# File: mlIfElse.asm

# Author: ************

# Date: mm/dd/yyyy

# Purpose: Practice if-else logic

#----------------------------------------------

# WRITE MIPS CODE FOR THE FOLLOWING C++ CODE:

#include

#include

#using namespace std;

#void main()

#{

# //declare variables

# string result;

# int x;

# //prompt for, read in a value for x

# cout << "Please enter a value for x (integer): ";

# cin >> x;

#

# ==========================================================

# //PROBLEM1 - if x has a value of 3 or 4, print "ddd", else print "eee"

# result = "";

# if(x==3 || x==4) result = result + "ddd";

# else result = result + "eee";

# cout << "1.\t" << result << endl;

#

# =============================================================

# //PROBLEM2 - if x is less than 5 and greater than 2,

# // then check to see if it is even. If it is even,

# // print "ddd". If its not even, the original "ccc" is printed.

# // But if x was not less than 5 and greater than 2,

# // print "eee".

# result = "ccc";

# if (x < 5 && x > 2)

# {

# if (x%2 == 0) result = "ddd";

# }

# else result = "eee";

# cout << "2.\t" << result << endl;

#

# ==========================================================

# //PROBLEM3 - if x has a value if 2, print "bbb"

# // if x has a value of 3, print "ccc"

# // if x has a value of 4, print "ddd"

# // if x has a value other than 2, 3, or 4 print "eee"

# result = "";

# switch (x)

# {

# case 2: result = result + "bbb"; break;

# case 3: result = result + "ccc"; break;

# case 4: result = result + "ddd"; break;

# default: result = result + "eee";

# }

# cout << "3.\t" << result << endl;

#

# =========================================================

# //PROBLEM4 - if x has a value of 4, print "ddd"

# // if x has a value of 3, print "ccc"

# // any other value (not 3 or 4), print "eee"

# result = "";

# if (x==4) result = result + "ddd";

# else if (x==3) result = result + "ccc";

# else result = result + "eee";

# cout << "4.\t" << result << endl;

#

# }//end main()

.data

.eqv SYS_PRINT_WORD 1 #word, byte, character

.eqv SYS_PRINT_FLOAT 2 #float

.eqv SYS_PRINT_DOUBLE 3 #double

.eqv SYS_PRINT_TEXT 4 #text (zero terminated)

.eqv SYS_INPUT_WORD 5 #input word

.eqv SYS_EXIT 10 #terminate

# //declare variables

# string result;

# int x;

result: .asciiz "0123456789012345" #max of 16 chars

x: .word 0 # copy of $s5

endl: .asciiz " "

tx_prompt: .asciiz "Please enter a value for x (integer): "

tx_bbb: .asciiz "bbb"

tx_ccc: .asciiz "ccc"

tx_ddd: .asciiz "ddd"

tx_eee: .asciiz "eee"

prob1_label: .asciiz "1.\t"

prob2_label: .asciiz "2.\t"

prob3_label: .asciiz "3.\t"

prob4_label: .asciiz "4.\t"

.text

.globl main

main:

# //prompt for, read in a value for x

# cout << "Please enter a value for x (integer): ";

# cin >> x;

la $a0, tx_prompt # load address of prompt for syscall

li $v0, SYS_PRINT_TEXT # specify Print String service

syscall # print the prompt string

li $v0, SYS_INPUT_WORD # specify Read Integer service

syscall # Read the number. After this instruction, the number read is in $v0.

add $s5, $v0, $zero # transfer the number to s5

la $t0, x

sw $s5, 0($t0) # s5 = x = input word number

la $s4, result # s4 = address of result string

# //PROBLEM1

sb $zero, 0($s4) #result = ""

li $t1, 3 #x==3?

beq $s5, $t1, ddd1 # yes, branch

li $t1, 4 #x== 4?

beq $s5, $t1, ddd1 #yes, branch

fals1: move $a0, $s4 #a0 = &result

la $a1, tx_eee #a1= &tx_eee

jal concatstr #result= result + "eee"

j prt1

ddd1: move $a0, $s4 #a0= &result

la $a1, tx_ddd # a1= &tx_ddd

jal concatstr

prt1: la $a0, prob1_label

li $v0, SYS_PRINT_TEXT

syscall

move $a0, $s4 #print result

li $v0, SYS_PRINT_TEXT

syscall

la $a0, endl

li $v0, SYS_PRINT_TEXT

syscall

# //PROBLEM2

# //PROBLEM3

# //PROBLEM4

#---- terminate ---

exit:

li $v0, SYS_EXIT

syscall

#-------------------------------------------------------------

# concatstr - concatenate $a1 to $a0 string

# input $a0 - address of result string

# input $a1 - address of string to concatenate to result

# output $a0 - address of end of string \0

# output $a1 - address of end of string \0

#-------------------------------------------------------------

concatstr:

#find \0 in a0 result string

findend:

lbu $t0, 0($a0)

beq $t0, $zero, docopy # branch if result.at(a0) == '\0'

addiu $a0, $a0, 1

j findend # move to next char and keep looking

# concatenate a1 chars to a0 chars

docopy:

lbu $t0, 0($a1) # get current char from a1

sb $t0, 0($a0) # copy current char to a0

beq $t0, $zero, concatstr_exit # if char == '\0', branch & stop if char was '\0'

addiu $a0, $a0, 1 # advance to next char

addiu $a1, $a1, 1 # advance to next char

j docopy

concatstr_exit:

jr $ra

#.end main