将键盘输入x:0~20并计算出f(x)用汇编
时间: 2023-06-27 10:06:35 浏览: 51
以下是汇编代码实现:
```asm
section .data
msg db 'Enter a number between 0 and 20: '
len_msg equ $-msg
result db 'f(x) = '
len_res equ $-result
newline db 10
section .bss
x resb 1
section .text
global _start
_start:
; prompt user to enter a number
mov eax, 4
mov ebx, 1
mov ecx, msg
mov edx, len_msg
int 0x80
; read input from user
mov eax, 3
mov ebx, 0
mov ecx, x
mov edx, 1
int 0x80
; convert input to integer
sub al, 0x30 ; convert ASCII code to number
movzx eax, al ; zero-extend to 32 bits
; calculate f(x)
mov ebx, eax
mov eax, 2
mul ebx
add eax, ebx
mov ebx, 3
mul ebx
sub eax, ebx
mov ebx, 4
mul ebx
add eax, 5
; convert result to string
push eax ; save result on stack
mov eax, 0 ; initialize counter
mov ebx, 10 ; divisor
div ebx ; divide result by 10
add edx, 0x30 ; convert remainder to ASCII code
mov byte [result+len_res], dl ; store remainder in result
inc eax ; increment counter
cmp dword [esp], 0 ; check if result is zero
je print_result ; if zero, skip loop
loop:
xor edx, edx ; clear edx
div ebx ; divide result by 10
add edx, 0x30 ; convert remainder to ASCII code
dec eax ; decrement counter
mov byte [result+len_res+eax], dl ; store remainder in result
cmp eax, 0 ; check if all digits have been converted
jne loop ; if not, repeat loop
print_result:
; print result
mov eax, 4
mov ebx, 1
mov ecx, result
sub ecx, len_res ; adjust pointer to beginning of string
add ecx, eax ; adjust pointer to beginning of result
mov edx, len_res+5 ; length of result string + newline
int 0x80
; print newline
mov eax, 4
mov ebx, 1
mov ecx, newline
mov edx, 1
int 0x80
; exit program
mov eax, 1
xor ebx, ebx
int 0x80
```
此程序首先提示用户输入一个数字,然后读取用户输入的数字并将其转换为整数。接下来,它计算 f(x) 的值并将结果存储在堆栈上。然后,它将结果转换为字符串并将其打印到屏幕上。最后,它打印一个新行并退出程序。