Courses/Computer Science/CPSC 355.W2014/Lecture Notes/InstrImpl

Instruction Implementation

Today we examined how these instructions are implemented in terms of logic gates, and how their functional units can form the basis for an implementation of other instructions.

• AND
• OR
• XOR
• NOT (logical negation, one's complement)
• NEG (arithmetic negation, two's complement)
• ADD (a combination of AND, XOR, and OR)

Announcements

• HW2 is due Feb 3
• Midterm exam is Feb 5
• Intel IA-32 developer manual: list of instructions
• Intel IA-32 developer manual: architectural detail (cf. http://www.cs.virginia.edu/~cs216/Fall2005/notes/x86-doc.pdf )

• Continue discussion of instruction implementation and use.

• How are INC and DEC implemented? Note that this is a good example of CISC vs. RISC again: e.g., ADD eax, 1 = INC eax
  • INC
  • DEC

• What are NOT and NEG?
  • NOT
  • NEG

• difference between arithmetic shift right and logical shift right
• examine instructions for manipulating binary values as bytes, words, double words, quad words
  • signed vs. unsigned global variables

• (Integer) Multiplication and division
  • IMUL
  • IDIV