Unit i CA- MIPS Addressing

1. A.S.PrabaharanAP/CSE
UNIT I MIPS Addressing

2. Addressing in Branches and Jumps
 The MIPS jump instructions have the simplest addressing.
 They use the final MIPS instruction format, called the J-type,
which consists of 6 bits for the operation field and the rest of the
bits for the address field.
 j 10000 # go to location 10000
 where the value of the jump opcode is 2 and the jump address is
10000.

3.  Unlike the jump instruction, the conditional branch instruction
must specify two operands in addition to the branch address.
 bne $s0,$s1,Exit # go to Exit if $s0 ≠ $s1
 branch instruction would calculate the following:
 Program counter Register Branch address
 PC-relative addressing

4.  Showing Branch Offset in Machine Language
 The while loop as compiled into this MIPS assembler code:
 Loop:sll $t1,$s3,2 #Temp reg $t1 = 4 * i
 add $t1,$t1,$s6 # $t1 = address of save[i]
 lw $t0,0($t1) #Temp reg $t0 = save[i]
 bne $t0,$s5, Exit # go to Exit if save[i] ≠ k
 addi $s3,$s3,1 # i = i + 1
 j Loop # go to Loop
 Exit:

5.  If we assume we place the loop starting at location 80000 in
memory, what is the MIPS machine code for this loop?
 The assembled instructions and their addresses are:

6. MIPS Addressing Mode
 Addressing mode One of several addressing regimes delimited by
their varied use of operands and/or addresses.
 1. Immediate addressing, where the operand is a constant within
the instruction itself
 2. Register addressing, where the operand is a register
 3. Base or displacement addressing, where the operand is at the
memory location whose address is the sum of a register and a
constant in the instruction
 4. PC-relative addressing, where the branch address is the sum of
the PC and a constant in the instruction
 5. Pseudo direct addressing, where the jump address is the 26
bits of the instruction concatenated with the upper bits of the PC

10. What is the Addressing Mode
 Add $s0,$s1,5
 A. Register addressing
 B. Immediate addressing
 C. Base addressing
 D. PC-relative addressing
 Ans:B

11. What is the Addressing Mode
 Add $s0,$s1,$s2
 A. Register addressing
 B. Immediate addressing
 C. Base addressing
 D. PC-relative addressing
 Ans:A

12. What is the Addressing Mode
 Lw $t0,32(s3)
 A. Register addressing
 B. Immediate addressing
 C. Base addressing
 D. PC-relative addressing
 Ans:C

13. What is the Addressing Mode
 beq $t0,$3,Label
 A. Register addressing
 B. Immediate addressing
 C. Base addressing
 D. PC-relative addressing
 Ans:D

14. What is the Addressing Mode
 J 2000
 A. Register addressing
 B. Immediate addressing
 C. Base addressing
 D. PC-relative addressing
 E. Pseudo direct Addressing
 Ans:E