fasm1 compilation process (memory point of view)

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ProMiNick

Joined: 24 Mar 2012
Posts: 825
Location: Russian Federation, Sochi

ProMiNick 05 Dec 2025, 13:58

Code:

        VirtualAlloc [compiler_memory] shl 10 ; shl 10 - kilobytes multiplier
        for initialization of blocks that grow up on all states usualy used edi.
        allocated memory divided in proportion 3:1

Code:

                                          3              :                     1
        [allocated_memory]={[memory_start...memory_end]  :  [additional_memory...additional_memory_end]} 
                             A
                             |
                             [code_start]

Code:

[tagged_blocks]=0

Code:

         call    preprocessor {

        [allocated_memory]={[include_paths...,0,memory_start][memory_start...memory_end]  :  [additional_memory...additional_memory_end]} ;memory_start moved right by size of include_paths
                                                                                              A                                       A
                                                                                              |                                       |
                                                                                              [free_additional_memory]                |
                                                                                                                                      |
                                                                                                                                      [labels_list]

file sources opened and placed in a way that their file end points to memory_end, each file stream grows down memory_end pointer. While its tokenization is placed from memory_start growing up that memory_start pointer

Code:

        [allocated_memory]={[include_paths...,0,memory_start][tokenized source...>][memory_start...memory_end][<...file sources mapped to memory]  :  [additional_memory...additional_memory_end]}

preprocessing_finished with

Code:

[source_start]=edi }

I guess additional_memory even on preprocessor state used for calculations of expressions. than parser state...
to be continued...
(please not judge me strong for bad shemes - they are as are|as I see)
[edited]:proportion of allocated_memory 3:1 not 4:1

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Last edited by ProMiNick on 05 Dec 2025, 21:36; edited 1 time in total

05 Dec 2025, 13:58

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8489
Location: Kraków, Poland

Tomasz Grysztar 05 Dec 2025, 14:53

You may find some information in my old unfinished guide, although only the preprocessor stage got covered in detail.

05 Dec 2025, 14:53

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8489
Location: Kraków, Poland

Tomasz Grysztar 05 Dec 2025, 15:02

For the areas of fasm's internals that were not covered by these few chapters, there may still be something to dig out in the oldest threads on these forums, like this description of parsed source tokens.

05 Dec 2025, 15:02

AsmGuru62

Joined: 28 Jan 2004
Posts: 1746
Location: Toronto, Canada

AsmGuru62 05 Dec 2025, 15:28

Is there any limits for the amount of code files included into FASM main file?
Please consider this main source specified on command line:

Code:

format  PE GUI 4.0
entry   start
stack   4000h, 4000h

    include 'Win32W.Inc'
    include 'Macros.Inc'
    include 'Macro\If.Inc'

; ---------------------------------------------------------------------------
section '.data' data readable writeable

    include 'Globals.Inc'

; ---------------------------------------------------------------------------
section '.code' code readable executable

    include 'Module_001.Asm'
    include 'Module_002.Asm'
    ...
    include 'Module_999.Asm'

; ---------------------------------------------------------------------------
; PROGRAM ENTRY POINT
; ---------------------------------------------------------------------------
align 32
start:
    ...

Lets assume I have included some (a thousand) files.
Are they limited in memory being consumed?
Process has 2Gb for user code and data.
Or, the memory specified on command line IS memory taken by FASM for included files and for data taken by Assembler itself?
Is there anything like a disk cache where included files may be stored?
Or, maybe each file is included and processed and then released?

05 Dec 2025, 15:28

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20787
Location: In your JS exploiting you and your system

revolution 05 Dec 2025, 15:58

All included files must fit into memory.

The memory limit is set by the -m argument and is limited to not more than 4GB. For some OSes the limit is lower, e.g. for Windows it can't be more than 2GB in normal boot mode.

05 Dec 2025, 15:58

AsmGuru62

Joined: 28 Jan 2004
Posts: 1746
Location: Toronto, Canada

AsmGuru62 05 Dec 2025, 18:37

Thanks, I was just curious.
The largest EXE file I ever made was around 128Kb.
Included files count was around 80 of them, no more than few Mb in total room.

05 Dec 2025, 18:37

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