bithacks.h

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This is "bithacks.h" C header file and it contains various macros for bit manipulations. It's accompanied with "bithacks-test.c", which tests all the macros.

It was written by Peteris Krumins ([email protected]). His blog is at http://www.catonmat.net -- good coders code, great reuse.

The code is licensed under the MIT license.

The code was written as a part of the article "bithacks.h - bit hacks header file" on my website. The whole article can be read at:

http://www.catonmat.net/blog/bit-hacks-header-file/

Table of contents: [1] Macros in bithacks.h file [2] The test program bithacks-test.c

[1]-Macros-in-bithhacks.h-file------------------------------------------------

The "bithacks.h" header provides the following macros:

* B8(x)            - turns x written in binary into decimal,
* B_EVEN(x)        - tests if x is even                    (bithack #1),
* B_ODD(x)         - tests if x is odd         (inverse of (bithack #1)),
* B_IS_SET(x, n)   - tests if n-th bit is set in x         (bithack #2),
* B_SET(x, n)      - sets n-th bit in x                    (bithack #3),
* B_UNSET(x, n)    - unsets n-th bit in x                  (bithack #4),
* B_TOGGLE(x, n)   - toggles n-th bit in x                 (bithack #5),
* B_TURNOFF_1(x)   - turns off the right-most 1-bit in x   (bithack #6),
* B_ISOLATE_1(x)   - isolates the right-most 1-bit in x    (bithack #7),
* B_PROPAGATE_1(x) - propagates the right-most 1-bit in x  (bithack #8),
* B_ISOLATE_0(x)   - isolates the right-most 0-bit in x    (bithack #9),
* B_TURNON_0(x)    - turn on the right-most 0-bit in x     (bithack #10).

[2]-The-test-program-bithacks-test.c------------------------------------------

The test program "bithacks-test.c" tests all the macros above.

You have to first compile it:

$ gcc bit-hacks-test.c -o bithacks-test

This will create the "bithacks-test" program. Now run it to verify all the bithacks in bithacks.h:

$ ./bithacks-test
All tests OK.

I explained all the bithacks in bithacks.h in another article "Bit Hacks You Absolutely Must Know About":

http://www.catonmat.net/blog/low-level-bit-hacks-you-absolutely-must-know/

Also see the original article on bithacks.h "bithacks.h - bit hacks header file":

http://www.catonmat.net/blog/bit-hacks-header-file/

That's it. Happy bithacking!

Sincerely, Peteris Krumins http://www.catonmat.net