example file 'example.bin'
example_size = $ - example    

virtual at 0
    file "example.bin"
    example_size = $
end virtual    

; WARNING: this snippet works with fasmg only
virtual at 0
    file 'example.bin'
    load example_string : $ from 0
end virtual

dd lengthof example_string      ; size of file
db example_string               ; contents of file    

If you use FILE directive to include contents of entire file, you can simply compute the difference in offsets to get the size of that file:

Code:

example file 'example.bin'
example_size = $ - example    

The above examples apply to both fasm 1 and fasmg with no difference. But in case of fasmg you can also do some trickier things, like loading the contents of a file into a string:

Code:

; WARNING: this snippet works with fasmg only
virtual at 0
    file 'example.bin'
    load example_string : $ from 0
end virtual

dd lengthof example_string      ; size of file
db example_string               ; contents of file    

struc str value
        . db lengthof value, value
end struc

hello str 'Hello world!'    

struc str value
{
        local ..length
        . db ..length,value
        ..length = $ - (.+1)
}

hello str 'Hello world!'    

scippie
You can put an ampersand directly after the argument name in the first line. This will tell fasm to use the whole remainder of an argument line as the last argument. Aside from that passing arguments surrounded by < and > allows to ignore commata as argument separators.