1 / 16

Bit Operator

Bit Operator. Bit operators. ! : invert logical value if value is 0 change to 1, otherwise set to 0 ~ : invert all bits ~0x1010 = 0xefef & : bits ‘and’ operator and | : ‘or’ operator or. Bit operators. ^ : ‘xor’ operator xor + : add << : left bit shifter >> : right bit shifter

frisco
Télécharger la présentation

Bit Operator

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Bit Operator

  2. Bit operators • ! : invert logical value • if value is 0 change to 1, otherwise set to 0 • ~ : invert all bits • ~0x1010 = 0xefef • & : bits ‘and’ operator • and • | : ‘or’ operator • or

  3. Bit operators • ^ : ‘xor’ operator • xor • + : add • << : left bit shifter • >> : right bit shifter • warning: it is arithmetic operator( if MSB is 1, go on filling 1 to MSB )

  4. Our program restrictions • We are only allowed to use the following eight operations( or more fewer op. depending each problem ) • ! ~ & ^ | + << >> • any constants longer than 8bits is not allowed • max constant is 0xff

  5. file download • wget http://aces.snu.ac.kr/~jongyoung/lecture/pa01.tar • tar -xvf pa01.tar • We modify only bits.c • dlc check our program whether coding rule is correct • btest check our ‘bits.c’ correctness

  6. Goal • Modify functions in bits.c to same result what we expected.

  7. bitAnd • Using de morgan’s law • ~(A and B) = ~A or ~B • Only use the operation ~ and |

  8. bitXor • Using only the operation & and ~ • Similar as bitAnd

  9. evenBits • Return a word with all even-numbered bits set to 1 • Sequence add and bit-shift for some constant. • Careful for constant’s length

  10. bitMask • First, make 32bit constant that all bits are ‘1’ • properly shift • If lowbit >= highbit, then the mask should be all 0’s • bitMask(5,3) returns 0x38

  11. bitParity • Reduce problem’s complexity by folding input variable • Return 1 if x contains an odd number of 0’s. • bitParity(5) = 0, bitParity(7) = 1

  12. fitsBit • Divide input into positive and negative. • Return 1 if x can be represented as an n-bit, two’s complement integer, where 1 <= n <= 32. • fitsBit(5,3) returns 0 • fitsBit(-4,3) returns 1

  13. sm2tc • Convert from sign-magnitude to two’s complement where the MSB is the sign bit • Extract sign bit and others • Sm2tc(0x80000005) returns -5

  14. Restriction

  15. Function Description

  16. Function Description

More Related