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Moddable SDK 4.7.0
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@mkellner mkellner released this 07 May 16:54
· 463 commits to public since this release
4.7.0
aa9c5cd

The Moddable SDK 4.7.0 release contains improvements made between April 3, 2024 and May 5, 2024.

This release features very low-level improvements to the Moddable SDK. Highlights include:

  • Nordic nRF52 IO enhancements
  • String performance optimizations
  • First implementation of draft ECMA-419 Files API
  • Significant additions to xst, the XS test tool, to expand test coverage including running test262 under Hardened JavaScript

Note: This release is expected to be the last using ESP-IDF 5.1.2. We will migrate to ESP-IDF 5.2.1 in the next few weeks. ESP-IDF 5.2.1 has many Wi-Fi and BLE improvements.

Release Details

  • XS JavaScript engine

    • String optimizations
      • Background: XS optimizes strings to minimize memory use. For some operations on larger strings (over 1024 bytes), this reduces performance.
      • Added optional side-table to optimize common string operations. The side-table caches the following information for the most recently used strings:
        • String length in bytes
        • String length in Unicode codepoints
        • Flag indicating string is 7-bit only ASCII
        • Last accessed index in bytes and Unicode codepoints
      • Side-table improves performance of common operations by 100x or more for long strings
      • Disabled by default in embedded runtimes
      • Enabled by default in command line build tools and xsbug
    • Upgrade to fdlibm from FreeBSD (previously using Netlib version)
      • Benefits
        • Actively maintained version
        • Fixes several undefined behavior errors
        • Generates results consistent with V8
      • Note: XS does not use fdlibm by default but provides it as an option for runtimes that need numerical consistency beyond what ECMA-262 requires
    • Fixes for issues uncovered through fuzz testing. Thank you to @Agoric for their support of this work.
      • String.prototype.at could read from arbitrary memory if garbage collection occurred while validating arguments
      • Eliminate overflow in newly added Uint8Array toBase64 and toHex
    • Fix build conflict between string cache and metering (contributed by @raphdev)

  • Modules

    • ECMA-419
      • Early implementation of Files for ECMA-419 3rd Edition. This is currently POSIX-only, for macOS and Linux. Embedded device support and unit tests are planned.
    • Poco
      • Option to allocate pixel buffers in DMA capable memory as required by ILI9341 (MIPI) 8-bit parallel display driver
      • Let display driver set minimum size of pixel rendering buffer
    • ILI9341 (MIPI) 8-bit parallel display driver keeps display output disabled until first frame is drawn to eliminate start-up display glitch

  • Devices

    • nRF52
      • Improvements when building on nRF targets on Windows
        • USE_WDT supported
        • Don't build USB sources on device without USB (UART-only)
      • ECMA-419 PWM
        • hz getter returns actual frequency, not requested frequency
        • Support more frequencies with nrF52 specific top_value property in constructor's options object
      • Instrumentation supported on UART-only builds
      • Reset pins to default configuration when closed (not in use). This can reduce energy use.
      • Uses SPI2 by default, instead of SPI3, to work around intermittent start-up failures
      • Fix build conflict with nRF52 _read and new read symbol from XS Base64 support
    • ESP32
      • Backlight management changes for Hosts that implement Backlight class (e.g. Moddable Two, Moddable Display 2)
        • Commodetto and Piu turn on backlight for projects that include them
        • Projects that don't use Commodetto or Piu leave backlight off at start-up

  • Documentation

  • Tools

    • xst
      • Option to track all XS memory allocations to support more efficient fuzzing
        • Optionally abort when memory limit exceeded
        • Free memory on unrecoverable VM exists
      • Source code split into three parts to contain test262 and fuzzing support in their own files for easier maintenance
      • Profiling data includes metering count when metering is enabled
      • Remove code to disable LSAN, now that xst can clean-up memory allocations on abort (contributed by @raphdev)
      • Options to run test262 under lockdown (-l) and inside a Compartment after lockdown (-lc) to validate test262 conformance under Hardened JavaScript.
    • serial2xsbug on macOS suggests launching xsbug if attempt to connect to it fails
    • nodered2mcu maps Blockly to Function node (enables Blockly support for embedded JavaScript using Node-RED) (thanks to @ralphwetzel for the suggestion and @spillz-dxb for the motivation) @phoddie/node-red-mcu#126

Contact Us

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Contributors

raphdev, spillz-dxb, and 3 other contributors
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