de-interleave bits

http://stackoverflow.com/a/3233173

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http://stackoverflow.com/questions/4909263/how-to-efficiently-de-interleave-bits-inverse-morton

// morton1 - extract even bits

uint32_t morton1(uint32_t x)
{
    x = x & 0x55555555;
    x = (x | (x >> 1)) & 0x33333333;
    x = (x | (x >> 2)) & 0x0F0F0F0F;
    x = (x | (x >> 4)) & 0x00FF00FF;
    x = (x | (x >> 8)) & 0x0000FFFF;
    return x;
}

// morton2 - extract odd and even bits

void morton2(uint32_t *x, uint32_t *y, uint32_t z)
{
    *x = morton1(z);
    *y = morton1(z >> 1);
}

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http://stackoverflow.com/a/4925461

int64 w = (z &0xAAAAAAAA)<<31 | (z &0x55555555 )
w = (w | (w >> 1)) & 0x3333333333333333;
w = (w | (w >> 2)) & 0x0F0F0F0F0F0F0F0F; 
...