Boost.MSM: Problem with defered events

From: Georg Gast (georg_at_[hidden])
Date: 2020-10-16 16:31:06

Dear Boost users,

i am currently writing a driver for the ADS1256 chip with Boost.MSM. 
Yes, there are other drivers. I do this for training and fun. During the 
startup phase i need to defer the requests from the user as the SPI bus 
is not yet available. To model the behaviour the most correct, i tried 
to model it with MSM.

In the transition table, i use the "Defer" action to defer these events. 
In my Idle state, after the startup phase, there is a transition with 
this defered event going to the "work" states. In the debugger i can 
see, that the defered_event_queue holds one defered event and it is of 
my type but it is not processed.

I did use boost 1.67.0 (from debian buster ) and also 1.74.0 (self 
compiled) to test this. My program can be also compiled under Windows 
and VS2019 as i handled the hardware interfacing with a abstract class. 
It works under  Windows and 1.74.0. With VS2017 and 1.67.0 it also does 
not work. Under Linux and gcc it always stops at the Idle state where i 
wait for the defered event.

At the end is my transition table.

Any ideas are welcome!

Georg

        // clang-format off
        struct transition_table : mpl::vector<
                // 
+----------------+-------------------+----------------+---------------------------+----------------------+
                //   Region 0
                // 
+----------------+-------------------+----------------+---------------------------+----------------------+
                //    Start            Event               Next             Action 
                  Guard
                // 
+----------------+-------------------+----------------+---------------------------+----------------------+
                Row < NotIntialized  , ev_Init           , WaitDRDYID     , none 
                , none                 >,
                Row < WaitDRDYID     , ev_CheckFlags     , ReadID         , none 
                , IsDrdy0              >,
                Row < ReadID         , ev_CheckFlags     , none           , none 
                , none                 >,
                Row < ReadID         , Spi::Reply        , ReadIDFailed   , none 
                , IsIDNotOk            >,
                Row < ReadID         , Spi::Reply        , Idle           , none 
                , IsIDOk               >,

                // during the startup phase these event must be defered
                Row < NotIntialized  , ev_MultiStart     , none           , Defer 
                , none                 >,
                Row < WaitDRDYID     , ev_MultiStart     , none           , Defer 
                , none                 >,
                Row < ReadID         , ev_MultiStart     , none           , Defer 
                , none                 >,

                // 
+----------------+-------------------+----------------+---------------------------+----------------------+
                Row < Idle           , ev_CheckFlags     , none           , none 
                , none                 >,
                Row < Idle           , ev_MultiStart     , MConfigWaitDRDY, none 
                , none                 >,
                // 
+----------------+-------------------+----------------+---------------------------+----------------------+
                Row < MConfigWaitDRDY, ev_CheckFlags     , MSwitchConfig  , none 
                , IsDrdy0              >,
                Row < MSwitchConfig  , ev_CheckFlags     , none           , none 
                , none                 >,
                Row < MSwitchConfig  , Spi::Reply        , MMuxWaitDRDY   , none 
                , IsECNotFailed        >,

                Row < MMuxWaitDRDY   , ev_CheckFlags     , MSwitchMux     , none 
                , IsDrdy0              >,
                Row < MSwitchMux     , ev_CheckFlags     , none           , none 
                , none                 >,
                Row < MSwitchMux     , Spi::Reply        , MSync          , none 
                , IsECNotFailed        >,

                Row < MSync          , Spi::Reply        , MDataWaitDRDY  , none 
                , IsECNotFailed        >,
                Row < MDataWaitDRDY  , ev_CheckFlags     , MReadData      , none 
                , IsDrdy0              >,
                Row < MReadData      , ev_CheckFlags     , none           , none 
                , none                 >,
                Row < MReadData      , Spi::Reply        , Idle           , WorkDone 
                , IsWorkDone           >,
                Row < MReadData      , Spi::Reply        , MMuxWaitDRDY   , 
RemoveDoneWork            , IsStillWorkTodo      >,

                // 
+----------------+-------------------+----------------+---------------------------+----------------------+
                //   Region 1
                // 
+----------------+-------------------+----------------+---------------------------+----------------------+
                Row < DrdyUndefined  , ev_DRDY_0         , Drdy0          , none 
                , none                 >,
                Row < DrdyUndefined  , ev_DRDY_1         , Drdy1          , none 
                , none                 >,

                Row < Drdy0          , ev_DRDY_0         , none           , none 
                , none                 >,
                Row < Drdy0          , ev_DRDY_1         , Drdy1          , none 
                , none                 >,

                Row < Drdy1          , ev_DRDY_0         , Drdy0          , none 
                , none                 >,
                Row < Drdy1          , ev_DRDY_1         , none           , none 
                , none                 >,

                // 
+----------------+-------------------+----------------+---------------------------+----------------------+
                //   Region 2
                // 
+----------------+-------------------+----------------+---------------------------+----------------------+
                //    Start            Event               Next             Action 
                  Guard
                // 
+----------------+-------------------+----------------+---------------------------+----------------------+
                Row < AllOk          , Spi::Reply        , ErrorMode      , none 
                , IsECFailed           >
                // 
+----------------+-------------------+----------------+---------------------------+----------------------+
	> {};
        // clang-format on