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VILLASnode/include/villas/webmsg_format.h

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C

/** Binary websocket message format.
*
* Note: Messages sent by the 'websocket' node-type are always send in little endian byte-order!
* This is different from the messages send with the 'socket' node-type!
*
* @file
* @author Steffen Vogel <stvogel@eonerc.rwth-aachen.de>
* @copyright 2017, Institute for Automation of Complex Power Systems, EONERC
* @license GNU General Public License (version 3)
*
* VILLASnode
*
* 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 3 of the License, or
* 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*********************************************************************************/
#pragma once
#include <stdint.h>
/** The current version number for the message format */
#define WEBMSG_VERSION 2
/** @todo Implement more message types */
#define WEBMSG_TYPE_DATA 0 /**< Message contains float values */
#define WEBMSG_TYPE_START 1 /**< Message marks the beginning of a new simulation case */
#define WEBMSG_TYPE_STOP 2 /**< Message marks the end of a simulation case */
/** The total size in bytes of a message */
#define WEBMSG_LEN(values) (sizeof(struct webmsg) + WEBMSG_DATA_LEN(values))
/** The length of \p values values in bytes. */
#define WEBMSG_DATA_LEN(values) (sizeof(float) * (values))
/** The offset to the first data value in a message. */
#define WEBMSG_DATA_OFFSET(msg) ((char *) (msg) + offsetof(struct webmsg, data))
/** Initialize a message with default values */
#define WEBMSG_INIT(len, seq) (struct webmsg) {\
.version = WEBMSG_VERSION, \
.type = WEBMSG_TYPE_DATA, \
.length = len, \
.sequence = seq \
}
/** The timestamp of a message in struct timespec format */
#define WEBMSG_TS(msg) (struct timespec) {\
.tv_sec = (msg)->ts.sec, \
.tv_nsec = (msg)->ts.nsec \
}
/** This message format is used by all clients
*
* @diafile msg_format.dia
**/
struct webmsg
{
unsigned rsvd1 : 2; /**< Reserved bits */
unsigned type : 2; /**< Data or control message (see MSG_TYPE_*) */
unsigned version: 4; /**< Specifies the format of the remaining message (see MGS_VERSION) */
uint8_t id; /**< The node index from / to which this sample received / sent to.
* Corresponds to the index of the node in the http://localhost/nodes.json array. */
uint16_t length; /**< The number of values in msg::data[]. */
uint32_t sequence; /**< The sequence number is incremented by one for consecutive messages. */
/** A timestamp per message. */
struct {
uint32_t sec; /**< Seconds since 1970-01-01 00:00:00 */
uint32_t nsec; /**< Nanoseconds of the current second. */
} ts;
/** The message payload. */
union {
float f; /**< Floating point values. */
uint32_t i; /**< Integer values. */
} data[];
} __attribute__((packed));