MIPS組件計算斜邊

Question

我有一個MIPS程序來計算兩個整數的斜邊。然而，程序打印一些奇怪的數字不是實際的結果，我最好的猜測是平方根函數有問題。

.data 
prompt1: .asciiz "Enter value for A: " 
prompt2: .asciiz "Enter value for B: " 
result: .asciiz "The hypotenuse is: " 

    .text 
main: 
     # save $ra 
     addi $sp, $sp, -4 
     sw $ra, 0($sp) 

     # accept input 
     la $a0, prompt1 
     addi $v0, $0, 4   # Print prompt1 string 
     syscall 
     addi $v0, $0, 6   # Read float 
     syscall 
     add.s $f12, $f5, $f0  # f12 = A(input float) 

     la $a0, prompt2 
     addi $v0, $0, 4   # Print prompt2 string 
     syscall 
     addi $v0, $0, 6   # Read float 
     syscall 
     add.s $f13, $f5, $f0  # f13 = B(input float) 

hypotenuse: 
    mul.s $f12, $f12, $f12  # A*A 
    mul.s $f13, $f13, $f13  # B*B 
    add.s $f12, $f12, $f13  # A*A + B*B 
    addi $sp, $sp, -4   # Allocate 
    sw $ra 0($sp) 

    add.s $f0, $f12, $f12 
    jal sqrt 
    li $v0, 3  # Print a Double  

    syscall   # Print the area 
    lw $ra 0($sp) 
    addi $sp, $sp, 4   # De-Allocate 
    mov.s $f0, $f12 
    jr $ra 

sqrt: add $v0, $zero, 0 # r := 0 
loop: mul $t0, $v0, $v0 # t0 := r*r 
    bgt $t0, $a0, end # if (r*r > n) goto end 
    addi $v0, $v0, 1 # r := r + 1 
    j loop  # goto loop 
end: addi $v0, $v0, -1 # r := r - 1 
    jr $ra  # return with r-1 in $v0 

# Exit 
    li $v0, 10  # loads op code into $v0 to exit program 
    syscall   # reads $v0 and exits program 

Answer 1

你sqrt函數返回一個虛假的價值，因爲你怎麼稱呼它，然後在寄存器$f0計算A*A + B*B，但函數本身執行對寄存器$v0整數運算，其中包含垃圾。