MIPSアセンブリの文字列内の空白を削除する

Question

私は書き込みしようとしているプログラムに小さな問題があります。基本的に私はユーザーに入力を促しています。私は、文字列内のスペースの数を数え、カウントを表示します。私もスペースを削除して元の文字列を印刷する必要があります。

私が抱えているバグは、文字列にスペースを入れずに文字を追加しているときだけです。最初の文字が追加されます。 $ t2は、追加する文字を保持しているレジスタです。実行時にレジスタの値が変更されていることを確認しました。私はどこを見るべきか分からない。 move $t7, $t6へ

.data 
str:  .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 

Answer 1

変更sll $t7, $t6, 2。手動で何かを配置する必要はありません。

ここでは、あなたのプログラムのデータセグメントが入力here's some spacesと実行後です。バグが見つかったら、その修正は明白でなければなりません。