Road Plan

• Build a MIPS-like very simple virtual machine
• Build an assembler
• Build a compiler for a Go-like language e8go
• Port the assembler and compiler to e8go.
• Reimplement the VM in Javascript. (Maybe NaCl for golang will come out at that time.)
• Write a small OS in e8go, so that is runs in the browser.
• Build an online platform where people can submit interfaces, test cases, and implementations
• Test cases works like executables (package main, but maybe package test is better). A test case link with other interface and implementation modules, and generate test scores as output. It could be testing the actual implementation, or just defining the public interfaces of a type of module.
• Interfaces and implementations are general library modules.
• A module can only access other modules via publicly defined interfaces, methods, functions, types, consts.
• Users write modules under version control (perferable the website works like something similar to github, but more language aware, where tests are automatically performed.)
• This is just for single vm open source testing
• For more complex stuff, we can have multiple vm testing, where all calls are performed over network RPC calls

Why

• This could be an online platform for ACM training
• This could be an online arena/platform for game AI fighting
• This could be used for collaborative programming
• This encourages users to collaborate by assembling modules via clearly defined interfaces and test them with testcases.
• Ideally, all the modules and interfaces could be easily reused, since they would likely be small, and hence easy for human to read, understand, modify and maintain.

See more on my Motivation page.

Design

• RISC: The MIPS-like simple instructions set that e8 uses only has less than 40 instructions, which means e8 CPU will be very easy to port. In fact, I have already ported the core to Javascript: e8js.
• System Page (wiki page coming soon): all IOs in e8 will be memory mapped, so there is no need for special instructions like in and out. Basic system functionality will be mapped to Page 0. Future fancy hardware will be mapped to the following small-id pages in the address space.
• Multi-core and ring protection (future plan): e8 will not have protection rings (e.g. kernel mode and user mode). Instead, it will use an approach similar to ARM's TrustZone, where there will be a previledged VM that can manipulate other child VMs' execution state and page tables.
• Interrupts (future plan): Inside a VM, there will be events, but there will be no interrupt handlers. A VM can suspend itself and wake up on an interrupt event, so a VM can be event driven, but code execution will not be forced to suspend and continue at another program counter. A previledged VM, however, can simulate interrupt handling on its child VMs, if it is desired to.
• Language support: The project (simulator, assembler, compiler) is written in golang, and I plan to implement a subset of golang that compiles to e8, the assembler and the compiler will be ported to that subset language later in the future, and there will be an advanced language compiler that runs in e8 where it can compile itself. More thoughts here.

TODO

• Const immediates support in assembly.
• Data section support in assembly.
• Assemble a project of multiple files.