---

; Lab 7, task 1.8 (Figure 3a) - point in square [-10..10] x [-10..10]
; Point (x, y) entered from console
; Subprogram returns 1 if inside/on border, else 0 (in AX)

dosseg
.model small
.stack 200h

.data
    msgX        db 'Enter X: $'
    msgY        db 'Enter Y: $'
    msgRes1     db 0ah, 'Point 1: $'
    msgRes2     db 0ah, 'Point 2: $'
    msgInside   db 'inside the shaded square$'
    msgOutside  db 'outside the shaded square$'
    cr          equ 0dh
    lf          equ 0ah

    string      db 255, 0, 255 dup(?)
    errmsg      db 'Invalid char, digits only', cr, lf, '$'
    negflag     dw ?

.code

; ----------------------------------------------
; IntegerIn - reads signed integer from console
; Returns: AX = integer value
; ----------------------------------------------
IntegerIn proc
start:
    mov ah, 0ah
    lea dx, string
    int 21h

    xor ax, ax
    lea si, string+2
    mov negflag, ax

    cmp byte ptr [si], '-'
    jne m2
    not negflag
    inc si
    jmp m3

m2:
    cmp byte ptr [si], '+'
    jne m3
    inc si

m3:
    cmp byte ptr [si], cr
    je ex1

    cmp byte ptr [si], '0'
    jb err1
    cmp byte ptr [si], '9'
    ja err1

    mov bx, 10
    mul bx
    sub byte ptr [si], '0'
    add al, [si]
    adc ah, 0

    inc si
    jmp m3

err1:
    lea dx, errmsg
    mov ah, 9
    int 21h
    jmp start

ex1:
    cmp negflag, 0
    je ex
    neg ax
ex:
    ret
IntegerIn endp

; ----------------------------------------------
; IntegerOut - prints signed integer in AX
; ----------------------------------------------
IntegerOut proc
    xor cx, cx
    mov bx, 10
    cmp ax, 0
    jge m
    neg ax
    push ax
    mov ah, 2
    mov dl, '-'
    int 21h
    pop ax

m:
    inc cx
    xor dx, dx
    div bx
    push dx
    or ax, ax
    jnz m

m1:
    pop dx
    add dl, '0'
    mov ah, 2
    int 21h
    loop m1
    ret
IntegerOut endp

; ----------------------------------------------
; IsPointInSquare
; Input via stack:
;   [bp+6] = Y
;   [bp+4] = X
; Returns AX = 1 (inside) or 0 (outside)
; Square: |X| <= 10 and |Y| <= 10
; ----------------------------------------------
IsPointInSquare proc near
    push bp
    mov bp, sp

    mov ax, [bp+4]   ; X
    cmp ax, -10
    jl outside
    cmp ax, 10
    jg outside

    mov ax, [bp+6]   ; Y
    cmp ax, -10
    jl outside
    cmp ax, 10
    jg outside

    mov ax, 1
    jmp finish

outside:
    xor ax, ax

finish:
    pop bp
    ret 4            ; remove 2 parameters (X, Y)
IsPointInSquare endp

; ----------------------------------------------
; Main program
; ----------------------------------------------
Begin:
    mov ax, @data
    mov ds, ax

    ; --- Point 1 ---
    mov ah, 9
    lea dx, msgX
    int 21h
    call IntegerIn
    push ax          ; X1

    mov ah, 9
    lea dx, msgY
    int 21h
    call IntegerIn
    push ax          ; Y1

    call IsPointInSquare
    push ax          ; save result 1

    ; --- Point 2 ---
    mov ah, 9
    lea dx, msgX
    int 21h
    call IntegerIn
    push ax          ; X2

    mov ah, 9
    lea dx, msgY
    int 21h
    call IntegerIn
    push ax          ; Y2

    call IsPointInSquare
    ; stack now: result1, result2

    ; Output results
    mov ah, 9
    lea dx, msgRes1
    int 21h
    pop ax
    call print_result

    mov ah, 9
    lea dx, msgRes2
    int 21h
    pop ax
    call print_result

    mov ax, 4C00h
    int 21h

; ----------------------------------------------
print_result proc
    cmp ax, 1
    jne out_msg
    lea dx, msgInside
    jmp print
out_msg:
    lea dx, msgOutside
print:
    mov ah, 9
    int 21h
    ret
print_result endp

end Begin