Uploading Programming Assignments -- Typeset assignments will come at a later date.HEADmaster

1 files changed, 123 insertions, 0 deletions

diff --git a/HW2/CS424_HW2_P3_Carpenter_Adam.asm b/HW2/CS424_HW2_P3_Carpenter_Adam.asm
new file mode 100644
index 0000000..fda28ff
--- /dev/null
+++ b/HW2/CS424_HW2_P3_Carpenter_Adam.asm
@@ -0,0 +1,123 @@
+# CSCI 424, Homework 2
+# Adam Carpenter - username acarpent - acarpenter@email.wm.edu
+	.text
+	
+	.globl	main
+main:
+	# Get the string to test and store it.
+	jal 	Input_string
+	la	$s0, ($a0)
+	
+	# ---Make a reversed copy of the string---
+	la 	$a0, buffer2 # set aside space for new string
+	la 	$s1, ($a0) # set s1 to space for new string
+	la 	$t0, ($s0) # create address pointer
+	add 	$t1, $zero, 10 # create index
+copier:
+	add	$t0, $s0, $t1 # point to character at index
+	lb	$t2, ($t0) # load byte located at index
+	beq	$t2, 0, skipJunk  # Skip null characters
+	beq	$t2, 10, skipJunk # Skip new lines
+	sb	$t2, ($a0) # store byte in reversed string
+	addi	$a0, $a0, 1 # increment reversed string pointer
+skipJunk:
+	addi	$t1, $t1, -1 # decrement string pointer
+	bne	$t1, -1, copier # if $t1 != -1, repeat the process
+	
+	# Now s0 points to the original string and
+	# s1 points to the reverse of the original 
+	# string, which has been stripped of 
+	# whitespace and null characters
+	# ----------------------------------------
+	
+	# Start printing out the response
+	la	$a0, str1
+	jal	Print_string
+	
+	la	$a0, ($s0)
+	jal	Print_string
+	
+	la	$a0, str2
+	jal	Print_string
+	
+	# ---Loop to check if strings match---
+	add	$t0, $zero, $zero # flag marks whether string is palindrome
+	add 	$t1, $zero, $zero # create index
+checkPalindrome:
+	add	$t2, $s0, $t1 # point to character at next index
+	lb	$s2, ($t2) # load character into t2
+	beq	$s2, 10, endLoop # end loop if newline
+	add	$t3, $s1, $t1 # point to character at same index
+	lb	$s3, ($t3) # load character into t3
+	sub	$t0, $s2, $s3 # if the two characters match, flag will remain 0
+	bne	$t0, $zero, notPalindrome # if flag is not zero, it's not a palindrome
+	addi	$t1, $t1, 1 # increment index
+	jal	checkPalindrome
+endLoop:
+	beq	$t0, $zero, isPalindrome
+	# This loop determines if the string is a 
+	# palindrome by comparing it to the 
+	# reversed duplicate string. The loop terminates
+	# when it finds the carriage return in the
+	# original string and jumps based on 
+	# how the flag was set.
+	# ------------------------------------
+	
+notPalindrome: # The string is NOT a palindrome
+	la	$a0, str3 
+	jal	Print_string
+	jal 	Exit
+	
+isPalindrome: # The string is a palindrome
+	la	$a0, str4 
+	jal	Print_string
+	jal	Exit	
+	
+# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+	.data
+	.align	0
+str1:
+	.asciiz "\nThe string "
+str2: 
+	.asciiz "is "
+str3:
+	.asciiz	"not a palindrome!\n"
+str4:
+	.asciiz "a palindrome!\n"
+buffer: 
+	.space 12
+buffer2: 
+	.space 12
+
+# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+# Wrapper functions around some of the system calls
+# From P&H COD, Fig. A.9.1
+	.text
+	
+	.globl Input_string
+Input_string:  # take in a string from keyboard. String is in $a0 and length is in $a1
+	la	$a0, buffer 	 # Place result in location of myString
+	li 	$a1, 12		 # Maximum length for string
+	addi	$v0, $zero, 8
+	syscall
+	jr	$ra
+
+	.globl	Print_string
+Print_string:	# print the string whose starting address is in register a0
+	addi	$v0, $zero, 4
+	syscall
+	jr	$ra
+
+	.globl	Exit
+Exit:		# end the program, no explicit return status
+	addi	$v0, $zero, 10
+	syscall
+	jr	$ra
+
+	.globl	Exit2
+Exit2:		# end the program, with return status from register a0
+	addi	$v0, $zero, 17
+	syscall
+	jr	$ra