.model tiny
.data
sInpMsg db 0dh, 0ah, "Number: $"
sResMsg db 0dh, 0ah, "Result: $"
sErrMsg db 0dh, 0ah, "Error!$"
.code
org 100h
start:
lea dx, sInpMsg
mov ah, 09h
int 21h
call Input10
jc errExit
cmp ax, 10
jg xBigTen
cmp ax, 1
jg xOneTen
sub ax, 2
jmp short xEnd
xBigTen:
inc ax ; x+1
rcl ax, 1 ; 2*(x+1)
jo errExit ; ---owerflow
add ax, 5 ; 5+2*(x+1)
jo errExit ; ---owerflow
jmp short xEnd
xOneTen:
rcl ax, 1 ; x*2
inc ax ; x*2+1
rcr ax, 1 ; (x*2+1)/2
xEnd:
push ax
lea dx, sResMsg
mov ah, 09h
int 21h
pop ax
call print10
int 20h
errExit:
lea dx, sErrMsg
mov ah, 09h
int 21h
int 20h
input10 proc
push bx
push cx
push dx
push si
xor si, si
lea di, inp
mov dx, di
mov ah, 0ah
int 21h
add di, 2
xor cx, cx
mov al, [di]
cmp al, '+'
je i3
cmp al, '-'
jne i1
mov si, 1
jmp short i3
i1: cmp al, 0dh
je i_exit
cmp al, '0'
jb err1
cmp al, '9'
ja err1
sub al, '0'
shl cx, 1
cmp cx, 32767
ja err2
mov bx, cx
shl cx, 1
cmp cx, 32767
ja err2
shl cx, 1
cmp cx, 32767
ja err2
add cx, bx
cbw
add cx, ax
cmp cx, 32767
ja err2
i3: inc di
mov al, [di]
jmp short i1
i_exit: cmp si, 1
jne i2
neg cx
i2: mov ax, cx
clc
i4: pop si
pop dx
pop cx
pop bx
ret
err1: stc
mov ax, 1
jmp short i4
err2: stc
mov ax, 2
jmp short i4
.data
inp db 7, 0, 7 dup(?)
input10 endp
print10 proc
push ax
push bx
push cx
push dx
xor cx, cx
test ax, ax
jge p1
mov dl, '-'
neg ax
jmp short p2
p1: mov dl, ' '
p2: push ax
mov ah, 02h
int 21h
pop ax
mov bx, 10
p3: cwd
div bx
add dl, '0'
push dx
inc cx
test ax, ax
jnz p3
mov ah, 02h
p4: pop dx
int 21h
loop p4
pop dx
pop cx
pop bx
pop ax
ret
print10 endp
end start |
