CPSC 233 TutorialXin Liu

2011/01/17

Self-intro Xin Liu

PhD student

Email: liuxin@ucalgary.ca

Homepage: http://pages.cpsc.ucalgary.ca/~liuxin

CT: Thursday 12:00-2:00 @ CT desk

Unix Environment Working in the lab is suggested

Remote access using SSH On Windows:

Download SSH Client program from http://www.ucalgary.ca/it/software/ssh

Quick Connect Host Name: csc.cpsc.ucalgary.ca User Name: xxx

On Mac: using terminal to connect to the UNIX system

ssh <username>@csc.cpsc.ucalgary.ca

Assignment Submit your Assignments with “submit” command of UNIX

Submit submit -c <course number> -a <assignment number>

<name of file or files to be submitted> eg. submit -c 233 -a 3 a3.p README

List submitted files showstuff -c <course number> -a <assignment number> eg. showstuff -c 233 -a 3

Submit early and update

Avoid plagiarism MOSS ( Measure of Software Similarity )

http://theory.stanford.edu/~aiken/moss/ Cite if necessary No marks lost by citing example code from TA/instructor

Binary Numbers

hexadecimal Binary hexadecimal Binary

0x0 0000 0x8 1000

0x1 0001 0x9 1001

0x2 0010 0xA / 10 1010

0x3 0011 0xB / 11 1011

0x4 0100 0xC / 12 1100

0x5 0101 0xD / 13 1101

0x6 0110 0xE / 14 1110

0x7 0111 0xF / 15 1111

Byte: 8 bits Word: 16 bits Double word: 32 bits Quad word: 64 bitsMultiples of 4 bits, corresponding to a hexadecimal number

Bin Dec 101011.0101

1*25 + 0*24 + 1*23 + 0*22 + 1*21 + 1*20 + 0*2-

1 + 1*2-2 + 0*2-3 + 1*2-4 = 32 + 0 + 8 + 0 + 2 + 1 + 0 + 0.25 + 0 + 0.0625 = 43.3125

Other examples …

Dec Bin Convert Integer and Decimal parts

seperately Example: 37.43 100101.01101b

Negative Integers Three representations

Regular binary (true code) 0110 0100 (DEC 100) 1110 0100 (DEC -100)

One’s complement (flip each bit) 0110 0100 (DEC 100) 1001 1011 (DEC -100)

Two’s complement (flip each bit + 1) most useful!!! 0110 0100 (DEC 100) 1001 1100 (DEC -100)

Negative integers Two’s complement

Definition: 2N-x for an N-bit number Regular binary two’s complement:

Positive: No change Negative: flip bitwise + 1

Dec: - 95 10100001-----------------------------95: - 0101 1111true code

1010 0000 Flip (one’s complement)

1010 0001 +1

Integer Addition Directly add the numbers, no matter

positive or negative

Check left two carry bit 00 or 11 valid 01 or 10 invalid (overflow)

11111 111 (carry) 0000 1111 (15)+ 1111 1011 (-5)================== 0000 1010 (10)

0111 (carry) invalid! 0111 (7)+ 0011 (3)============= 1010 (−6)

Integer Subtraction x - y = x + two’s complement of y

Procedures: Compute the two’s complement of y (flip bits

+ 1) Addition Check for overflow

01100100 (x, equals decimal 100) - 00010110 (y, equals decimal 22)========== 11100000 (carry) valid! 01100100 (x) + 11101010 (two’s complement of y)========== 101001110 (two’s complement of result) 01001110 (regular binary of result 78)

Integer Subtraction Another example

01100100 (x, equals decimal 100) --11001000 (y, equals decimal -200)========== 01100000 (carry) invalid! 01100100 (x) + 00111000 (two’s complement of y)========== 010011100 (two’s complement of result) - 01100100 (regular binary of result -196)