############################### 
# SOLUTION FOR PROBLEM 1.    ##
###############################

#       $t0 = location of the string 
#       $t1 = hold scanned character
#       $s2 = holds the ascii value for a space(32)
#       $t3 = used for address computation
#       $s5 = used for starting address of TABLE2 for a word statistics
#       $s4 = used for starting address of TABLE4 for sentence statistics
#       $s0 = holds the word length cnt
#       $s1 = holds the address for TABLE

        .data
        
string:
        .asciiz "IN A DISTANT GALAXY EONS BEFORE THE CREATION OF THE MYTHICAL PLANET KNOWN \n"
return:
        .asciiz "\n"

newline:
        .asciiz "\n"

word_msg:
        .asciiz  " number of occurences of words containing \n"
eq_msg:  .ascii  " = "

        .align 4

TABLE2: .space 104   # for temporary use
        .align 4
TABLE4: .space 104   # for occurences cnt
        .text
        .globl main
main:

        la $t0, string                  # stores the address for string in $t0
      
        la $s5, TABLE2
        la $s4, TABLE4
        addi $s2, $0, 32                # stores the ascii value for space in $t2
  


LOOP:
         lbu $t1, 0($t0)                       # load the next charater 
         beq $t1, $0, DONE               # END of STRING
         nop
         beq $t1,$s2,RESETWLC            # space
         nop
         addi $s0,$s0,1                  #inclement word length cnt.
         
         ########## Goal:  Record the word Statistics  at the TABLE2 ############
         ### Step1: Capitalize the Character #######
         ### Step2: Record Statistics  at TABLE2####
         ########################################################################
         slti  $t2, $t1, 97         # < 'a'   // not a lower case.
         bne   $t2, $0, CAPITAL_DONE
         slti  $t2, $t1, 123        # 'z' + 1 // 97-122 lower case.
         beq   $t2, $0, CAPITAL_DONE # $t2 =1 means , character is lower case.
         addi  $t1, $t1, -32  
CAPITAL_DONE:                      
         addi  $t1, $t1, -65    # Set $t1 to table index. ( A->0, B->1, etc.)
         sltiu $t2, $t1, 26     # If $t1 is >= 26 then it's not a letter.
         beq   $t2, $0, NEXT    # Note that comparison above is unsigned.
         nop
         sll   $t1, $t1, 2      # Scale index.
         add   $t5, $s5, $t1    # Add index on to address of first element
         add   $t9, $s4, $t1
         
        

         lw    $t6, 0($t5)       
         addi  $t6, $t6, 1
         sw    $t6, 0($t5)

NEXT:    addi $t0,$t0,1          #point next character.
         j LOOP
         nop
         
RESETWLC:
        
         
         beq $s0,$0,PreviousSF
         nop 

         ###  Goal : Update TABLE 4 for occurences of Words Character contain.
         ###  TABLE2 has Character statistics of a word.
         ###  Using that statistics, Update TABLE 4.
         #### If contents of TABLE2's cell is not zero, 
         #####Inclement by one the contents of
         #### TABLE4's matching cell
         # address computation
        
         addi $t6,$0,25   # $t6 = for scanning TABLE2 
         add  $t5,$0,$0
         add  $t9,$0,$0
REPEAT26:        
         add  $t8,$s5,$t9  # Starting Address of TABLE2
         lw   $t7,0($t8)
         beq  $t7,$zero,NO_INC
         nop
         sw   $0,0($t8)  
         add  $t8,$s4,$t9  # Starting Address of TABLE4
         lw   $t7,0($t8)   # inclement and store back to TABLE4
         addi $t7,$t7,1    #
         sw   $t7,0($t8)   #
NO_INC:  addi  $t5,$t5,1
         add   $t9,$0,$t5
         sll   $t9,$t9,2
         bne   $t6,$t5,REPEAT26            
         nop  
        
NOCLEAR: nop        
         
         
      
PreviousSF:         
         addi $t0,$t0,1  #point next character.
    
         j LOOP
         nop
DONE:   # print and Exit..         
           
         beq $s0,$0,PRINT
         nop 
         
PRINT:  
        

PW_LOOP_MAIN: 
         la $a0,word_msg
         li $v0,4
         syscall
         li $t1,0
         li $t0,25
PW_LOOP:
        
         move $a0,$t1
         addi $a0,$a0,65
         li $v0,11
         syscall  
         la $a0,eq_msg
         li $v0,4
         syscall       
         add $t3,$0,$t1  # 
         sll $t3,$t3,2   # multiply 4 to get byte address.
         add $t3,$t3,$s4 # get momory address.
         lw  $a0,0($t3)  # get Character information.                 
         li $v0,1
         syscall
         la $a0,newline
         li $v0,4
         syscall
         addi $t1,$t1,1
         beq $t1,$t0,EXIT
         nop
         j PW_LOOP
         nop
     
         
           

EXIT:   addi $v0, $0, 10
        syscall                         # Exits program
       
        jr $ra                          #
        nop
##############################################
## THIS IS OUTPUT OF THE ABOVE PROGRAM  ######
##############################################
#number of occurences of words containing
# A = 6
# B = 1
# C = 2
# D = 1
# E = 6
# F = 2
# G = 1
# H = 3
# I = 4
# J = 0
# K = 1
# L = 3
# M = 1
# N = 6
# O = 5
# P = 1
# Q = 0
# R = 2
# S = 2
# T = 6
# U = 0
# W = 1
# X = 1
# Y = 2 

#Problem 2:
2-1)	Write  MIPS programs  for the following c programs ,
..    # REGISTER USAGE ..SUM , $s0, i, $t0,
        1)...for(i = 1; i<5 ;++1)    
             {
               sum = sum + i;
             }
            2.1.1.1) assume Delayed branch without delay slot
2.1.1.2) assume Delayed branch with delay slot
       2)...for(i = 1; i<5;i = i+2)  
            {  
               sum = sum + i;
                 sum = sum + i + 1;
            }
2.1.2.1) assume Delayed branch without delay slot
2.1.2.2) assume Delayed branch with delay slot
       2-2)Count  the total numbers of instructions(running instruction count)  to compute sum for  the 4 programs (2.1.1.1, 2.1.1.2,  2.1.2.1 and 2.1.2.2).   


######################################
###  Delayed Branch ....Assume the instruction immeadately 
####                  following Branch instruction is always excuted
####                  usuary put "NOP" instruction after a branch instruction 
#### Delay Slot ........Instead of putting "NOP"
#####                   putting some instruction which is useful



2.1.1.1)
      li $t0,1
      li $t1,5
LOOP: beq $t0,$t1,EXIT_LOOP
      nop
      add $s0,$s0,$t0
      addi $t0,$t0,1
      j LOOP
      nop
EXIT_LOOP:


2.1.1.2) ## Rearrange and get rid of "NOP"
      li $t0,1
      li $t1,5
LOOP: beq $t0,$t1,EXIT_LOOP
      nop
      add $s0,$s0,$t0
      j LOOP
      addi $t0,$t0,1


EXIT_LOOP:


2.1.2.1)
      li $t0,1
      li $t1,5
LOOP: beq $t0,$t1,EXIT_LOOP
      nop
      add $s0,$s0,$t0
      addi $t0,$t0,1
      add $s0,$s0,$t0
      addi $t0,$t0,1 
      j LOOP
      nop
EXIT_LOOP:

2.1.2.2)## Rearrange and get rid of "NOP"
      li $t0,1
      li $t1,5
LOOP: beq $t0,$t1,EXIT_LOOP
      nop
      add $s0,$s0,$t0
      addi $t0,$t0,1
      add $s0,$s0,$t0
      j LOOP
      addi $t0,$t0,1 
      
EXIT_LOOP:


2.2)  2.1.1.1    28inst.(inside loop 4times)
      2.1.1.2    24inst.(inside loop 4times)
      2.1.2.1    20inst.(inside loop twice)
      2.1.2.2    18inst.(inside loop twice)