# Lookup table for Virtual Registers including renaming Links * * [[!img isa_to_virtual_regs_table.png size="800x390"]] Explanation: * ISA reg numbers are in rows * Virtual (including renamed) reg numbers are in columns * from both the bottom *and* the right are multi-issue (unary) "Set1, Set2" signals * where these cross they are ANDed to set a Latch in a given cell - at no time will there be more than one cell set per row - OR per column * there being only one per column a "reset" signal can be per column * for regfile port "lookup" the per-column Set1/Set2 wires may be re-used - they may be binary or unary as preferred - read and write ports are all numbered * a "request virtual-to-real regfile port redirection" signal is along the bottom - this is ANDed with the Latch - that is MUXed with the per-column Set1/Set2 wires - ANDs which accumulate in Great Big ORs fire per-row outputs in this way any "virtual" read or write request to a register file port may be translated to a "real" request. the actual regfile data transfers on respective associated broadcast buses are external and do not need routing through this Matrix: the Matrix simply provides name translation, nothing else. note that if regfile port IDs are encoded in binary, an entire column can light up like a Mythbusters Christmas tree with XOR gates unless the EN is carefully arranged.