ID Number: Q11833
1.25 1.27 3.0x 4.00 5.00 5.10 6.00 | 5.10 6.00
MS-DOS | OS/2
Summary:
The are programming situations in which it is necessary to determine
the length of a program at run-time. For instance, services (such as
DOS function 31H) need this information. Ordinarily, one could define
a symbol at the end of a segment known to be loaded last; however,
this does not work when linking with libraries because the libraries load
after the .OBJ's.
RESOLUTION
The following is a method that be used to perform the equivolent operation
when linking with library files that may rearange the segment order:
Begin your program with a list of declarations for all segments in
your program. This will solve the load-order problem. However, if your
segments are all named to classes and the order of the classes is all
that is important, you only need one segment declaration per class.
Define a new and empty segment to be the last segment in your load
image. Place your empty segment at the end of the list. The following
is an example:
; Declarations to fix the load order. First, MYCODE
; and all segments of class CODE.
MYCODE SEGMENT 'CODE'
MYCODE ENDS
; Next MYDATA and all segments of class DATA
MYDATA SEGMENT PUBLIC 'DATA'
MYDATA ENDS
; Finally, LASTSEG.
LASTSEG SEGMENT
LASTSEG ENDS
In the above, LASTSEG is the last segment in the load order (assuming
all other segments in the program belong to either class CODE or DATA)
and thus marks the beginning of free memory above the load image.
If your segment declarations occur randomly throughout your source
files and libraries, the solution is not as simple. The method to use
is to make a new library, to be linked in last, that defines this last
empty segment and a label in this segment. (You must have a reference
to this label in some part of the program so the linker will pull in
this library.)