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  240   23 Dec 2005 Stefan RittInfomidas max event size?
> My TPC events are fairly large: 18 FEC cards * 128 channels per card * 2 Kbytes
> per channel = about 4 Mbytes. In my
> frontend, when I request this event size, MIDAS complaints (in mfe.c) that it is
> bigger than MAX_EVENT_SIZE, which
> is set to 0.5 Mbytes in midas.h. What is the best way to deal with this? Should
> we increase MAX_EVENT_SIZE to
> something bigger? Remove the MAX_EVENT_SIZE limitation altogether?

If you teach me how to remove the MAX_EVENT_SIZE, that would be perfect!

Unfortunately the limit comes from the shared memory on the back end (the so-called
"SYSTEM" shared memory). Due to the structure of the buffer manager, the shared
memory has to hold at least two events simultaneously. And once the shared memeory
is created, it's size cannot be changed without restarting all the clients. That's
the origin of the MAX_EVENT_SIZE. In former days, the total allowed shared memory on
a typical linux machine was 2MB. That's why I set MAX_EVENT_SIZE to 0.5 MB, so midas
takes 2*0.5MB=1MB plus 0.2MB for the ODB, leaving 0.8MB for other applications.
Nowadays, the shared memory might be bigger (actually it's a parameter during kernel
compilation), so one could consider increasing the default MAX_EVENT_SIZE. If you
make a survey of the shared memory sizes in some of the current distributions, we
can choose a safe value.

> For now, I increased the value MAX_EVENT_SIZE & co to (10*1024*1024) and it
> seems to work (I also had to bump the
> sanity check in bm_open_buffer() from 10E6 to 100E6). With 1/4 of the FEC cards,
> the event size is 1 Mbyte at ~6
> ev/sec the machine is almost idle, with the biggest CPU user being the event
> builder at 10% CPU utilization.

I made sure that there is no other limitation as the one given by MAX_EVENT_SIZE, so
it should work fine. Thanks for telling me the wrong sanity check, that should be
changed in the repository.
  239   22 Dec 2005 Konstantin OlchanskiInfoHow do I do custom event building?
It turns out the the standard event builder fragment matching algorithm cannot
be used in my TPC application. I have two TPC-USB interfaces, which lack any
"busy" or synchronization logic. I send the hardware trigger into both
interfaces, and if one of them misses it, the data is out of sync forever. Consider:

Hardware
trigger    trig1     trig2    trig3    trig4
TPC01      serial1   serial2  serial3  serial4
TPC02      serial1  (missing) serial2  serial3

With the event builder matching only the event serial numbers, the first event
will be okey, but the second event will have trig2 data from TPC01 and trig3
data from TPC02, etc.

The problem exists even if the TPC-USB interfaces do not miss any triggers:
during begin and end of run, the interfaces are enabled one at a time, so if a
trigger arrives after the first interface was enabled, but before the second is
enabled, the data starts being out of sync (and if the same happens during the
end-of-run, the event counts from both frontends will match, but all data would
*still* be out of sync).

Obviously additional data is needed to match the fragments.

So in each frontend, I have a high-precision timestamp (gettimeofday(), usec
resolution) and I would like to have the event builder match the timestamps
instead of event serial numbers. What is the best way to do this? The mevb.c
code does not have any user callbacks for checking "do these fragments belong to
the same event?".

P.S. The event rate will be about 1/sec from cosmic ray tests and at most
10-50/sec in the M11 beam line at TRIUMF, at these low rates, the gettimeofday()
timestamps should be adequate.

K.O.
  238   22 Dec 2005 Konstantin OlchanskiInfomidas max event size?
My TPC events are fairly large: 18 FEC cards * 128 channels per card * 2 Kbytes
per channel = about 4 Mbytes. In my
frontend, when I request this event size, MIDAS complaints (in mfe.c) that it is
bigger than MAX_EVENT_SIZE, which
is set to 0.5 Mbytes in midas.h. What is the best way to deal with this? Should
we increase MAX_EVENT_SIZE to
something bigger? Remove the MAX_EVENT_SIZE limitation altogether?
  
For now, I increased the value MAX_EVENT_SIZE & co to (10*1024*1024) and it
seems to work (I also had to bump the
sanity check in bm_open_buffer() from 10E6 to 100E6). With 1/4 of the FEC cards,
the event size is 1 Mbyte at ~6
ev/sec the machine is almost idle, with the biggest CPU user being the event
builder at 10% CPU utilization.

K.O.
  237   14 Dec 2005 Konstantin OlchanskiBug Reportmisc problems
I would like to document a few problems I ran into while setting up a new
experiment (two USB interfaces to Alice TPC electronics, plus maybe a USB
interface to CAMAC). I am using a midas cvs checkout from last October, so I am
not sure if these problems exist in the very latest code. I have fixes for all
of them and I will commit them after some more testing and after I figure out
how to commit into this new svn thingy.

- mxml: writing xml into an in-memory buffer probably produces invalid xml
because one of the mxml functions always writes "/>" into writer->fh, which is 0
for in-memory writers, so the "/>" tag goes to the console instead of the xml
data stream.

- hs_write_event() closes fd 0 (standard input), which confuses ss_getch(),
which makes mlogger not work (at least on my machine). I traced this down to the
history file file descriptors being initialized to zero and hs_write_event()
closing files without checking that it ever opened them.

- mevb: event builder did not work with a single frontend (a two-liner fix, once
Pierre showed me where to look. Why? My second TPC-USB interface did not yet
arrive and I wanted to test my frontend code. Yes, it had enough bugs to prevent
the event builder from working).

- mevb: consumes 100% CPU. Fix: add a delay in the main busy-loop.

- mlogger ROOT tree output does not work for data banks coming through the event
builder: mlogger looks for the bank definition under the event_id of mevb, in 
/equipment/evb/variables, which is empty, as the data banks are under
/equipment/frontendNN/variables. This may be hard to fix: bank "TPCA" may be
under "fe01", "TPCB" under "fe02" and mlogger knows nothing about any of this.
Fix: go back to .mid files.

K.O.
  236   02 Dec 2005 Greg HackmanInfoMIDAS on Cygwin
If you want to run MIDAS on Cygwin, make sure you have cygserver running. First set a Windows system environment variable CYGWIN=server. This is best done through the Control Panel -> System -> Advanced -> Environment Variables. Then run /usr/bin/cygserver-config in a Cygwin console window. Then reboot. After that your MIDAS executables should run properly.

If cygserver is not running, one (obvious) symptom is that odbedit fails immediately with a "Bad system call" error.

I've only tested this so far with odbedit and an offline analyzer that generates histograms in the same structure . Both of those work properly.
  235   23 Nov 2005 Stefan RittBug FixEndian swapping in mana.c
It was reported that following code in mana.c :
  /* swap event header if in wrong format */
  if (pevent->serial_number > 0x1000000) {
     WORD_SWAP(&pevent->event_id);
     WORD_SWAP(&pevent->trigger_mask);
     DWORD_SWAP(&pevent->serial_number);
     DWORD_SWAP(&pevent->time_stamp);
     DWORD_SWAP(&pevent->data_size);
  }

does not work correctly for events having a true serial number above 16777216 (=0x10000000). After some considerations, I concluded that there is no good way to determine automatically the endian format of midas events, without adding another field in the header, which would break the compatibility with all recorded data up to date. I therefore changed the above code to
  /* swap event header if in wrong format */
#ifdef SWAP_EVENTS
  WORD_SWAP(&pevent->event_id);
  WORD_SWAP(&pevent->trigger_mask);
  DWORD_SWAP(&pevent->serial_number);
  DWORD_SWAP(&pevent->time_stamp);
  DWORD_SWAP(&pevent->data_size);
#endif

So if one wants to analyze events with the midas analyzer on a PC system for example where the events come from a VxWorks system with the opposite endian encoding, one has to set the flag -DSWAP_EVENTS when compiling the analyzer for that type of analysis.
  234   06 Nov 2005 Stefan RittSuggestionWhere to put drivers?

Stefan Ritt wrote:
We have both the example experiment and the MSCB Makefile which both expect to find the midas drivers under $MIDASSYS/drivers/camac or $MIDASSYS/drivers/usb. The documentation does not explicitely mention to define MIDASSYS as /usr/local, but some people do it. That however requires to put all drivers then under /usr/local/drivers, which is not the case in the current Makefile for midas. Do you think that we should add this? Or should we better ask (->documentation) people to define MIDASSYS to wherever they install the midas package (usually /usr/home/<name>/midas or so)?



Pierre-André Amaudruz wrote:

The purpose of the MIDASSYS introduction was to permit the placement of the package in the user area as well as publishing the Midas entry point. Doing so, we lessen the necessity to "install" Midas in the standard OS directory such as /opt or /usr/local. Static linking, use of rpath, new "make minimal_install" go in that direction.
Regarding the drivers, organizing the directories per hardware type (camac, vme, fastbus, usb, etc) seems better to me. Originally, we mostly dealt with CAMAC and therefore the diverse Makefile had a default reference to /drivers/bus/(camacrpc). Now that we removed cnaf/rpc from the automatic mfe build, it indicates that CAMAC is no longer the prime hardware. Then we should leave open to the user the selection of the hardware and document the necessity for him/her to adjust the build appropriately ( $MIDASSYS/drivers/<HW_type> ). The different Makefile examples should be adjusted to the proper driver location they're dealing with.
Pierre-André


I agree with what you say. So I will include the drivers in the ("full") install to be copied under /usr/local/drivers, just for the people using midas in an "installed" way, but we keep the possibility to use a minimal_install to skip the driver installation.
  233   06 Nov 2005 Pierre-Andre AmaudruzSuggestionWhere to put drivers?

Stefan Ritt wrote:
Hi,

I would like to raise the question where to put the midas drivers.

We have both the example experiment and the MSCB Makefile which both expect to find the midas drivers under $MIDASSYS/drivers/camac or $MIDASSYS/drivers/usb. The documentation does not explicitely mention to define MIDASSYS as /usr/local, but some people do it. That however requires to put all drivers then under /usr/local/drivers, which is not the case in the current Makefile for midas. Do you think that we should add this? Or should we better ask (->documentation) people to define MIDASSYS to wherever they install the midas package (usually /usr/home/<name>/midas or so)?

Looking forward to hear your opinion,

Stefan



Pierre-André Amaudruz wrote:

The purpose of the MIDASSYS introduction was to permit the placement of the package in the user area as well as publishing the Midas entry point. Doing so, we lessen the necessity to "install" Midas in the standard OS directory such as /opt or /usr/local. Static linking, use of rpath, new "make minimal_install" go in that direction.
Regarding the drivers, organizing the directories per hardware type (camac, vme, fastbus, usb, etc) seems better to me. Originally, we mostly dealt with CAMAC and therefore the diverse Makefile had a default reference to /drivers/bus/(camacrpc). Now that we removed cnaf/rpc from the automatic mfe build, it indicates that CAMAC is no longer the prime hardware. Then we should leave open to the user the selection of the hardware and document the necessity for him/her to adjust the build appropriately ( $MIDASSYS/drivers/<HW_type> ). The different Makefile examples should be adjusted to the proper driver location they're dealing with.
Pierre-André
  232   02 Nov 2005 Stefan RittSuggestionWhere to put drivers?
Hi,

I would like to raise the question where to put the midas drivers.

We have both the example experiment and the MSCB Makefile which both expect to find the midas drivers under $MIDASSYS/drivers/camac or $MIDASSYS/drivers/usb. The documentation does not explicitely mention to define MIDASSYS as /usr/local, but some people do it. That however requires to put all drivers then under /usr/local/drivers, which is not the case in the current Makefile for midas. Do you think that we should add this? Or should we better ask (->documentation) people to define MIDASSYS to wherever they install the midas package (usually /usr/home/<name>/midas or so)?

Looking forward to hear your opinion,

Stefan
  231   02 Nov 2005 Pierre-Andre AmaudruzInfonew mvmestd api
> I manage to access some vme modules with the older vmicvme interface and seemed
> confused with the
> new interface as the sample code provided does not have a specific test sample.
> The test code
> provided in the earlier version for accessing  V792 32ch. QDC was quite handy,
> how can I apply it
> for the new interface?  

Hello Ian,

I'm in the process of updating the V1190B, V792 and other to the new mvmestd.
These drivers will soon be committed to the repository.

Cheers, Pierre-André 
  230   02 Nov 2005 I. K. arapkorirInfonew mvmestd api
I manage to access some vme modules with the older vmicvme interface and seemed
confused with the
new interface as the sample code provided does not have a specific test sample.
The test code
provided in the earlier version for accessing  V792 32ch. QDC was quite handy,
how can I apply it
for the new interface?  
  229   17 Oct 2005 Exaos LeeBug Fix"make install" error under MacOS X
Under MacOS X, "make install" will cours an error like this:
...
install: darwin/bin/dio: No such file or directory
make: *** [install] Error 71

This can be fixed as the following diff:
404,405c404,405
< $(BIN_DIR)/mcnaf: $(UTL_DIR)/mcnaf.c $(DRV_DIR)/camac/camacrpc.c
<       $(CC) $(CFLAGS) $(OSFLAGS) -o $@ $(UTL_DIR)/mcnaf.c $(DRV_DIR)/camac/camacrpc.c $(LIB) $(LIBS)
---
> $(BIN_DIR)/mcnaf: $(UTL_DIR)/mcnaf.c $(DRV_DIR)/bus/camacrpc.c
>       $(CC) $(CFLAGS) $(OSFLAGS) -o $@ $(UTL_DIR)/mcnaf.c $(DRV_DIR)/bus/camacrpc.c $(LIB) $(LIBS)
438c438,439
<       @for i in mserver mhttpd odbedit mlogger ; \
---
> 
>       @for i in mserver mhttpd odbedit mlogger dio ; \
444,447d444
<       chmod +s $(SYSBIN_DIR)/mhttpd
< 
< ifeq ($(OSTYPE),linux)
<       install -v -m 755 $(BIN_DIR)/dio $(SYSBIN_DIR)
449c446
< endif
---
>       chmod +s $(SYSBIN_DIR)/mhttpd
  228   15 Oct 2005 Exaos LeeInfoBus drivers moved in repository
The Makefile should be modified too. Please see the diff below:
diff Makefile Makefile.modify
-------------------------------------
404,405c404,405
< $(BIN_DIR)/mcnaf: $(UTL_DIR)/mcnaf.c $(DRV_DIR)/bus/camacrpc.c
<       $(CC) $(CFLAGS) $(OSFLAGS) -o $@ $(UTL_DIR)/mcnaf.c $(DRV_DIR)/bus/camacrpc.c $(LIB) $(LIBS)
---
> $(BIN_DIR)/mcnaf: $(UTL_DIR)/mcnaf.c $(DRV_DIR)/camac/camacrpc.c
>       $(CC) $(CFLAGS) $(OSFLAGS) -o $@ $(UTL_DIR)/mcnaf.c $(DRV_DIR)/camac/camacrpc.c $(LIB) $(LIBS)
  227   10 Oct 2005 Stefan RittInfoBus drivers moved in repository
The previous midas/drivers/bus dirctory contains both midas slow control bus drivers plus vme & fastbus & camac drivers. I separated them now in different directories:

midas/drivers/bus
midas/drivers/camac
midas/drivers/vme
midas/drivers/fastbus

which is a more appropriate structure. Doing this in subversion was really simple and showed me that the moveover to subversion was worth it.
  226   07 Oct 2005 Stefan RittInfoMIDAS moved from CVS to Subversion
Dear Midas users,

I have moved midas from CVS to Subversion today. There were many reasons for doing so, which I don't want to explain in detail here. To use the new repository, there a several things to note:

  • Anonymous checkout can be done now with
    svn co svn+ssh://svn@savannah.psi.ch/afs/psi.ch/project/meg/svn/midas/trunk midas
    svn co svn+ssh://svn@savannah.psi.ch/afs/psi.ch/project/meg/svn/mxml/trunk mxml

    Use password svn (you might have to enter it several times). The mxml package is now outside from midas, so you have to check it out separately.
  • Non-anonymous access (for commits!) is only possible if you have an account at PSI. While it is possible via
    svn co svn+ssh://<your_name>@savannah.psi.ch/afs/psi.ch/project/meg/svn/midas/trunk midas
    it is more convenient if you access the repository via AFS, since then you only have to obtain a valid AFS token once a day and do not have to supply passwords on each SVN access
  • Before you do a checkout, delete (or rename) your old CVS working directory
  • Subversion does not use file revisions, but a global revision number for the whole repository, which is now at 2752. To get some idea about subversion, read this very good book
  • The Web access to the repository is at http://savannah.psi.ch/viewcvs/trunk/?root=midas
  • The ViewCVS web interface allows on-the-fly generation of TAR balls from the current repository. Just click on the link Download tarball
  • The old CVS repository has been switched to read-only and will be completely closed in a few weeks
  • The machine midas.psi.ch will in the near future not be available any more for any repository
  • All the $Log: tags in the midas files have been replaced by $Id: tags, since the former ones are not supported by SVN (for good reasons actually). To view the change log, do a svn log <filename>.

For the windows users, I have some additional notes:

  • Do not use the Cygwin subversion package, but the binaries from here if you plan to access the SVN repository through AFS at PSI (or other places where AFS is available). If you map the AFS repository for example to "Y:", then the binaries access this under file:///Y:/svn/meg/... whicl the cygwin ones access this under file:///cygwin/y/svn/meg/... While this is ok in principle, it gives a conflict with the TortoiseSVN which expects the first path. So if you want to use command line utilities together with TortoiseSVN, the Cygwin package won't work.
  • Use the TortoiseSVN package. It's really great! It has a very nice "diff" viewer/merger, it's integrated into the Windows explorer, has a spell checker for composing comments for commits, etc.
  • For the SVN binaries under Windows, you have to set the environment variable LANG=en_US, otherwise svn will talk in German to you on a standard PSI Windows PC.

If there are any problems in accessing the new repository, please let me know.

Note: This elog entry has been updated since the original one did have a wrong username in the SVN URL.
  225   03 Oct 2005 Stefan RittInfoRevised MVMESTD API
Dear MIDAS users and developers,

The "Midas VME Standard API" has been revised. We tried to incorporate all
comments and ideas we got so far. The mvme_ioctl() function was abandoned in
favor of several mvme_get/set_xxx functions. Furthermore, two additional
functions for read and write have been implemented to simplify writing/reading
single values to VME. The current API looks like this:

int mvme_open(MVME_INTERFACE **vme, int index);
int mvme_close(MVME_INTERFACE *vme);
int mvme_sysreset(MVME_INTERFACE *vme);
int mvme_read(MVME_INTERFACE *vme, void *dst, mvme_addr_t vme_addr,
              mvme_size_t n_bytes);
DWORD mvme_read_value(MVME_INTERFACE *vme, mvme_addr_t vme_addr);
int mvme_write(MVME_INTERFACE *vme, mvme_addr_t vme_addr, void *src,
               mvme_size_t n_bytes);
int mvme_write_value(MVME_INTERFACE *vme, mvme_addr_t vme_addr, DWORD value);
int mvme_set_am(MVME_INTERFACE *vme, int am);
int mvme_get_am(MVME_INTERFACE *vme, int *am);
int mvme_set_dmode(MVME_INTERFACE *vme, int dmode);
int mvme_get_dmode(MVME_INTERFACE *vme, int *dmode);
int mvme_set_blt(MVME_INTERFACE *vme, int mode);
int mvme_get_blt(MVME_INTERFACE *vme, int *mode);

The MVME_INTERFACE structure holds all internal data, similar to the FILE
structure in stdio.h. If several VME interfaces (of the same type) are present
in a PC, the function mvme_open can be called once for each crate, specifying
the index. The block transfer modes passed to mvme_set_blt control the usage of
DMA, MBLT64 and so on. Not all interfaces might support all modes, in which case
mvme_set_blt should return MVME_UNSUPPORTED. Then it's up to the user code to
ignore this error or choose a different mode.

So far we have implemented drivers for the SIS3100, SBS617/SBS618 and VMIC
interfaces using this standard. It should be noted that the VMIC uses solely
memory mapped VME I/O, which is completely hidden in the VMIC MVMESTD driver.

We would like to encourage people to switch to the revised MVMESTD API wherever
possible. If new drivers for ADCs and TDCs for example are written using this
standard, groups with different VME interfaces can use them without modification.

Although the standard works now for three different interfaces, it might be that
new interfaces need slight additions. They should be identified as soon as
possible, in order to adapt the MVMESTD quickly and freeze the API soon.

Interrupts are not (yet) implemented in the MVMESTD, because most experiments
use polling anyhow. If there is a need for interrupts by someone, he should come
up quickly with this and make a proposal for implementation.
  224   19 Sep 2005 Konstantin OlchanskiInfoAdded driver for the Wiener CC-USB CAMAC interface
Commited to CVS is the preliminary driver for the Wiener CC-USB CAMAC interface.
The driver implements all the mcstd.h camac access functions, except for those
not supported by hardware (8-bit operations, interrupts) and a few esoteric
functions not implemented in any other camac driver. The driver uses the
musbstd.h library to access USB, also commited in preliminary form.

Affected files:
midas/Makefile (added musbstd.c to libmidas.{a,so})
include/musbstd.h, src/musbstd.c (preliminary USB access library)
drivers/bus/ccusb.{c,h}

Most of the CAMAC access functions have been tested (see comments in ccusb.c).
If you find errors and problems, please email me (olchansk@triumf.ca) or write
an elog reply to this elog message.

Missing is the documentation and finalization of USB access library.
Missing is conformity to some MIDAS coding conventions.

Enjoy,
K.O.
  223   11 Sep 2005 Stefan RittInfonew mvmestd api
> Right, but I can only complete the parts that I thought of and for which I already have
> code. This leaves out support for DMA (read: any block transfers) and interrupts.

DMA should be simple. We have a dma_flag in the MVME_INTERFACE structure, which only needs to
be set with mvme_set_dma_mode(...). The mvme_read/write subroutine then checks this flag and
calls the appropriate routine from the native API. About interrupts I haven't thought so much.
Does TRIUMF use interrupts anywhere? Or are all midas frontends in polled mode?

> Well, all interfaces are different and no amount of software will make them look all the
> same. 
>
> > - "cover" any specialities from the drivers, like memory mapping.
> 
> Exactly. We are facing a tricky task of inventing one API for two completely different
> modes of operation- purely memory mapped access on UniverseII based hardware and message
> passing access for the SIS3100 and VMUSB (Wiener VME-USB2).

Not all the same, but some common denominator. The memory mapped architecture can probably be
hidden in an API. So if one calls mvme_read/write, the routine checks if that region is already
mapped, and maps it if necessary. Then all you need is a proper offset and a memcpy(). Checking
about mapping causes some overhead. You have to check a hash table or a linked list which takes
time. But I think (see previous message) that this overhead should be small compared with the
IO operation. 

> I am now facing this problem with the Wiener CCUSB CAMAC-USB2 interface. I can
> implement all of mcstd.h, but the interface is intended to be used by downloading it with a
> CAMAC readout program and mcstd.h knows nothing about that.

Downloading a program you probably cannot cover with a common API, you are right. The problem
with USB is that you can only make ~1000 transfers per second, even with 2.0. So if you want
more, you need the old list concept.
> > So one should only use explicity vme_read/vme_write functions.
> 
> Rightey-ho. The fly in the ointement is that all VME ADC and TDC drivers in TRIUMF are
> written assuming memory mapped access, and I will not convert them to vme_read/vme_write
> overnight (think of testing).

You don't have to. This question only comes up if you (have to) use a non-memory mapped
interface. You can then either write then two separate drivers, or one driver and two MVME APIs.

> > Now I would like to hear anybody's comments. If we agree on this method, we have to
> > define a complete set of functions mvme_set_xxx.
> 
> We currently require only single-word transfers so we can concentrate on mvme_set_xxx for
> block-transfers later.

I need block transfers end of this month, so we should it include it in our current discussion.
The problem is that I use our (own) DRS2 waveform digitizing board, where each board produces
70kB of data per event. In non-DMA mode, the transfer would take forever.

> > maybe we can make a more generic mvme_set_vme_mode(mode), where mode could be fifomode,
> > 2eVME mode, chained block transfer mode and so on.
> 
> This is a can of worms and I would rather postpone discussion of block transfers. To give
> you a taste: UniverseII does not have a "fifo mode"- it *always* increments the vme address
>  (silly). A fifo mode can be emulated using chained transfers (read 256 bytes from
> addresses A through A+256, then read 256 more from address A, etc.), but the present VMIC
> VME library does not support chained transfers. On VxWorks, we do not even have a driver
> for the DMA engine, so not block transfers there at all.

If a native API does not support block transfer, the MVME driver should just ignore the DMA
setting. A ADC driver might then run slower, but still run. 

> I will now think about and post an updated proposal for mvmestd.h

Please also consider elog:221, I guess this is a cleaner and more flexible way of implementing
any MXXX standard.

- Stefan
  222   10 Sep 2005 Konstantin OlchanskiInfonew mvmestd api
> Good that you brought up the MIDAS VME API again, since this is still not complete, but
> has to be completed soon.

Right, but I can only complete the parts that I thought of and for which I already have
code. This leaves out support for DMA (read: any block transfers) and interrupts.

> Let me summarize the goals:
> - have a single set of functions which can be used with all VME CPUs/Interfaces at our
> institutes. Using this technique, one can change the interface or CPU and still keep
> the same frontend source code. This was already successfully done with the MIDAS CAMAC
> standard (as defined in mcstd.h)

Well, all interfaces are different and no amount of software will make them look all the
same. I am now facing this problem with the Wiener CCUSB CAMAC-USB2 interface. I can
implement all of mcstd.h, but the interface is intended to be used by downloading it with a
CAMAC readout program and mcstd.h knows nothing about that.

> - base any ADC/TDC driver we write on that API, so these modules can be used with any
> CPU/Interface without changing the driver

Right. Most useful.

> - have a simple and easy to understand set of functions

Right.

> - "cover" any specialities from the drivers, like memory mapping.

Exactly. We are facing a tricky task of inventing one API for two completely different
modes of operation- purely memory mapped access on UniverseII based hardware and message
passing access for the SIS3100 and VMUSB (Wiener VME-USB2).

> So one should only use explicity vme_read/vme_write functions.

Rightey-ho. The fly in the ointement is that all VME ADC and TDC drivers in TRIUMF are
written assuming memory mapped access, and I will not convert them to vme_read/vme_write
overnight (think of testing).

> So I would propose the following:
> 
>   mvme_set_crate()   each funciton has a _get_ partner, like mvme_get_crate()
>   mvme_set_address_mode()
>   mvme_set_amod()
>   mvme_set_blocktransfer()
>   mvme_set_fifomode()             // speciality of the SIS3100 interface, write a
>                                   // block of data to the same address
>   ...
> 
>   mvme_read(vme_address, dest_addr, num_bytes);
>   mvme_write(src_addr, vme_address, num_bytes);

This is compatible with what we do now and I will look into implementing this for
VMIC/Linux and MVME/VxWorks interfaces.

> Now I would like to hear anybody's comments. If we agree on this method, we have to
> define a complete set of functions mvme_set_xxx.

We currently require only single-word transfers so we can concentrate on mvme_set_xxx for
block-transfers later.

> If we get a new interface in the
> future which has new functionality (like 2eVME block transfers), we have to change the
> API each time (while with the ioctl() we only would have to add one parameter).

This amounts to the same thing: add a new function or add a new ioctl() call.

> maybe we can make a more generic mvme_set_vme_mode(mode), where mode could be fifomode,
> 2eVME mode, chained block transfer mode and so on.

This is a can of worms and I would rather postpone discussion of block transfers. To give
you a taste: UniverseII does not have a "fifo mode"- it *always* increments the vme address
 (silly). A fifo mode can be emulated using chained transfers (read 256 bytes from
addresses A through A+256, then read 256 more from address A, etc.), but the present VMIC
VME library does not support chained transfers. On VxWorks, we do not even have a driver
for the DMA engine, so not block transfers there at all.

I will now think about and post an updated proposal for mvmestd.h

K.O.

P.S. There is a proposal for musbstd.h heading your way, too.
  221   01 Sep 2005 Stefan RittSuggestionnew mvmestd api
Anothe idea which comes to my mind, we could make it kind of object oriented, like

typedef struct {
  int handle;
  int crate;
  int amod;
  int fifo_mode;
  ...
} MVME_INTERFACE;

main()
{
  MVME_INERFACE *vme;

  vme = mvme_init(); // allocated and fills MVME_INTERFACE structure

  mvme_set_crate(vme, crate_no);
  mvme_set_address_mode(vme, A24);
  ...

  mvme_read(vme, vme_address, dest_addr, num_bytes);
  mvme_exit(vme);    // frees memory allocated in mvme_init()
}

------------------------------------------

This way we would only have one structure containing all required parameters, and get/set
functions for it, like the OO textbooks propose it. This would actually make it thread
save. The "vme" pointer from above still has to be passed around to subroutines, but a
single pointer is better than lots of handles.
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