75 lines
2.1 KiB
Ruby
75 lines
2.1 KiB
Ruby
require_relative "block"
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module Vm
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# Functions are similar to Blocks. Where Blocks can be jumped to, Functions can be called.
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# Functions also have arguments, though they are handled differently (in register allocation)
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# Functions have a exactly three blocks, entry, exit and body, which are created for you
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# with straight branches between them.
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# Also remember that if your den body exists of severa blocks, they must be wrapped in a
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# block as the function really only has the one, and blocks only assemble their codes,
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# not their next links
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# This comes at zero runtime cost though, as the wrapper is just the sum of it's codes
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# If you change the body block to point elsewhere, remember to end up at exit
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class Function < Code
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def initialize(name , args = [])
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super()
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@name = name
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@args = args
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@entry = Core::Kernel::function_entry( name )
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@exit = Core::Kernel::function_exit( name )
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@body = Block.new("#{name}_body")
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branch_body
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end
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attr_reader :args , :entry , :exit , :body , :name
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# this creates a branch from entry here and from here to exit
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# unless there is a link existing, in which you are resposible
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def set_body body
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@body = body
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branch_body
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end
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def arity
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@args.length
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end
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def link_at address , context
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raise "undefined code #{inspect}" if @body.nil?
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super #just sets the position
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@entry.link_at address , context
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address += @entry.length
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@body.link_at(address , context)
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address += @entry.length
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@exit.link_at(address,context)
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end
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def length
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@entry.length + @exit.length + @body.length
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end
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def assemble io
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@entry.assemble(io)
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@body.assemble(io)
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@exit.assemble(io)
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end
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private
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# set up the braches from entry to body and body to exit (unless that exists, see set_body)
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def branch_body
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@entry.set_next(@body)
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@body.set_next(@exit) if @body and !@body.next
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end
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def add_arg value
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# TODO check
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@args << value
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end
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end
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end |