85 lines
2.5 KiB
Ruby
85 lines
2.5 KiB
Ruby
require_relative "function"
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require_relative "function_call"
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require "arm/arm_machine"
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module Vm
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# A Program represents an executable that we want to build
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# it has a list of functions and (global) objects
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# The main entry is a function called (of all things) "main", This _must be supplied by the compling
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# There is a start and exit block that call main, which receives an array of strings
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# While data "ususally" would live in a .data section, we may also "inline" it into the code
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# in an oo system all data is represented as objects
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# in terms of variables and their visibility, things are simple. They are either local or global
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# throwing in a context for unspecified use (well one is to pass the programm/globals around)
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class Program < Block
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# Initialize with a string for cpu. Naming conventions are: for Machine XXX there exists a module XXX
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# with a XXXMachine in it that derives from Vm::Machine
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def initialize machine
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super("start")
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Machine.instance = eval("#{machine}::#{machine}Machine").new
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@context = Context.new(self)
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#global objects (data)
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@objects = []
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# global functions
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@functions = []
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@entry = Vm::Kernel::start
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#main gets executed between entry and exit
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@main = nil
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@exit = Vm::Kernel::exit
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end
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attr_reader :context , :main , :functions
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def add_object o
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return if @objects.include? o
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@objects << o # TODO check type , no basic values allowed (must be wrapped)
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end
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def get_function name
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@functions.detect{ |f| (f.name == name) && (f.class == Function) }
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end
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# preferred way of creating new functions (also forward declarations, will flag unresolved later)
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def get_or_create_function name
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fun = get_function name
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unless fun
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fun = Function.new(name)
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@functions << fun
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end
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fun
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end
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def link_at( start , context)
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@position = start
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@entry.link_at( start , context )
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start += @entry.length
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@main.link_at( start , context )
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start += @main.length
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@functions.each do |function|
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function.link_at(start , context)
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start += function.length
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end
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@objects.each do |o|
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o.link_at(start , context)
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start += o.length
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end
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@exit.link_at( start , context)
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start += @exit.length
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end
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def main= code
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@main = code
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end
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private
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# the main function
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def create_main
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end
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end
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end
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