• #### Let's play "Name that code fragment"

From James Dow Allen@21:1/5 to All on Sat Jul 18 01:26:46 2020
The party game "Name that tune" is fun. Hum just a few notes and
see who can guess the song. How about "Name that code fragment"?
From a few lines of programming code can you guess what sort of
application the code is from or what function is implemented?

There are some top programmers who hang out in this ng, so this might
be as good a newsgroup as any to try this game. PLEASE POST YOUR OWN
CODE FRAGMENTS AS A CHALLENGE. But I will get us started with
three examples.

In every case, the code is taken from real code, but some of the
identifier names are replaced with "FOO..." to make the application
less obvious. And silly micro-optimizations are allowed to increase
the challenge.

REMEMBER: You needn't "debug" the code fragment, or reconstruct
missing macros, etc. It's enough to just GUESS what sort of
thing the code does.

~~~~~~~
Fragment #01:
int FOO_100(uint64 newboard)
{
uint64 y = newboard & (newboard >> HEIGHT);
if ((y & (y >> 2 * HEIGHT)) != 0)
return 1;
y = newboard & (newboard >> H1);
if ((y & (y >> 2 * H1)) != 0)
return 1;
y = newboard & (newboard >> H2);
if ((y & (y >> 2 * H2)) != 0)
return 1;
y = newboard & (newboard >> 1);
return (y & (y >> 2)) != 0;
}

~~~~~~~
Fragment #02:
lg = long2 - long1;
y = sin(lat1);
t = cos(lat1);
x = t * sin(lg);
z = t * cos(lg);
r = sqrt(y*y + z*z);
a2 = cos(atan2(y, z) - lat2);
y = - r * a2;
return 10008 + 6371 * atan2(y, sqrt(1 - y*y));

~~~~~~~
Fragment #03:
#define DX(a,b) (Pt[a].x - Pt[b].x)
#define DY(a,b) (Pt[a].y - Pt[b].y)
#define NX(a,b,c) (DX(a,b) * DY(c,a) > DX(c,a) * DY(a,b))

...
return 1 ^ NX(0,1,2) ^ NX(1,2,3) ^ NX(2,3,0) ^ NX(3,0,1);

Hope to see some response!
Yours truly,
James Dow Allen

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)