我似乎碰壁了,找不到任何关于这个的例子。我需要将ascii字符转换为数字,即用户键入150 + 123
,所以我必须读取ascii中的第一个数字,然后通过从每个数字减去0将其转换为dec,但这是问题所在。我不知道如何实际创建这些数字中的数字,因为用户可以输入1位数或5位。请忽略代码中的外来注释。谢谢
.model small
.stack 100h
.data
prompt1 db "Please enter an action: ", 10, 13, "$"
prompt2 db "Answer: ", 10, 13, "$"
newline db 10, 13, '$'
buffer db 255 ; Denotes the number of maximal symbols hope
sizeread db 0 ; It will be available on how many characters scanned
buffer_data db 255 dup (?) ; It will be hosted on-line scanned data to fill 255 characters $
.code
start:
mov dx, @data ;
mov ds, dx ;
print_prompt:
mov ah, 9
mov dx, offset prompt1 ; Messages placed in the DX register address
int 21h ; welcome petraukimą
ret
input:
mov ah, 0Ah
mov dx, offset buffer
int 21h
ret
number:
xor bx,bx
xor ax,ax
mov al, 10 ;set al to 0 so i can MUL
mov cx, 5
loopstart: ;start the cycle
cmp [buffer_data+bx], ' ' ;check if I reached a space
je space ; jump to space (the space func will read the + or - sign later on)
mov bx, [bx+1] ; bx++
;Now i got no idea how to go about this....
space:
end start
答案 0 :(得分:2)
你需要将累加器乘以10(假设你的输入是十进制的,即如果十六进制乘以16):
xor ax, ax ; zero the accumulator
mov cx, 10 ; cx = 10
input:
movzx bx, <next input char from left to right>
cmp bl, '\n' ; end of input
je out
sub bl, '0' ; convert ascii char to numeric value
mul cx ; ax = ax*10, prepare for next digit (assuming result fits in 16 bits)
add ax, bx ; ax = ax + bx, add current digit
jmp input
out:
达到'out'时,cx具有输入数字的数值。