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flat assembler > Macroinstructions > What logic of fasmg struct macro that comatibable with fasm1

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ProMiNick



Joined: 24 Mar 2012
Posts: 353
Location: Russian Federation, Sochi
what understand I: "macro struct? definition" - for parsing name of structure from name of ancestor structure and placing ancestor structure infront of definition structure.

"macro struct? name" - declared all needed macroses and started declaration of "macro struct?.name".

"macro ends?!" - finished declaration of macros previously started and launched macro "struct?.end" that defined in "macro struct? name" and possibli redefined in "macro struct?.begin" & "macro union?.begin".

Back to "macro struct? name": declaration of "struc name args&" is clear it is needed for later use of structure (with couple of helper macros for that "struc struct?.init_field name,field,value&" & "struc struct?.init name,args&"), declaration of "macro struct?.end" looks like does nothing except counting fields of structure and its substructures, setting inexes to fields and calculating size of fields.
But...
parameterless "macro struct?!" is absolutely blackbox for me - I can`t understand on what step it is launched.
Code:
define struct?
define union?

struct?.counter = -1
struct?.subcounter = -1

struc struct?.init_field name,field,value&
        match =struct type, name.field.__type
                .field struct?.init type,value
        else match =substruct type, name.field.__type
                . struct?.init name.type,value
        else match first=,rest, value
                local data
                virtual at 0
                        emit sizeof .field : value
                        load data : $ from 0
                end virtual
                if lengthof data <= name.field.__length
                        store data : lengthof data at .field
                else
                        err 'data too long for ',`name,'.',`field
                end if
        else if value eqtype ''
                if lengthof value <= name.field.__length
                        store value : lengthof value at .field
                else
                        err 'data too long for ',`name,'.',`field
                end if
        else
                store value at .field
        end if
end struc

struc struct?.init name,args&
        iterate definition, args
                match field:value, definition
                        . struct?.init_field name,field,value
                else match field==value, definition
                        . struct?.init_field name,field,value
                else match value, definition
                        match field, name.__field#%
                                match root.sub, name
                                        . struct?.init_field root,field,value
                                else
                                        . struct?.init_field name,field,value
                                end match
                        end match
                end match
        end iterate
end struc

macro struct? name
        struc name args&
                label . : sizeof.name
                namespace .
                        struct?.name
                end namespace
                . struct?.init name,args
                if struct?.counter > 0
                        repeat 1, i:struct?.counter
                                match field, __field#i
                                        define field.__type struct name
                                end match
                        end repeat
                end if
        end struc
        macro struct?!
                struct?.begin
                esc macro struct?.current
        end macro
        macro struct?.end
                purge struct?.end
                virtual at 0
                        namespace name
                                struct?.counter = 0
                                struct?.subcounter = 0
                                define struct?.substruct
                                struc (field) ? def&
                                        match ==v, def
                                                field def
                                        else match :v, def
                                                field def
                                        else if struct?.counter < 0
                                                field def
                                        else
                                                struct?.counter = struct?.counter + 1
                                                repeat 1, i:struct?.counter
                                                        match sub, struct?.substruct
                                                                define sub.__field#i field
                                                        else
                                                                define __field#i field
                                                        end match
                                                end repeat
                                                field def
                                                if defined field
                                                        field.__length := $ - field
                                                end if
                                        end if
                                end struc
                                struct?.name
                                restruc ?
                                struct?.counter = -1
                                struct?.subcounter = -1
                        end namespace
                        label name:$ at $
                        sizeof.name = sizeof name
                end virtual
                purge struct?
        end macro
        esc macro struct?.name
end macro

macro struct?.container
        struct?.current
end macro

macro struct?.begin
        macro struct?.end
                purge struct?.end
                if struct?.subcounter >= 0
                        struct?.subcounter = struct?.subcounter + 1
                        repeat 1, j:struct?.subcounter
                                if struct?.counter >= 0
                                        struct?.counter = struct?.counter + 1
                                        repeat 1, i:struct?.counter
                                                match sub, struct?.substruct
                                                        define sub.__field#i __substruct#j
                                                else
                                                        define __field#i __substruct#j
                                                end match
                                        end repeat
                                end if
                                define struct?.substruct __substruct#j
                                define __substruct#j.__type substruct __substruct#j
                                struct?.counter =: 0
                        end repeat
                end if
                struct?.container
                if struct?.subcounter > 0
                        purge struct?.current
                        restore struct?.substruct,struct?.counter
                end if
        end macro
end macro

macro union?.begin
        local instance
        label instance
        macro struct?!
                struct?.begin
                esc macro struct?.current
        end macro
        macro struct?.end
                purge struct?.end
                macro struct?.container
                        instance !--
                end macro
                struc (field) ? def&
                        if $-instance = 0
                                match !--, def
                                        struct?.current
                                else
                                        field def
                                end match
                                if $-instance > 0
                                        struct?.counter =: -1
                                end if
                        else
                                virtual at instance
                                        match !--, def
                                                struct?.current
                                        else
                                                field def
                                        end match
                                        local size
                                        size = $-instance
                                end virtual
                                if size > $-instance
                                        rb size-($-instance)
                                end if
                        end if
                end struc
                union?.current
                restruc ?
                purge union?.current,struct?.container
                if $-instance > 0
                        restore struct?.counter
                end if
                purge struct?
        end macro
end macro

macro union?!
        union?.begin
        esc macro union?.current
end macro

macro ends?!
        esc end macro
        struct?.end
end macro

macro struct? definition
        match name base, definition
                macro struct?.launcher
                        purge struct?.launcher
                        struct name
                        struct?.base
                end macro
        else
                macro struct?.launcher
                        purge struct?.launcher
                        struct definition
                end macro
        end match
        struct?.launcher
end macro
    

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Post 15 May 2019, 14:34
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Tomasz Grysztar
Assembly Artist


Joined: 16 Jun 2003
Posts: 7312
Location: Kraków, Poland
ProMiNick wrote:
But...
parameterless "macro struct?!" is absolutely blackbox for me - I can`t understand on what step it is launched.
It is needed to handle syntax like:
Code:
  struct WBB
    word dw ?
    struct
      byte1 db ?
      byte2 db ?
    ends
  ends    
or even:
Code:
  struct LINE
    union
      start POINT
      struct
        x1  dd ?
        y1  dd ?
      ends
    ends
    union
      end   POINT
      struct
        x2  dd ?
        y2  dd ?
      ends
    ends
  ends    
Both these examples come straight from fasm's documentation.
Post 15 May 2019, 21:07
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