Assembly 8086汇编中的简易斐波那契打印机
几天前，我开始学习汇编，我正试图制作一个程序来打印最多5个字符的斐波那契数列，但我的代码打印出了奇怪的字符 我认为这是因为ASCII转换系统，但即使我将值48添加到数字中，它仍然不正确Assembly 8086汇编中的简易斐波那契打印机,assembly,dos,x86-16,Assembly,Dos,X86 16,几天前，我开始学习汇编，我正试图制作一个程序来打印最多5个字符的斐波那契数列，但我的代码打印出了奇怪的字符 我认为这是因为ASCII转换系统，但即使我将值48添加到数字中，它仍然不正确 .model small .data lastFib DB 0 .code main PROC mov cx,5 mov dl,48 loopy: add dl,lastFib mov ah,2h int 21h mov las
.model small
.data
lastFib DB 0
.code
main PROC
mov cx,5
mov dl,48
loopy:
add dl,lastFib
mov ah,2h
int 21h
mov lastFib,dl
loop loopy
ENDP
end main
我没有你的汇编程序（MASM？），但代码相当简单，应该可以工作 在
C.model small
.data
.code
main PROC
mov di, 0 ; Fibonacci(n-1); n = 1
mov si, 1 ; Fibonacci(n); n = 1
loopA: mov ax, si ; prepare for counting digits
xor cx, cx ; cx will be number of digits
mov bx, 10 ; print as decimal
loopDigit: xor dx, dx ; dx:ax is the dividend
div bx
inc cx
or ax, ax ; test if the quotient is 0
jnz loopDigit
; cx should be the number of digit
mov bp, si ; the number to be printed
cmp cx, 5 ; test if there are 5 digits
jb digit4
mov ax, bp ; get the number
mov bx, 10000
div bx
mov bp, dx ; the next number to be printed
mov dl, al ; the quotient, current digit
add dl, 48 ; convert to ASCII
mov ah, 2h
int 21h
digit4: cmp cx, 4 ; test if there are 4 or more digits
jb digit3
mov ax, bp ; get the number
mov bx, 1000
div bx
mov bp, dx ; the next number to be printed
mov dl, al ; the quotient, current digit
add dl, 48 ; convert to ASCII
mov ah, 2h
int 21h
digit3: cmp cx, 3 ; test if there are 4 or more digits
jb digit2
mov ax, bp ; get the number
mov bx, 100
div bx
mov bp, dx ; the next number to be printed
mov dl, al ; the quotient, current digit
add dl, 48 ; convert to ASCII
mov ah, 2h
int 21h
digit2: cmp cx, 2 ; test if there are 4 or more digits
jb digit1
mov ax, bp ; get the number
mov bx, 10
div bx
mov bp, dx ; the next number to be printed
mov dl, al ; the quotient, current digit
add dl, 48 ; convert to ASCII
mov ah, 2h
int 21h
digit1: mov dx, bp ; always need to print the last digit
add dl, 48 ; convert to ASCII
mov ah, 2h
int 21h
add di, si ; Fibonacci(n) = Fibonacci(n-1) + Fibonacci(n-2)
jc done ; overflow, done!
xchg di, si ; to keep them in order; si = F(n); di = F(n-1)
jmp loopA
done:
ENDP
end main
cx.model small
.data
.code
main PROC
mov di, 0 ; Fibonacci(n-1); n = 1
mov si, 1 ; Fibonacci(n); n = 1
mov cx, 1 ; 10^n_digits
loopA: mov ax, si ; prepare for counting digits
mov bx, 10 ; print as decimal
loopDigit: xchg ax, cx ; calculate 10^n_digits
mul bx
xchg cx, ax
xor dx, dx ; can be omitted, dx should be 0
div bx
or ax, ax ; test if the quotient is 0
jnz loopDigit
mov bx, si
mov bp, 10
loopPrint: mov ax, cx ; need to divide cx by 10 first
xor dx, dx
div bp
mov cx, ax
mov ax, bx ; get the number
xor dx, dx
div cx
mov bx, dx ; the next number to be printed
mov dl, al ; the quotient, current digit
add dl, 48 ; convert to ASCII
mov ah, 2h
int 21h
cmp cx, 1 ; should end?
jnz loopPrint
add di, si ; Fibonacci(n) = Fibonacci(n-1) + Fibonacci(n-2)
jc done ; overflow, done!
xchg di, si ; to keep them in order; si = F(n); di = F(n-1)
jmp loopA
done:
ENDP
end main
xchg dl, lastFib ; Exchange current with previous
add dl, lastFib ; Add previous to current
通过在计算下一个斐波那契数之前输出，下面的代码可以在一个循环中打印所有6个数。已计算第七个数字（13），但从未显示
.model small
.data
lastFib DB 0 ;previous
.code
main PROC
mov cx, 6
mov dl, 1 ;current
loopy:
add dl, 48 ;make character
mov ah, 02h
int 21h
sub dl, 48 ;take back
xchg dl, lastFib
add dl, lastFib
loop loopy
ENDP
end main
- 有了大量可用的寄存器，没有理由在内存中保留lastFib变量
- 我们还可以避免慢速
循环指令 - 为当前斐波那契数选择除DL之外的寄存器将删除额外的“收回”指令
.model small
.code
main PROC
xor cx, cx ; Previous
mov bx, 1 ; Current
loopy:
lea dx, [bx+48] ; Make character in DL
mov ah, 02h ; DOS.PrintChar
int 21h
xchg bx, cx
add bx, cx
cmp bx, 10
jb loopy
ENDP
end main
这一次，只要
BX09011148xchgloop循环xadd dl、dhmovaddleaf+'0'