Why fasm segment can be used within Windows environment. The data can only be used in the Linux section?

and instead of section there should be the segment directive used, followed by one or more segment permission flags and optionally a marker of special ELF executable segment, which can be interpreter, dynamic or note. The origin of segment is aligned to page (4096 bytes), and available permission flags are: readable, writeable and executable.

segment readable writeable executable
segment interpreter readable
segment readable writeable    

If you are talking about compiling executable ELF file in Windows, after "segment" directive, only some flags can be set. Here is the quote from the FASM manual:

Quote:

and instead of section there should be the segment directive used, followed by one or more segment permission flags and optionally a marker of special ELF executable segment, which can be interpreter, dynamic or note. The origin of segment is aligned to page (4096 bytes), and available permission flags are: readable, writeable and executable.

For example, valid definitions are:

Code:

segment readable writeable executable
segment interpreter readable
segment readable writeable    

segment data
msg  db 'hello world!',0xa
segment code
mov eax,msg
    

section .data
msg  db 'hello world!',0xa
section .code
mov eax,msg
    

"code" and "data" are not sections that the OS knows, or cares, about. You (as the programmer) decide "code" by making a section "executable", and "data" by making it "readable/writeable". Or if you want something else just combine the flags as needed.

Even the definition of "data" is ambiguous. Do you want constant data or changeable data? Should it be initialised first or doesn't it matter?

segment .data
        msg     db "hello world",10
        len     equ $-msg
segment .text   
        global  _start:
_start:
        mov dx,len
        mov cx,msg
        mov bx,1
        mov ax,4
        int 80h
        mov bx,0
        mov ax,1
        int 80h
    

"code" and "data" are not sections that the OS knows, or cares, about. You (as the programmer) decide "code" by making a section "executable", and "data" by making it "readable/writeable". Or if you want something else just combine the flags as needed.

Even the definition of "data" is ambiguous. Do you want constant data or changeable data? Should it be initialised first or doesn't it matter?

format MZ
entry .code:start
segment .code
start:
mov ax, .data
mov ds, ax   
mov dx, msg   
mov ah, 9h
int 21h
mov ah, 4ch
int 21h
segment .data
msg db 'Hello World', '$'
    

format ELF executable 3
entry start
segment readable writeable executable 
start:

        mov     eax,4
        mov     ebx,1
        mov     ecx,msg
        mov     edx,msg_size
        int     0x80

        mov     eax,1
        xor     ebx,ebx
        int     0x80
msg db 'Hello world!',0xA
msg_size = $-msg
    

fasm != NASM, or MASM, or GASM, or TASM.

fasm does not have ".code" or ".data" anywhere in its internals. If you see them in code then they are macros that expand to something else.

kerr, this is not different "grammar". The different directives in your examples are simply because of the different binary formats FASM compiles. The best way to improve your knowledge is simply to read carefully the FASM manual. All these details are explained there.

Also, as revolution noticed, you must learn to separate FASM directives from FASM macros.

Thank you @JohnFound @revolution @system error

format ELF ;this is for Linux. Don't confuse this for Windows

public _start

section '.text' executable
_start:
        mov edx,len 
        mov ecx,msg 
        mov ebx,1 
        mov eax,4 
        int 80h 
        mov ebx,0 
        mov eax,1 
        int 80h 

section '.data' writeable
msg db "hello world",10 
len  = $-msg     

Oh yeah!Can I get a full manual in what place? format pdf file

kerr, I won't blame you if you are confused.

1. If you want to produce EXECUTABLES (.exe, .a;

in Linux, use segment or flat (no segment no section)
in Windows, use segment (for MZ 16-bit), section (for PE, PE64) or flat.
in DOS, use "org".


2. If you want to produce OBJECTS (by using linker, .o, .obj);

in Linux, use section ".text" executable, section ".data" writeable
in Windows, use section (COFF, MS COFF format)

So which one that you want to produce? An object or an executable? Answer this question first and then pick one format that is suitable for such purpose.

By the way, most of the NASM examples you been reading are using linkers, that is they compile to objects. That's why they use section .text, section .data, section .bss. But unfortunately, FASM can produce executables directly without using linkers, so most FASM examples you see use segments instead of section.

BUT....

if you want to use FASM to produce objects (like NASM always do), here's the equivalent example;

Code:

format ELF ;this is for Linux. Don't confuse this for Windows

public _start

section '.text' executable
_start:
        mov edx,len 
        mov ecx,msg 
        mov ebx,1 
        mov eax,4 
        int 80h 
        mov ebx,0 
        mov eax,1 
        int 80h 

section '.data' writeable
msg db "hello world",10 
len  = $-msg     

I haven't tested this but it should work.

kerr wrote:

Oh yeah!Can I get a full manual in what place? format pdf file

Full FASM manual is packed inside every FASM package you download from FlatAssembler web site. All these packages use different text formats for shipping the manual.

If you need exactly PDF - download the package for Windows.

Also, the manual is published online here: FASM manual. You can read it in your web browser.