50.004-ALU-Check-off

This Readme File serves as justification purpose for all possible test cases in each component of ALU

It contains a folder only which has all of our work inside.

Compare unit justification

There would be nine test cases for the compare unit and three cases for each compare unit.

COMPEQ

value == value

true

bigValue == smallValue

false

smallValue == bigValue

false

CMPLE

value == value

false

smallValue >= bigValue

false

smallValue <= bigValue

true

CMPLT

value == value

false

smallValue > bigValue

false

smallValue < bigValue

true

Adder unit justification

Overflow can never happen if two operands have differnt signs and it's only possible in operands with the same signs.

There would be four cases for addiction only

zero+zero no overflow

positive+positive no overflow

positive+positive overflow

positive+negative never overflow(same for negative+positive by swaping a,b position)

Subtractor unit justification

There would be four cases for subtarctor only

zero-zero no overflow

positive-positive never overflow(same for negative-negative by swaping a,b position)

negative-positive overflow

negative-positive no overflow

Boolean unit justification

We have AND, NAND, OR, NOR, XOR, A six gates in total

Multiplier unit justification

There would be seven cases in total

postive multiplies postive no overflow

postive multiplies postive overflow

negative multiplies negative no overflow

negative multiplies negative overflow

postive multiplies negative no overflow

postive multiplies negtive overflow

zero multiplies zero no overflow

Shifter unit justification

basically shifer for this 16bit ALU would be able to shift at most 15bits.In specific, any value and sum of among 2^0, 2^1, 2^2,2^3.