Commit graph

5 commits

Author SHA1 Message Date
Joe Finney 194f19a428 Merge branch 'simplified-eventing' 2015-11-01 18:22:27 +00:00
Joe Finney 84da6a4a09 microbit: Minor bug fixes and refinements
- Add maximum depth for event queues, to prevent buggy scripts causing total memory exhaustion.
  - Suppress generation of A/B click events when A+B click is generated
  - preservation of event ordering on messagebus for resursive event generation cases.
  - bugfix of message bus processing to prevent occasional dual processing of events
  - bugfix MicroBitDisplay to behave correctly when delay parameter is zero.
2015-10-31 10:27:38 +00:00
Joe Finney 823a956d68 microbit: First cut at updates to provide tight validation within the runtime code, with a view to moving
NOP/clamping behaviour out of teh micro:bit runtime and into the glue layers of higher level
languages.

 - Updates to many functions to provide explicut return codes.
 - Updates to many functions to remove heuristic calidation (NOP/clamping/defaults)
 - Updates to ErrorNo.h to provide clearer return values, and place return values in a better scope
 - Updates to MicroBitDisplay to use enums where appropriate.
2015-10-25 21:51:33 +00:00
Joe Finney 857a626ed0 microbit: Memory Optimisation Mega Update
This release contains a widespread set of updates and optimisations to the micro:bit
runtime, with a view to reducing the SRAM footprint of the whole system. This is to
provide as much usable HEAP storage for application programs as possible.

Specific updates and optimisations include:

  - Additional compilation flags to allow the core micro:bit runtime to be configured.
    These are defined in MicroBitConfig.h

  - A custom heap allocator. This is now included for two reasons:

    1) To provide a simple mechanism to to utilise both the mbed heap space and other memory
       regions (such as unused memory in the SoftDevice region) as a single virtual heap.
    2) To address some issues that have been noted that are attributable to heap fragmentation.
       The micro:bit heap allocator has a simple algorithm, but one that is chosen to respond
       well to the relativelt high 'heap churn' found in the micro:bit environment.

    All micro:bit components and user programs now use this heap allocator trasparently.

  - Updates to BLE services to remove persistent references to their GATT services. This consumes
    vast amounts SRAM, rather unecessarily. Instead only handles to the relevant GATT characteristics
    are now stored. This specifically includes:
      + MicroBitDFUService
      + MicroBitEventService
      + DeviceInformationService

  - Updates to the Fiber scheduler to save SRAM. More specifically:
      + Removed the need to hold an empty processor context to intialise fibers.
      + The IDLE fiber now runs without a stack
      + fiber stacks are now only created when a fiber is descheduled for the first time, thereby reducing heap churn.
      + the 'main' fiber is now recycled into the fiber_pool if it leaves app_main()
      + fibers created through invoke() now only maintains the necessary part of teh parent stack that is needed, thereby
        reducing the stack size of spawned fibers.

  - Updates to the Message Bus to reduce the overall memory footprint of processing events. More specifically:
      + Event handlers are now always called using invoke(), such that non-blocking event handlers no longer need
        a dedicated fiber to execute - thereby saving SRAM and processor time.
      + Processing of events from the event queue is now rate paced. Events only continue to be processed as long as there
        are no fibers on the run queue. i.e. event processing is no longer greedy, thereby reducing the number of fibers
        created on the runqueue.

  - Updates to BLUEZOENE code to bring up core BLE services even if they are not enabled by default. This allows
    programs that do not require BLE to operate to benefit from the full range of SRAM, whilst still allowing the
    device to be programmed over BLE.

  - Updates to the Soft Device initialisation configuration, reducing the size of the GATT table held in the top 1.8K
    of its 8K memory region to around 800 bytes. This is sufficient to run the default set of BLE services on the micro:bit
    so the additional memory is configured as HEAP storage by MicroBitHeapAllocator.

  - Minor changes to a range of components to integrate with the above changes.
    + rename of free() to release() in DynamicPWM to avoid namespace collision with MicroBitHeap free()
    + rename of fork_on_block to invoke() to enhance readbility.

  - Many code cleanups and updates to out of date comments.
2015-08-31 23:25:10 +01:00
James Devine 538e1c48bd microbit-dal: Initial Commit
This is the first commit of the microbit-dal on GitHub.
This repository contains the runtime, which is a light
weight operating system developed by Lancaster University.
2015-08-12 11:53:41 +01:00