MIPS integer implementation of floating point addition - Programmers Heaven

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# MIPS integer implementation of floating point addition

Posts: 8Member
So I'm trying to write a program in MIPS assembly code to help me better understand how floating point addition works. I understand how a floating point number is broken up into a 1 bit sign, 8 bit exponent, and 23 bit fraction. I've written a program that gets two inputs from a user, and adds them WITHOUT using any floating point instructions except mtc1 and mfc1 (for input and output). My code has bugs because when I add 1 + 2 I get 2.74804688. I'm still trying to debug the code but can't seem to grasp the problem. If anyone can help, I would greatly appreciate it.

THIS IS MY CODE (excluding the user input...the first floating point value is in \$s0, and the second in \$s1)

#Initialize variables
add \$s2,\$zero,\$zero #initialize sum variable to 0
add \$t3,\$zero,\$zero #initialize SUM OF SIGNIFICANDS value to 0

#get EXPONENT from values
sll \$s5,\$s0,1 #getting the exponent value
srl \$s5,\$s5,24 #\$s5 = first value EXPONENT

sll \$s6,\$s1,1 #getting the exponent value
srl \$s6,\$s6,24 #\$s6 = second value EXPONENT

#get SIGN from values
srl \$s3,\$s0,31 #\$s3 = first value SIGN
srl \$s4,\$s1,31 #\$s4 = second value SIGN

#get FRACTION from values
sll \$s7,\$s0,9
srl \$s7,\$s0,9 #\$s7 = first value FRACTION
sll \$t8,\$s1,9
srl \$t8,\$s1,9 #\$t8 = second value FRACTION

#compare the exponents of the two numbers
compareExp: ######################

blt \$s5,\$s6, shift1 #if first < second, go to shift1
blt \$s6,\$s5, shift2 #if second < first, go to shift2
j compareExp

shift1: #shift the smaller number to the right
srl \$s7,\$s7,1 #shift to the right 1
j compareExp

shift2: #shift the smaller number to the right
#srl \$s0,\$s0,1 #shift to the right 1
#j compareExp
srl \$t8,\$t8,1 #shift to the right 1
j compareExp

li \$v0, 4
la \$a0, sum
syscall

li \$v0, 1
move \$a0, \$t3
syscall

j result

result:
li \$v0, 4
la \$a0, newline
syscall

sll \$t4,\$s3,31 #SIGN
#FRACTION
sll \$t5,\$s6,23 #EXPONENT

li \$v0, 4
la \$a0, sum2
syscall

li \$v0, 1
move \$a0, \$t6
syscall

li \$v0, 4
la \$a0, newline
syscall

li \$v0, 4
la \$a0, sum2
syscall

li \$v0,2
mtc1 \$t6,\$f12
syscall
jr \$31
# END OF PROGRAM