Question

# File: mlRemoveBlanks

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

# Date: mm/dd/yyyy

# Purpose: Practice rotate & AND to remove spare blanks

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

# Write a MIPS assembler program to remove the extra blanks from

# a string:

# INPUT: "Two bee ore knot too Bea that"

# PATTERN:00011000100011000010001100010000

# ROTATE: 00110001000110000100011000100000

# AND: 00010000000010000000001000000000

# RESULT:"Two bee ore knot too Bea that "

.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_INPUT_FLOAT 6 #input float

.eqv SYS_PRINT_BIN 35 #print binary

.eqv SYS_EXIT 10 #terminate

# declare variables

.eqv BLANK 32

#12345678901234567890123456789012

text: .ascii "Two bee ore knot too Bea that"

end_text: .asciiz "\n"

result: .ascii " "

end_result: .asciiz "\n"

blank: .byte ' '

endl: .asciiz "\n"

endl2: .asciiz "\n\n"

.text

.globl main

main:

# Print starting text

la $a0, text

li $v0, SYS_PRINT_TEXT

syscall

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

# Create the bit pattern with a 1 where each blanks exists

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

# s7 = ending address for loop

# s1 = text address

# s0 = the bit pattern

loop1:

# shift pattern left

# get 'text' byte

# compare with BLANK

# set s0 bit0 for BLANK, else skip to noBlank, not setting bit0

noBlank:

# move to next character

# loop1 if not done (s1 != s7)

# print s0 pattern

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

# Duplicate bit pattern, Rotate left, AND the two patterns

# should be where extra blanks exist

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

# duplicate s0 pattern into s2

# rotate s2 left one bit

# print s2 rotate

# AND the two patterns: s2 & s0

# print the AND pattern

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

# Copy 'text' into 'result' for each zero bit in s3 pattern

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

# ending s7 'end_text' address

# source address 'text' in s0

# destination address 'result' in s1

loop2:

# rotate high bit to bit0

# test bit0

# skip if bit0 is 1

# get character at (s0)

# save character in (s1)

# advance s1 'result' address

skip:

# advance s0 'text' address

# loop2 if not done (s0 != s7)

# print 'result'

#---- terminate ---

exit:

li $v0, SYS_EXIT

syscall

#.end main

# move to next character

# loop1 if not done (s1 != s7)

# print s0 pattern

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

# Duplicate bit pattern, Rotate left, AND the two patterns

# should be where extra blanks exist

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

# duplicate s0 pattern into s2

# rotate s2 left one bit

# print s2 rotate

# AND the two patterns: s2 & s0

# print the AND pattern

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

# Copy 'text' into 'result' for each zero bit in s3 pattern

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

# ending s7 'end_text' address

# source address 'text' in s0

# destination address 'result' in s1

loop2:

# rotate high bit to bit0

# test bit0

# skip if bit0 is 1

# get character at (s0)

# save character in (s1)

# advance s1 'result' address

skip:

# advance s0 'text' address

# loop2 if not done (s0 != s7)

# print 'result'

#---- terminate ---

exit:

li $v0, SYS_EXIT

syscall

#.end main

Answer 1

tr: .space 81 # buffer for input string
strNS: .space 81 # buffer for string w/o spaces
prompt: .asciiz "Enter a string up to 80 characters\n"
head1: .asciiz "\nOriginal String: "
head2: .asciiz "\nNumber of spaces: "
head3: .asciiz "\nWith spaces removed: "

.text   
main:   
#print the first prompt and get the input string from console
li $v0, 4 #load syscall value to print string into $v0
la $a0, prompt #address of prompt to print
syscall #print prompt to console
li $v0, 8 #load syscall value to read input string
la $a0, str #addr of allocated space for input string is now in $a0
li $a1, 81
syscall

jal countSpace

addi $t1, $v0, 0 #the count of spaces is in $v0, save it into $t1
li $v0, 4 #print header then the count
la $a0, head1
syscall
la $a0, str #print the original string
syscall
la $a0, head2 #print second header before printing count
syscall
li $v0, 1
addi $a0, $t1, 0 #place the count in $a0
syscall #print the count

li $v0, 4
la $a0, head3 #print the third header
syscall
la $a0, strNS #print no spaces string
syscall

End:
li $v0, 10 #load syscall value for exit
syscall #exit

countSpace:
la $s0, strNS
addi $sp, $sp, -12 #adjust the stack pointer for saving
sw $s0, 8($sp) #store addr of nospace string
sw $ra, 4($sp) #store return addr on the stack
sw $a0, 0($sp) #store the count on the stack

#Begin counting spaces
addi $t3, $a0, 0 #$t3 has addr of user input
addi $t5, $s0, 0 #$t5 has addr of string with no spaces
li $t6, 0 #$t6 holds index of string with no spaces
li $t0, 0 #$t0 will hold the count of spaces
li $t4, 0 #$t4 holds the index of the string
loop:   
add $t1, $t3, $t4 #$t1 = addr of str[i]
lb $t2, 0($t1) #$t2 = character in str[i]
beq $t2, $zero, exitCS #break from loop if $t2 contains null character
addi $a0, $t2, 0 #place value to be checked in $a0

#save values onto stack from temp registers to preserve them
addi $sp, $sp, -28 #adjust the stack pointer for 5 values
sw $t6, 24($sp) #save index of string with no spaces
sw $t5, 20($sp) #save addr of string with no spaces
sw $t4, 16($sp) #save index of user input
sw $t3, 12($sp) #save the addr of user input
sb $t2, 8($sp) #save the character in str[i]
sw $t1, 4($sp) #save the address of str[i]
sw $t0, 0($sp) #save the count of spaces

jal isSpace #result from this jump and link will be in $v0 after call

#pop saved values from the stack, then reset the pointer
lw $t6, 24($sp)
lw $t5, 20($sp)
lw $t4, 16($sp)
lw $t3, 12($sp)
lb $t2, 8($sp)
lw $t1, 4($sp)
lw $t0, 0($sp)
addi $sp, $sp, 28 #reset stack pointer
beq $v0, $zero, addTo #if not a space, continue to next character
addi $t0, $t0, 1 #if it is a space, increment count
addTo:
bne $v0, $zero, nextChar #If character is a space, branch
sll $t7, $t6, 2 #index if nospaces string stores width of 4
add $t7, $t7, $t5 #now $t7 points at nospaces[i]
sb $t2, 0($t7) #store the character in the nospaces string
addi $t6, $t6, 1 #increment the index of nospaces

nextChar:

addi $t4, $t4, 1 #increment the index value
j loop #jump back to loop and continue processing

exitCS:
addi $v0, $t0, 0 #count of spaces placed into $v0
addi $v1, $t5, 0
lw $ra, 4($sp) #load return addr from the stack
lw $a0, 0($sp) #load value to check from the stack
addi $sp, $sp, 8 #reset stack pointer
jr $ra #return

isSpace:
addi $sp, $sp, -12 #adjust stack pointer to make room
sw $s0, 8($sp)
sw $ra, 4($sp) #store value of return addr onto stack
sw $a0, 0($sp) #store value to check onto stack

#Check to see if the character is a space
li $t0, 32 #ascii value for space character loaded into $t0
li $v0, 0 #Set default return to 0, or "not a space character"
bne $t0, $a0, endSC #if ascii values match, character is a space
li $v0, 1 #$v0 = 1 means it is a space character

endSC:
lw $s0, 8($sp)
lw $ra, 4($sp) #restore return address
lw $a0, 0($sp) #restore addr of str
addi $sp, $sp, 12 #reset the stack pointer

end: jr $ra