Instruction Set Architecture An overview of MIPS R3000 assembly language

1. Instruction Set Architecture An overview of MIPS R3000 assembly language SYCS-401 Operating Systems

2. Overview • Review of the concept of an Instruction SetArchitecture (ISA) • Understand the format of MIPS assembly source files • Be able to identify the registers of the R3000 and their purpose • Be able to understand the effects of a subset of instructions of the MIPS R3000 Instruction Set Architecture (ISA) SYCS-401 Operating Systems

3. Opcodes and Operands add $a0, $t1, $t0 Operands (“arguments”) Opcode (Instruction) SYCS-401 Operating Systems

4. Simple Assembler Program .globl main .text main: # Program starts here. li $t0, 5 # Load the integer value 5 # into register t0 li $t1, 19 # Load 19 into register t1 add $t2, $t1, $t0 # Add registers t0 and t1 # to produce t2 li $v0, 1 # Setup a print integer call # to print the result move $a0, $t2 syscall li $v0, 10 # Setup an exit call syscall # Do the exit thing Add the integers 5 and 19, and print the result. 8 SYCS-401 Operating Systems

5. Instruction Set Architecture (ISA) • Think of the ISA as the hardware/software interface • In this lecture we look at some aspects of MIPS ISA, • including: • Some opcodes • Required operands • there are no implicit operands in MIPS • Means of accessing RAM • Number of registers • Instruction format • etc., etc. SYCS-401 Operating Systems

6. MIPS: ISA generations (‘I’ to ‘IV’) • MIPS I (8 MHz, 32b architecture) • R2000 (first commercial MIPS processor) • MIPS II (40 MHz, 32b architecture) • R3000 • MIPS III (to 250 MHz pipeline, 64b architecture) • R4x00 • MIPS IV • R8000 • R10000 • R5000 SYCS-401 Operating Systems

7. SYCS-401 Operating Systems

8. MIPS Registers SYCS-401 Operating Systems

9. General-Purpose Registers SYCS-401 Operating Systems

10. General-Purpose Registers SYCS-401 Operating Systems

11. General-Purpose Registers SYCS-401 Operating Systems

12. General-Purpose Registers SYCS-401 Operating Systems

13. General-Purpose Registers SYCS-401 Operating Systems

14. General-Purpose Registers SYCS-401 Operating Systems

15. General-Purpose Registers SYCS-401 Operating Systems

16. General-Purpose Registers SYCS-401 Operating Systems

17. MIPS opcode formats SYCS-401 Operating Systems

18. MIPS Instruction Categories • Arithmetic instructions • add, subtract, multiply, divide comparison • Logical instructions • Branch and jump instructions • conditional (branch) • unconditional (jump) • Data transfer (load & store) instructions SYCS-401 Operating Systems

19. Arithmetic Instructions • add • subtract • multiply • divide • compare • shift / rotate • not covered here SYCS-401 Operating Systems

20. Arithmetic Instructions: Add Registers ADD destinationReg, sourceReg, targetReg Destination ¬Source + Target SYCS-401 Operating Systems

21. Arithmetic Instructions: Add Unsigned ADDU destinationReg, sourceReg, targetReg Destination ¬Source + Target SYCS-401 Operating Systems

22. Arithmetic Instructions: Add Immediate ADDI destinationReg, sourceReg, targetReg Destination ¬Source + Target SYCS-401 Operating Systems

23. MIPS Opcode Map SYCS-401 Operating Systems

24. MIPS Opcode Map SYCS-401 Operating Systems

25. MIPS System Calls (syscall) SYCS-401 Operating Systems

26. Arithmetic Instructions: Divide Registers DIV sourceReg, targetReg $lo (quotient), $hi (remainder) ¬Source / Target SYCS-401 Operating Systems

27. Arithmetic Instructions: Multiply Registers MUL sourceReg, targetReg $lo (low word), $hi (high word) ¬Source x Target SYCS-401 Operating Systems

28. Arithmetic Instructions: Set if Less Than SLT destinationReg, sourceReg, targetReg Destination ¬(Source < Target) ? 1 : 0 SYCS-401 Operating Systems

29. Arithmetic Instructions: SLT Immediate SLTI destinationReg, sourceReg, immediate Destination ¬(Source < immediate) ? 1 : 0 SYCS-401 Operating Systems

30. Some other arithmetic instructions SYCS-401 Operating Systems

31. Logical Instructions • Logical AND • logical OR • XOR • NOT SYCS-401 Operating Systems

32. Arithmetic Instructions: Logical AND AND destinationReg, sourceReg, targetReg Destination ¬Source AND Target SYCS-401 Operating Systems

33. Arithmetic Instructions: Logical OR OR destinationReg, sourceReg, targetReg Destination ¬Source OR Target SYCS-401 Operating Systems

34. Some other Logical instructions SYCS-401 Operating Systems

35. Branch and Jump Instructions • These alter the (otherwise) linear flow of control. • There are two main types of “go to” instruction • unconditional ( always go to … ) • > jump • conditional ( if … then go to … ) • > branch (indicating an alternative flow) SYCS-401 Operating Systems

36. Branch and Jump Instructions SYCS-401 Operating Systems

37. Jump Instructions: Jump J label Jump to instruction at label SYCS-401 Operating Systems

38. Jump Instructions: Jump & Link JAL label Place the address of the next instruction (PC + 4) in $ra. Jump to the instruction at ‘label’ SYCS-401 Operating Systems

39. Jump Instructions: Jump & Link SYCS-401 Operating Systems

40. Branch Instructions: Branch on Equal BEQ sourceRegister, targetRegister, label If (sourceRegister == targetRegister) go to instruction at ‘label’ SYCS-401 Operating Systems

41. Branch Instructions: Branch if Equal to Zero BEQZ sourceRegister, label If (sourceRegister == 0) go to instruction at ‘label’ SYCS-401 Operating Systems

42. Some other Jump/Branch instructions SYCS-401 Operating Systems

43. Data transfer instructions • MIPS is a load-and-store architecture • The only instructions that access RAM are those\ which load to (or store from) registers • Note that all other instructions operate on registers • To change a value in memory, you must therefore: • load it to a register • alter it • store it back in memory SYCS-401 Operating Systems

44. Data Transfer Instructions: Load Address LA destinationRegister, address destinationRegister ¬calculated address SYCS-401 Operating Systems

45. Data Transfer Instructions: Load Immediate LI destinationRegister, immediate destinationRegister ¬immediate value SYCS-401 Operating Systems

46. Data Transfer Instructions: Move from HI MFHI destinationRegister destinationRegister ¬HI register SYCS-401 Operating Systems

47. Data Transfer Instructions: Load Byte LB targetRegister, label Load targetRegister with the byte value at address “label” SYCS-401 Operating Systems

48. Data Transfer Instructions: Store Byte SB targetRegister, label Store low byte value in targetRegister at address “label” SYCS-401 Operating Systems

49. Data Transfer Instructions: Load Word LW targetRegister, label Load targetRegister with the word value at address “label” SYCS-401 Operating Systems

50. Data Transfer Instructions: Move MOVE destinationRegister, sourceRegister destinationRegister ¬sourceRegister SYCS-401 Operating Systems