_BSS and STACK Segment Order

[dedndave]

i learned something new about Masm, when building 16-bit projects   :P

as usual, i started a program like this...

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        .MODEL  Small
        .STACK  1024

        .DATA

;some initialized data stuff

        .DATA?

;some uninitialized data stuff

        .CODE

;some code stuff
in the code, i calculated the end of the program's memory by using SS:SP
much to my surprise, i found that the segment order was:
_TEXT
_DATA
STACK
_BSS
and of course, DGROUP included the _DATA, STACK, and _BSS segments
i knew that DGROUP included the STACK segment, but did not know that it was jammed in between _DATA and _BSS
i modified the program a little, as follows:

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        .MODEL  Small

        .DATA

;some initialized data stuff

        .DATA?

;some uninitialized data stuff

        .STACK  1024

        .CODE

;some code stuff
and all is right with the world   :P
the new segment order is:
_TEXT
_DATA
_BSS
STACK

back in the day, when i wrote a lot of 16-bit code using MASM version 5.10,
i always opened and closed segments using SEGMENT - i never used the .DATA/.CODE shortcuts
i determined which segments were in DGROUP with a GROUP directive
when you do it that way, you have complete control over segment order
they appear in the program in the order in which they are first opened

[sinsi]

.dosseg is good too.

[dedndave]

thanks, Sinsi
not that i am writing any 16-bit libraries - lol
but the masm manual says not to use .DOSSEG in any module that is to be called by another module
not sure why that is   :P
probably because the segment order is controlled by the calling module
at any rate, i had forgotten about that one   :bg

i wound up with this...

Code Select Expand

        .MODEL  Small
        .CODE
        .DATA
        .DATA?
        .STACK  1024            ;ensure that STACK is highest segment

        .DATA

;some initialized data stuff

        .DATA?

;some uninitialized data stuff

        .CODE

;some code stuff

i wanted to control the segment order - and i wanted it to be highly visible
i also prefer the .STACK directive be near the beginning of the file, where it belongs