov [edi],al add edi,1 or ecx,ecx jz l3 jmp l1 l2: sub ecx,4 jnz @f mov eax,[esi+ecx] bswap eax mov [edi],eax jmp l3 @@: mov eax,[esi+ecx] ; 4 byte aligned string bswap eax mov [edi],eax add edi,4 sub ecx,4 jnz @b mov eax,[esi] bswap eax mov [edi],eax l3: str1 db 'abcdefghijklmnopqrstuvwxyzabc',0 str2 db 64 dup(0) lea esi,str1 ; 43-45 cycles lea edi,str2 mov ecx,[sizeof str1-1] mov ebx,ecx cmp ecx,4 jb l1 and ebx,3 ; test for alignment jz l2 cmp ebx,3 jnz @f sub ecx,1 mov al,[esi+ecx] sub ebx,1 mov [edi],al add edi,1 @@: cmp ebx,2 jnz @f sub ecx,1 mov al,[esi+ecx] sub ebx,1 mov [edi],al add edi,1 @@: cmp ebx,1 jnz l1 sub ecx,1 mov al,[esi+ecx] mov [edi],al add edi,1 jmp l2 l1: sub ecx,1 ; string is less than 4 characters mov al,[esi+ecx] mov [edi],al add edi,1 or ecx,ecx jz l3 jmp l1 l2: sub ecx,4 jnz @f mov eax,[esi+ecx] bswap eax mov [edi],eax jmp l3 @@: mov eax,[esi+ecx] ; 4 byte aligned string bswap eax mov [edi],eax add edi,4 sub ecx,4 jnz @b mov eax,[esi] bswap eax mov [edi],eax l3: __________________ -- lostcauz Stepped in what?... Behind whose barn?... I didn't even know they had a cow!

Sep 26th, 2005, 10:46 AM	#10
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Reading this thread is getting under my skin. Pooh on you. I think I'll wait about a month and take a Caribbean cruise. Noooooo poison oak be's dere. :p __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Sep 20th, 2005, 10:13 AM	#3
Polyphemus_ Expert Programmer Join Date: Aug 2005 Location: Rotterdam, the Netherlands Posts: 942 Rep Power: 4	@lostcauz: you must have been really bored .. nice code

Sep 26th, 2005, 9:26 AM	#5
Teecha Newbie Join Date: Aug 2005 Location: U.S. Posts: 13 Rep Power: 0	Women are great!! You men wouldn't know what to do without us!!! =0) What's wrong with sleeping in a cave, lostcauz? lol

Sep 26th, 2005, 9:54 AM	#7
Teecha Newbie Join Date: Aug 2005 Location: U.S. Posts: 13 Rep Power: 0	See... Now your woman can take care of you and all your ailments!

Sep 26th, 2005, 10:28 AM	#9
Teecha Newbie Join Date: Aug 2005 Location: U.S. Posts: 13 Rep Power: 0	Dehumidifier... hmmm.. I need one of those in my classroom NOW!! I'm about to sweat to death, and being in a little bitty room with 22 other people doesn't help matters

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Programming Forums > Application Development > Assembly

String reversal