stevedlawrence commented on a change in pull request #210: Add midBitsToEnd layer transform URL: https://github.com/apache/incubator-daffodil/pull/210#discussion_r278117620
########## File path: daffodil-runtime1/src/main/scala/org/apache/daffodil/layers/midBitsToEndTransformer.scala ########## @@ -0,0 +1,345 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +package org.apache.daffodil.layers + +import org.apache.daffodil.processors.TermRuntimeData +import org.apache.daffodil.util.Maybe +import org.apache.daffodil.processors.LayerCharsetEv +import org.apache.daffodil.schema.annotation.props.gen.LayerLengthKind +import org.apache.daffodil.processors.LayerLengthInBytesEv +import org.apache.daffodil.schema.annotation.props.gen.LayerLengthUnits +import org.apache.daffodil.processors.LayerBoundaryMarkEv +import org.apache.daffodil.processors.LayerTransformArgsEv +import java.io.InputStream +import java.io.OutputStream +import org.apache.daffodil.processors.unparsers.UState +import org.apache.daffodil.processors.parsers.PState +import org.apache.daffodil.exceptions.Assert +import org.apache.daffodil.processors.ParseOrUnparseState +import org.apache.daffodil.processors.parsers.Parser + +import org.apache.daffodil.processors.ExplicitLengthEv +import org.apache.daffodil.io.ExplicitLengthLimitingStream +import java.io.ByteArrayOutputStream +import java.io.ByteArrayInputStream +import org.apache.daffodil.util.MaybeULong +import org.apache.daffodil.processors.Failure + +class midBitsToEndTransformer( + layerLengthInBytesEv: LayerLengthInBytesEv, + layerTransformArgsEv: LayerTransformArgsEv) + extends LayerTransformer { + /* + * For unparsing, it is more or less unavoidable that we cannot stream, as we need to reach + * the end of the input before we can provide the mid-bits that were moved. + * In practice, it is not expected that this transform will be used on "large" blocks, + * so it is not worth the effort to figure out how to implement some form of streaming. + */ + + var length: Int = -1 + + var firstBitIndex0b: Int = -1 + var numBits: Int = -1 + + /* + * Note the extra padding bytes. One of these bytes is just to accomodate rounding from integer division. + * The other one is because, to simplify the code, a portion of the encoder may attempt to read up to 7 extra bits, + * then discard them. (This would happen when the last bit that gets moved is the first bit of a byte in the encoded form; + * the encoder will attempt to read enough bits to be able to fully replace the entire byte, then mask out the lower 7 bits) + */ + def tmpByteCount = numBits / 8 + 2 + def buffSize = length + tmpByteCount + + def byteShift = numBits / 8 + def bitShift = numBits % 8 + + def firstBitByteIndex0b = (firstBitIndex0b / 8) + def lastBitByteIndex0b = ((firstBitIndex0b + numBits) / 8) + def firstBitBitIndex0b = firstBitIndex0b % 8 + def lastBitBitIndex0b = (firstBitIndex0b + numBits) % 8 + + private def buffToHex(buff: Array[Byte]): String = { + buff.map(b => String.format("%02x", Byte.box(b))).mkString(" ") + } + + private def initialize(state: ParseOrUnparseState) { + length = layerLengthInBytesEv.evaluate(state).toInt Review comment: Can length be made a val and move this up where length is defined? Similarly, it parse and validate were split up into multiple functions (mentioned below), i think both first firstBitIndex0b and numBits could be made val's that are assigned when the transform is constructed. Then alot of those defs (e.g. bitShift, lastBitBitInde0b) can become vals too. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services
