# Array summation Loop
# Kweequeg W Yjibo
# kwyjibo


# Sum an array of integers.  
# Leave the result in Sum.

# To demonstrate that the result is as predicted, place the value in r4 to be printed

# Registers
#   $1 -- true if done
#   $2 -- current address in array
#   $3 -- last address of array
#   $4 -- running sum	
#   $5 -- temp to get value from memory

.globl main

main:   add     $4, $0, $0      # Initialize $4
        llo     $2, First       # get first address
        lhi     $2, First
        llo     $3, Last        # get last address
        lhi     $3, Last

loop:   slt     $1, $3, $2      # test if done
        bne     $1, $0, done    # if yes, branch
        lw      $5, 0($2)       # load array value 
        add     $4, $4, $5      # add to sum
        addi    $2, $2, 4       # inc array pointer
        j       loop            # do it again

done:   llo     $5, Sum         # store sum
        lhi     $5, Sum
        sw      $4, 0($5)

        trap    1               # print contents of $4 (This will be the sum)
	
        trap    10              # Quit

# Data

First:  .word   10
        .word   20
        .word    1
        .word   15
        .word    3
        .word   10
Last:   .word    5
Sum:    .word    0     # should be 64