assignment 4

section .data
        nline       db  10,10
    nline_len   equ $-nline

    ano     db  10,"    Assignment no   :3",
            db  10,"------------------------------------------------------------",
            db      10,"    Assignment Name:Conversion From HEX to BCD and BCD to HEX Number.",
            db      10,"----------------------------------------------------------",10
    ano_len     equ $-ano

    menu        db  10,"1.Hex To BCD.",
            db  10,"2.BCD To Hex.",
            db  10,"3.Exit."
            db  10,"Enter Your Choice::"
    menu_len    equ $-menu

    hmsg        db  10,"Enter 4 digit Hex Number::"
    hmsg_len    equ $-hmsg

    bmsg        db  10,"Enter 5 digit BCD Number::"
    bmsg_len    equ $-bmsg

    ebmsg       db  10,"The Equivalent BCD Number is::"
    ebmsg_len   equ $-ebmsg

    ehmsg       db  10,"The Equivalent Hex Number is::"
    ehmsg_len   equ $-ehmsg

    emsg        db  10,"INVALID NUMBER INPUT",10
    emsg_len    equ $-emsg
;------------------------------------------------------------------------------
section .bss
    buf     resB    6
    char_ans    resB    4
    ans     resW    1

;-----------------------------------------------------------------------------

%macro  Print   2
     MOV    RAX,1
     MOV    RDI,1
         MOV    RSI,%1
         MOV    RDX,%2
    syscall
%endmacro

%macro  Read    2
     MOV    RAX,0
     MOV    RDI,0
         MOV    RSI,%1
         MOV    RDX,%2
    syscall
%endmacro


%macro Exit 0
    Print   nline,nline_len
    MOV RAX,60
        MOV RDI,0
    syscall
%endmacro
;---------------------------------------------------------------

section .text
    global _start

_start:
        Print   ano,ano_len

MENU:   Print   menu,menu_len
    Read    buf,2       ;accept choice i.e 1 digit+enter

    mov al,[buf]    ;contains only digit character

c1: cmp al,'1'
    jne c2
    call    HEX_BCD
    jmp MENU

c2: cmp al,'2'
    jne c3
    call    BCD_HEX
    jmp MENU

c3: cmp al,'3'
    jne invalid
    Exit

invalid:
    Print   emsg,emsg_len
    jmp MENU
;---------------------------------------------------------------

HEX_BCD:
    Print   hmsg,hmsg_len
    call    Accept_16       ;accept 4 digit hex number
    mov ax,bx           ;mov hex number in ax

    mov bx,10           ;for divide hex number by 10
    xor bp,bp           ;counter

back:   xor dx,dx           ;as dx each time contains remainder
    div bx          ;divide ax by 10 ax=Q,dx=R
    push    dx          ;push dx on stack as it is bcd
    inc bp          ;inc counter by 1

    cmp ax,0            ;compare whether Q is 0 if 0 means number get over
    jne back            ;mov to conversion of quotient

    Print   ebmsg,ebmsg_len

back1:  pop dx          ;pop last digit pushed on stack
    add dl,30h          ;add 30 to digit to make them decimal
    mov [char_ans],dl       ;print individual digit
    Print   char_ans,1

    dec bp
    jnz back1           ;mov to next digit

RET
;---------------------------------------------------------------

BCD_HEX:
    Print   bmsg,bmsg_len
    Read    buf,6       ;5 digit + 1 enter

    mov rsi,buf     ;Points at the start of buffer
    xor ax,ax       ;Previous digit =0
    mov rbp,5       ;counter
    mov rbx,10      ;multiplier

next:   xor cx,cx       ;contains next digit each time
    mul bx      ;(ax*bx)+cl
    mov cl,[rsi]
    sub cl,30h
    add ax,cx

    inc rsi     ;Point at the next digit
    dec rbp
    jnz next

    mov [ans],ax    ;store ax in ans because ax get change in Print macro
    Print   ehmsg,ehmsg_len

    mov ax,[ans]
    call    Disp_16     ;Print hex number



RET
;---------------------------------------------------------------
Disp_16:                ;Hex to Ascii(character) display
    MOV RSI,char_ans+3
    MOV RCX,4               ;counter
    MOV RBX,16          ;Hex no

next_digit:
    XOR RDX,RDX
    DIV RBX

    CMP DL,9
    JBE add30
    ADD DL,07H

add30   :
    ADD DL,30H
    MOV [RSI],DL

    DEC RSI
    DEC RCX
    JNZ next_digit

    Print   char_ans,4
ret
;-------------------------------------------------------------------
Accept_16:              ;Ascii(character) to hex number input
    Read    buf,5

    MOV RCX,4
    MOV RSI,buf
    XOR BX,BX

next_byte:
    SHL BX,4
    MOV AL,[RSI]

    CMP AL,'0'
    JB  error
    CMP AL,'9'
    JBE sub30

    CMP AL,'A'
    JB  error
    CMP AL,'F'
    JBE sub37

    CMP AL,'a'
    JB  error
    CMP AL,'f'
    JBE sub57

error:
    Print   emsg,emsg_len
    Exit

sub57:  SUB AL,20H
sub37:  SUB AL,07H
sub30:  SUB AL,30H

    ADD     BX,AX

    INC RSI
    DEC RCX
    JNZ next_byte

RET
;-------------------------------------------------------------------------------------