LCM_MAX_MESSAGE_SIZE

#define LCM_MAX_MESSAGE_SIZE (1 << 28)

LCM_MAX_CHANNEL_NAME_LENGTH

#define LCM_MAX_CHANNEL_NAME_LENGTH 63

lcm_t

typedef struct _lcm_t lcm_t;

lcm_recv_buf_t

typedef struct {
    void *data;
    uint32_t data_size;
    int64_t recv_utime;
    lcm_t *lcm;
} lcm_recv_buf_t;

Received messages are passed to user programs using this data structure. One struct represents one message.

lcm_subscription_t

typedef struct _lcm_subscription_t lcm_subscription_t;

This is an opaque data structure that identifies an LCM subscription.

lcm_msg_handler_t ()

void                (*lcm_msg_handler_t)                (const lcm_recv_buf_t *rbuf,
                                                         const char *channel,
                                                         void *user_data);

callback function prototype.

lcm_create ()

lcm_t *             lcm_create                          (const char *provider);

Constructor. Allocates and initializes a lcm_t. provider must be either NULL, or a string of the form

"provider://network?option1=value1&option2=value2&...&optionN=valueN"

The currently supported providers are:

udpm://
    UDP Multicast provider
    network can be of the form "multicast_address:port".  Either the
    multicast address or the port may be ommitted for the default.

    options:

        recv_buf_size = N
            size of the kernel UDP receive buffer to request.  Defaults to
            operating system defaults

        ttl = N
            time to live of transmitted packets.  Default 0

    examples:

        "udpm://239.255.76.67:7667"
            Default initialization string

        "udpm://239.255.76.67:7667?ttl=1"
            Sets the multicast TTL to 1 so that packets published will enter
            the local network.

file://
    LCM Log file-based provider
    network should be the path to the log file

    Events are read from or written to the log file.  In read mode, events
    are generated from the log file in real-time, or at the rate specified
    by the speed option.  In write mode, events published to the LCM instance
    will be written to the log file in real-time.

    options:

        speed = N
            Scale factor controlling the playback speed of the log file.
            Defaults to 1.  If less than or equal to zero, then the events
            in the log file are played back as fast as possible.
        
        mode = r | w
            Specifies the log file mode.  Defaults to 'r'

    examples:
        
        "file:///home/albert/path/to/logfile"
            Loads the file "/home/albert/path/to/logfile" as an LCM event
            source.

        "file:///home/albert/path/to/logfile?speed=4"
            Loads the file "/home/albert/path/to/logfile" as an LCM event
            source.  Events are played back at 4x speed.
            

lcm_destroy ()

void                lcm_destroy                         (lcm_t *lcm);

destructor

lcm_get_fileno ()

int                 lcm_get_fileno                      (lcm_t *lcm);

lcm_subscribe ()

lcm_subscription_t * lcm_subscribe                      (lcm_t *lcm,
                                                         const char *channel,
                                                         lcm_msg_handler_t handler,
                                                         void *userdata);

registers a callback function that will be invoked any time a message on the specified channel is received. Multiple callbacks can be subscribed for a given channel.

channel can also be a GLib regular expression, and is treated as a regex implicitly surrounded by '^' and '$'.

lcm_unsubscribe ()

int                 lcm_unsubscribe                     (lcm_t *lcm,
                                                         lcm_subscription_t *handler);

unregisters a message handler so that it will no longer be invoked when the specified message type is received.

lcm_publish ()

int                 lcm_publish                         (lcm_t *lcm,
                                                         const char *channel,
                                                         const void *data,
                                                         unsigned int datalen);

transmits a message to a multicast group

lcm_handle ()

int                 lcm_handle                          (lcm_t *lcm);

waits for and dispatches the next incoming message

Message handlers are invoked in the order registered.