Anyone know the performance of the BIOS Sqrt() call (typical clock cycles)?
I assume this would already be the worlds fastest ARM Square Root. I am
trying to avoid doing Sqrt but there may be no choice...
Anyone know the performance of the BIOS Sqrt() call (typical clock cycles)? I assume this would already be the worlds fastest ARM Square Root. I am trying to...
Jack Ukleja
jack.ukleja@...
May 2, 2001 1:34 pm
well you could always to a tablebased one that'd be even faster (but with less precision as usual) / jonas ... From: Jack Ukleja To: gbadev@yahoogroups.com ...
Jonas Lund
jonas.lund@...
May 2, 2001 3:12 pm
The following URL is an interesting presentation of ARM square root code. http://www.finesse.demon.co.uk/steven/sqrt.html Cheers A -- _ _ _| _ _ _| _...
Andrew Davie
adavie@...
May 2, 2001 3:15 pm
If you do end up using the BIOS square root, don't test it on IGBA as it seems not to emulate the real thing completely accurately. Well, I may be wrong but...
Tom Prosser
tom@...
May 2, 2001 4:44 pm
You can be almost sure, that most emus will fake the system calls, which of course makes the cycle count very inccurate. ... From: Tom Prosser To:...
Eloist
Eloist@...
May 3, 2001 9:22 pm
I wasn't bothered about the cycle count, I just found that my enemy AI doesn't work at all on IGBA, and can only guess that it's because the square root call...
Tom Prosser
tom@...
May 3, 2001 11:49 pm
why on earth would you be using a squareroot in your AI ?!?!? evil CPU time sucking function - avoid! :0) heh ninge ... From: Tom Prosser To:...
ninge1
ninge1@...
May 4, 2001 7:51 am
To find the distance between two points? Always handy in AI... --Jim ... From: ninge1 <ninge1@...> To: <gbadev@yahoogroups.com> Sent: Friday, May 04,...
James Boulton
jim@...
May 4, 2001 8:40 am
In message <003601c0d475$9aa06940$0500a8c0@jimlaptop> ... For most AI purposes you can work perfectly well with an approximation like the following: in: r0,r1...
Dennis Ranke
exoticorn@...
May 4, 2001 8:49 am
Ok, but surely there is no need at all to use the suareroot of that value? whats wrong with just doing your distance checking using the squared value? it'll be...
ninge1
ninge1@...
May 4, 2001 8:45 am
... And for most purposes you can approximate even quicker than that. Something like largest(x, y) + smallest(x, y) >> 1 where x = abs(dx) and y = abs(dy) In...
Alex Amsel
gba@...
May 4, 2001 10:26 am
Hello Alex, Friday, May 04, 2001, 12:30:57 PM, you wrote: AA> Oh, where are those warez everyone keeps talking about. I want all AA> 255 roms available on the...
groepaz
groepaz@...
May 4, 2001 10:39 am
This is true of course, but note that "finding the distance between two points" and "doing distance checking" are not necessarily one and the same.... Tom...
Tom Prosser
tom@...
May 4, 2001 11:54 am
Well, unless you like a whole lot of jitter, I recommend using a real sqrt function for camera control. The one someone posted up here (which is the one I've...
Shawn Freeman
sfreeman@...
May 4, 2001 2:52 pm
That trick has served me well on many 8-bit systems! It was sure close enough to do 'homing' weapons and so on. I think you can even extend it into 3D but I've...
Sean Dunlevy
sean@...
May 4, 2001 3:43 pm
How good is the 4 cycle/bit, 70 cycle worst case ARM code routine on the page http://www.finesse.demon.co.uk/steven/sqrt.html is it really 70 cycles worst ...
Dan Phillips
Dan.P@...
May 4, 2001 3:45 pm
RE: [gbadev] Sqaure RootFrom my tests, it's just as accurate, but doesn't run in 70 cycles :) (it does for a small enough number). But if you're doing big...
Shawn Freeman
sfreeman@...
May 4, 2001 4:04 pm
... You can :). Fortunately the square root function is a well behaved function so approximations are easy and accurate. Just Me, *SF...
Shawn Freeman
sfreeman@...
May 4, 2001 4:08 pm
... I used this technique too, and though I don't remember the exact formula I used (something like 3a+b, where a was the larger number), I do remember the ...
Andrew Davie
adavie@...
May 4, 2001 4:16 pm
Does anyone know what this approximation is in 3d? is it largest(a,b,c) + middle(a,b,c)>>1 + smallest(a,b,c)>>2?...
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