anchor.diff:  
   // Assume reads try to read entire word
   function MMIOReq#(addrSz, logNumBytes) toMMIOReq(memReqT req) provisos (IsMemReq#(memReqT, memRespT, addrSz, logNumBytes));
  -    return MMIOReq { write: isWrite(req), byte_en: isWrite(req) ? getWriteEn(req) : '1, atomic_op: getAtomicOp(req), addr: getAddr(req), data: getData(req) };
  +    return MMIOReq { write: isWrite(req), byte_en: isWrite(req) ? getWriteEn(req) : getReadEn(req), atomic_op: getAtomicOp(req), addr: getAddr(req), data: getData(req) };
   endfunction
   function Bool isMMIOReq(memReqT req) provisos (IsMemReq#(memReqT, memRespT, addrSz, logNumBytes));
       return True;
  
positive.code:     function Bit#(TMul#(8,TExp#(logNumBytes))) getData(AtomicMemReq#(addrSz, logNumBytes) req) = req.data;
      function Bool isWrite(AtomicMemReq#(addrSz, logNumBytes) req) = req.write_en != 0;
      function Bit#(TExp#(logNumBytes)) getWriteEn(AtomicMemReq#(addrSz, logNumBytes) req) = req.write_en;
      function AtomicMemOp getAtomicOp(AtomicMemReq#(addrSz, logNumBytes) req) = req.atomic_op;
      function Bool isAtomicOp(AtomicMemReq#(addrSz, logNumBytes) req) = req.atomic_op != None;
      function AtomicMemResp#(logNumBytes) getDefaultResp(AtomicMemReq#(addrSz, logNumBytes) req) = AtomicMemResp{ write: req.write_en != 0, data: 0 };
  
negative.code:     function Bit#(TMul#(8,TExp#(logNumBytes))) getData(ByteEnMemReq#(addrSz, logNumBytes) req) = req.data;
      function Bool isWrite(ByteEnMemReq#(addrSz, logNumBytes) req) = req.write_en != 0;
      function Bit#(TExp#(logNumBytes)) getWriteEn(ByteEnMemReq#(addrSz, logNumBytes) req) = req.write_en;
      function Bit#(TExp#(logNumBytes)) getReadEn(ByteEnMemReq#(addrSz, logNumBytes) req) = (req.write_en != 0) ? 0 : '1;
      function AtomicMemOp getAtomicOp(ByteEnMemReq#(addrSz, logNumBytes) req) = None;
      function Bool isAtomicOp(ByteEnMemReq#(addrSz, logNumBytes) req) = False;
      function ByteEnMemResp#(logNumBytes) getDefaultResp(ByteEnMemReq#(addrSz, logNumBytes) req) = ByteEnMemResp{ write: req.write_en != 0, data: 0 };
  