Re: [rfa/doco] Srink the overlay diagram

Andrew Cagney
2002-01-29T21:58:34Z

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> I think:
>
> @example @group
>
> @anchor{x-spot the title}
> @end end
>
> Diagram @xref{x-spot the title} .... would work better.

The attached does this. I ended up using @pxref{}.

Andrew

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2002-01-21 Andrew Cagney <ac131313@redhat.com>

* gdb.texinfo (How Overlays Work): Srink the overlay diagram.

Index: gdb.texinfo
===================================================================
RCS file: /cvs/src/src/gdb/doc/gdb.texinfo,v
retrieving revision 1.76
diff -p -r1.76 gdb.texinfo
*** gdb.texinfo 2002/01/20 11:59:38 1.76
--- gdb.texinfo 2002/01/29 21:55:57
*************** overlay's machine code from the large me
*** 6418,6461 ****
for it in the instruction memory, and then jump to its entry point
there.

@example
@group
! Data Instruction Larger
! Address Space Address Space Address Space
! +-----------+ +-----------+ +-----------+
! | | | | | |
! +-----------+ +-----------+ +-----------+<-- overlay 1
! | program | | main | | | load address
! | variables | | program | | overlay 1 |
! | and heap | | | ,---| |
! +-----------+ | | | | |
! | | +-----------+ | +-----------+
! +-----------+ | | | | |
! mapped --->+-----------+ / +-----------+<-- overlay 2
! address | overlay | <-' | overlay 2 | load address
! | area | <-----| |
! | | <---. +-----------+
! | | | | |
! +-----------+ | | |
! | | | +-----------+<-- overlay 3
! +-----------+ `--| | load address
! | overlay 3 |
! | |
! +-----------+
! | |
! +-----------+

! To map an overlay, copy its code from the larger address space
! to the instruction address space. Since the overlays shown here
! all use the same mapped address, only one may be mapped at a time.
@end group
@end example

! This diagram shows a system with separate data and instruction address
! spaces. For a system with a single address space for data and
! instructions, the diagram would be similar, except that the program
! variables and heap would share an address space with the main program
! and the overlay area.

An overlay loaded into instruction memory and ready for use is called a
@dfn{mapped} overlay; its @dfn{mapped address} is its address in the
--- 6418,6465 ----
for it in the instruction memory, and then jump to its entry point
there.

+ @c NB: In the below the mapped area's size is greater or equal to the
+ @c size of all overlays. This is intentional to remind the developer
+ @c overlays don't necessarily need to be the same size.
+
@example
@group
! Data Instruction Larger
! Address Space Address Space Address Space
! +-----------+ +-----------+ +-----------+
! | | | | | |
! +-----------+ +-----------+ +-----------+<-- overlay 1
! | program | | main | .----| overlay 1 | load address
! | variables | | program | | +-----------+
! | and heap | | | | | |
! +-----------+ | | | +-----------+<-- overlay 2
! | | +-----------+ | | | load address
! +-----------+ | | | .-| overlay 2 |
! | | | | | |
! mapped --->+-----------+ | | +-----------+
! address | | | | | |
! | overlay | <-' | | |
! | area | <---' +-----------+<-- overlay 3
! | | <---. | | load address
! +-----------+ `--| overlay 3 |
! | | | |
! +-----------+ | |
! +-----------+
! | |
! +-----------+

! @anchor{A code overlay}A code overlay
@end group
@end example

! The diagram (@pxref{A code overlay}) shows a system with separate data
! and instruction address spaces. To map an overlay, the program copies
! its code from the larger address space to the instruction address space.
! Since the overlays shown here all use the same mapped address, only one
! may be mapped at a time. For a system with a single address space for
! data and instructions, the diagram would be similar, except that the
! program variables and heap would share an address space with the main
! program and the overlay area.

An overlay loaded into instruction memory and ready for use is called a
@dfn{mapped} overlay; its @dfn{mapped address} is its address in the