Display 64bit MASM values using printf call

;---------------------------------------------------;
;   App: MASM printf usage                          ;
;   Version: 1.0                                    ;
;---------------------------------------------------;
;   Date: 04 June 2017                              ;
;   Author: Jose Madureira                          ;
;   License: copy at will, just give credit         ;
;---------------------------------------------------;

; ## Global Constants ##
NL EQU 0Dh,0Ah      ;new line
TAB EQU 09h         ;tab character
STRMAX  EQU 21      ;max string size
T64 EQU TYPE RAX    ;64 bit size (8 BYTES)

; ## External Prototypes ##
includelib msvcrt.lib   ;necessary for printf
EXTRN printf:PROC   ;display formatted string with args

ExitProcess PROTO   ;terminate program


.data
    msgNl byte NL,0     ;simply a new line

    ;simple formats
    msgInt byte "%d",0
    msgFlt byte "%f",0
    msgStr byte "%s",0

    ;test data
    valInt qword 666
    valFlt real8 6.54321
    valStr byte "This is not a test",0
    valStrNlTab byte NL,TAB,"new lined and tabbed",0

.code
PUBLIC Main

Main PROC
    ;display an integer
    mov rax,1
    mov rcx,offset msgInt   ;"%d"
    mov rdx,valInt          ;some integer value
    call PrintfMe64

    ;display new line using PrintfMe64
    mov rax,1
    mov rcx,offset msgStr   ;"%s"
    mov rdx,offset msgNl    ;crlf
    call PrintfMe64

    ;display a float
    mov rax,1
    mov rcx,offset msgFlt   ;"%f"
    mov rdx,valFlt          ;some float value
    call PrintfMe64

    ;display new line using PNL -> PrintfMe64
    call PNL

    ;display a string
    mov rax,1
    mov rcx,offset msgStr   ;"%s"
    mov rdx,offset valStr   ;some string
    call PrintfMe64

    ;display a string with new line and tab before it
    mov rax,1
    mov rcx,offset msgStr   ;"%s"
    mov rdx,offset valStrNlTab ;new line -> tab -> string
    call PrintfMe64



finish:
    call PNL
    call PNL
    call ExitProcess

Main ENDP


; *******************************************************************
PrintfMe64 PROC uses RAX
; * Purpose: display a 'c' style formated message and arguments     *
; *-----------------------------------------------------------------*
; * IN : RAX, number of arguments                                   *
; *      RCX, message with format flags                             *
; *      RDX...R15, arguments for formatted message                 *
; * OUT: none                                                       *
; *+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*
; * implementation idea:                                            *
; *     http://cx20.main.jp/blog/hello/2012/01/04/hello-masm-world  *
; *******************************************************************
    ;prevent disaster
    push RBP
    mov RBP, RSP

    imul RAX, 8         ;allocate additional 8 bytes per argument
    add RAX, 64         ;(8*args) + 64 bytes
    mov [RBP], RAX      ;save total allocated local space
    sub RSP, RAX        ;allocate local stack space

    call printf         ;display formated message

    add RSP, [RBP]      ;clean the stack
    pop RBP

    ret
PrintfMe64 ENDP

; *******************************************************************
PNL PROC uses RAX RCX RDX
; * Purpose: displays a new line                                    *
; *-----------------------------------------------------------------*
; * IN : none                                                       *
; * OUT: none                                                       *
; *******************************************************************
    mov rax,1
    mov rcx,offset msgStr       ;"%s"
    mov rdx,offset msgNl        ; cr lf
    call PrintfMe64

ret
PNL ENDP

END