Bits, Bits operator, bitwise function
Download as PPTX, PDF0 likes75 views
Bit fields allow packing of data into a structure to save memory by defining individual bit fields within an integer. There are two bit shift operators in C - left shift (<<) which moves bits left, and right shift (>>) which moves bits right. Bit fields are useful for things like packing multiple boolean flags, reading compact file formats, and storing non-standard data types efficiently.
Bits, Bits operator, bitwise function
- 2. Basic of Bits • In C "A bit field is set up with a structure declaration that labels each field and determines its width."
- 3. Bit operator
- 8. Shift operator • There are two types of operator used in c language. • Left shit operator (<<) • Right shift operator (>>)
- 14. Bit field • A bit field is a term used in comp programming to store multiple, logical where each of the sets of bits, and single bit can be addressed.
- 15. Cont,, Bit Fields allow the packing of data in a structure. This is especially useful when memory or data storage is at a premium. Typical examples: Packing several objects into a machine word. e.g. 1 bit flags can be compacted -- Symbol tables in compilers. Reading external file formats -- non-standard file formats could be read in. E.g. 9 bit integers. C lets us do this in a structure definition by putting :bit length after the variable. i.e. struct packed_struct { unsigned int f1:1; unsigned int f2:1; unsigned int f3:1; unsigned int f4:1; unsigned int type:4; unsigned int funny_int:9; } pack; Here the packed_struct contains 6 members: Four 1 bit flags f1..f3, a 4 bit type and a 9 bit funny_int. C automatically packs the above bit fields as compactly as possible, provided that the maximum length of the field is less than or equal to the integer word length of the computer. If this is not the case then some compilers may allow memory overlap for the fields whilst other would store the next field in the next word (see comments on bit fiels portability below). Access members as usual via: pack.type = 7;
- 17. Cont,,
- 18. Rotating bits If I were to try and `rotateRight(5): y becomes 11111110 z becomes 01100000 Then g becomes 111111110