Changing Bits in Flag Words
Writing, reading or toggling bits in flags can be done only using the OR, AND and NOT operations - operations which can be performed quickly in the processor.
To set a bit, OR the status byte with a mask byte. Any bits set in the mask byte or the status byte will be set in the result.
int setBit(int val, int bit_position) { return val | (1 << bit_position); }To clear a bit, perform a NOT operation on the mask byte, then AND it with the status byte. The result will have the appropriate flag cleared (set to 0).
int clearBit(int val, int bit_position) { return val & ~(1 << bit_position); }To toggle a bit, XOR the status byte and the mask byte. This will set a bit if it is cleared or clear a bit if it is set.
int toggleBit(int val, int bit_position) { return val ^ (1 << bit_position); }Read more about this topic: Flag Word
Famous quotes containing the words changing, bits, flag and/or words:
“Armies, though always the supporters and tools of absolute power for the time being, are always the destroyers of it too; by frequently changing the hands in which they think proper to lodge it.”
—Philip Dormer Stanhope, 4th Earl Chesterfield (1694–1773)
“What in fact have I achieved, however much it may seem? Bits and pieces ... trivialities. But here they won’t tolerate anything else, or anything more. If I wanted to take one step in advance of the current views and opinions of the day, that would put paid to any power I have. Do you know what we are ... those of us who count as pillars of society? We are society’s tools, neither more nor less.”
—Henrik Ibsen (1828–1906)
“Hath not the morning dawned with added light?
And shall not evening call another star
Out of the infinite regions of the night,
To mark this day in Heaven? At last, we are
A nation among nations; and the world
Shall soon behold in many a distant port
Another flag unfurled!”
—Henry Timrod (1828–1867)
“Old-fashioned determinism was what we may call hard determinism. It did not shrink from such words as fatality, bondage of the will, necessitation, and the like. Nowadays, we have a soft determinism which abhors harsh words, and, repudiating fatality, necessity, and even predetermination, says that its real name is freedom; for freedom is only necessity understood, and bondage to the highest is identical with true freedom.”
—William James (1842–1910)