Permutation:

http://blog.csdn.net/hackbuteer1/article/details/6657435

Tomorrow:

CORDIC

- FastLog
- Finding integer log base 2 of an integer (aka the position of the highest bit set)
- Find the log base 2 of an integer with the MSB N set in O(N) operations (the obvious way)
- Find the integer log base 2 of an integer with an 64-bit IEEE float
- Find the log base 2 of an integer with a lookup table
- Find the log base 2 of an N-bit integer in O(lg(N)) operations
- Find the log base 2 of an N-bit integer in O(lg(N)) operations with multiply and lookup

- Find integer log base 10 of an integer
- Find integer log base 10 of an integer the obvious way
- Find integer log base 2 of a 32-bit IEEE float
- Find integer log base 2 of the pow(2, r)-root of a 32-bit IEEE float (for unsigned integer r)

- Finding integer log base 2 of an integer (aka the position of the highest bit set)
- Question: Can glsl do bitwise operation?
- Answer1: Can https://web.cs.ship.edu/~djmoon/cg/cg-notes/cg-glsl-language.pdf
- Answer2: No.