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Thank you for coming to this session.
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This talk starts to explore a topic under the dome.
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Before we begin, we would like to make some announcements. This presentation will be a little technical and includes some specific details.
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We will explain the implementation of a movie, and for that, we must use specific terminology during this presentation.
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You do not need prior knowledge about movies to understand it.
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Let me introduce ourselves. I'm Yurie Yamane. Along with Masayoshi Takahashi, we are a team involved in developing a movie and applications surrounding it. I am particularly interested in microcomputers and real-time operating systems. I'm also a member of the TAPAS project, which aims to create tools for real-time operating systems. Additionally, I have demonstrated and presented at many exhibitions.
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We will be hosting RubyKaigi 2019 in Fukuoka next April, and we hope you can come join us.
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Okay, let's get into the main topics.
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The topic of this talk is about movies. We will briefly explain what a movie is. A movie is an implementation that closely resembles Ruby, targeting small embedded systems.
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The primary goal of a movie is to provide a small implementation compared to standard Ruby implementations like CRuby and JRuby.
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It is compiled with the OpenGL library and targets embedded systems and applications such as robotics and games.
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We have conducted experiments on various microcontroller boards.
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In this talk, we will showcase two devices. One is the Nucleo-F401RE, which features an ARM Cortex-M4 microcontroller.
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The other device is the M5Stack, a well-known board in China and Japan featuring the ESP32 microcontroller.
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This is a demonstration of the Nucleo board. The LCD screen has a joystick, allowing you to control a cursor.
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For additional use cases, the M5Stack comes with speakers and buttons to enhance interactivity.
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Let's explain some basics about microcontrollers.
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Microcontrollers can be thought of as small computers on a single chip.
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They contain a processor and various peripherals and are commonly used in smartphones, home appliances, and automobiles.
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Now, let's get back to the topic of movies.
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What is the difference between a movie and other implementations? The main difference lies in how a movie manages its resources. It is separated from other environments, allowing you to execute movie programs without the need for compilation.
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In this situation, you can use ML files that contain bytecode for a movie. For high performance, you can also use bytecode generated by M Ruby, but it is not explicit—it is utilized internally.
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The content of movies is based on the Ruby 2.0 specification and is expected to be released soon, potentially within the next month.
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This update is considered a significant advancement for a movie, as it includes integer compatibility while also introducing some incompatibilities.
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The architecture of the bytecode is entirely different, indicating that you cannot use bytecode generated by version 2.0 in previous versions.
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This necessitates converting your programs to the newer format.
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Let's now discuss ROM, which stands for Read-Only Memory. This type of memory is also non-volatile, meaning it retains its contents even when the power is off.
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The different types of ROMs include EEPROM and Flash memory, primarily used for data storage.
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EEPROM allows for data to be programmed and erased electrically, while Flash memory permits larger blocks of data to be written.
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The current trend is to use Flash memory due to its larger capacity and cost-effectiveness.
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The relationship between EEPROM and Flash memory can be simplified into a part-to-whole analogy.
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The main reason we focus on ROM is that embedded systems often prioritize limited resources; therefore, efficient memory management is crucial.
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Also, ROM storage allows data to remain intact even when powered down, which is necessary for various applications.
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With limited RAM available in many microcontroller systems, we need to explore ways of using ROM to our advantage.
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A significant challenge in using dynamic languages like Ruby in embedded systems is managing the inherent resource consumption.
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Since Ruby is a dynamic language, it can be complex to ensure that programs run efficiently on microcontrollers without significant overhead.
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Dynamic languages require substantial runtime resources, becoming a barrier in constrained environments.
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In the case of microcontrollers, we need to initialize memory and deal with garbage collection to handle memory management properly.
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As classes are used in Ruby, you need to prepare all classes before running any script, which can lead to memory constraints.
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In contrast, more traditional approaches in languages such as C++ or Python may seem more efficient as they do not need to allocate as much memory at runtime.
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This is particularly noticeable when considering class and object definitions.
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Since Ruby allows for the addition and deletion of methods and classes dynamically, it requires significant resources.
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We must find a balance between the highly dynamic capabilities of Ruby and the constraints of embedded systems. We should aim to resolve this contradiction.
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Now, let’s discuss the structure of the movie project. The memory manager used to implement various data structures in C.
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For example, the internal layout of Emily uses structures defined in C.
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Specifying structures allows managing the Ruby object model effectively. Each Ruby class can hold a pointer to its method table and retain instances.
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We designed a clear and efficient runtime environment for objects.
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Now, it is important to consider how to manage both Ruby and the movie effectively.
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A movie must maintain its integrity while providing a user-friendly interface for Ruby developers.
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This involves ensuring the collections, classes, and data types function efficiently with the core principles of Ruby.
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As we wrap up, we would like to emphasize the importance of this project. It is constantly evolving, with opportunities for contributions from developers around the world.
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We appreciate all the feedback and collaboration we have received.
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Thank you again for being here with us today; without your participation, this journey into the final frontier of mruby would not be possible.
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Let's embrace the potential of mruby together.
