我应该将小数转换为-2.25，结果为1 |。 10000000 | 00100000000000000000000
这是我的尝试，但是没有用
.data
String db "enter num $",0
DecStr dd ?
BinStr db 40 dup (0)
result dd ?
number dd 0
frac dd 0
divisor dd 1
.code
main PROC
mov ax,@data
mov ds,ax
mov ah, 9
lea dx, String
int 21h
mov ah, 0ah
mov dx, DecStr
int 21h
start: ; integer part
mov si, offset DecStr
xor dx, dx
mov al, byte ptr [si]
xor ah, ah
inc si
test al, al ; end of string?
jz retRes ; yes: end of parsing
cmp al, '.' ; decimal point?
je fraction ; yes: end of loop (jump forward to the next @@)
cmp al, '-' ; negative?
je start ; yes: next character (jump backward to the last @@)
xor bx,bx
imul bx:dx, 10 ; prior result * 10
and al, 0Fh ; eliminate ASCII-part
add dx, ax ; add eax store result
jmp start ; loop: next character (jump backward to the last @@)
fraction: ; end of loop
mov number, dx ; fractional part
mov cx, 1 ; divisor for later division
xor dx, dx ; holds the result
binn:
mov al, byte ptr DecStr[si] ; loop
xor ah, ah
inc si
test al, al ; end of string?
jz retRes ; yes
and al, 0Fh ; eliminate ASCII-part
imul bx:cx, 10 ; "increment" divisor
xor bx,bx
imul bx:dx, 10 ; prior number * 10
add dx, ax ; new number
jmp binn ; loop (jump backward to the last @@)
retRes:
mov frac, dx ; for 'fild'
mov divisor, cx ; for 'fidiv'
div divisor ; correct fractional number
add cx,number ; add integer part
cmp byte ptr DecStr, '-' ; negative?
jne ress ; no: jump forward to the next @@
xor number, 0x8000 ; change sign of st(0) to '-'
mov ax, number
mov result, ax
ress:
mov ax, number
mov result, ax
ToBinStr:
mov si, offset BinStr ; first position in string
mov ax, result ; result
; Sign
push cx
mov ch, cl
mov cl, 7
sub cl, ch
mov bx, ax
shr bx, cl ; carry if sign-bit is set
jnc binnStr ; jump if positive (forward to the next @@)
mov bl, '-' ; minus-character
mov BinStr[si], bl ; store it into BinStr
inc si ; increment pointer to BinStr
binnStr:
;integer part & point
mov bl, "1" ; store '1.' into BinStr
mov BinStr[si], bl
add si, 2 ; increment pointer to BinStr
; fractional part
mov cx, 7 ; first bit position for bt
and ax, 7Fh ; isolate mantissa
binn1:
push cx
mov ch, cl
mov cl, 7
sub cl, ch
mov bx, ax
shr bx, cl
and bl, 1
or bl, 0x30
pop cx
mov BinStr[si], bl ; store it into BinStr
inc si ; next position in string
dec cx ; next bit
jns binn1 ; loop (jump backward to the last @@)
pop bx
; exponent
add si, 2 ; increment pointer to BinStr
mov al, byte ptr result + 2
xor ah, ah ; we need only the high word
shr ax, 7 ; exponent -> al
xor ah, ah ; the sign bit was left
sub al, 127 ; minus BIAS
mov bl, '+'
jnc storeSign ; jump if positive exponent (forward to the next @@)
mov bl, '-'
neg al ; abs(al)
storeSign:
mov BinStr[si], bl ; store sign into BinStr
inc si ; increment pointer to BinStr
mov cx, 7 ; first bit-position for 'bt'
binn2:
push cx
mov ch, cl
mov cl, 7
sub cl, ch
mov bx, ax
shr bx, cl
and bl, 1
or bl, 0x30
pop cx
mov BinStr[si], bl ; store it into BinStr
inc si ; next position in string
dec cx ; next bit
jns binn2 ; loop (jump backward to the last @@)
pop bx
jmp printres
printres:
mov ah,9
lea dx,BinStr ; print result
int 21h
main ENDP
END main