###################################################################
# Program Name: MIPS Assembly Language Practice
# Programmer: Phillip Vaira
# Date Last Modified: August 18, 2004
####################################################################
# Functional Description:
# A simple program that asks for the user's age and determines
# whether it is under eighteen or over. Output would result.
####################################################################
# Pseudocode Description or Algorithm:
#
# $t0;
# cout << "What is your age? ";
# cin >> $t0;
# if ($t0 > 17)
# {
# cout << "You are either eighteen or older.";
# }
# else
# {
# cout << "Your age is less than eighteen.";
# }
#
###################################################################
# Cross References:
# $t0 = Age
###################################################################
.data
Prompt: .asciiz "\n What is your age? "
Over18: .asciiz "\n You are either eighteen or older."
Under18: .asciiz "\n Your age is less than eighteen."
.globl main
.text
main:
li $v0, 4 # system call code for Print String
la $a0, Prompt # load address of prompt into $a0
syscall # print the prompt message
li $v0, 5 # system call code for Read Integer
syscall # reads the value of Age into $v0
li $v0, 10 # terminate program run and
syscall # return control to system
MIPS Assembly: if/else help
Author
I don't see a branch for comparing two registers in my college book on MIPS. Any idea on what it would be?
EDIT: I found a macro instruction ('ble') but do I need to write in something so it recognizes the instruction?
To compare to registers in mips you would use the following:
beq rs, rt, offset
if (rs == rt)
PC += offset
bne rs, rt, offset
if (rs != rt)
PC += offset
beq rs, rt, offset
if (rs == rt)
PC += offset
bne rs, rt, offset
if (rs != rt)
PC += offset
To compare two numbers, use "slt", which means "set on less than". slt rd, rs, rt sets rd to 1 if rs<rt and to 0 otherwise. Then use bne rd, $0, whatever. Alternatively, you can subtract the two registers and use bgtz or bltz on the result.
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