model small
.386
.stack 100h
.data
str1 db 'Input two numbers:',0Dh,0Ah,'$'
str2 db 'Wrong Number. Please input correct number:',0Dh,0Ah,'$'
max db 10
len db 0
buffer db 11 dup(0)
ten dw 10
digit dw 0
x dq 0
x1 dq 0
x2 dq 0
delta_x dq 0
max_y dq -999.9
min_y dq 999.9
screen_height dw 480
screen_width dw 639
func_arr dq 640 dup(0)
func_arr_scale dw 640 dup(0)
.code
start:
    mov ax,@data
    mov ds,ax
    mov ah,09h
    lea dx,str1
    int 21h
    finit
input:
    lea di,x1
    call input_number
    cmp al,01h
    je re_input
    mov ah,0Eh
    mov al,0Ah
    int 10h
    mov ah,0Eh
    mov al,0Dh
    int 10h
    lea di,x2
    call input_number
    cmp al,01h
    je re_input
    fld x1
    fld x2
    fcom st(1)
    fstsw ax
    fwait
    sahf
    jbe re_input
    fstp x2
    fstp x1
draw:
    fld x2
    fld x1
    fsubp st(1),st(0)
    fild screen_width
    fdivp st(1),st(0)
    fstp delta_x
    fld x1
    fstp x
    mov cx,screen_width
    xor di,di
calc_step:
    call func
    fld x
    fld delta_x
    faddp st(1),st(0)
    fstp x
    loop calc_step
scale:
    fild screen_height
    fld max_y
    fld min_y
    fsubp st(1),st(0)
    fdivp st(1),st(0)
    xor si,si
    mov cx,640
    xor di,di
loop_scale:
    fld max_y
    fld func_arr[si]
    fsubp st(1),st(0)
    fmul st(0),st(1)
    fistp func_arr_scale[di]
    add di,02h
    add si,08h
    loop loop_scale
    fstp min_y
drawing:
    mov ah,00h
    mov al,12h
    int 10h
    mov si,1278
    mov cx,640
    xor bh,bh
draw_loop:
    push cx
    dec cx
    mov ah,0Ch
    mov al,15
    mov dx,func_arr_scale[si]
    int 10h
    sub si,2
    pop cx
    loop draw_loop
    mov ah,00h
    int 16h
    mov ax,4C00h
    int 21h
re_input:
    mov ax,03h
    int 10h
    mov ah,09h
    lea dx,str2
    int 21h
    jmp input
func proc
    fld x
    fcos
    fmul st(0),st(0)
    fmulp st(1),st(0)
    fld x
    fmul st(0),st(0)
    fmul st(0),st(0)
    fld x
    fsin
    fmul st(0),st(0)
    fmul st(0),st(0)
    fmulp st(1),st(0)
    faddp st(1),st(0)
comp_max:
    fcom max_y
    fstsw ax
    fwait
    sahf
    ja bigger
comp_min:
    fcom min_y
    fstsw ax
    fwait
    sahf
    jb smaller
    jmp end_calc
bigger:
    fst max_y
    jmp comp_min
smaller:
    fst min_y
end_calc:
    fstp func_arr[di]
    add di,08h
ret
func endp
input_number proc
    mov ah,0Ah
    lea dx,max
    int 21h
    xor ax,ax
    xor bx,bx
    xor cx,cx
    xor si,si
    xor dx,dx
    fldz
    mov al,buffer[si]
    inc si
    cmp al,'-'
    jne plus
    mov dh,01h
    jmp number
plus:
    cmp al,'+'
    jne dot
    jmp number
dot:
    cmp al,'.'
    jne digits
    mov dl,01h
next_is_digit:
    mov al,buffer[si]
    inc si
start_parse:
    dec si
number:
    xor ax,ax
    mov al,len
    cmp si,ax
    je fraction
    mov al,buffer[si]
    inc si
    cmp al,'.'
    jne digits
    cmp dl,01h
    je error_input
    mov dl,01h
    jmp next_is_digit
digits:
    cmp al,'0'
    jb error_input
    cmp al,'9'
    ja error_input
    inc bx
    fild ten
    fmulp st(1)
    sub al,'0'
    mov digit,ax
    fiadd digit
    cmp dl,00h
    je number
    inc cx
    jmp number
fraction:
    cmp cx,00h
    je final
    fild ten
    fdivp st(1),st(0)
    loop fraction
final:
    cmp bx,00h
    je error_input
    cmp dh,01h
    jne is_over
    fchs
is_over:
    mov al,00h
store:
    fstp qword ptr [di]
ret
error_input:
    mov al,01h
    jmp store
ret
input_number endp
end start