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#!/usr/bin/env ruby

 

class MRISC

  def run(code)

    tokens = code.gsub(/(\*.*?\*)|[^a-z0-9,-;@\._]/,'').split(';')

    @vars,stack,i = {:_pc=>-1,:_oc=>0},[],0

    tokens.map!{|t| t.chars.first=='@' ? (@vars[t.to_sym]=i-1;nil) : (i+=1;t.split(',').map{|e|numeric?(e) ? e.to_i : e.to_sym})}.compact!

    while @vars[:_pc] < tokens.size-1

      @vars[:_pc] += 1

      @vars[:_oc] += 1

      @vars[:_ss] = stack.size

      raise 'too many operations!' if @vars[:_oc] > 9999

      cmd,a,b,c = tokens[@vars[:_pc]]

      case cmd

        when :let; set(a,b)

        when :out; puts get(a)

        when :dbg; puts a

        when :add; set(a,get(a)+get(b))

        when :sub; set(a,get(a)-get(b))

        when :mul; set(a,get(a)*get(b))

        when :mod; set(a,get(a)%get(b))

        when :div; set(a,get(a)/get(b))

        when :jmp; @vars[:_pc]=get(a)

        when :jis; @vars[:_pc]=get(c) if get(a)<get(b)

        when :jig; @vars[:_pc]=get(c) if get(a)>get(b)

        when :jie; @vars[:_pc]=get(c) if get(a)==get(b)

        when :jiu; @vars[:_pc]=get(c) if get(a)!=get(b)

        when :end; @vars[:_pc]=tokens.size

        when :pus; stack.push(get(a))

        when :pop; set(a,stack.pop)

        else raise "unknown command '#{cmd}' at #{tokens[@vars[:_pc]].join(',')}"

      end

    end

    @vars

  end

 

  private

  def get(s); (@vars.key?(s) ? @vars[s] : numeric?(s) ? s : 0).to_i; end

  def set(s,v); @vars[s] = get(v); end

  def numeric?(n); true if Float(n) rescue false; end

end

 

MRISC.new.run('

*=== Main ===*

let,a,3;            *arg 1 and result*

let,b,5;            *arg 2*

let,@rj,_pc;        *return address*

add,@rj,2;

jmp,@power;         *subroutine call*

out,a;              *print result*

end;

*=== Subroutines ===*

@power;             *calculates pow(a,b) result in a. uses tmp*

  let,tmp,a;

  @power1;

    mul,a,tmp;

    sub,b,1;

    jig,b,1,@power1;

  jmp,@rj;          *return from subroutine*

')