Assembly [Assignment2]

.model small
.stack 100h

.data
ret_msg  db  'Process returned 0 (0x0)$'
ip_msg   db  'n = $'
inv      db  'Invalid Input!$'
new_line db  0ah,0dh,"$"
space    db  ' $'
i        db  1
j        db  1
char     db  1  ; for storing input char
n        db  1  ; pre-process input char into numeric
type     db  1  ; type = 1 denotes number, type = 2 denotes upper case, type = 3 denotes lower case
val      db  1  ; for printing a character
cnt_sp   db  1  ; for storing number of spaces

.code
main proc
    mov ax, @data
    mov ds, ax

    INPUT:
    mov ah, 9
    lea dx, ip_msg
    int 21h
    mov ah, 1
    int 21h
    mov char, al

    ; new line
    mov ah, 9
    lea dx, new_line
    int 21h

    ; check if it is '$'
    cmp char, '$'
    je EXIT

    ; check if input character is a number
    cmp char, '9'
    jg Alphabet
    cmp char, '0'
    jle Invalid

    ; assigning input type and pre-process n for number
    mov type, 1
    mov bl, char
    mov n, bl
    sub n, 48
    jmp Display

    ; check if it is an Alphabet
    Alphabet:
    cmp char, 'A'
    jl Invalid
    cmp char, 'Z'
    jg Lower_Case

    ; assigning input type and pre-process n for Upper Case Alphabet
    mov type, 2
    mov bl, char
    mov n, bl
    sub n, 64
    jmp Display

    ; check for valid lower case alphabet
    Lower_Case:
    cmp char, 'a'
    jl Invalid
    cmp char, 'z'
    jg Invalid

    ; assigning input type and pre-process n for Lower Case Alphabet
    mov type, 3
    mov bl, char
    mov n, bl
    sub n, 96
    jmp Display

    Invalid:
    mov ah, 9
    lea dx, inv
    int 21h

    ; new line
    mov ah, 9
    lea dx, new_line
    int 21h
    int 21h

    jmp INPUT

    Display:

    ; Outer for loop
    mov i, 1
    mov bl, n
    OUTER_FOR:
    cmp i, bl
    jg OUTER_FOR_EXIT

    ; Inside Outer for
    mov cl, n
    sub cl, i
    mov cnt_sp, cl
    add cnt_sp, cl

    ; Loop for printing spaces
    mov j, 1
    mov cl, cnt_sp
    SPACE_FOR:
    cmp j, cl
    jg SPACE_FOR_EXIT

    ; inside space printing loop
    mov ah, 9
    lea dx, space
    int 21h
    inc j
    jmp SPACE_FOR

    SPACE_FOR_EXIT:

    ; First half
    mov j, 1
    mov cl, i
    FIRST_HALF_FOR:
    cmp j, cl
    jg FIRST_HALF_FOR_EXIT

    ; inside printing first half
    mov ch, j
    mov val, ch
    cmp type, 1
    je generate_number_first
    cmp type, 2
    je generate_upper_first
    jmp generate_lower_first

    generate_number_first:
    add val, 48
    jmp print_char_first
    generate_upper_first:
    add val, 64
    jmp print_char_first
    generate_lower_first:
    add val, 96
    jmp print_char_first

    print_char_first:
    mov ah, 2
    mov dl, val
    int 21h
    mov ah, 9
    lea dx, space
    int 21h

    inc j
    jmp FIRST_HALF_FOR

    FIRST_HALF_FOR_EXIT:

    ; Second half
    mov cl, i
    mov j, cl
    sub j, 1
    SECOND_HALF_FOR:
    cmp j, 1
    jl SECOND_HALF_FOR_EXIT

    ; inside printing second half
    mov ch, j
    mov val, ch
    cmp type, 1
    je generate_number_second
    cmp type, 2
    je generate_upper_second
    jmp generate_lower_second

    generate_number_second:
    add val, 48
    jmp print_char_second
    generate_upper_second:
    add val, 64
    jmp print_char_second
    generate_lower_second:
    add val, 96
    jmp print_char_second

    print_char_second:
    mov ah, 2
    mov dl, val
    int 21h
    mov ah, 9
    lea dx, space
    int 21h

    dec j
    jmp SECOND_HALF_FOR

    SECOND_HALF_FOR_EXIT:

    mov ah, 9
    lea dx, new_line
    int 21h

    inc i
    jmp OUTER_FOR

    OUTER_FOR_EXIT:

    mov ah, 9
    lea dx, new_line
    int 21h

    jmp INPUT

    ; exit
    EXIT:
    mov ah, 9
    lea dx, new_line
    int 21h
    lea dx, ret_msg
    int 21h

    main endp
end main