멀티 또는 div를 사용하지 않고 MIPS 32 비트 부호없는 곱셈

Question

MIPS mult (multu) 또는 div (divu) 명령을 사용하지 않고 두 개의 32 비트 부호없는 정수를 곱하는 프로그램을 작성했습니다. 64-bit high word/low word 콤보처럼 multu 함수가 어떻게 생겼는지를 출력으로 보여주고 싶습니다. 나는 승수 그래서 제품의 오른쪽 인 모델을 사용하고있다 : 내 코드에서 현재

for (i=0; i<32; i++) 
{ 
    if LSB(multiplier)==1 
    { 
     LH product += multiplicand; 
    } 
    right shift product-multiplier 1; 
} 

내가 32에서 가능한 캐리 아웃 비트 돌보는하고 있다면 확실하지 오전 비트 추가.

어떤 정수 값을 선택하더라도 현재 "0 0"의 출력을 얻고 있습니다.

내 코드에서 가장 오른쪽 비트를 LSB (낮은 워드)라고하고, 대부분 MSB (상위 워드)를 남겼습니다.

내 코드 :

지금까지 내가 말할 수있는

.data 

    promptStart: .asciiz "This prrogram does AxB without using mult or div" 
      getA: .asciiz "Please enter the first number(multiplicand): " 
      getB: .asciiz "Please enter the second number(multiplier): " 

      space: .asciiz " " 

     result: .asciiz "The product, using my program is: " 
     mipMult: .asciiz "The product, using MIPs multu is: " 

     endLine: .asciiz "\n" 

.text 

main: 
    #"welcome" screen 
    li $v0,4   # code for print_string 
    la $a0,promptStart  # point $a0 to prompt string 
    syscall    # print the prompt 


    li $v0,4   # code for print_string 
    la $a0,endLine  # point $a0 to prompt string 
    syscall    # print the prompt 

    #prompt for multiplicand 
    li $v0,4   # code for print_string 
    la $a0,getA  # point $a0 to prompt string 
    syscall    # print the prompt 

    #acquire multiplicand 
    li $v0,5   # code for read_int 
    syscall    # get an int from user --> returned in $v0 
    move $s0,$v0   # move the resulting int to $s0 

    move $s4,$s0   #copy of multiplicand to use in multu 

    #prompt for multiplier 
    li $v0,4   # code for print_string 
    la $a0,getB  # point $a0 to prompt string 
    syscall    # print the prompt 

    #acquire multiplier 
    li $v0,5   # code for read_int 
    syscall    # get an int from user --> returned in $v0 
    move $s1,$v0   # move the resulting int to $s0 

    move $s5,$s1   #copy of multiplier to use in multu 

    jal MyMult 
    j print 

MyMult: 

    #$s2 -> lw product, $s1 -> hw multiplier, $s0 -> multiplicand 

    beq $s1, $0, done  # if multiplier=0--> mult gives 0 
    beq $s0, $0, done 

    move $t0, $0   #initialize 'counter'= 31 
    add $t0, $t0, 31 

    move $s2, $0   #initialize product = 0 

    loopOut: 
     beq $t0, $0, done #loop check 

     andi $t1, $s1, 1 #Stores LSB(MSB?) of $s1 in $t1 
     bne $t1, $0, loopIn #check if LSB is equal to 1 
     srl $s1, $s1, 1 
     srl $s2, $s2, 1 #right shift product & multiplier 

     add $t0, $t0,-1 # counter = counter -1 
     j loopOut 

    loopIn: 
     addu $s2, $s2, $s0 #Lw product($s2/$s1)+= multiplicand($s0) 
     sltu $t2, $s2, $s0 #catch carry-out(0 or 1) and stores in $t2  

     srl $s1, $s1, 1 
     srl $s2, $s2, 1 #right shift pro-plier..how to save LSB of $s2? 

     #add carry-out $t2 to LSB of product $s2 
     addu $s2, $s2, $t0 #Is this right? 

     addu $t0, $t0,-1 # counter = counter -1 
     j loopOut 

    done: 
     jr $ra 

print: 
    # print result string 
    li $v0,4   # code for print_string 
    la $a0,result  # point $a0 to string 
    syscall    # print the result string 

    # print out the result 
    li $v0,1   # code for print_int 
    move $a0,$s2   # put result in $a0 
    syscall    # print out result 

    li $v0,4   # code for print_string 
    la $a0,space  # point $a0 to string 
    syscall    # print the result string 

    li $v0,1   # code for print_int 
    move $a0,$s1   # put result in $a0 
    syscall    # print out result 


    # print the line feed 
    li $v0,4   # code for print_string 
    la $a0,endLine  # point $a0 to string 
    syscall    # print the linefeed 

doMult: 
#Do same computation using Mult 
    multu $s4, $s5 
    mfhi $t0 
    mflo $t1 

    li $v0,4   # code for print_string 
    la $a0,mipMult  # point $a0 to string 
    syscall 

    # print out the result 
    li $v0,1   # code for print_int 
    move $a0,$t0   # put high in $a0 
    syscall    # print out result 

    li $v0,4   # code for print_string 
    la $a0,space  # point $a0 to string 
    syscall    # print the result string 

    # print out the result 
    li $v0,1   # code for print_int 
    move $a0,$t1   # put low in $a0 
    syscall    # print out result 

    # print the line feed 
    li $v0,4   # code for print_string 
    la $a0,endLine  # point $a0 to string 
    syscall    # print the linefeed 

    # All done, thank you! 
    li $v0,10   # code for exit 
    syscall    # exit program 

Answer 1

, 심지어 알고리즘이 끊어집니다. 피승수를 왼쪽 (덧셈)으로, 오른쪽으로 계수 (비트 테스트 용)로 이동해야합니다. 제품을 옮겨서는 안됩니다. 또한 피승수는 64 비트로 확장해야하며 단어 경계에서 비트를 올바르게 전송하는 64 비트 시프트가 필요합니다.

.data 

    promptStart: .asciiz "This program does AxB without using mult or div" 
      getA: .asciiz "Please enter the first number(multiplicand): " 
      getB: .asciiz "Please enter the second number(multiplier): " 

      space: .asciiz " " 

     result: .asciiz "The product, using my program is: " 
     mipMult: .asciiz "The product, using MIPs multu is: " 

     endLine: .asciiz "\n" 

.text 

main: 
    #"welcome" screen 
    li $v0,4   # code for print_string 
    la $a0,promptStart # point $a0 to prompt string 
    syscall    # print the prompt 


    li $v0,4   # code for print_string 
    la $a0,endLine  # point $a0 to prompt string 
    syscall    # print the prompt 

    #prompt for multiplicand 
    li $v0,4   # code for print_string 
    la $a0,getA  # point $a0 to prompt string 
    syscall    # print the prompt 

    #acquire multiplicand 
    li $v0,5   # code for read_int 
    syscall    # get an int from user --> returned in $v0 
    move $s0,$v0  # move the resulting int to $s0 
    move $s5,$s0  # copy of multiplicand to use in multu 

    #prompt for multiplier 
    li $v0,4   # code for print_string 
    la $a0,getB  # point $a0 to prompt string 
    syscall    # print the prompt 

    #acquire multiplier 
    li $v0,5   # code for read_int 
    syscall    # get an int from user --> returned in $v0 
    move $s1,$v0  # move the resulting int to $s0 

    move $s6,$s1  # copy of multiplier to use in multu 

    jal MyMult 
    j print 

MyMult: 
    move $s3, $0  # lw product 
    move $s4, $0  # hw product 

    beq $s1, $0, done 
    beq $s0, $0, done 

    move $s2, $0  # extend multiplicand to 64 bits 

loop: 
    andi $t0, $s0, 1 # LSB(multiplier) 
    beq $t0, $0, next # skip if zero 
    addu $s3, $s3, $s1 # lw(product) += lw(multiplicand) 
    sltu $t0, $s3, $s1 # catch carry-out(0 or 1) 
    addu $s4, $s4, $t0 # hw(product) += carry 
    addu $s4, $s4, $s2 # hw(product) += hw(multiplicand) 
next: 
    # shift multiplicand left 
    srl $t0, $s1, 31 # copy bit from lw to hw 
    sll $s1, $s1, 1 
    sll $s2, $s2, 1 
    addu $s2, $s2, $t0 

    srl $s0, $s0, 1  # shift multiplier right 
    bne $s0, $0, loop 

done: 
    jr $ra 

print: 
    # print result string 
    li $v0,4   # code for print_string 
    la $a0,result  # point $a0 to string 
    syscall    # print the result string 

    # print out the result 
    li $v0,1   # code for print_int 
    move $a0,$s4  # put result in $a0 
    syscall    # print out result 

    li $v0,4   # code for print_string 
    la $a0,space  # point $a0 to string 
    syscall    # print the result string 

    li $v0,1   # code for print_int 
    move $a0,$s3  # put result in $a0 
    syscall    # print out result 


    # print the line feed 
    li $v0,4   # code for print_string 
    la $a0,endLine  # point $a0 to string 
    syscall    # print the linefeed 

doMult: 
#Do same computation using Mult 
    multu $s5, $s6 
    mfhi $t0 
    mflo $t1 

    li $v0,4   # code for print_string 
    la $a0,mipMult  # point $a0 to string 
    syscall 

    # print out the result 
    li $v0,1   # code for print_int 
    move $a0,$t0   # put high in $a0 
    syscall    # print out result 

    li $v0,4   # code for print_string 
    la $a0,space  # point $a0 to string 
    syscall    # print the result string 

    # print out the result 
    li $v0,1   # code for print_int 
    move $a0,$t1   # put low in $a0 
    syscall    # print out result 

    # print the line feed 
    li $v0,4   # code for print_string 
    la $a0,endLine  # point $a0 to string 
    syscall    # print the linefeed 

    # All done, thank you! 
    li $v0,10   # code for exit 
    syscall    # exit program