microcorruption prototype cspec

<prototype name="microcorruption" extrapop="2" stackshift="2">
            <input>
				<pentry maxsize="2" minsize="1">
                    <register name="R15"/>
                </pentry>
				<pentry maxsize="2" minsize="1">
                    <register name="R14"/>
                </pentry>
                <pentry maxsize="2" minsize="1">
                    <register name="R13"/>
                </pentry>
                <pentry maxsize="2" minsize="1">
                    <register name="R12"/>
                </pentry>
                <pentry maxsize="500" minsize="1" align="2">
                    <addr space="stack" offset="2"/>
                </pentry>
            </input>
            <output>
                <pentry minsize="1" maxsize="2">
                    <register name="R15"/>
                </pentry>
                <pentry minsize="3" maxsize="4">
                    <addr space="join" piece1="R14" piece2="R15"/>
                </pentry>
                <pentry minsize="5" maxsize="6">
                    <addr space="join" piece1="R13" piece2="R14" piece3="R15"/>
                </pentry>
                <pentry minsize="7" maxsize="8">
                    <addr space="join" piece1="R12" piece2="R13" piece3="R14" piece4="R15"/>
                </pentry>
            </output>
            <unaffected>
                <register name="SP"/>
                <register name="SR"/>
                <register name="R3"/>
                <register name="R4"/>
                <register name="R5"/>
                <register name="R6"/>
                <register name="R8"/>
                <register name="R9"/>
                <register name="R10"/>
                <register name="R11"/>
            </unaffected>
        </prototype>