[cooja] Added base class MemoryBuffer for reading and writing both simple and complex data structures
to and from memory with support for padding.
This commit is contained in:
Enrico Joerns
parent
579f0a9a93
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1 changed files with 481 additions and 0 deletions
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/*
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* Copyright (c) 2014, TU Braunschweig
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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package org.contikios.cooja.mote.memory;
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import java.nio.ByteBuffer;
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import org.contikios.cooja.mote.memory.MemoryLayout.DataType;
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/**
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* Basic routines for memory access with multi-arch support.
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*
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* Handles endianess, integer size and address size.
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*
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* Supports padding/aligning.
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*
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* @author Enrico Jorns
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*/
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public class MemoryBuffer {
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private final MemoryLayout memLayout;
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private final ByteBuffer bbuf;
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private final DataType[] structure;
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private int structIndex;
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private MemoryBuffer(MemoryLayout memLayout, ByteBuffer buffer, DataType[] structure) {
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this.memLayout = memLayout;
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this.bbuf = buffer;
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this.structure = structure;
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this.structIndex = 0;
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}
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/**
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* Wraps a byte array into an unstructered MemoryBuffer with given MemoryLayout.
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*<p>
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* Note that modifications to the buffer are applied to the backed array and vice versa.
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*
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* @param layout MemoryLayout for memory to access array from
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* @param array Byte array that will back this buffer
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* @return the new MemroyBuffer
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*/
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public static MemoryBuffer wrap(MemoryLayout layout, byte[] array) {
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return wrap(layout, array, null);
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}
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/**
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* Wraps a byte array into a structured MemoryBuffer with given MemoryLayout.
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*<p>
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* Note that modifications to the buffer are applied to the backed array and vice versa.
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*<p>
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* A structured MemoryBuffer can be used to simplify reading c struct data
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* from the memory as it provides support for data aligning.
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*<p>
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* The structure array elements should be set to exactly the same types and order
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* that the corresponding c struct has.
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*
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* @param layout MemoryLayout for memory to access array from
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* @param structure Array of data types representing the structure to read
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* @param array Byte array that will back this buffer
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* @return the new MemroyBuffer
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*/
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public static MemoryBuffer wrap(MemoryLayout layout, byte[] array, DataType[] structure) {
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ByteBuffer b = ByteBuffer.wrap(array);
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b.order(layout.order); // preset endianess
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return new MemoryBuffer(layout, b, structure);
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}
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/**
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* Returns the byte array that backs this buffer
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*
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* @return byte array that backs this buffer
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*/
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public byte[] getBytes() {
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if (bbuf.hasArray()) {
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return bbuf.array();
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}
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else {
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return null;
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}
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}
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/**
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* Calculates the padding bytes to be added/skipped between current and next
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* element.
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*
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* @param type Current data type
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*/
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private void skipPaddingBytesFor(DataType type) {
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/* Check if we have a structure and not yet reached the last element */
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if (structure != null && structure[structIndex + 1] != null) {
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/* get size of next element in structure */
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int nextsize = structure[structIndex + 1].getSize();
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/* limit padding to word size */
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nextsize = nextsize > memLayout.WORD_SIZE ? memLayout.WORD_SIZE : nextsize;
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/* calc padding */
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int pad = nextsize - type.getSize();
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/* Skip padding bytes */
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if (pad > 0) {
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bbuf.position(bbuf.position() + pad);
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}
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}
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structIndex++;
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}
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/**
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* Returns current element type.
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*
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* @return current element type or null if no struct is used
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*/
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public DataType getType() {
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if (structure == null) {
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return null;
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}
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return structure[structIndex];
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}
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// --- fixed size types
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/**
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* Reads 8 bit integer from current buffer position,
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* and then increments position.
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* <p>
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* Note: If structured reading is enabled,
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* additional padding bytes may be skipped automatically.
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*
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* @return 8 bit integer at the buffer's current position
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*/
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public byte getInt8() {
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byte value = bbuf.get();
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skipPaddingBytesFor(DataType.INT8);
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return value;
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}
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/**
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* Reads 16 bit integer from current buffer position,
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* and then increments position.
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* <p>
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* Note: If structured reading is enabled,
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* additional padding bytes may be skipped automatically.
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*
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* @return 16 bit integer at the buffer's current position
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*/
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public short getInt16() {
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short value = bbuf.getShort();
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skipPaddingBytesFor(DataType.INT16);
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return value;
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}
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/**
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* Reads 32 bit integer from current buffer position,
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* and then increments position.
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* <p>
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* Note: If structured reading is enabled,
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* additional padding bytes may be skipped automatically.
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*
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* @return 32 bit integer at the buffer's current position
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*/
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public int getInt32() {
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int value = bbuf.getInt();
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skipPaddingBytesFor(DataType.INT32);
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return value;
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}
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/**
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* Reads 64 bit integer from current buffer position,
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* and then increments position.
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* <p>
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* Note: If structured reading is enabled,
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* additional padding bytes may be skipped automatically.
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*
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* @return 64 bit integer at the buffer's current position
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*/
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public long getInt64() {
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long value = bbuf.getLong();
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skipPaddingBytesFor(DataType.INT64);
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return value;
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}
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// --- platform-dependent types
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/**
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* Reads byte from current buffer position,
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* and then increments position.
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* <p>
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* Note: If structured reading is enabled,
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* additional padding bytes may be skipped automatically.
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*
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* @return byte at the buffer's current position
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*/
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public byte getByte() {
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byte value = bbuf.get();
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skipPaddingBytesFor(DataType.BYTE);
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return value;
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}
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/**
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* Reads short from current buffer position,
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* and then increments position.
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* <p>
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* Note: If structured reading is enabled,
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* additional padding bytes may be skipped automatically.
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*
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* @return short at the buffer's current position
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*/
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public short getShort() {
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short value = bbuf.getShort();
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skipPaddingBytesFor(DataType.SHORT);
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return value;
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}
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/**
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* Reads integer from current buffer position,
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* and then increments position.
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* <p>
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* Note: If structured reading is enabled,
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* additional padding bytes may be skipped automatically.
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*
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* @return integer at the buffer's current position
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*/
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public int getInt() {
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int value;
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switch (memLayout.intSize) {
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case 2:
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value = bbuf.getShort();
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break;
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case 4:
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default:
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value = bbuf.getInt();
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break;
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}
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skipPaddingBytesFor(DataType.INT);
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return value;
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}
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/**
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* Reads long from current buffer position,
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* and then increments position.
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* <p>
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* Note: If structured reading is enabled,
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* additional padding bytes may be skipped automatically.
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*
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* @return long at the buffer's current position
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*/
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public long getLong() {
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long value = bbuf.getLong();
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skipPaddingBytesFor(DataType.LONG);
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return value;
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}
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/**
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* Reads pointer from current buffer position,
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* and then increments position.
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* <p>
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* Note: If structured reading is enabled,
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* additional padding bytes may be skipped automatically.
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*
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* @return pointer at the buffer's current position
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*/
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public long getAddr() {
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long value;
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switch (memLayout.addrSize) {
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case 2:
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value = bbuf.getShort();
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break;
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case 4:
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value = bbuf.getInt();
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break;
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case 8:
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value = bbuf.getLong();
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break;
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default:
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value = bbuf.getInt();
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break;
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}
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skipPaddingBytesFor(DataType.POINTER);
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return value;
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}
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// --- fixed size types
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/**
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* Writes 8 bit integer to current buffer position,
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* and then increments position.
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* <p>
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* Note: If structured writing is enabled,
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* additional padding bytes may be skipped automatically.
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*
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* @param value 8 bit integer to write
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* @return A reference to this object
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*/
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public MemoryBuffer putInt8(byte value) {
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bbuf.put(value);
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skipPaddingBytesFor(DataType.INT8);
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return this;
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}
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/**
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* Writes 16 bit integer to current buffer position,
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* and then increments position.
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* <p>
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* Note: If structured writing is enabled,
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* additional padding bytes may be skipped automatically.
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*
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* @param value 16 bit integer to write
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* @return A reference to this object
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*/
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public MemoryBuffer putInt16(short value) {
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bbuf.putShort(value);
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skipPaddingBytesFor(DataType.INT16);
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return this;
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}
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/**
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* Writes 32 bit integer to current buffer position,
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* and then increments position.
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* <p>
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* Note: If structured writing is enabled,
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* additional padding bytes may be skipped automatically.
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*
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* @param value 32 bit integer to write
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* @return A reference to this object
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*/
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public MemoryBuffer putInt32(int value) {
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bbuf.putInt(value);
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skipPaddingBytesFor(DataType.INT32);
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return this;
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}
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/**
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* Writes 64 bit integer to current buffer position,
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* and then increments position.
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* <p>
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* Note: If structured writing is enabled,
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* additional padding bytes may be skipped automatically.
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*
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* @param value 64 bit integer to write
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* @return A reference to this object
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*/
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public MemoryBuffer putInt64(long value) {
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bbuf.putLong(value);
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skipPaddingBytesFor(DataType.INT64);
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return this;
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}
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// --- platform-dependent types
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/**
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* Writes byte to current buffer position,
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* and then increments position.
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* <p>
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* Note: If structured writing is enabled,
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* additional padding bytes may be skipped automatically.
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*
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* @param value byte to write
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* @return A reference to this object
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*/
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public MemoryBuffer putByte(byte value) {
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bbuf.put(value);
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skipPaddingBytesFor(DataType.BYTE);
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return this;
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}
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/**
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* Writes short to current buffer position,
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* and then increments position.
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* <p>
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* Note: If structured writing is enabled,
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* additional padding bytes may be skipped automatically.
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*
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* @param value short to write
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* @return A reference to this object
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*/
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public MemoryBuffer putShort(short value) {
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bbuf.putShort(value);
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skipPaddingBytesFor(DataType.SHORT);
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return this;
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}
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/**
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* Writes integer to current buffer position,
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* and then increments position.
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* <p>
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* Note: If structured writing is enabled,
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* additional padding bytes may be skipped automatically.
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* <p>
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* Note: Size of integer depends on platform type
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*
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* @param value integer to write
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* @return A reference to this object
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*/
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public MemoryBuffer putInt(int value) {
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switch (memLayout.intSize) {
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case 2:
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/**
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* @TODO: check for size?
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*/
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bbuf.putShort((short) value);
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break;
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case 4:
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default:
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bbuf.putInt(value);
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break;
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}
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skipPaddingBytesFor(DataType.INT);
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return this;
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}
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/**
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* Writes long to current buffer position,
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* and then increments position.
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* <p>
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* Note: If structured writing is enabled,
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* additional padding bytes may be skipped automatically.
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*
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* @param value long to write
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* @return A reference to this object
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*/
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public MemoryBuffer putLong(long value) {
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bbuf.putLong(value);
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skipPaddingBytesFor(DataType.LONG);
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return this;
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}
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/**
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* Writes pointer to current buffer position,
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* and then increments position.
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* <p>
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* Note: If structured writing is enabled,
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* additional padding bytes may be skipped automatically.
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* <p>
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* Note: Size of pointer depends on platform type
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*
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* @param value pointer to write
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* @return A reference to this object
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*/
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public MemoryBuffer putAddr(long value) {
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/**
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* @TODO: check for size?
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*/
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switch (memLayout.addrSize) {
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case 2:
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bbuf.putShort((short) value);
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break;
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case 4:
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bbuf.putInt((int) value);
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break;
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case 8:
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bbuf.putLong(value);
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break;
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default:
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bbuf.putInt((int) value);
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break;
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}
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skipPaddingBytesFor(DataType.POINTER);
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return this;
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}
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}
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