## ECE2030 Intro to Computer Engineering
##
## Array.s
## 
## Author: Prof. Hsien-Hsin S. Lee			
## 
## School of Electrical & Computer Engineering
## Georgia Institute of Technology
## Atlanta, GA 30332
##
## leehs@gatech.edu
##
##							 
		
	.data
       .globl array_A		
array_A:
	.ascii "MIPS----SPIM    "
	.ascii "O:-)    " 	
	.word 0x64636261  
	.word 0x33323130 
	.word 0x00000000  
	.word 0x00000000

array_B:
	.space 64	
	.word 0x00000000
A_name:	
	.asciiz "array_A= "	# end with a NULL character
B_name:	
	.asciiz "array_B= "	
caret:	
	.asciiz "\n"		

# Standard startup code.  Invoke the routine main with no arguments.

	.text
	.globl __start
__start: jal main
	addu $0, $0, $0		# Nop
	addiu $v0, $0, 10
	syscall			# syscall 10 (exit)

	.globl main
main:
	addu $20, $0, $31	# Save return PC

	divu $20, $0
	
	la $8,  array_A
	la $13, array_B
loop:
	lw $15, ($8)
	beqz $15, end_loop
	lb $9, ($8)
	lb $10, 1($8)
	lb $11, 2($8)
	lb $12, 3($8)

	sb $12, ($13)
	sb $11, 1($13)
	sb $10, 2($13)
	sb $9,  3($13)
	addiu $13, $13, 4
	addiu $8, $8, 4
	j loop
	
end_loop:	
	li $v0, 4
	la $a0, A_name
	syscall
				# system call (type 4) for printing out string (See fig A.17 in Appendix A)
	la $a0, array_A		# point the base address of crypt to register $a0 (=$4) 
	syscall			# make system call, this will print out all the strings pointed by address in $a0, i.e. crypt, which
				# is unreadable
	la $a0, caret
	syscall
	
	
	la $a0, B_name
	syscall
				# system call (type 4) for printing out string (See fig A.17 in Appendix A)
	la $a0, array_B		# point the base address of crypt to register $a0 (=$4) 
	syscall			# make system call, this will print out all the strings pointed by address in $a0, i.e. crypt, which
				# is unreadable
	la $a0, caret
	syscall
Exit:	
	jr $31