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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: STM32F4 GNAT Run Time System - roadmap
Date: Tue, 09 Jun 2015 13:02:22 +0100
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Date: 2015-06-09T13:02:22+01:00
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Looking for some input on priorities for work.

* Standard library packages.
* Other MCUs.
* Finalization.
* ?

Standard library packages
-------------------------

An obvious omission is the rest of the Ada.Containers.Bounded* packages:
  Doubly_Linked_Lists
  Ordered_Maps
  Hashed_Sets
  Ordered_Sets
  Multiway_Trees
  Synchronized_Queues
  Priority_Queues

Any other nice-to-haves? (I haven't looked at Annex G, might be
problematic!)

Other MCUs
----------

STM have just released a significant number of affordable Nucleo
development kits. The NUCLEO-F091RC has 48 MHz Cortex-M0 core, 256-KB
Flash, 32-KB SRAM, which would just-about take my current testbed
program; for the princely sum of UKP7.94 + p&p, 88 in stock in UK for
next day delivery from Farnell[0].

The problem with this is that different MCUs require different compiler
options, and building GCC for ARM with multilibs is only supported in
the ARM fork at [1]; so far there are only GCC 4.9-based releases. GCC
4.9 is a perfectly competent compiler, of course.

Finalization
------------

It would be very nice to be able to use the generalized container
iterators of Ada 2012 (generalized array iterators are already OK).

They require finalization: I've implemented finalization and generalized
iteration over Bounded_Vectors in the 'finalization' branch at [2].

Unfortunately, adding finalization to a restricted runtime triggers bugs
in GCC.

I've raised two GCC PRs; "gnatbind generates invalid code when
finalization is enabled in restricted runtime"[3], and "Front-end error
if exception propagation disabled"[4].

=====================================================================
[0] http://uk.farnell.com/stm32-mcu-nucleo-board-flexible-prototyping
[1] https://launchpad.net/gcc-arm-embedded
[2]
https://sourceforge.net/p/stm32f4-gnat-rts/code/ci/finalization/tree/
[3] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66205
[4] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66242