Diff: source/drivers/MicroBitRadioDatagram.cpp

Revision:

1:8aa5cdb4ab67

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/source/drivers/MicroBitRadioDatagram.cpp	Thu Apr 07 01:33:22 2016 +0100
@@ -0,0 +1,203 @@
+/*
+The MIT License (MIT)
+
+Copyright (c) 2016 British Broadcasting Corporation.
+This software is provided by Lancaster University by arrangement with the BBC.
+
+Permission is hereby granted, free of charge, to any person obtaining a
+copy of this software and associated documentation files (the "Software"),
+to deal in the Software without restriction, including without limitation
+the rights to use, copy, modify, merge, publish, distribute, sublicense,
+and/or sell copies of the Software, and to permit persons to whom the
+Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
+*/
+
+#include "MicroBitConfig.h"
+#include "MicroBitRadio.h"
+
+/**
+  * Provides a simple broadcast radio abstraction, built upon the raw nrf51822 RADIO module.
+  *
+  * This class provides the ability to broadcast simple text or binary messages to other micro:bits in the vicinity
+  * It is envisaged that this would provide the basis for children to experiment with building their own, simple,
+  * custom protocols.
+  *
+  * @note This API does not contain any form of encryption, authentication or authorisation. Its purpose is solely for use as a
+  * teaching aid to demonstrate how simple communications operates, and to provide a sandpit through which learning can take place.
+  * For serious applications, BLE should be considered a substantially more secure alternative.
+  */
+
+/**
+* Constructor.
+*
+* Creates an instance of a MicroBitRadioDatagram which offers the ability
+* to broadcast simple text or binary messages to other micro:bits in the vicinity
+*
+* @param r The underlying radio module used to send and receive data.
+*/
+MicroBitRadioDatagram::MicroBitRadioDatagram(MicroBitRadio &r) : radio(r)
+{
+    this->rxQueue = NULL;
+}
+
+/**
+  * Retrieves packet payload data into the given buffer.
+  *
+  * If a data packet is already available, then it will be returned immediately to the caller.
+  * If no data is available then MICROBIT_INVALID_PARAMETER is returned.
+  *
+  * @param buf A pointer to a valid memory location where the received data is to be stored
+  *
+  * @param len The maximum amount of data that can safely be stored in 'buf'
+  *
+  * @return The length of the data stored, or MICROBIT_INVALID_PARAMETER if no data is available, or the memory regions provided are invalid.
+  */
+int MicroBitRadioDatagram::recv(uint8_t *buf, int len)
+{
+    if (buf == NULL || rxQueue == NULL || len < 0)
+        return MICROBIT_INVALID_PARAMETER;
+
+    // Take the first buffer from the queue.
+    FrameBuffer *p = rxQueue;
+    rxQueue = rxQueue->next;
+
+    int l = min(len, p->length - (MICROBIT_RADIO_HEADER_SIZE - 1));
+
+    // Fill in the buffer provided, if possible.
+    memcpy(buf, p->payload, l);
+
+    delete p;
+    return l;
+}
+
+/**
+  * Retreives packet payload data into the given buffer.
+  *
+  * If a data packet is already available, then it will be returned immediately to the caller
+  * in the form of a PacketBuffer.
+  *
+  * @return the data received, or an empty PacketBuffer if no data is available.
+  */
+PacketBuffer MicroBitRadioDatagram::recv()
+{
+    if (rxQueue == NULL)
+        return PacketBuffer::EmptyPacket;
+
+    FrameBuffer *p = rxQueue;
+    rxQueue = rxQueue->next;
+
+    PacketBuffer packet(p->payload, p->length - (MICROBIT_RADIO_HEADER_SIZE - 1), p->rssi);
+
+    delete p;
+    return packet;
+}
+
+/**
+  * Transmits the given buffer onto the broadcast radio.
+  *
+  * This is a synchronous call that will wait until the transmission of the packet
+  * has completed before returning.
+  *
+  * @param buffer The packet contents to transmit.
+  *
+  * @param len The number of bytes to transmit.
+  *
+  * @return MICROBIT_OK on success, or MICROBIT_INVALID_PARAMETER if the buffer is invalid,
+  *         or the number of bytes to transmit is greater than `MICROBIT_RADIO_MAX_PACKET_SIZE + MICROBIT_RADIO_HEADER_SIZE`.
+  */
+int MicroBitRadioDatagram::send(uint8_t *buffer, int len)
+{
+    if (buffer == NULL || len < 0 || len > MICROBIT_RADIO_MAX_PACKET_SIZE + MICROBIT_RADIO_HEADER_SIZE - 1)
+        return MICROBIT_INVALID_PARAMETER;
+
+    FrameBuffer buf;
+
+    buf.length = len + MICROBIT_RADIO_HEADER_SIZE - 1;
+    buf.version = 1;
+    buf.group = 0;
+    buf.protocol = MICROBIT_RADIO_PROTOCOL_DATAGRAM;
+    memcpy(buf.payload, buffer, len);
+
+    return radio.send(&buf);
+}
+
+/**
+  * Transmits the given string onto the broadcast radio.
+  *
+  * This is a synchronous call that will wait until the transmission of the packet
+  * has completed before returning.
+  *
+  * @param data The packet contents to transmit.
+  *
+  * @return MICROBIT_OK on success, or MICROBIT_INVALID_PARAMETER if the buffer is invalid,
+  *         or the number of bytes to transmit is greater than `MICROBIT_RADIO_MAX_PACKET_SIZE + MICROBIT_RADIO_HEADER_SIZE`.
+  */
+int MicroBitRadioDatagram::send(PacketBuffer data)
+{
+    return send((uint8_t *)data.getBytes(), data.length());
+}
+
+/**
+  * Transmits the given string onto the broadcast radio.
+  *
+  * This is a synchronous call that will wait until the transmission of the packet
+  * has completed before returning.
+  *
+  * @param data The packet contents to transmit.
+  *
+  * @return MICROBIT_OK on success, or MICROBIT_INVALID_PARAMETER if the buffer is invalid,
+  *         or the number of bytes to transmit is greater than `MICROBIT_RADIO_MAX_PACKET_SIZE + MICROBIT_RADIO_HEADER_SIZE`.
+  */
+int MicroBitRadioDatagram::send(ManagedString data)
+{
+    return send((uint8_t *)data.toCharArray(), data.length());
+}
+
+/**
+  * Protocol handler callback. This is called when the radio receives a packet marked as a datagram.
+  *
+  * This function process this packet, and queues it for user reception.
+  */
+void MicroBitRadioDatagram::packetReceived()
+{
+    FrameBuffer *packet = radio.recv();
+    int queueDepth = 0;
+
+    // We add to the tail of the queue to preserve causal ordering.
+    packet->next = NULL;
+
+    if (rxQueue == NULL)
+    {
+        rxQueue = packet;
+    }
+    else
+    {
+        FrameBuffer *p = rxQueue;
+        while (p->next != NULL)
+        {
+            p = p->next;
+            queueDepth++;
+        }
+
+        if (queueDepth >= MICROBIT_RADIO_MAXIMUM_RX_BUFFERS)
+        {
+            delete packet;
+            return;
+        }
+
+        p->next = packet;
+    }
+
+    MicroBitEvent(MICROBIT_ID_RADIO, MICROBIT_RADIO_EVT_DATAGRAM);
+}