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(nasm.info)Section 4.8.4

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4.8.4. `__FILE__' and `__LINE__': File Name and Line Number
-----------------------------------------------------------

   Like the C preprocessor, NASM allows the user to find out the file
name and line number containing the current instruction. The macro
`__FILE__' expands to a string constant giving the name of the current
input file (which may change through the course of assembly if
`%include' directives are used), and `__LINE__' expands to a numeric
constant giving the current line number in the input file.

   These macros could be used, for example, to communicate debugging
information to a macro, since invoking `__LINE__' inside a macro
definition (either single-line or multi-line) will return the line
number of the macro _call_, rather than _definition_. So to determine
where in a piece of code a crash is occurring, for example, one could
write a routine `stillhere', which is passed a line number in `EAX' and
outputs something like `line 155: still here'. You could then write a
macro

     %macro  notdeadyet 0
     
             push    eax
             mov     eax,__LINE__
             call    stillhere
             pop     eax
     
     %endmacro

   and then pepper your code with calls to `notdeadyet' until you find
the crash point.