https://github.com/WebBluetoothCG/demos/pull/42
Dependencies: BLE_API mbed-dev-bin nRF51822
Fork of microbit-dal by
MicroBitRadioDatagram.cpp
00001 /* 00002 The MIT License (MIT) 00003 00004 Copyright (c) 2016 British Broadcasting Corporation. 00005 This software is provided by Lancaster University by arrangement with the BBC. 00006 00007 Permission is hereby granted, free of charge, to any person obtaining a 00008 copy of this software and associated documentation files (the "Software"), 00009 to deal in the Software without restriction, including without limitation 00010 the rights to use, copy, modify, merge, publish, distribute, sublicense, 00011 and/or sell copies of the Software, and to permit persons to whom the 00012 Software is furnished to do so, subject to the following conditions: 00013 00014 The above copyright notice and this permission notice shall be included in 00015 all copies or substantial portions of the Software. 00016 00017 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 00018 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 00019 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 00020 THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 00021 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 00022 FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 00023 DEALINGS IN THE SOFTWARE. 00024 */ 00025 00026 #include "MicroBitConfig.h" 00027 #include "MicroBitRadio.h" 00028 00029 /** 00030 * Provides a simple broadcast radio abstraction, built upon the raw nrf51822 RADIO module. 00031 * 00032 * This class provides the ability to broadcast simple text or binary messages to other micro:bits in the vicinity 00033 * It is envisaged that this would provide the basis for children to experiment with building their own, simple, 00034 * custom protocols. 00035 * 00036 * @note This API does not contain any form of encryption, authentication or authorisation. Its purpose is solely for use as a 00037 * teaching aid to demonstrate how simple communications operates, and to provide a sandpit through which learning can take place. 00038 * For serious applications, BLE should be considered a substantially more secure alternative. 00039 */ 00040 00041 /** 00042 * Constructor. 00043 * 00044 * Creates an instance of a MicroBitRadioDatagram which offers the ability 00045 * to broadcast simple text or binary messages to other micro:bits in the vicinity 00046 * 00047 * @param r The underlying radio module used to send and receive data. 00048 */ 00049 MicroBitRadioDatagram::MicroBitRadioDatagram(MicroBitRadio &r) : radio(r) 00050 { 00051 this->rxQueue = NULL; 00052 } 00053 00054 /** 00055 * Retrieves packet payload data into the given buffer. 00056 * 00057 * If a data packet is already available, then it will be returned immediately to the caller. 00058 * If no data is available then MICROBIT_INVALID_PARAMETER is returned. 00059 * 00060 * @param buf A pointer to a valid memory location where the received data is to be stored 00061 * 00062 * @param len The maximum amount of data that can safely be stored in 'buf' 00063 * 00064 * @return The length of the data stored, or MICROBIT_INVALID_PARAMETER if no data is available, or the memory regions provided are invalid. 00065 */ 00066 int MicroBitRadioDatagram::recv(uint8_t *buf, int len) 00067 { 00068 if (buf == NULL || rxQueue == NULL || len < 0) 00069 return MICROBIT_INVALID_PARAMETER; 00070 00071 // Take the first buffer from the queue. 00072 FrameBuffer *p = rxQueue; 00073 rxQueue = rxQueue->next; 00074 00075 int l = min(len, p->length - (MICROBIT_RADIO_HEADER_SIZE - 1)); 00076 00077 // Fill in the buffer provided, if possible. 00078 memcpy(buf, p->payload, l); 00079 00080 delete p; 00081 return l; 00082 } 00083 00084 /** 00085 * Retreives packet payload data into the given buffer. 00086 * 00087 * If a data packet is already available, then it will be returned immediately to the caller 00088 * in the form of a PacketBuffer. 00089 * 00090 * @return the data received, or an empty PacketBuffer if no data is available. 00091 */ 00092 PacketBuffer MicroBitRadioDatagram::recv() 00093 { 00094 if (rxQueue == NULL) 00095 return PacketBuffer::EmptyPacket; 00096 00097 FrameBuffer *p = rxQueue; 00098 rxQueue = rxQueue->next; 00099 00100 PacketBuffer packet(p->payload, p->length - (MICROBIT_RADIO_HEADER_SIZE - 1), p->rssi); 00101 00102 delete p; 00103 return packet; 00104 } 00105 00106 /** 00107 * Transmits the given buffer onto the broadcast radio. 00108 * 00109 * This is a synchronous call that will wait until the transmission of the packet 00110 * has completed before returning. 00111 * 00112 * @param buffer The packet contents to transmit. 00113 * 00114 * @param len The number of bytes to transmit. 00115 * 00116 * @return MICROBIT_OK on success, or MICROBIT_INVALID_PARAMETER if the buffer is invalid, 00117 * or the number of bytes to transmit is greater than `MICROBIT_RADIO_MAX_PACKET_SIZE + MICROBIT_RADIO_HEADER_SIZE`. 00118 */ 00119 int MicroBitRadioDatagram::send(uint8_t *buffer, int len) 00120 { 00121 if (buffer == NULL || len < 0 || len > MICROBIT_RADIO_MAX_PACKET_SIZE + MICROBIT_RADIO_HEADER_SIZE - 1) 00122 return MICROBIT_INVALID_PARAMETER; 00123 00124 FrameBuffer buf; 00125 00126 buf.length = len + MICROBIT_RADIO_HEADER_SIZE - 1; 00127 buf.version = 1; 00128 buf.group = 0; 00129 buf.protocol = MICROBIT_RADIO_PROTOCOL_DATAGRAM; 00130 memcpy(buf.payload, buffer, len); 00131 00132 return radio.send(&buf); 00133 } 00134 00135 /** 00136 * Transmits the given string onto the broadcast radio. 00137 * 00138 * This is a synchronous call that will wait until the transmission of the packet 00139 * has completed before returning. 00140 * 00141 * @param data The packet contents to transmit. 00142 * 00143 * @return MICROBIT_OK on success, or MICROBIT_INVALID_PARAMETER if the buffer is invalid, 00144 * or the number of bytes to transmit is greater than `MICROBIT_RADIO_MAX_PACKET_SIZE + MICROBIT_RADIO_HEADER_SIZE`. 00145 */ 00146 int MicroBitRadioDatagram::send(PacketBuffer data) 00147 { 00148 return send((uint8_t *)data.getBytes(), data.length()); 00149 } 00150 00151 /** 00152 * Transmits the given string onto the broadcast radio. 00153 * 00154 * This is a synchronous call that will wait until the transmission of the packet 00155 * has completed before returning. 00156 * 00157 * @param data The packet contents to transmit. 00158 * 00159 * @return MICROBIT_OK on success, or MICROBIT_INVALID_PARAMETER if the buffer is invalid, 00160 * or the number of bytes to transmit is greater than `MICROBIT_RADIO_MAX_PACKET_SIZE + MICROBIT_RADIO_HEADER_SIZE`. 00161 */ 00162 int MicroBitRadioDatagram::send(ManagedString data) 00163 { 00164 return send((uint8_t *)data.toCharArray(), data.length()); 00165 } 00166 00167 /** 00168 * Protocol handler callback. This is called when the radio receives a packet marked as a datagram. 00169 * 00170 * This function process this packet, and queues it for user reception. 00171 */ 00172 void MicroBitRadioDatagram::packetReceived() 00173 { 00174 FrameBuffer *packet = radio.recv(); 00175 int queueDepth = 0; 00176 00177 // We add to the tail of the queue to preserve causal ordering. 00178 packet->next = NULL; 00179 00180 if (rxQueue == NULL) 00181 { 00182 rxQueue = packet; 00183 } 00184 else 00185 { 00186 FrameBuffer *p = rxQueue; 00187 while (p->next != NULL) 00188 { 00189 p = p->next; 00190 queueDepth++; 00191 } 00192 00193 if (queueDepth >= MICROBIT_RADIO_MAXIMUM_RX_BUFFERS) 00194 { 00195 delete packet; 00196 return; 00197 } 00198 00199 p->next = packet; 00200 } 00201 00202 MicroBitEvent(MICROBIT_ID_RADIO, MICROBIT_RADIO_EVT_DATAGRAM); 00203 }
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