Question

[5] <§2.7> Translate the following C code to MIPS assembly code. Use a minimum number of instructions. Assume that the values of a, b, i, and j are in registers \(s0, \)s1, \(t0, and \)t1, respectively. Also, assume that register $s2 holds the base address of the array D.

for(i=0; i<a; i++)

for(j=0; j<b; j++)

D[4*j] = i + j;

Short answer

The corresponding MIPS code is :

add$t0, $0, $0
LP1:slt$t2, $t0, $s0
beq$t2, $0, EXIT
add$t1, $0, $0
LP2:slt$t2, $t1, $s1
beq$t2, $0, LP3
add$t2, $t0, $t1
sll$t4, $t1, 4
add$t3, $t4, $s2
sw $t2, 0($t3)
addi$t1, $t1, 1
j LP2
LP3:addi$t0, $t0, 1
j LP1
EXIT:

Step-by-step solution

Define the concept of the MIPS instructions.

• One of the MIPS instructions is “add $t3 $t4 $t5” for add where

$t3 = $t4 + $t5.

• The full form of “slt” MIPS instruction is set on less than. The MIPS instruction “slt $t3, $0, $t2” is used in the sequence where “$t3” is the register destination, “$0” is the source register, “$t2” is the destination register. If $0<$t2 then $t3 = 1 else $t3 = 0.
• The “branch-on-equal (beq)” is a decision-making instruction in MIPS assembly language. The purpose of using this MIPS assembly instruction “beq reg1, reg2 Label” is going to the statement “Label” if the value of “reg1” is equal to the “reg2”.
• One of the “R type(Register type)” MIPS instruction is “sll $t3 $t4 1” where “$t4” is the source register, “$t3” is the destination register, and “1” is the specified shift amount. The purpose of using this is for shifting the value of the register to the left by the specified shift amount.
• The “I type” instruction “sw$t2, 0($t3)” is used for storing the word where “$t2” is the source register and “$t3” is the destination register and “0” is the offset.
• One of the “I type” MIPS instruction is “addi $t3 $t4 1” “$t4” is the source register, “$t3” is the destination register, and “1” is the immediate value. The purpose of using it for add immediately.
• The “jump(j)” is the MIPS assembly instructions. This instruction is used for transferring the sequence of the program to the specified memory address. The purpose of using this MIPS assembly instruction -“j 2400” is to jump to the specified memory address “2400”.

Determine the MIPS assembly code.

In the given c code is:

for(i=0; i<a; i++)

for(j=0; j<b; j++)

D[4*j] = i + j;

The corresponding MIPS code is :

add $t0, $0, $0 // i is initialized as 0
LP1: slt $t2, $t0, $s0 // i is less than a
beq $t2, $0, EXIT // if $t2 is equal to 0 then go to Exit
add $t1, $0, $0// j is initialized as 0(zero)
LP2: slt $t2, $t1, $s1 // j is less than b
beq $t2, $0, LP3 //if $t2 is equal to 0 then go to LP3
add $t2, $t0, $t1// add i and j
sll $t4, $t1, 4//$t4 is initialized as (4*j)
add $t3, $t4, $s2//$t3 is initialized as &D[4*j]
sw $t2, 0($t3)// D[4*j] is initialized as (i+j)
addi $t1, $t1, 1//j is initialized as (j+1)
j LP2
LP3:addi$t0, $t0, 1//i is initialized as (i+1)
j LP1
EXIT: