What's in a pulse?

From the <sys/neutrino.h> header file, here's the definition of the _pulse structure:

struct _pulse {
    uint16_t        type;
    uint16_t        subtype;
    int8_t          code;
    uint8_t         zero [3];
    union sigval    value;
    int32_t         scoid;
};

The value member is actually a union:

union sigval {
    int     sival_int;
    void    *sival_ptr;
    long    sival_long;
};

Therefore (expanding on the server example above), you often see code like:

#include <sys/neutrino.h>

    rcvid = MsgReceive (chid, …);

    if (rcvid == 0) {   // it's a pulse

        // determine the type of pulse
        switch (msg.pulse.code) {

        case    MY_PULSE_TIMER:
            // One of your timers went off, do something about it...

            break;

        case    MY_PULSE_HWINT:
            // An interrupt service thread sent you a pulse.
            // There's a value in the "value" member that you need to
            // examine:
            val = msg.pulse.value.sival_int;

            // Do something about it...

            break;

        case    _PULSE_CODE_UNBLOCK:
            // A pulse from the kernel, indicating a client 
            // unblock was received, do something about it...

            break;

        // etc...

    } else { // it's a regular message

        // determine the type of message and handle it
    }