Question

Provided code:
.data
arrayB: .word 0xffff, 0xffff, 0xffff, 0xffff
.text

Using syscalls

o A “syscall” is a function that is provided by the operating system of the MIPS computer, not by the MIPS architecture itself. Examples are the ability to print data to the MIPS computer’s display monitor, obtain the time of day, etc.

o Open the MARS help screen, and select the Syscalls tab to bring up the available syscalls. Find and review the section “How to use SYSCALL system services.”

o You will use syscall 41, “random int.” Use of a syscall requires a series of MIPS instructions. You must provide the “setup” of a syscall by setting values in registers, then make the syscall itself.

• MIPS instruction to put the value 41 into register $v0. This specifies which syscall will be executed.
• The random integer syscall needs no other parameters. In general, a syscall may require that other parameter values be placed in registers.
• MIPS instruction syscall (just the word “syscall” by itself on a line)
• The outcome of this syscall is that a random number will have been placed into a register. Use the documentation in the help page to find out which register.

Write a loop that will generate 6 random integers and store them in arrayB.

Write instructions to prepare for a future loop, including the following actions:

• Initialize a loop counter
• Put the address of arrayB into a register, using the la instruction.

Write instructions to complete the body of the loop, including the following actions:

• Syscalls for random integer (see above)
• Store that random integer into the the arrayB at the correct location.
• Modify the base address for the next iteration of the loop
• Modify the loop counter value

Answer 1

Answer:

Given that

provided code:

.data

arrayB:.word 0xffff,0xffff,0xffff,0xffff

.text

I have implemented Using "syscall" is a function that is provided by the operating system of the MIPS computer, not the MIPS architecture itself.

code:

.data

arrayB: .word 0:5

.text

la $a1, arrayB

loop:

bgt $t0,5,exit #check if greater than 6

li $v0, 41 #syscall for random int

syscall

mul $t1, $t0, 4 #multiply to calculate offset for array

addu $t2, $t1, $a1 #calculate offseted address

sw $a0, 0($t2) #store at offseted address

addi $t0,$t0,1 #increment loop counter

j loop #jump to label

exit:

Screenshot: