arrcp.s

~~~~~~~~~~~~~

.data source: .word 3, 1, 4, 1, 5, 9, 0 dest: .word 0, 0, 0, 0, 0, 0, 0 countmsg: .asciiz " values copied. "

.text

main: la $a0,source la $a1,dest

loop: lw $v1, 0($a0) # read next word from source addiu $v0, $v0, 1 # increment count words copied sw $v1, 0($a1) # write to destination addiu $a0, $a0, 1 # advance pointer to next source addiu $a1, $a1, 1 # advance pointer to next dest bne $v1, $zero, loop# loop if word copied not zero

loopend: move $a0,$v0 # $a0

la $a0,countmsg # $a0

li $a0,0x0A # $a0

finish: li $v0, 10 # Exit the program syscall

### The following functions do syscalls in order to print data (integer, string, character) #Note: argument $a0 to syscall has already been set by the CALLEE

puti: li $v0, 1 # specify Print Integer service syscall # Print it jr $ra # Return

puts: li $v0, 4 # specify Print String service syscall # Print it jr $ra # Return

putc: li $v0, 11 # specify Print Character service syscall # Print it jr $ra # Return

(Exercise) Debugging MIPS Debug the loop written in arrcp.s. The program is suppose to copy integers from memory address in $a0 to memory address in $a1, until it reads a zero value. The number of integers copied (up to but not including the zero value) should be returned so stored into $v0 Q1. How many bugs are there? Q2. How do you fix the bug(s)? Q3. What is your strategy to finding the bug(s)? Fix the code so it works in arrcp.s