TITLE Convert Number to ASCII Format  (convert.asm)

.686
.MODEL flat, stdcall
.STACK 4096

INCLUDE Irvine32.inc

.data
hexstring   BYTE    9 DUP(?)
binstring   BYTE    33 DUP(?)

.code
main PROC
    mov  eax, 123456789
    mov  edx, OFFSET hexstring
    call Convert2Hex
    call WriteString
    call Crlf

    ; Add instructions to test Convert2Bin, Convert2Dec, and Convert2Int

    exit
main ENDP


; Convert number in EAX to ASCII hexadecimal format
; Store hexadecimal characters in the string passed by reference
; Receives: EAX = 32-bit number
;           EDX = string address
; Returns:  store converted hexadecimal characters

Convert2Hex PROC
    push ebx                ; save registers
    push ecx
    push edx
    mov  ecx, 8             ; 8 iterations
L1:
    rol  eax, 4             ; rotate upper 4 bits of eax
    mov  ebx, eax
    and  ebx, 15            ; keep lower 4 bits in ebx
    mov  bl,  hexarray[ebx] ; convert 4 bits to Hex character
    mov  [edx], bl          ; store Hex char in string
    add  edx, 1             ; point to next char in string
    loop L1

    mov  BYTE PTR [edx], 0  ; Terminate string with a NULL char
    pop  edx                ; restore register values
    pop  ecx
    pop  ebx
    ret                     ; return
    hexarray BYTE "0123456789ABCDEF"
Convert2Hex ENDP


; Convert number in EAX to ASCII binary format
; Store '0' and '1' characters in the string passed by reference
; Receives: EAX = 32-bit number
;           EDX = string address
; Returns:  store converted binary characters

Convert2Bin PROC
    ; to be completed
Convert2Bin ENDP



; Convert unsigned number in EAX to ASCII decimal format
; Receives: EAX = 32-bit number
;           EDX = string address
; Returns:  Store characters in the string passed by reference

Convert2Dec PROC
    pushad                  ; save all general-purpose registers
    mov  esi, edx           ; ESI = string address
    mov  ecx, 0             ; counts decimal digits
    mov  ebx, 10            ; divisor = 10
L1:
    mov  edx, 0             ; dividend = EDX:EAX
    div  ebx                ; EDX = remainder digit = 0 to 9 (stored in DL)
    add  dl, '0'            ; convert DL to ASCII digit
    push dx                 ; save digit on the stack
    inc  ecx                ; count digit
    cmp  eax, 0
    jnz  L1                 ; loop back if EAX != 0
L2:
    pop  dx                 ; last digit pushed is the most significant
    mov  [esi], dl          ; save ASCII digit in string
    inc  esi
    loop L2

    mov  BYTE PTR [esi], 0  ; Terminate string with a NULL char
    popad                   ; restore all general-purpose registers
    ret                     ; return
Convert2Dec ENDP



; Convert signed number in EAX to ASCII integer format prefixed with sign
; Receives: EAX = 32-bit number
;           EDX = string address
; Returns:  Store characters in the string passed by reference

Convert2Int PROC
    ; to be completed
Convert2Int ENDP
END main