Saturday, August 29, 2015

HTTP Status Cats API

https://http.cat/

Three years ago, I called out the proposed new TLDs as stupid. Today, I formally withdraw my oppositionIt turns out .cat is not one of the new TLDs so my opposition has been reinstated.

Monday, August 24, 2015

Dolphins

http://www.theguardian.com/science/2003/jul/03/research.science
At the Institute for Marine Mammal Studies in Mississippi, Kelly the dolphin has built up quite a reputation. All the dolphins at the institute are trained to hold onto any litter that falls into their pools until they see a trainer, when they can trade the litter for fish. In this way, the dolphins help to keep their pools clean.

Kelly has taken this task one step further. When people drop paper into the water she hides it under a rock at the bottom of the pool. The next time a trainer passes, she goes down to the rock and tears off a piece of paper to give to the trainer. After a fish reward, she goes back down, tears off another piece of paper, gets another fish, and so on. This behaviour is interesting because it shows that Kelly has a sense of the future and delays gratification. She has realised that a big piece of paper gets the same reward as a small piece and so delivers only small pieces to keep the extra food coming. She has, in effect, trained the humans.

Her cunning has not stopped there. One day, when a gull flew into her pool, she grabbed it, waited for the trainers and then gave it to them. It was a large bird and so the trainers gave her lots of fish. This seemed to give Kelly a new idea. The next time she was fed, instead of eating the last fish, she took it to the bottom of the pool and hid it under the rock where she had been hiding the paper. When no trainers were present, she brought the fish to the surface and used it to lure the gulls, which she would catch to get even more fish. After mastering this lucrative strategy, she taught her calf, who taught other calves, and so gull-baiting has become a hot game among the dolphins.

Thursday, July 30, 2015

Crashes only on Wednesdays

http://gyrovague.com/2015/07/29/crashes-only-on-wednesdays/
Caught on yet?  On Wednesdays, and only on Wednesdays, if somebody manually twiddled certain bits in the monitor settings in a certain way, two events would occur during the same millisecond and caused the DB to throw an exception, and the error message that logged this would be exactly 81 bytes long including the null terminator, overflowing the 80-char buffer and causing the program to crash!

Friday, July 17, 2015

The View from the Front Seat of the Google Self-Driving Car

https://medium.com/backchannel/the-view-from-the-front-seat-of-the-google-self-driving-car-46fc9f3e6088

https://medium.com/@chris_urmson/the-view-from-the-front-seat-of-the-google-self-driving-car-chapter-2-8d5e2990101b
But we’re now driving enough — and getting hit enough — that we can start to make some assumptions about that real crashes-per-miles-driven rate; it’s looking higher than we thought. (Our cars, with safety drivers aboard, are now self-driving about 10,000 miles per week, which is about what a typical American adult drives in a year.) It’s particularly telling that we’re getting hit more often now that the majority of our driving is on surface streets rather than freeways; this is exactly where you’d expect a lot of minor, usually-unreported collisions to happen. Other drivers have hit us 14 times since the start of our project in 2009 (including 11 rear-enders), and not once has the self-driving car been the cause of the collision. Instead, the clear theme is human error and inattention. We’ll take all this as a signal that we’re starting to compare favorably with human drivers.

Wednesday, July 8, 2015

Concise electronics for geeks

http://lcamtuf.coredump.cx/electronics/

This is a really good overview of analog electronics.

Wednesday, July 1, 2015

One dot per person for the entire US

http://demographics.coopercenter.org/DotMap/

This is a really good population map of the US, even ignoring that it has racial data too.

Tuesday, June 30, 2015

Randomness in Doom

Doom's source code is all online.  Someone posted a link to the RNG used, which is actually just returning a value from the same list of 256 numbers over and over in the same order:

unsigned char rndtable[256] = {
    0,   8, 109, 220, 222, 241, 149, 107,  75, 248, 254, 140,  16,  66 ,
    74,  21, 211,  47,  80, 242, 154,  27, 205, 128, 161,  89,  77,  36 ,
    95, 110,  85,  48, 212, 140, 211, 249,  22,  79, 200,  50,  28, 188 ,
    52, 140, 202, 120,  68, 145,  62,  70, 184, 190,  91, 197, 152, 224 ,
    149, 104,  25, 178, 252, 182, 202, 182, 141, 197,   4,  81, 181, 242 ,
    145,  42,  39, 227, 156, 198, 225, 193, 219,  93, 122, 175, 249,   0 ,
    175, 143,  70, 239,  46, 246, 163,  53, 163, 109, 168, 135,   2, 235 ,
    25,  92,  20, 145, 138,  77,  69, 166,  78, 176, 173, 212, 166, 113 ,
    94, 161,  41,  50, 239,  49, 111, 164,  70,  60,   2,  37, 171,  75 ,
    136, 156,  11,  56,  42, 146, 138, 229,  73, 146,  77,  61,  98, 196 ,
    135, 106,  63, 197, 195,  86,  96, 203, 113, 101, 170, 247, 181, 113 ,
    80, 250, 108,   7, 255, 237, 129, 226,  79, 107, 112, 166, 103, 241 ,
    24, 223, 239, 120, 198,  58,  60,  82, 128,   3, 184,  66, 143, 224 ,
    145, 224,  81, 206, 163,  45,  63,  90, 168, 114,  59,  33, 159,  95 ,
    28, 139, 123,  98, 125, 196,  15,  70, 194, 253,  54,  14, 109, 226 ,
    71,  17, 161,  93, 186,  87, 244, 138,  20,  52, 123, 251,  26,  36 ,
    17,  46,  52, 231, 232,  76,  31, 221,  84,  37, 216, 165, 212, 106 ,
    197, 242,  98,  43,  39, 175, 254, 145, 190,  84, 118, 222, 187, 136 ,
    120, 163, 236, 249
};

int rndindex = 0;
int prndindex = 0;

// Which one is deterministic?
int P_Random (void)
{
    prndindex = (prndindex+1)&0xff;
    return rndtable[prndindex];
}

int M_Random (void)
{
    rndindex = (rndindex+1)&0xff;
    return rndtable[rndindex];
}

void M_ClearRandom (void)
{
    rndindex = prndindex = 0;
}

There is an explanation of it here.  I find these kinds of hacks, used in 80s and 90s era games to save space and increase speed, interesting.

Here is a story of a guy that replaced all the values with the same number:
What does it play like? I tried two values, 0x00 and 0xFF. With either value, the screen "melt" effect that is used at the end of levels is replaced with a level vertical wipe: the randomness was used to offset each column. Monsters do not make different death noises at different times; only one is played for each category of monster. The bullet-based (hitscan) weapons have no spread at all: the shotgun becomes like a sniper rifle, and the chain-gun is likewise always true. You'd think this would make the super-shotgun a pretty lethal weapon, but it seems to have been nerfed: the spread pattern is integral to its function.

With 0x00, monsters never make their idle noises (breathing etc.) On the other hand, with 0xFF, they always do: so often, that each sample collides with the previous one, and you just get a sort-of monster drone. This is quite overwhelming with even a small pack of monsters.