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LSP and Pokemon Decomp

February 2023

lsp, nvim

Extra Credit

Most people tend to use VS Code for Pokemon decomp and it works very nicely for them with clangd all set up and tools. However, I’m different. I like to use neovim and just doing clangd normally will give errors. Why? Well, you need to generate the compile_commands.json first. So, using a tool called compiledb, I’ll do that now for pokeemerald.

compiledb make

This will fix most of the previous errors because now, clangd sees the custom compiler that Pokemon decompilations use. There are still some warnings and errors. Mainly, with how the code sets graphics like:

const u32 gMonFrontPic_Ivysaur[] = INCBIN_U32("graphics/pokemon/ivysaur/anim_front.4bpp.lz");

We can tweak .clangd with the following config:

CompileFlags:
    Remove: [-mthumb-interwork, -fhex-asm]
    Add: [--include=include/global.h, --include=include/gba/types.h, -Wno-pointer-sign, -D __APPLE__] # include GBA global to fix type errors, silence pointer warnings for text, and use define to silence other warnings

-D __APPLE__ tricks the compiler to take an optimized route in the code and use the workarounds that VS Code uses.

--include=include/global.h, --include=include/gba/types.h, -Wno-pointer-sign adds in our custom types and other gba/pokemon specific things to clang.

-mthumb-interwork, -fhex-asm these flags cause some issues with clang so we’ll remove it. It won’t make a difference in our diagnostics/warnings.

Extra Credit

If you go down the hole of scripting in pokeemerald, there is an interesting project called poryscript, which can replace normal scripting. It is a different language and has an LSP server! So, install poryscrip-pls (however you do it for your OS). Now, we need to make neovim call poryscript-pls when it enters the buffer. We can do this via a custom nvim-lspconfig configuration. I created the following in lua/lspconfig/server_configurations/poryscript_lsp.lua.

local util = require 'lspconfig.util'

return {
    default_config = {
        cmd = { "poryscript-pls" },
        filetypes = { 'pory' },
        root_dir = util.find_git_ancestor,
        single_file_support = true,
    },
    docs = {
        description = [[
https://github.com/huderlem/poryscript-pls

Language server for poryscript (a high level scripting language for pokemon decompilation projects)

 ]]      ,
        default_config = {
            root_dir = [[util.find_git_ancestor]],
        },
    },
}

Nice, so now this is registered in nvim-lspconfig and we can call the following in our config to autostart the lsp on the buffer.

lspconfig('poryscript_lsp').setup()

Check your :LspInfo and verify it’s attached. Now, it is working but we don’t have any meaningful diagnostics/warnings yet because this LSP is a little special and needs some special handlers. poryscript-lsp calls custom methods that standard neovim doesn’t know yet. So, we’ll add them to our config then:

local handlers = {}

handlers["poryscript/getPoryscriptFiles"] = function(_, result, ctx, _)
    -- search for all *pory files for this request
    -- and return a table of URIs

    -- get all files ending with .pory
    local files = vim.fs.find(function(name, path)
        return name:match('.*%.pory$')
    end, { limit = math.huge, type = 'file' })

    --print(vim.inspect(files))

    local files_array = {}
    for k, v in pairs(files) do
        local uri_file = vim.uri_from_fname(v)
        table.insert(files_array, uri_file)
    end
    --print(vim.inspect(files_array))
    return files_array
end

handlers["poryscript/getfileuri"] = function(_, result, ctx, _)
    --print("get file uri")
    --print(vim.inspect(result))
    return vim.uri_from_bufnr(0)
end

handlers["poryscript/readfile"] = function(_, result, ctx, _)
    local bufnr = vim.uri_to_bufnr(result)
    if vim.api.nvim_buf_is_loaded(bufnr) then
        -- NOTE: Read the lines in the buffer and then combine into a string since poryscript-pls expects a string
        local lines = vim.api.nvim_buf_get_lines(bufnr, 0, -1, false)
        return table.concat(lines, "\n")
    else
        return ""
    end
end

handlers["poryscript/readfs"] = function(_, result, ctx, _)
    local bufnr = vim.uri_to_bufnr(result)
    if vim.api.nvim_buf_is_loaded(bufnr) then
        -- NOTE: Read the lines in the buffer and then combine into a string since poryscript-pls expects a string
        local lines = vim.api.nvim_buf_get_lines(bufnr, 0, -1, false)
        return table.concat(lines, "\n")
    else
        return ""
    end

end

return handlers