macro not displaying mesg

[zak100]

Hi,
Following program is working fine without macro:

Code Select Expand



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

        .MODEL  TINY
.data
msg db "We be bootin2'!",0
        .CODE

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

        ORG     0

;code branch

boot0:  jmp short boot1

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

        ORG     3

;OEM identifier

boot03  db      'BootDisk'     ;always 8 characters
.STACK 2048; removes the stack warning

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

        ORG     0Bh


boot0B  dw      200h           ;bytes per sector
boot0D  db      1              ;sectors per cluster
boot0E  dw      1              ;reserved sectors (the boot sector is reserved)
boot10  db      2              ;number of copies of the FAT
boot11  dw      0E0h           ;root directory entries (224 for 1.4 mb)
boot13  dw      0B40h          ;total disk sectors
boot15  db      0F0h           ;media descriptor byte (F0 for 1.4 mb)
boot16  dw      9              ;sectors per FAT
boot18  dw      12h            ;sectors per cylinder
boot1A  dw      2              ;number of heads
boot1C  dw      0              ;hidden sectors

xCursor db 0
yCursor db 0
;----------------------------------------------------------------------------------

boot1: cli                     ;disable maskable interrupts
       xor     di,di
       mov     ss,di
       mov     sp,7C00h        ;SS:SP = 0000:7C00


       XOR AX,AX      ;Makes AX=0.
       MOV ES,AX      ;Make ES=0
       mov DS,ax
       sti

       mov     ax,0B800h       ;notice that di is already 0
       mov     es,ax
       cld
       mov     ax,1F41h
       stosw
;----------------------------------call procedures
       CALL GetKey                    ;Call GetKey()
       Call ClearScreen       ;ClearScreen()
       LEA AX,msg         ;Get Address of szReady.
       CALL PrintMessage      ;Call PrintfMessage()
boot2: jmp     boot2
;-------------------------------------procedure definitions
GetKey PROC near

        mov ah,0
        int 16h ;Wait for a key press.
        Ret
       
GetKey EndP

ClearScreen PROC near

        mov ax,0600h   ;//Scroll All Screen UP to Clear Screen.
        mov bh,07
        mov cx,0
        mov dx,184fh   
        int 10h
       
        Mov byte ptr xCursor,0  ;//Set Cursor Position So next
                        ;//write would start in
                        ;//the beginning of screen.
        Mov byte ptr yCursor,0

        Ret
       
ClearScreen EndP


PrintMessage PROC near

     xor di,di
     mov ds,di
     mov ax,0B800h
     mov es,ax
     ; should probably set up a sane stack here, too.

     mov si,offset msg    ; "our dear string"

     mov ah,04h    ; color
msgloop:
     lodsb  ;loads AL with a byte of data from mem location pointed by SI
     or al,al
     jz blackhole
     stosw ; transfers the contents of AL to the mem location pointed by di
     jmp msgloop
blackhole:     ret
       
               
PrintMessage EndP
;----------------------------------------------------------------------------------

        ORG     1FEh

;validation marker

        dw      0AA55h

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

        END     boot0



but when I add a macro in this program, I am not getting any string displayed. The new program after induction of
macro is given below:

Code Select Expand



;----------------------------------------------------------------------------------
print_mesg macro offset1
mov     ax,7C0h
       mov     ds,ax
       push    ax
       mov     ax,xlat0
       push    ax
       retf

;at this point, the registers are as follows:

;DI = 0000
;CS = DS = 07C0
;IP = xlat0 offset
;SS:SP = 0000:7C00

;display the message at B800:0000

xlat0: mov     ax,0B800h       ;notice that di is already 0
       mov     es,ax
       mov     si,offset offset1
       cld
       mov     ah,1Fh
       mov     cx,sizeof offset1

disp0: lodsb
       stosw
       loop    disp0
endm


        .MODEL  TINY



        .CODE

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

        ORG     0

;code branch

boot0:  jmp short boot1

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

        ORG     3

;OEM identifier

boot03  db      'BootDisk'     ;always 8 characters
.STACK 2048; removes the stack warning

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

        ORG     0Bh


boot0B  dw      200h           ;bytes per sector
boot0D  db      1              ;sectors per cluster
boot0E  dw      1              ;reserved sectors (the boot sector is reserved)
boot10  db      2              ;number of copies of the FAT
boot11  dw      0E0h           ;root directory entries (224 for 1.4 mb)
boot13  dw      0B40h          ;total disk sectors
boot15  db      0F0h           ;media descriptor byte (F0 for 1.4 mb)
boot16  dw      9              ;sectors per FAT
boot18  dw      12h            ;sectors per cylinder
boot1A  dw      2              ;number of heads
boot1C  dw      0              ;hidden sectors

xCursor db 0
yCursor db 0
;----------------------------------------------------------------------------------

boot1: cli                     ;disable maskable interrupts
       xor     di,di
       mov     ss,di
       mov     sp,7C00h        ;SS:SP = 0000:7C00


       XOR AX,AX      ;Makes AX=0.
       MOV ES,AX      ;Make ES=0
       mov DS,ax
       sti

       mov     ax,0B800h       ;notice that di is already 0
       mov     es,ax
       cld
       mov     ax,1F41h
       stosw
;----------------------------------call procedures
       CALL GetKey                    ;Call GetKey()
       Call ClearScreen       ;ClearScreen()
       LEA AX,msg         ;Get Address of szReady.
       CALL PrintMessage      ;Call PrintfMessage()
       CALL GetKey
       print_mesg msg
boot2: jmp     boot2
;-------------------------------------procedure definitions

msg2     db      "Zulfi We be bootin2'!"
msg db "We be bootin2'!",0

GetKey PROC near

        mov ah,0
        int 16h ;Wait for a key press.
        Ret
       
GetKey EndP

ClearScreen PROC near

        mov ax,0600h   ;//Scroll All Screen UP to Clear Screen.
        mov bh,07
        mov cx,0
        mov dx,184fh   
        int 10h
       
        Mov byte ptr xCursor,0  ;//Set Cursor Position So next
                        ;//write would start in
                        ;//the beginning of screen.
        Mov byte ptr yCursor,0

        Ret
       
ClearScreen EndP


PrintMessage PROC near

     xor di,di
     mov ds,di
     mov ax,0B800h
     mov es,ax
     ; should probably set up a sane stack here, too.

     mov si,offset msg    ; "our dear string"

     mov ah,04h    ; color
msgloop:
     lodsb  ;loads AL with a byte of data from mem location pointed by SI
     or al,al
     jz blackhole
     stosw ; transfers the contents of AL to the mem location pointed by di
     jmp msgloop
blackhole:     ret
       
               
PrintMessage EndP
;----------------------------------------------------------------------------------

        ORG     1FEh

;validation marker

        dw      0AA55h

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

        END     boot0



Can somebody plz help me with this?

Zulfi.

[dedndave]

i am not sure why you want all those PROCs (and macros for that matter)
most of the PROCs you have are only called once - that adds 4 bytes each
GetKey is the only one that makes sense, as it is called twice
even then, mov ah,0;int 16h is only 4 bytes
a call is 3 bytes and a ret is 1 byte, so you aren't saving any space unless you use it at least 5 times
what you have now is 2 call's (6 bytes) and the mov ah,0;int 16h (4 bytes) with a ret (1 byte) - total 11 bytes
if you just put in mov ah,0;int 16h twice - total 8 bytes

as for macros, a boot sector, as well as ROMable code, is just no place for a macro
you are trying to conserve precious real-estate

[zak100]

Hi,
Boot sector is of 512 bytes so why we cant have a macro in it??


Zulfi.

[dedndave]

well, you can
but, that 512 bytes can be precious space when it comes time to
add the code to locate the boot-loader and load it from the floppy

macros are used to repeat sections of code whenever the name is typed
they are a great time-saver in normal programming
but, in this case, we do not to want repeat sections of code
the code that you originally wanted to put into a macro was the display-text code
no need to repeat that code several times - i.e. no need for it to be in a macro

[zak100]

Ok, I am just doing an experiment. I can remove macro but I dont know what problem is being caused by this macro in displaying mesg?

Zulfi.

[dedndave]

first, when you define a macro, that definition does not generate any code
the definition must appear before it is referenced

so, to make a simple macro, place it near the beginning of the file (after the .model, but before a segment is opened)

        .MODEL  TINY

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

PrintMessage MACRO

     xor di,di
     mov ax,0B800h
     mov es,ax
     mov ah,04h    ; color

msgloop:
     lodsb
     or al,al
     jz msgdone

     stosw
     jmp msgloop

msgdone:

        ENDM

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

        .DATA
;
Message1 db 'Hello World',0
;
        .CODE
;
;
;
;
        mov     si,offset Message1
        PrintMessage

DeadLoop: jmp DeadLoop


you can also pass arguments to the macro
so, if you define the macro as

PrintMessage MACRO MessageAddr:REQ

        mov     si,MessageAddr
.
.

you can now use the macro like this:

        PrintMessage offset Message1

if you look at the file \masm32\help\asmintro.chm
read the section "Working with Macros"
all of this is explained in there, including more ways to pass arguments