mASM BYTE

[David]

Hi, how is a BYTE done in mASM? I have tried the following, but it does not work:

BYTE sz[2] = {0x00, 0x00};

[dedndave]

we use DB (define byte) for bytes

Label0  db 0       ;byte - 1 byte
Label1  dw 0       ;word - 2 bytes
Label2  dd 0       ;dword - 4 bytes
Label3  dq 0       ;qword - 8 bytes
Label4  dt 0       ;tbyte - 10 bytes

for reals

Real0   Real4 1.0  ;4 bytes
Real1   Real8 1.0  ;8 bytes
Real2   Real10 1.0 ;10 bytes

[David]

we use DB (define byte) for bytes

Label0  db 0       ;byte - 1 byte
Label1  dw 0       ;word - 2 bytes
Label2  dd 0       ;dword - 4 bytes
Label3  dq 0       ;qword - 8 bytes
Label4  dt 0       ;tbyte - 10 bytes

for reals

Real0   Real4 1.0  ;4 bytes
Real1   Real8 1.0  ;8 bytes
Real2   Real10 1.0 ;10 bytes

Ah I see, but how would I define more then 1 byte?

Is it like this?

BYTE Label1[1] = {0x90}; = 1 byte :  Label0 db 0x90
BYTE Label1[2] = {0x90,0x90}; = 2 bytes : Label1 dw 0x90, 0x90
BYTE Label3[3] = {0x90, 0x90, 0x90}; = 3 bytes : ??
BYTE Label1[4] = {0x90, 0x90, 0x90, 0x90}; = 4 bytes : Label3 dd 0x90, 0x90, 0x90, 0x90

?

[dedndave]

Label0  db 20 dup(0)            ;creates 20 0's
Label1  db 'String',0,20 dup(?) ;creates a string, a 0, and 20 unknowns

[oex]

Label0  db 20 dup(0)            ;creates 20 0's
Label1  db 'String',0,20 dup(?) ;creates a string, a 0, and 20 unknowns

Is that effectively allocate 20 unknowns then 0 fill? Could (?) ever be anything other than (0)?

[RuiLoureiro]

Hi, how is a BYTE done in mASM? I have tried the following, but it does not work:

BYTE sz[2] = {0x00, 0x00};

is
sz     db 2 dup (00h)                  ; 0x00 = 00h      0x90=90h

BYTE Label1[4] = {0x90, 0x90, 0x90, 0x90};
is
Label1   db 4 dup (90h) 
Rui

[David]

Hi, how is a BYTE done in mASM? I have tried the following, but it does not work:

BYTE sz[2] = {0x00, 0x00};

is
sz     db 2 dup (00h)                  ; 0x00 = 00h      0x90=90h

BYTE Label1[4] = {0x90, 0x90, 0x90, 0x90};
is
Label1   db 4 dup (90h) 
Rui

How about if I want to create a BYTE with not just one value?  Like BYTE Label1[4] = {0x94, 0x19, 0x20, 0x20};

[RuiLoureiro]

How about if I want to create a BYTE with not just one value?  Like BYTE Label1[4] = {0x94, 0x19, 0x20, 0x20};

Label1    db 94h                    or    Label1  db 94h,19h,20h,20h
             db 19h
             db 20h
             db 20h
Label X ...
Rui

[David]

Thank you very much.

[hutch--]

Try this,

Code Select Expand


LOCAL Buffer[128]:BYTE


128 bytes allocated on the stack with local scope. Note that the content of the allocated stack buffer is undefined, it can be any trash on the stack. If you want it initialised to anything you must do it yourself.

You get the start address with LEA.

Code Select Expand


    lea eax, Buffer
  ; set it to zero length for zero terminated strings
    mov BYTE PTR [eax], 0