microbit-dal/source/PacketBuffer.cpp

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#include "MicroBit.h"
// Create the EmptyPacket reference.
PacketBuffer PacketBuffer::EmptyPacket = PacketBuffer(1);
/**
* Default Constructor.
* Creates an empty Packet Buffer.
*
* Example:
* @code
* PacketBuffer p();
* @endcode
*/
PacketBuffer::PacketBuffer()
{
this->init(NULL, 0, 0);
}
/**
* Constructor.
* Creates an empty Packet Buffer of the given size.
*
* @param length The length of the buffer to create.
*
* Example:
* @code
* PacketBuffer p(16); // Creates a PacketBuffer 16 bytes long.
* @endcode
*/
PacketBuffer::PacketBuffer(int length)
{
this->init(NULL, length, 0);
}
/**
* Constructor.
* Creates a new PacketBuffer of the given size,
* and fills it with the data provided.
*
* @param data The data with which to fill the buffer.
* @param length The length of the buffer to create.
* @param rssi The radio signal strength at the time this packet was recieved.
*
* Example:
* @code
* uint8_t buf = {13,5,2};
* PacketBuffer p(buf, 3); // Creates a PacketBuffer 3 bytes long.
* @endcode
*/
PacketBuffer::PacketBuffer(uint8_t *data, int length, int rssi)
{
this->init(data, length, rssi);
}
/**
* Copy Constructor.
* Add ourselves as a reference to an existing PacketBuffer.
*
* @param buffer The PacketBuffer to reference.
*
* Example:
* @code
* PacketBuffer p();
* PacketBuffer p2(i); // Refers to the same packet as p.
* @endcode
*/
PacketBuffer::PacketBuffer(const PacketBuffer &buffer)
{
ptr = buffer.ptr;
ptr->incr();
}
/**
* Internal constructor-initialiser.
*
* @param data The data with which to fill the buffer.
* @param length The length of the buffer to create.
* @param rssi The radio signal strength at the time this pacer was recieved.
*
*/
void PacketBuffer::init(uint8_t *data, int length, int rssi)
{
if (length < 0)
length = 0;
ptr = (PacketData *) malloc(sizeof(PacketData) + length);
ptr->init();
ptr->length = length;
ptr->rssi = rssi;
// Copy in the data buffer, if provided.
if (data)
memcpy(ptr->payload, data, length);
}
/**
* Destructor.
* Removes buffer resources held by the instance.
*/
PacketBuffer::~PacketBuffer()
{
ptr->decr();
}
/**
* Copy assign operation.
*
* Called when one PacketBuffer is assigned the value of another using the '=' operator.
* Decrements our reference count and free up the buffer as necessary.
* Then, update our buffer to refer to that of the supplied PacketBuffer,
* and increase its reference count.
*
* @param p The PacketBuffer to reference.
*
* Example:
* @code
* uint8_t buf = {13,5,2};
* PacketBuffer p1(16);
* PacketBuffer p2(buf, 3);
*
* p1 = p2;
* @endcode
*/
PacketBuffer& PacketBuffer::operator = (const PacketBuffer &p)
{
if(ptr == p.ptr)
return *this;
ptr->decr();
ptr = p.ptr;
ptr->incr();
return *this;
}
/**
* Array access operation (read).
*
* Called when a PacketBuffer is dereferenced with a [] operation.
* Transparently map this through to the underlying payload for elegance of programming.
*
* Example:
* @code
* PacketBuffer p1(16);
* uint8_t data = p1[0];
* @endcode
*/
uint8_t PacketBuffer::operator [] (int i) const
{
return ptr->payload[i];
}
/**
* Array access operation (modify).
*
* Called when a PacketBuffer is dereferenced with a [] operation.
* Transparently map this through to the underlying payload for elegance of programming.
*
* Example:
* @code
* PacketBuffer p1(16);
* p1[0] = 42;
* @endcode
*/
uint8_t& PacketBuffer::operator [] (int i)
{
return ptr->payload[i];
}
/**
* Equality operation.
*
* Called when one PacketBuffer is tested to be equal to another using the '==' operator.
*
* @param p The PacketBuffer to test ourselves against.
* @return true if this PacketBuffer is identical to the one supplied, false otherwise.
*
* Example:
* @code
*
* uint8_t buf = {13,5,2};
* PacketBuffer p1(16);
* PacketBuffer p2(buf, 3);
*
* if(p1 == p2) // will be true
* uBit.display.scroll("same!");
* @endcode
*/
bool PacketBuffer::operator== (const PacketBuffer& p)
{
if (ptr == p.ptr)
return true;
else
return (ptr->length == p.ptr->length && (memcmp(ptr->payload, p.ptr->payload, ptr->length)==0));
}
/**
* Sets the byte at the given index to value provided.
* @param position The index of the byte to change.
* @param value The new value of the byte (0-255).
* @return MICROBIT_OK, or MICROBIT_INVALID_PARAMETER.
*
* Example:
* @code
* PacketBuffer p1(16);
* p1.setByte(0,255); // Sets the firts byte in the buffer to the value 255.
* @endcode
*/
int PacketBuffer::setByte(int position, uint8_t value)
{
if (position < ptr->length)
{
ptr->payload[position] = value;
return MICROBIT_OK;
}
else
{
return MICROBIT_INVALID_PARAMETER;
}
}
/**
* Determines the value of the given byte in the packet.
*
* @param position The index of the byte to read.
* @return The value of the byte at the given position, or MICROBIT_INVALID_PARAMETER.
*
* Example:
* @code
* PacketBuffer p1(16);
* p1.setByte(0,255); // Sets the firts byte in the buffer to the value 255.
* p1.getByte(0); // Returns 255.
* @endcode
*/
int PacketBuffer::getByte(int position)
{
if (position < ptr->length)
return ptr->payload[position];
else
return MICROBIT_INVALID_PARAMETER;
}
/**
* Provide an array containing the packet data.
* @return The contents of this packet, as an array of bytes.
*/
uint8_t*PacketBuffer::getBytes()
{
return ptr->payload;
}
/**
* Gets number of bytes in this buffer
* @return The size of the buffer in bytes.
*
* Example:
* @code
* PacketBuffer p1(16);
* p1.length(); // Returns 16.
* @endcode
*/
int PacketBuffer::length()
{
return ptr->length;
}
/**
* Gets the received signal strength of this packet.
*
* @return The signal strength of the radio when this packet was received.
*
* Example:
* @code
* PacketBuffer p1(16);
* p1.getRSSI();
* @endcode
*/
int PacketBuffer::getRSSI()
{
return ptr->rssi;
}
/**
* Sets the received signal strength of this packet.
*
* Example:
* @code
* PacketBuffer p1(16);
* p1.setRSSI(37);
* @endcode
*/
void PacketBuffer::setRSSI(uint8_t rssi)
{
ptr->rssi = rssi;
}