/** @file * @brief Main MAVLink comm protocol routines. * @see http://qgroundcontrol.org/mavlink/ * Edited on Monday, August 8 2011 */ #ifndef _MAVLINK_PROTOCOL_H_ #define _MAVLINK_PROTOCOL_H_ #include "mavlink_types.h" #include "mavlink_checksum.h" #ifdef MAVLINK_CHECK_LENGTH extern const uint8_t MAVLINK_CONST mavlink_msg_lengths[256]; #endif extern const uint8_t MAVLINK_CONST mavlink_msg_keys[256]; extern mavlink_status_t m_mavlink_status[MAVLINK_COMM_NB]; extern mavlink_message_t m_mavlink_message[MAVLINK_COMM_NB]; /** * @brief Initialize the communication stack * * This function has to be called before using commParseBuffer() to initialize the different status registers. * * @return Will initialize the different buffers and status registers. */ static void mavlink_parse_state_initialize(mavlink_status_t* initStatus) { if ((initStatus->parse_state <= MAVLINK_PARSE_STATE_UNINIT) || (initStatus->parse_state > MAVLINK_PARSE_STATE_GOT_CRC1)) { initStatus->ck_a = 0; initStatus->ck_b = 0; initStatus->msg_received = 0; initStatus->buffer_overrun = 0; initStatus->parse_error = 0; initStatus->parse_state = MAVLINK_PARSE_STATE_UNINIT; initStatus->packet_idx = 0; initStatus->packet_rx_drop_count = 0; initStatus->packet_rx_success_count = 0; initStatus->current_rx_seq = 0; initStatus->current_tx_seq = 0; } } static inline mavlink_status_t* mavlink_get_channel_status(uint8_t chan) { return &m_mavlink_status[chan]; } /** * @brief Finalize a MAVLink message with MAVLINK_COMM_0 as default channel * * This function calculates the checksum and sets length and aircraft id correctly. * It assumes that the message id and the payload are already correctly set. * * @warning This function implicitely assumes the message is sent over channel zero. * if the message is sent over a different channel it will reach the receiver * without error, BUT the sequence number might be wrong due to the wrong * channel sequence counter. This will result is wrongly reported excessive * packet loss. Please use @see mavlink_{pack|encode}_headerless and then * @see mavlink_finalize_message_chan before sending for a correct channel * assignment. Please note that the mavlink_msg_xxx_pack and encode functions * assign channel zero as default and thus induce possible loss counter errors.\ * They have been left to ensure code compatibility. * * @see mavlink_finalize_message_chan * @param msg Message to finalize * @param system_id Id of the sending (this) system, 1-127 * @param length Message length, usually just the counter incremented while packing the message */ static inline uint16_t mavlink_finalize_message(mavlink_message_t* msg, uint8_t system_id, uint8_t component_id, uint16_t length) { // This code part is the same for all messages; uint16_t checksum; msg->len = length; msg->sysid = system_id; msg->compid = component_id; // One sequence number per component msg->seq = mavlink_get_channel_status(MAVLINK_COMM_0)->current_tx_seq; mavlink_get_channel_status(MAVLINK_COMM_0)->current_tx_seq = mavlink_get_channel_status(MAVLINK_COMM_0)->current_tx_seq+1; // checksum = crc_calculate((uint8_t*)((void*)msg), length + MAVLINK_CORE_HEADER_LEN); checksum = crc_calculate_msg(msg, length + MAVLINK_CORE_HEADER_LEN); msg->ck_a = (uint8_t)(checksum & 0xFF); ///< High byte msg->ck_b = (uint8_t)(checksum >> 8); ///< Low byte return length + MAVLINK_NUM_NON_STX_PAYLOAD_BYTES; } /** * @brief Finalize a MAVLink message with channel assignment * * This function calculates the checksum and sets length and aircraft id correctly. * It assumes that the message id and the payload are already correctly set. This function * can also be used if the message header has already been written before (as in mavlink_msg_xxx_pack * instead of mavlink_msg_xxx_pack_headerless), it just introduces little extra overhead. * * @param msg Message to finalize * @param system_id Id of the sending (this) system, 1-127 * @param length Message length, usually just the counter incremented while packing the message */ static inline uint16_t mavlink_finalize_message_chan(mavlink_message_t* msg, uint8_t system_id, uint8_t component_id, uint8_t chan, uint16_t length) { // This code part is the same for all messages; uint16_t checksum; msg->len = length; msg->sysid = system_id; msg->compid = component_id; // One sequence number per component msg->seq = mavlink_get_channel_status(chan)->current_tx_seq; mavlink_get_channel_status(chan)->current_tx_seq = mavlink_get_channel_status(chan)->current_tx_seq+1; // checksum = crc_calculate((uint8_t*)((void*)msg), length + MAVLINK_CORE_HEADER_LEN); checksum = crc_calculate_msg(msg, length + MAVLINK_CORE_HEADER_LEN); msg->ck_a = (uint8_t)(checksum & 0xFF); ///< High byte msg->ck_b = (uint8_t)(checksum >> 8); ///< Low byte return length + MAVLINK_NUM_NON_STX_PAYLOAD_BYTES; } /** * @brief Pack a message to send it over a serial byte stream */ static inline uint16_t mavlink_msg_to_send_buffer(uint8_t* buffer, const mavlink_message_t* msg) { *(buffer+0) = MAVLINK_STX; ///< Start transmit // memcpy((buffer+1), msg, msg->len + MAVLINK_CORE_HEADER_LEN); ///< Core header plus payload memcpy((buffer+1), &msg->len, MAVLINK_CORE_HEADER_LEN); ///< Core header memcpy((buffer+1+MAVLINK_CORE_HEADER_LEN), &msg->payload[0], msg->len); ///< payload *(buffer + msg->len + MAVLINK_CORE_HEADER_LEN + 1) = msg->ck_a; *(buffer + msg->len + MAVLINK_CORE_HEADER_LEN + 2) = msg->ck_b; return msg->len + MAVLINK_NUM_NON_PAYLOAD_BYTES; // return 0; } /** * @brief Get the required buffer size for this message */ static inline uint16_t mavlink_msg_get_send_buffer_length(const mavlink_message_t* msg) { return msg->len + MAVLINK_NUM_NON_PAYLOAD_BYTES; } union checksum_ { uint16_t s; uint8_t c[2]; }; union __mavlink_bitfield { uint8_t uint8; int8_t int8; uint16_t uint16; int16_t int16; uint32_t uint32; int32_t int32; }; static inline void mavlink_start_checksum(mavlink_message_t* msg) { union checksum_ ck; crc_init(&(ck.s)); msg->ck_a = ck.c[0]; msg->ck_b = ck.c[1]; } static inline void mavlink_update_checksum(mavlink_message_t* msg, uint8_t c) { union checksum_ ck; ck.c[0] = msg->ck_a; ck.c[1] = msg->ck_b; crc_accumulate(c, &(ck.s)); msg->ck_a = ck.c[0]; msg->ck_b = ck.c[1]; } /** * This is a convenience function which handles the complete MAVLink parsing. * the function will parse one byte at a time and return the complete packet once * it could be successfully decoded. Checksum and other failures will be silently * ignored. * * @param chan ID of the current channel. This allows to parse different channels with this function. * a channel is not a physical message channel like a serial port, but a logic partition of * the communication streams in this case. COMM_NB is the limit for the number of channels * on MCU (e.g. ARM7), while COMM_NB_HIGH is the limit for the number of channels in Linux/Windows * @param c The char to barse * * @param returnMsg NULL if no message could be decoded, the message data else * @return 0 if no message could be decoded, 1 else * * A typical use scenario of this function call is: * * @code * #include // For fixed-width uint8_t type * * mavlink_message_t msg; * int chan = 0; * * * while(serial.bytesAvailable > 0) * { * uint8_t byte = serial.getNextByte(); * if (mavlink_parse_char(chan, byte, &msg)) * { * printf("Received message with ID %d, sequence: %d from component %d of system %d", msg.msgid, msg.seq, msg.compid, msg.sysid); * } * } * * * @endcode */ #ifdef MAVLINK_STAIC_BUFFER static inline mavlink_message_t* mavlink_parse_char(uint8_t chan, uint8_t c, mavlink_message_t* r_message, mavlink_status_t* r_mavlink_status) #else static inline int16_t mavlink_parse_char(uint8_t chan, uint8_t c, mavlink_message_t* r_message, mavlink_status_t* r_mavlink_status) #endif { // Initializes only once, values keep unchanged after first initialization mavlink_parse_state_initialize(mavlink_get_channel_status(chan)); mavlink_message_t* rxmsg = &m_mavlink_message[chan]; ///< The currently decoded message mavlink_status_t* status = mavlink_get_channel_status(chan); ///< The current decode status int bufferIndex = 0; status->msg_received = 0; switch (status->parse_state) { case MAVLINK_PARSE_STATE_UNINIT: case MAVLINK_PARSE_STATE_IDLE: if (c == MAVLINK_STX) { status->parse_state = MAVLINK_PARSE_STATE_GOT_STX; mavlink_start_checksum(rxmsg); } break; case MAVLINK_PARSE_STATE_GOT_STX: if (status->msg_received) { status->buffer_overrun++; status->parse_error++; status->msg_received = 0; status->parse_state = MAVLINK_PARSE_STATE_IDLE; } else { // NOT counting STX, LENGTH, SEQ, SYSID, COMPID, MSGID, CRC1 and CRC2 rxmsg->len = c; status->packet_idx = 0; mavlink_update_checksum(rxmsg, c); status->parse_state = MAVLINK_PARSE_STATE_GOT_LENGTH; } break; case MAVLINK_PARSE_STATE_GOT_LENGTH: rxmsg->seq = c; mavlink_update_checksum(rxmsg, c); status->parse_state = MAVLINK_PARSE_STATE_GOT_SEQ; break; case MAVLINK_PARSE_STATE_GOT_SEQ: rxmsg->sysid = c; mavlink_update_checksum(rxmsg, c); status->parse_state = MAVLINK_PARSE_STATE_GOT_SYSID; break; case MAVLINK_PARSE_STATE_GOT_SYSID: rxmsg->compid = c; mavlink_update_checksum(rxmsg, c); status->parse_state = MAVLINK_PARSE_STATE_GOT_COMPID; break; case MAVLINK_PARSE_STATE_GOT_COMPID: rxmsg->msgid = c; mavlink_update_checksum(rxmsg, c); #ifdef MAVLINK_CHECK_LENGTH if (rxmsg->len != MAVLINK_CONST_READ( mavlink_msg_lengths[c] ) ) status->parse_state = MAVLINK_PARSE_STATE_IDLE; // abort, not going to understand it anyway else ; #endif if (rxmsg->len == 0) { status->parse_state = MAVLINK_PARSE_STATE_GOT_PAYLOAD; } else { status->parse_state = MAVLINK_PARSE_STATE_GOT_MSGID; } break; case MAVLINK_PARSE_STATE_GOT_MSGID: rxmsg->payload[status->packet_idx++] = c; mavlink_update_checksum(rxmsg, c); if (status->packet_idx == rxmsg->len) { status->parse_state = MAVLINK_PARSE_STATE_GOT_PAYLOAD; mavlink_update_checksum(rxmsg, MAVLINK_CONST_READ( mavlink_msg_lengths[rxmsg->msgid] ) ); } break; case MAVLINK_PARSE_STATE_GOT_PAYLOAD: if (c != rxmsg->ck_a) { // Check first checksum byte status->parse_error++; status->msg_received = 0; status->parse_state = MAVLINK_PARSE_STATE_IDLE; if (c == MAVLINK_STX) { status->parse_state = MAVLINK_PARSE_STATE_GOT_STX; mavlink_start_checksum(rxmsg); } } else { status->parse_state = MAVLINK_PARSE_STATE_GOT_CRC1; } break; case MAVLINK_PARSE_STATE_GOT_CRC1: if (c != rxmsg->ck_b) {// Check second checksum byte status->parse_error++; status->msg_received = 0; status->parse_state = MAVLINK_PARSE_STATE_IDLE; if (c == MAVLINK_STX) { status->parse_state = MAVLINK_PARSE_STATE_GOT_STX; mavlink_start_checksum(rxmsg); } } else { // Successfully got message status->msg_received = 1; status->parse_state = MAVLINK_PARSE_STATE_IDLE; if ( r_message != NULL ) memcpy(r_message, rxmsg, sizeof(mavlink_message_t)); else ; } break; } bufferIndex++; // If a message has been sucessfully decoded, check index if (status->msg_received == 1) { //while(status->current_seq != rxmsg->seq) //{ // status->packet_rx_drop_count++; // status->current_seq++; //} status->current_rx_seq = rxmsg->seq; // Initial condition: If no packet has been received so far, drop count is undefined if (status->packet_rx_success_count == 0) status->packet_rx_drop_count = 0; // Count this packet as received status->packet_rx_success_count++; } r_mavlink_status->current_rx_seq = status->current_rx_seq+1; r_mavlink_status->packet_rx_success_count = status->packet_rx_success_count; r_mavlink_status->packet_rx_drop_count = status->parse_error; status->parse_error = 0; if (status->msg_received == 1) { if ( r_message != NULL ) return r_message; else return rxmsg; } else return NULL; } #ifdef MAVLINK_USE_CONVENIENCE_FUNCTIONS // To make MAVLink work on your MCU, define a similar function /* #include "mavlink_types.h" void comm_send_ch(mavlink_channel_t chan, uint8_t ch) { if (chan == MAVLINK_COMM_0) { uart0_transmit(ch); } if (chan == MAVLINK_COMM_1) { uart1_transmit(ch); } } static inline void mavlink_send_msg(mavlink_channel_t chan, mavlink_message_t* msg) { // ARM7 MCU board implementation // Create pointer on message struct // Send STX comm_send_ch(chan, MAVLINK_STX); comm_send_ch(chan, msg->len); comm_send_ch(chan, msg->seq); comm_send_ch(chan, msg->sysid); comm_send_ch(chan, msg->compid); comm_send_ch(chan, msg->msgid); for(uint16_t i = 0; i < msg->len; i++) { comm_send_ch(chan, msg->payload[i]); } comm_send_ch(chan, msg->ck_a); comm_send_ch(chan, msg->ck_b); } static inline void mavlink_send_mem(mavlink_channel_t chan, (uint8_t *)mem, uint8_t num) { // ARM7 MCU board implementation // Create pointer on message struct // Send STX for(uint16_t i = 0; i < num; i++) { comm_send_ch( chan, mem[i] ); } } */ static inline void mavlink_send_uart(mavlink_channel_t chan, mavlink_message_t* msg); static inline void mavlink_send_mem(mavlink_channel_t chan, (uint8_t *)mem, uint8_t num); #define mavlink_send_msg( a, b ) mavlink_send_uart( a, b ) #endif #define FILE_FINISHED #ifndef FILE_FINISHED /** * This is a convenience function which handles the complete MAVLink parsing. * the function will parse one byte at a time and return the complete packet once * it could be successfully decoded. Checksum and other failures will be silently * ignored. * * @param chan ID of the current channel. This allows to parse different channels with this function. * a channel is not a physical message channel like a serial port, but a logic partition of * the communication streams in this case. COMM_NB is the limit for the number of channels * on MCU (e.g. ARM7), while COMM_NB_HIGH is the limit for the number of channels in Linux/Windows * @param c The char to barse * * @param returnMsg NULL if no message could be decoded, the message data else * @return 0 if no message could be decoded, 1 else * * A typical use scenario of this function call is: * * @code * #include // For fixed-width uint8_t type * * mavlink_message_t msg; * int chan = 0; * * * while(serial.bytesAvailable > 0) * { * uint8_t byte = serial.getNextByte(); * if (mavlink_parse_char(chan, byte, &msg)) * { * printf("Received message with ID %d, sequence: %d from component %d of system %d", msg.msgid, msg.seq, msg.compid, msg.sysid); * } * } * * * @endcode */ #define MAVLINK_PACKET_START_CANDIDATES 50 /* static inline uint8_t mavlink_parse_char_new(uint8_t chan, uint8_t c, mavlink_message_t* r_message, mavlink_status_t* r_mavlink_status) { #if (defined linux) | (defined __linux) | (defined __MACH__) | (defined _WIN32) static mavlink_status_t m_mavlink_status[MAVLINK_COMM_NB_HIGH]; static uint8_t m_msgbuf[MAVLINK_COMM_NB_HIGH][MAVLINK_MAX_PACKET_LEN * 2]; static uint8_t m_msgbuf_index[MAVLINK_COMM_NB_HIGH]; static mavlink_message_t m_mavlink_message[MAVLINK_COMM_NB_HIGH]; static uint8_t m_packet_start[MAVLINK_COMM_NB_HIGH][MAVLINK_PACKET_START_CANDIDATES]; static uint8_t m_packet_start_index_read[MAVLINK_COMM_NB_HIGH]; static uint8_t m_packet_start_index_write[MAVLINK_COMM_NB_HIGH]; #else static mavlink_status_t m_mavlink_status[MAVLINK_COMM_NB]; static uint8_t m_msgbuf[MAVLINK_COMM_NB][MAVLINK_MAX_PACKET_LEN * 2]; static uint8_t m_msgbuf_index[MAVLINK_COMM_NB]; static mavlink_message_t m_mavlink_message[MAVLINK_COMM_NB]; static uint8_t m_packet_start[MAVLINK_COMM_NB][MAVLINK_PACKET_START_CANDIDATES]; static uint8_t m_packet_start_index_read[MAVLINK_COMM_NB]; static uint8_t m_packet_start_index_write[MAVLINK_COMM_NB]; #endif // Set a packet start candidate index if sign is start sign if (c == MAVLINK_STX) { m_packet_start[chan][++(m_packet_start_index_write[chan]) % MAVLINK_PACKET_START_CANDIDATES] = m_msgbuf_index[chan]; } // Parse normally, if a CRC mismatch occurs retry with the next packet index } //#if (defined linux) | (defined __linux) | (defined __MACH__) | (defined _WIN32) // static mavlink_status_t m_mavlink_status[MAVLINK_COMM_NB_HIGH]; // static mavlink_message_t m_mavlink_message[MAVLINK_COMM_NB_HIGH]; //#else // static mavlink_status_t m_mavlink_status[MAVLINK_COMM_NB]; // static mavlink_message_t m_mavlink_message[MAVLINK_COMM_NB]; //#endif //// Initializes only once, values keep unchanged after first initialization // mavlink_parse_state_initialize(&m_mavlink_status[chan]); // //mavlink_message_t* rxmsg = &m_mavlink_message[chan]; ///< The currently decoded message //mavlink_status_t* status = &m_mavlink_status[chan]; ///< The current decode status //int bufferIndex = 0; // //status->msg_received = 0; // //switch (status->parse_state) //{ //case MAVLINK_PARSE_STATE_UNINIT: //case MAVLINK_PARSE_STATE_IDLE: // if (c == MAVLINK_STX) // { // status->parse_state = MAVLINK_PARSE_STATE_GOT_STX; // mavlink_start_checksum(rxmsg); // } // break; // //case MAVLINK_PARSE_STATE_GOT_STX: // if (status->msg_received) // { // status->buffer_overrun++; // status->parse_error++; // status->msg_received = 0; // status->parse_state = MAVLINK_PARSE_STATE_IDLE; // } // else // { // // NOT counting STX, LENGTH, SEQ, SYSID, COMPID, MSGID, CRC1 and CRC2 // rxmsg->len = c; // status->packet_idx = 0; // mavlink_update_checksum(rxmsg, c); // status->parse_state = MAVLINK_PARSE_STATE_GOT_LENGTH; // } // break; // //case MAVLINK_PARSE_STATE_GOT_LENGTH: // rxmsg->seq = c; // mavlink_update_checksum(rxmsg, c); // status->parse_state = MAVLINK_PARSE_STATE_GOT_SEQ; // break; // //case MAVLINK_PARSE_STATE_GOT_SEQ: // rxmsg->sysid = c; // mavlink_update_checksum(rxmsg, c); // status->parse_state = MAVLINK_PARSE_STATE_GOT_SYSID; // break; // //case MAVLINK_PARSE_STATE_GOT_SYSID: // rxmsg->compid = c; // mavlink_update_checksum(rxmsg, c); // status->parse_state = MAVLINK_PARSE_STATE_GOT_COMPID; // break; // //case MAVLINK_PARSE_STATE_GOT_COMPID: // rxmsg->msgid = c; // mavlink_update_checksum(rxmsg, c); // if (rxmsg->len == 0) // { // status->parse_state = MAVLINK_PARSE_STATE_GOT_PAYLOAD; // } // else // { // status->parse_state = MAVLINK_PARSE_STATE_GOT_MSGID; // } // break; // //case MAVLINK_PARSE_STATE_GOT_MSGID: // rxmsg->payload[status->packet_idx++] = c; // mavlink_update_checksum(rxmsg, c); // if (status->packet_idx == rxmsg->len) // { // status->parse_state = MAVLINK_PARSE_STATE_GOT_PAYLOAD; // } // break; // //case MAVLINK_PARSE_STATE_GOT_PAYLOAD: // if (c != rxmsg->ck_a) // { // // Check first checksum byte // status->parse_error++; // status->msg_received = 0; // status->parse_state = MAVLINK_PARSE_STATE_IDLE; // } // else // { // status->parse_state = MAVLINK_PARSE_STATE_GOT_CRC1; // } // break; // //case MAVLINK_PARSE_STATE_GOT_CRC1: // if (c != rxmsg->ck_b) // {// Check second checksum byte // status->parse_error++; // status->msg_received = 0; // status->parse_state = MAVLINK_PARSE_STATE_IDLE; // } // else // { // // Successfully got message // status->msg_received = 1; // status->parse_state = MAVLINK_PARSE_STATE_IDLE; // memcpy(r_message, rxmsg, sizeof(mavlink_message_t)); // } // break; //} bufferIndex++; // If a message has been sucessfully decoded, check index if (status->msg_received == 1) { //while(status->current_seq != rxmsg->seq) //{ // status->packet_rx_drop_count++; // status->current_seq++; //} status->current_seq = rxmsg->seq; // Initial condition: If no packet has been received so far, drop count is undefined if (status->packet_rx_success_count == 0) status->packet_rx_drop_count = 0; // Count this packet as received status->packet_rx_success_count++; } r_mavlink_status->current_seq = status->current_seq+1; r_mavlink_status->packet_rx_success_count = status->packet_rx_success_count; r_mavlink_status->packet_rx_drop_count = status->parse_error; return status->msg_received; } */ typedef union __generic_16bit { uint8_t b[2]; int16_t s; } generic_16bit; typedef union __generic_32bit { uint8_t b[4]; float f; int32_t i; int16_t s; } generic_32bit; typedef union __generic_64bit { uint8_t b[8]; int64_t ll; ///< Long long (64 bit) } generic_64bit; /** * @brief Place an unsigned byte into the buffer * * @param b the byte to add * @param bindex the position in the packet * @param buffer the packet buffer * @return the new position of the last used byte in the buffer */ static inline uint8_t put_uint8_t_by_index(uint8_t b, uint8_t bindex, uint8_t* buffer) { *(buffer + bindex) = b; return sizeof(b); } /** * @brief Place a signed byte into the buffer * * @param b the byte to add * @param bindex the position in the packet * @param buffer the packet buffer * @return the new position of the last used byte in the buffer */ static inline uint8_t put_int8_t_by_index(int8_t b, int8_t bindex, uint8_t* buffer) { *(buffer + bindex) = (uint8_t)b; return sizeof(b); } /** * @brief Place two unsigned bytes into the buffer * * @param b the bytes to add * @param bindex the position in the packet * @param buffer the packet buffer * @return the new position of the last used byte in the buffer */ static inline uint8_t put_uint16_t_by_index(uint16_t b, const uint8_t bindex, uint8_t* buffer) { buffer[bindex] = (b>>8)&0xff; buffer[bindex+1] = (b & 0xff); return sizeof(b); } /** * @brief Place two signed bytes into the buffer * * @param b the bytes to add * @param bindex the position in the packet * @param buffer the packet buffer * @return the new position of the last used byte in the buffer */ static inline uint8_t put_int16_t_by_index(int16_t b, uint8_t bindex, uint8_t* buffer) { return put_uint16_t_by_index(b, bindex, buffer); } /** * @brief Place four unsigned bytes into the buffer * * @param b the bytes to add * @param bindex the position in the packet * @param buffer the packet buffer * @return the new position of the last used byte in the buffer */ static inline uint8_t put_uint32_t_by_index(uint32_t b, const uint8_t bindex, uint8_t* buffer) { buffer[bindex] = (b>>24)&0xff; buffer[bindex+1] = (b>>16)&0xff; buffer[bindex+2] = (b>>8)&0xff; buffer[bindex+3] = (b & 0xff); return sizeof(b); } /** * @brief Place four signed bytes into the buffer * * @param b the bytes to add * @param bindex the position in the packet * @param buffer the packet buffer * @return the new position of the last used byte in the buffer */ static inline uint8_t put_int32_t_by_index(int32_t b, uint8_t bindex, uint8_t* buffer) { buffer[bindex] = (b>>24)&0xff; buffer[bindex+1] = (b>>16)&0xff; buffer[bindex+2] = (b>>8)&0xff; buffer[bindex+3] = (b & 0xff); return sizeof(b); } /** * @brief Place four unsigned bytes into the buffer * * @param b the bytes to add * @param bindex the position in the packet * @param buffer the packet buffer * @return the new position of the last used byte in the buffer */ static inline uint8_t put_uint64_t_by_index(uint64_t b, const uint8_t bindex, uint8_t* buffer) { buffer[bindex] = (b>>56)&0xff; buffer[bindex+1] = (b>>48)&0xff; buffer[bindex+2] = (b>>40)&0xff; buffer[bindex+3] = (b>>32)&0xff; buffer[bindex+4] = (b>>24)&0xff; buffer[bindex+5] = (b>>16)&0xff; buffer[bindex+6] = (b>>8)&0xff; buffer[bindex+7] = (b & 0xff); return sizeof(b); } /** * @brief Place four signed bytes into the buffer * * @param b the bytes to add * @param bindex the position in the packet * @param buffer the packet buffer * @return the new position of the last used byte in the buffer */ static inline uint8_t put_int64_t_by_index(int64_t b, uint8_t bindex, uint8_t* buffer) { return put_uint64_t_by_index(b, bindex, buffer); } /** * @brief Place a float into the buffer * * @param b the float to add * @param bindex the position in the packet * @param buffer the packet buffer * @return the new position of the last used byte in the buffer */ static inline uint8_t put_float_by_index(float b, uint8_t bindex, uint8_t* buffer) { generic_32bit g; g.f = b; return put_int32_t_by_index(g.i, bindex, buffer); } /** * @brief Place an array into the buffer * * @param b the array to add * @param length size of the array (for strings: length WITH '\0' char) * @param bindex the position in the packet * @param buffer packet buffer * @return new position of the last used byte in the buffer */ static inline uint8_t put_array_by_index(const int8_t* b, uint8_t length, uint8_t bindex, uint8_t* buffer) { memcpy(buffer+bindex, b, length); return length; } /** * @brief Place a string into the buffer * * @param b the string to add * @param maxlength size of the array (for strings: length WITHOUT '\0' char) * @param bindex the position in the packet * @param buffer packet buffer * @return new position of the last used byte in the buffer */ static inline uint8_t put_string_by_index(const char* b, uint8_t maxlength, uint8_t bindex, uint8_t* buffer) { uint16_t length = 0; // Copy string into buffer, ensuring not to exceed the buffer size int i; for (i = 1; i < maxlength; i++) { length++; // String characters if (i < (maxlength - 1)) { buffer[bindex+i] = b[i]; // Stop at null character if (b[i] == '\0') { break; } } // Enforce null termination at end of buffer else if (i == (maxlength - 1)) { buffer[i] = '\0'; } } // Write length into first field put_uint8_t_by_index(length, bindex, buffer); return length; } /** * @brief Put a bitfield of length 1-32 bit into the buffer * * @param b the value to add, will be encoded in the bitfield * @param bits number of bits to use to encode b, e.g. 1 for boolean, 2, 3, etc. * @param packet_index the position in the packet (the index of the first byte to use) * @param bit_index the position in the byte (the index of the first bit to use) * @param buffer packet buffer to write into * @return new position of the last used byte in the buffer */ static inline uint8_t put_bitfield_n_by_index(int32_t b, uint8_t bits, uint8_t packet_index, uint8_t bit_index, uint8_t* r_bit_index, uint8_t* buffer) { uint16_t bits_remain = bits; // Transform number into network order generic_32bit bin; generic_32bit bout; uint8_t i_bit_index, i_byte_index, curr_bits_n; bin.i = b; bout.b[0] = bin.b[3]; bout.b[1] = bin.b[2]; bout.b[2] = bin.b[1]; bout.b[3] = bin.b[0]; // buffer in // 01100000 01000000 00000000 11110001 // buffer out // 11110001 00000000 01000000 01100000 // Existing partly filled byte (four free slots) // 0111xxxx // Mask n free bits // 00001111 = 2^0 + 2^1 + 2^2 + 2^3 = 2^n - 1 // = ((uint32_t)(1 << n)) - 1; // = 2^n - 1 // Shift n bits into the right position // out = in >> n; // Mask and shift bytes i_bit_index = bit_index; i_byte_index = packet_index; if (bit_index > 0) { // If bits were available at start, they were available // in the byte before the current index i_byte_index--; } // While bits have not been packed yet while (bits_remain > 0) { // Bits still have to be packed // there can be more than 8 bits, so // we might have to pack them into more than one byte // First pack everything we can into the current 'open' byte //curr_bits_n = bits_remain << 3; // Equals bits_remain mod 8 //FIXME if (bits_remain <= (8 - i_bit_index)) { // Enough space curr_bits_n = bits_remain; } else { curr_bits_n = (8 - i_bit_index); } // Pack these n bits into the current byte // Mask out whatever was at that position with ones (xxx11111) buffer[i_byte_index] &= (0xFF >> (8 - curr_bits_n)); // Put content to this position, by masking out the non-used part buffer[i_byte_index] |= ((0x00 << curr_bits_n) & bout.i); // Increment the bit index i_bit_index += curr_bits_n; // Now proceed to the next byte, if necessary bits_remain -= curr_bits_n; if (bits_remain > 0) { // Offer another 8 bits / one byte i_byte_index++; i_bit_index = 0; } } *r_bit_index = i_bit_index; // If a partly filled byte is present, mark this as consumed if (i_bit_index != 7) i_byte_index++; return i_byte_index - packet_index; } */ #endif /* FILE_FINISHED */ #endif /* _MAVLINK_PROTOCOL_H_ */