Flag Word - Changing Bits in Flag Words

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:

    Dissonance between family and school, therefore, is not only inevitable in a changing society; it also helps to make children more malleable and responsive to a changing world. By the same token, one could say that absolute homogeneity between family and school would reflect a static, authoritarian society and discourage creative, adaptive development in children.
    Sara Lawrence Lightfoot (20th century)

    On their slag heap, these children
    Wear skins peeped through by bones and spectacles of steel
    With mended glass, like bottle bits in slag.
    Stephen Spender (1909–1995)

    Up rose old Barbara Frietchie then,
    Bowed with her fourscore years and ten;

    Bravest of all in Frederick town,
    She took up the flag the men hauled down;
    John Greenleaf Whittier (1807–1892)

    Where words are restrained, the eyes often talk a great deal.
    Samuel Richardson (1689–1761)