PDU.h

/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Library General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * PDU.h
 * Interface for the PDU and PDUBlock classes
 * Copyright (C) 2007 Simon Newton
 */

#ifndef LIBS_ACN_PDU_H_
#define LIBS_ACN_PDU_H_

#include <stdint.h>
#include <ola/io/OutputStream.h>
#include <ola/io/OutputBuffer.h>
#include <vector>

namespace ola {
namespace acn {

/*
 * The Base PDU class
 * TODO(simon): make this into a template based on vector size.
 */
class PDU {
 public:
 typedef enum {
 ONE_BYTE = 1,
 TWO_BYTES = 2,
 FOUR_BYTES = 4,
 } vector_size;

 explicit PDU(unsigned int vector, vector_size size = FOUR_BYTES):
 m_vector(vector),
 m_vector_size(size) {}
 virtual ~PDU() {}

 // Returns the size of this PDU
 virtual unsigned int Size() const;
 virtual unsigned int VectorSize() const { return m_vector_size; }
 virtual unsigned int HeaderSize() const = 0;
 virtual unsigned int DataSize() const = 0;

 // Set the vector
 void SetVector(unsigned int vector) { m_vector = vector; }

 /*
 * Pack the PDU into the memory pointed to by data
 * @return true on success, false on failure
 */
 virtual bool Pack(uint8_t *data, unsigned int *length) const;
 virtual bool PackHeader(uint8_t *data, unsigned int *length) const = 0;
 virtual bool PackData(uint8_t *data, unsigned int *length) const = 0;

 virtual void Write(ola::io::OutputStream *stream) const;
 virtual void PackHeader(ola::io::OutputStream *stream) const = 0;
 virtual void PackData(ola::io::OutputStream *stream) const = 0;

 static void PrependFlagsAndLength(
 ola::io::OutputBufferInterface *output,
 uint8_t flags = VFLAG_MASK | HFLAG_MASK | DFLAG_MASK);

 static void PrependFlagsAndLength(
 ola::io::OutputBufferInterface *output,
 unsigned int length,
 uint8_t flags);

 // This indicates a vector is present
 static const uint8_t VFLAG_MASK = 0x40;
 // This indicates a header field is present
 static const uint8_t HFLAG_MASK = 0x20;
 // This indicates a data field is present
 static const uint8_t DFLAG_MASK = 0x10;

 private:
 unsigned int m_vector;
 unsigned int m_vector_size;

 // The max PDU length that can be represented with the 2 byte format for
 // the length field.
 static const unsigned int TWOB_LENGTH_LIMIT = 0x0FFF;
};


/*
 * Represents a block of pdus
 */
template <class C>
class PDUBlock {
 public:
 PDUBlock(): m_size(0) {}
 ~PDUBlock() {}

 // Add a PDU to this block
 void AddPDU(const C *msg) {
 m_pdus.push_back(msg);
 m_size += msg->Size();
 }
 // Remove all PDUs from the block
 void Clear() {
 m_pdus.clear();
 m_size = 0;
 }
 // The number of bytes this block would consume, this ignores optimizations
 // like repeating headers/vectors.
 unsigned int Size() const { return m_size; }
 /*
 * Pack this PDUBlock into memory pointed to by data
 * @return true on success, false on failure
 */
 bool Pack(uint8_t *data, unsigned int *length) const;

 void Write(ola::io::OutputStream *stream) const;

 private:
 std::vector<const C*> m_pdus;
 unsigned int m_size;
};


/*
 * Pack this block of PDUs into a buffer
 * @param data a pointer to the buffer
 * @param length size of the buffer, updated with the number of bytes used
 * @return true on success, false on failure
 */
template <class C>
bool PDUBlock<C>::Pack(uint8_t *data, unsigned int *length) const {
 bool status = true;
 unsigned int i = 0;
 typename std::vector<const C*>::const_iterator iter;
 for (iter = m_pdus.begin(); iter != m_pdus.end(); ++iter) {
 // TODO(simon): optimize repeated headers & vectors here
 unsigned int remaining = i < *length ? *length - i : 0;
 status &= (*iter)->Pack(data + i, &remaining);
 i+= remaining;
 }
 *length = i;
 return status;
}


/*
 * Write this block of PDUs to an OutputStream.
 * @param stream the OutputStream to write to
 * @return true on success, false on failure
 */
template <class C>
void PDUBlock<C>::Write(ola::io::OutputStream *stream) const {
 typename std::vector<const C*>::const_iterator iter;
 for (iter = m_pdus.begin(); iter != m_pdus.end(); ++iter) {
 // TODO(simon): optimize repeated headers & vectors here
 (*iter)->Write(stream);
 }
}
} // namespace acn
} // namespace ola
#endif // LIBS_ACN_PDU_H_