getWriteData method

Implementation

Logic getWriteData(Logic wd) {
  // if the whole register is ready only, return the current value
  if (access == CsrAccess.readOnly) {
    return this;
  }
  // register can be written, but still need to look at the fields...
  else {
    // special case of no explicit fields defined
    // in this case, we have an implicit read/write field
    // so there is nothing special to do
    if (fields.isEmpty) {
      return wd;
    }

    // otherwise, we need to look at the fields
    var finalWd = wd;
    var currIdx = 0;
    var currField = 0;
    for (var i = 0; i < elements.length; i++) {
      // if the given field is reserved or read only
      // take the current value instead of the new value
      final chk1 = rsvdIndices.contains(i);
      if (chk1) {
        finalWd = finalWd.withSet(currIdx, elements[i]);
        currIdx += elements[i].width;
        continue;
      }

      // if the given field is read only
      // take the current value instead of the new value
      final chk2 = fields[currField].access == CsrFieldAccess.readOnly ||
          fields[currField].access == CsrFieldAccess.writeOnesClear;
      if (chk2) {
        finalWd = finalWd.withSet(currIdx, elements[i]);
        currField++;
        currIdx += elements[i].width;
        continue;
      }

      if (fields[currField].access == CsrFieldAccess.readWriteLegal) {
        // if the given field is write legal
        // make sure the value is in fact legal
        // and transform it if not
        final origVal =
            wd.getRange(currIdx, currIdx + fields[currField].width);
        final legalCases = <Logic, Logic>{};
        for (var i = 0; i < fields[currField].legalValues.length; i++) {
          legalCases[Const(fields[currField].legalValues[i],
              width: fields[currField].width)] = origVal;
        }
        final newVal = cases(
            origVal,
            conditionalType: ConditionalType.unique,
            legalCases,
            defaultValue: Const(fields[currField].transformIllegalValue(),
                width: fields[currField].width));

        finalWd = finalWd.withSet(currIdx, newVal);
        currField++;
        currIdx += elements[i].width;
      } else {
        // normal read/write field
        currField++;
        currIdx += elements[i].width;
      }
    }
    return finalWd;
  }
}