; multi-segment executable file template.

data segment
    name_contents db "c:\contents.bin", 0
    string_formula db "Formula", 0
    string_result db "Result", 0
    string_menu db "Menu", 0
    num_hcell dw 04h
    matrix_lenght dw 200 ;estava 240 antes
    matrix_height dw 64
    ;formula_lenght 88
ends

stack segment
    dw   128  dup(0)
ends

code segment
start:
; set segment registers:
    mov ax, data
    mov ds, ax
    mov es, ax

    ;open contents.bin
        call open_contents

    ;iniciate video mode
        mov ah, 00h
        mov al, 13h
        int 10h

    ;draw spreadsheet
        call createMatrix

        call createMenuBox

        call createFormulaBox

        call createResultBox

        call showLetters

        mov ax, 00h
        int 33h

    keep_checking:
        mov ax, 03h
        int 33h
        shr cx, 1       ; x/2 - in this mode the value of CX is doubled.
        cmp bx, 1
        jnz keep_checking

    ;saves contents.bin
        ;call save_contents

    mov ax, 4c00h ; exit to operating system.
    int 21h


;*****************************************************************
; hLine -
; descricao: creates horizontal lines for the matrix
; input - bx= numero de linhas ; cx = horizontal margin ; dx = vertical margin ; ax = line lenght
; output -
; destroi -
;*****************************************************************

    hLine proc

        n_hlines:
            push ax
            push cx

            h_change_pixel:
            push ax
            mov ah, 0Ch
            mov al, 0Fh
            int 10h

            pop ax
            dec ax
            jz h_done
            inc cx
            jmp h_change_pixel

        h_done:
        pop cx
        pop ax
        add dx, 16
        dec bx
        jnz n_hlines
        ret
    hLine endp


;*****************************************************************
; vLine -
; descricao: creates vertical lines for the matrix
; input - bx= numero de linhas ; cx = horizontal margin ; dx = vertical margin ; ax = matrix_height
; output -
; destroi -
;*****************************************************************

    vLine proc

        n_vlines:
            push ax
            push dx

            v_change_pixel:
            push ax
            mov ah, 0Ch
            mov al, 0Fh
            int 10h

            pop ax
            dec ax
            jz v_done
            inc dx
            jmp v_change_pixel

        v_done:
        pop dx
        pop ax
        add cx, 50
        dec bx
        jnz n_vlines
        ret
    vLine endp



;*****************************************************************
; createMatrix -
; descricao: creates horizontal lines for the matrix
; input - bx= numero de linhas ; cx = horizontal margin ; dx = vertical margin ; ax = line lenght
; output -
; destroi -
;*****************************************************************

  createMatrix proc
    mov bx, 05h ; se calhar temos de remover isto
    mov dx, 23
    mov cx, 23
    mov ax, matrix_lenght
    call hLine

    mov bx, 05h
    mov cx, 23
    mov dx, 23
    mov ax, matrix_height
    call vLine

    ret

  createMatrix endp

;*****************************************************************
; createMatrix -
; descricao: creates horizontal lines for the matrix
; input - bx= numero de linhas ; cx = horizontal margin ; dx = vertical margin ; ax = line lenght
; output -
; destroi -
;*****************************************************************


  createMenuBox proc

    mov bx, 2
    mov ax, 50
    mov cx, 23
    mov dx, 164
    call hLine

    mov bx, 2
    mov ax, 16
    mov cx, 23
    mov dx, 164
    call vLine

    ;writes "Menu" inside the cell
        mov al, 1
        mov bl, 0Fh
        mov cx, 5    ;string lenght
        mov dh, 21
        mov dl, 4
        mov ah, 13h
        mov bp, offset string_menu
        int 10h

  ret

  createMenuBox endp

;*****************************************************************
; createFormulaBox -
; descricao: creates a box where the user will input operations
; input -
; output -
; destroi -
;*****************************************************************

    createFormulaBox proc ;Provavelmente vamos ter de alterar o
                          ;tamanho da caixa da formula

        mov ax, 120 ; formula lenght
        mov cx, 23
        mov dx, 140
        mov bx, 02h
        call hLine

        mov ax, 16 ; formula height
        mov cx, 23
        mov dx, 140
        mov bx, 01h
        call vLine

        mov ax, 16 ; formula height
        mov cx, 143
        mov dx, 140
        mov bx, 01h
        call vLine

    ret

    createFormulaBox endp


;*****************************************************************
; createResultBox -
; descricao: creates a box to output the result
; input -
; output -
; destroi -
;*****************************************************************

    createResultBox proc

        mov ax, 60 ;cell lenght
        mov cx, 200
        mov dx, 140
        mov bx, 02h
        call hLine

        mov ax, 16 ; formula height
        mov cx, 200
        mov dx, 140
        mov bx, 01h
        call vLine

        mov ax, 16 ; formula height
        mov cx, 260
        mov dx, 140
        mov bx, 01h
        call vLine

    ret

    createResultBox endp

;*****************************************************************
; showLetter -
; descricao: prints a letter for each matrix collumn,
;            also prints "Formula" and "Result"
; input -
; output -
; destroi -
;*****************************************************************

    showLetters proc

        xor bh, bh
        mov bl, 0Fh
        mov cx, 1
        mov dl, 06
        mov al, 'A'

        new_letter:
            ;set cursor position
            mov dh, 01h
            mov ah, 02h
            int 10h

            ;write char at cursor position
            mov ah, 09h
            int 10h

            inc al
            add dl, 6
            cmp al, 'E'
            jnz new_letter

        ;writes "Formula" above the big cell
        mov al, 1
        mov bl, 0Fh
        mov cx, 8    ;string lenght
        mov dh, 16
        mov dl, 3
        mov ah, 13h
        mov bp, offset string_formula
        int 10h

        ;writes "Result" aove the small cell
        mov dl, 25
        mov cx, 7   ;string lenght
        mov bp, offset string_result
        int 10h

    ret

    showLetters endp

;*****************************************************************
; showNumbers -
; descricao: prints a number for each matrix row
; input -
; output -
; destroi -
;*****************************************************************

    showNumbers proc

        xor bh, bh
        mov bl, 0Fh
        mov cx, 1
        mov dh, 03h
        mov al, '1'

        new_number:
        ;set cursor position
        mov dl, 01h
        mov ah, 02h
        int 10h

        ;write char at cursor position
        mov ah, 09h
        int 10h

        inc al
        add dh, 2
        cmp al, '5'
        jnz new_number

    ret

    showNumbers endp

;*****************************************************************
; fopen -
; descricao: abre um ficheiro em modo read(al==0), write(al==1) ou append(al==2)
; input - dx=offset nome ficheiro
; output - ax=file_handle
; destroi -
;*****************************************************************

    fopen proc
        mov ah, 3Dh
        mov al, 02h
        mov cx, 00h
        int 21h

        ret
    fopen endp

;*****************************************************************
; fclose -
; descricao:
; input - bx= file handle
; output -
; destroi -
;*****************************************************************

    fclose proc
        mov ah, 3Eh
        int 21h

        ret
    fclose endp

;*****************************************************************
; fcreate -
; descricao: cria um ficheiro
; input - dx=offset nome ficheiro
; output - ax=file_handle
; destroi -
;*****************************************************************

    fcreate proc
        mov ah, 3Ch
        mov cx, 00h
        int 21h

        ret
    fcreate endp

;*****************************************************************
; save_contents -
; descricao: saves contents.bin or creates it
; input -
; output -
; destroi -
;*****************************************************************

    save_contents proc
        ;tries to open file
        mov dx, offset name_contents
        call fopen
        jnc save

        ;in case it doesn't exist, creates it
        call fcreate

        save:
        mov bx, ax ;move handle

        mov cx, 0 ;number of bytes
        mov dx, 0 ;offset to write to
        mov ah, 40h
        int 21h

        ;closes file
        call fclose

        ret
    save_contents endp

;*****************************************************************
; open_contents -
; descricao: opens contents.bin if it exists
; input -
; output -
; destroi -
;*****************************************************************

    open_contents proc
        ;tries to open file
        mov dx, offset name_contents
        call fopen
        jc end_open_cont ;in case it doesn't exist yet

        mov bx, ax

        mov cx, 0 ;number of bytes
        mov dx, 0 ;offset to write to
        mov ah, 3Fh

        call fclose
        end_open_cont:
        ret
    open_contents endp

ends

end start ; set entry point and stop the assembler.