Dear MIDAS users,

I want to add several .root-files produced by the MIDAS analyzer, in a fast 
and convenient way. ROOT's hadd fails because it does not know how to treat 
TFolders. I guess this problem is not unique to me, so I hope that somebody of 
you might already have found a solution.

Why don't I just run "analyzer -r 1 10000"?
We have taken lots of runs under (rapidly) varying conditions, so it would be 
lots of "-r". And the analysis is quite involved, so rerunning all data takes 
about one hour on a fast PC making this quite painful.
Therefore, I would like to rerun all data only once, and then add the result 
files depending on different criteria.

Of course, I tried to write a script that does the adding. But somehow it is 
incredibly slow. And I am not the Master Of C++, too.

Is there any deeper reason for MIDAS using TFolders, not TDirectorys? ROOT's 
hadd can treat TDirectory. Can I simply patch "my" MIDAS? Is there general 
interest in a change like this? (Does anyone have experience with the speed of 
hadd?)

Looking forward to comments from the Forum.

Cheers,

Randolf

> Dear Stephan,
> 
> I am writting on behalf of the LiBeRACE collaboration
> at Berkeley/Livermore.
> 
> We are trying to use midas (2.0.0) for our acquisition system.
> However we had some difficulties to compile it on LINUX Fedora
> Core 6 with gcc 4.1.1
> I tried to trace back the problem and I found that _syscall0 in
> system.c is actually an obsolete call (since gcc 4.x apparently).
> Playing with assembly language being behond my competence, I would 
> like to know if you ever came across this situation recently and
> if you have any suggestion(s).

The '_syscall0' function call was replaced by 'syscall' in SVN revision 3583. I
would recommend that you switch to the current SVN version (see
http://ladd00.triumf.ca/~daqweb/doc/midas/html/quickstart.html on how to obtain
the SVN version). If the problem still persists, please let us know.

- Stefan

Dear Stephan,

I am writting on behalf of the LiBeRACE collaboration
at Berkeley/Livermore.

We are trying to use midas (2.0.0) for our acquisition system.
However we had some difficulties to compile it on LINUX Fedora
Core 6 with gcc 4.1.1
I tried to trace back the problem and I found that _syscall0 in
system.c is actually an obsolete call (since gcc 4.x apparently).
Playing with assembly language being behond my competence, I would 
like to know if you ever came across this situation recently and
if you have any suggestion(s).

With my best regards
Julien GIBELIN


------------------------------------------------------
GIBELIN Julien

Lawrence Berkeley National Laboratory
Nuclear Science Division
One Cyclotron Rd.
MS 88R0192
BERKELEY, CA 94720-8101

Tel: +1 (510) 495-2695
Fax: +1 (510) 486-7983
------------------------------------------------------

> Hi,
>     I found that midas banks can be given an extra 32 bits of zeros when
> trying to keep to 32bit boundary on my x86_64. 
> 
> This can be fixed by changing (in midas.h)
> #define ALIGN8(x)  (((x)+7) & ~7)
> to
> #define ALIGN8(x)  (((x)+3) & ~3)
> 
> Is there any bad consequences doing this?

Yes. ALIGN8 means 'align to 8-byte boundary' (64-bit), and if you change that, you
break the code at various locations. Furthermore, 8-byte aligned access is faster
on x86_64 than 4-byte aligned access, so you will get a performance penalty. If
course if you have very many small banks, the zero padding can cause some
overhead, but in that case you could combine some data into a single bank.

Hi,
    I found that midas banks can be given an extra 32 bits of zeros when
trying to keep to 32bit boundary on my x86_64. 

This can be fixed by changing (in midas.h)
#define ALIGN8(x)  (((x)+7) & ~7)
to
#define ALIGN8(x)  (((x)+3) & ~3)

Is there any bad consequences doing this?

The ROODY online histogram viewer and the ROOTANA midas analyzer toolkit have been updated to work 
with ROOT version 5.16 and tested on Linux (SL4.4) and MacOS (10.4.10/PPC).

This update includes the library called "TNetDirectory" for access to remote ROOT objects. This library is 
still under development, but is complete enough for use with ROODY. To try it, please specify -P9091 in 
rootana and -Plocalhost:9091 in ROODY.

K.O.

We had the problem that different experiments used different MAX_EVENT_SIZE
values (the MEG experiment actually 10 MB!). If each experiment changes the
value in midas.h and accidentally commits it, other experiments are affected.
Therefore I modified midas.h and the Makefile to accept a new environment
variable MIDAS_MAX_EVENT_SIZE. If this value is set, the Makefile passes it's
value to midas.h where it supersedes the default value which is currently at 4 MB.

PAA: Can you pleas add this to the documentation at the right spot? Thanks.

> I am having problems with handling the end-of-run situation in my midas
> frontend. I have a device that continuously sends data (over USB) and I read
> this data in my "read_event" function.
> 
> Everything is good until the end-of-run, at which time this happens:
> 0) mfe.c calls my read_event() to read the data (loop until the end-of-run
> transition)
> 1) mfe.c calls my end_of_run()
> 2) here, I tell the device "please stop sending data"
> 3) all seems good, but wait!!!
> 4) there is all this data generated between step 0 and step 2 still sitting
> inside the device and it has nowhere to go: the run is ended, the output file is
> closed, my read_event() will never be called ever again (well, until the next run).
> 
> It seems to me mfe.c needs to have one more function, something like
> "pre_end_of_run()" that works like this:
> 0) mfe.c calls my read_event() to read the data (loop until the end-of-run
> transition)
> 1) mfe.c calls pre_end_of_run(), here I tell the device to stop sending data
> 2) mfe.c calls read_event() for the very last time, to give me the opportunity
> to read and send away any data I still may have.
> 3) mfe.c calls the end_of_run(). The run is truely finished.
> 
> Any thoughts?

You can achieve the desired functionality without changing mfe.c:

0) mfe.c calls read_event
1) mfe.c calls end_of_run. Your end_of_run tells the device to stop data and flushes
the remaining data. At this point you have to re-make actually a part of the mfe.c
functionality, but basically you need a bm_compose_event() and a bm_send_event(), so
just a few lines of code. If you want to have the final event number right in your
equipment, you also need to update eq->events_sent accordingly. 

Given the fact that 99% of the experiments do not need this functionality, I propose
that we keep mfe.c and you add the few lines of code into your user part of the
specific frontend.

Stefan

I now commited the changes to mlogger (mlogger.c, msystem.h) implementing data
compression using zlib (svn revision 3845)

To enable compression, observe that mlogger is compiled with -DHAVE_ZLIB (see
the Makefile), in "/Logger/Channels/NNN/Settings", set "compression" to "1" and
the filename to "run%05d.mid.gz" (note the suffix ".gz").

In the Makefile, I only enabled HAVE_ZLIB for Linux, as that is the only
platform I tested. If somebody can test compression on Windows, please do and
let us know.

My ROOT analyzer (rootana) package can read compressed MIDAS files directly and
if one wants to add this capability to other MIDAS-related packages, one is
welcome to use my TMidasFile.cxx as an example
(http://ladd00.triumf.ca/viewcvs/rootana/trunk/TMidasFile.cxx?view=markup).

K.O.

> > > I agree to make 32-bit and 64-bit compatible. In the long run, everything will be 64-bit, so I would suggest
> > > in breaking the 32-bit ODB, add some padding there where needed, probably with some conditional compiling.
> > 1) midas.h: remove unused field "dispatch" from EVENT_REQUEST and bump DATABASE_VERSION from 2 to 3
> > 2) msystem.h: add 32-bit padding to CHN_STATISTICS and CHN_SETTINGS

I am now trying a different solution of to fixing the issue of CHN_STATISTICS and CHN_SETTINGS changing size.

1) midas.h: (same as before) remove unused field "dispatch" from EVENT_REQUEST and bump DATABASE_VERSION from 2 to 3
2) msystem.h: in CHN_STATISTICS and CHN_SETTINGS change type of "event_limit" and "files_written" from int to "double".

Below are the latest ODBv3 meta patches:

ladd03:midas$ svn diff
Index: include/midas.h
===================================================================
--- include/midas.h     (revision 3844)
+++ include/midas.h     (working copy)
 /* has to be changed whenever binary ODB format changes */
-#define DATABASE_VERSION 2
+#define DATABASE_VERSION 3
.........
    short int trigger_mask;       /**< trigger mask                    */
    INT sampling_type;            /**< GET_ALL, GET_SOME, GET_FARM     */
-                                 /**< dispatch function */
-   void (*dispatch) (HNDLE, HNDLE, EVENT_HEADER *, void *);
 } EVENT_REQUEST;

Index: include/msystem.h
===================================================================
--- include/msystem.h   (revision 3845)
+++ include/msystem.h   (working copy)
-"Event limit = DWORD : 0",\
+"Event limit = DOUBLE : 0",\
..................
-"Files written = INT : 0",\
+"Files written = DOUBLE : 0",\
..................
-   DWORD event_limit;
+   double event_limit;
..................
-   INT files_written;
+   double files_written;

K.O.

> > I commited the latest driver for the Wiener CCUSB USB-CAMAC driver. It
> > implements all functions from mcstd.h and has been tested to be plug-compatible
> > with at least one of our CAMAC frontends. K.O.

Well, it took almost a year to finish an updated driver, which has now been
commited to MIDAS SVN (see http://savannah.psi.ch/viewcvs/trunk/drivers/camac/ccusb/?root=midas).

This supports ccusb firmware release 0x402. With earlier firmware, simple CAMAC operations should work,
but to use the readout list feature one has to have the latest main firmware (0x402 as of today) and the latest CPLD
firmware.

The driver kit includes:
- the "ccusb" driver which implements the MIDAS mcstd.h CAMAC interface;
- test_ccusb to probe the interface and generally make the lights flash;
- ccusb_flash for updating the ccusb main firmware (assembled from bits and pieces found on the CCUSB driver CD);
- feccusb, an example midas frontend, which uses the ccusb readout list feature and has extensive error handling,
should be good enough for production use (unlike the Wiener libxxusb drivers, which lack basic error handling).
- analyzer.cxx, an rootana-based example on how to decode the ccusb data;
- README file with release notes.

If you use this driver, please drop me an email (even if it works perfectly for you, hah!) - the ccusb device is very
nice but can be hard to use and I would like to hear about problems other people have with it.

Today's version of the README files is attached below:

MIDAS driver for the Wiener/JTec CC-USB CAMAC-USB interface.

Date: 22-AUG-2007/KO

Note 1: The CC-USB interface comes with a CD which contains manuals,
firmware files, Windows and Linux software. The Wiener/JTec driver
is called "libxxusb". These MIDAS/musbstd drivers were written before
libxxusb bacame available and do not use libxxusb.

This driver implements the MIDAS CAMAC interafce "mcstd.h" using
the MIDAS USB interface musbstd.h.

Note 2: There exist many revisions of CCUSB firmware. Basic CAMAC
access works in all of them, but the "readout list" feature seems
to be only functional with firmware revision 0x402 or older and
with CPLD revisions CC_atmmgr_101406.jed, CC_datamgr_021905.jed,
CC_lammgr_brdcst_041906.jed or older.

To upgrade the main CCUSB firmware, follow instructions from
the CCUSB manual. On Linux, one can use the ccusb_flash
program included with these MIDAS drivers. It is a copy
of ccusb_flash from the Wiener CD, with all the pieces
assembled into one place and with a working Makefile. (I am too
lazy to add the flashing bits to the ccusb.c driver).

To upgrade the CPLD firmware, one needs a Xilinx JTag programmer
cable (we use a "parallel port to JTag" cable provided by Wiener),
and the Xilinx software (on Linux, we use Xilinx91i). For successful
upgrade, follow instructions from Xilinx and Wiener.

Note 3: Before starting to use the CCUSB interface, one should obtain
the latest version of the CCUSB manual and firmware by downloading
the latest version the CCUSB driver CD from the Wiener web
site (registration required)

Note 4: The example CCUSB frontend assumes this hardware configuration:
LeCroy 2249A 12 channel ADC in slot 20, Kinetic Systems 3615 6 channel
scaler in slot 12. NIM trigger input connected to CCUSB input "I1"
firing at 10-100 Hz. Without the external trigger CCUSB will not
generate any data and the frontend will only give "data timeout"
errors. With the trigger, the LED on the scaler should flash at 1 Hz
and the LEDs on the CCUSB should flash at the trigger rate.

Note 5: The CCUSB interface does not reliably power up in some CAMAC
crates (this has something to do with the sequence in which
different voltages start at different times with different CAMAC
power supplies). Some newer CCUSB modules may have this
problem fixed in the hardware and in the CPLD firmware. For modules
exhibiting this problem (i.e. no USB communication after power up),
try to cycle the power several time, or implement the "hardware reset
switch" (ask Wiener).

Note 6: The CCUSB firmware is very fickle and would crash if you look
at it the wrong way. This MIDAS driver tries to avoid all known crashers
and together with the example frontend, can recover from some
of them. Other crashes cannot be recovered from other than by
a hardware reset or power cycle.

//end

I am having problems with handling the end-of-run situation in my midas
frontend. I have a device that continuously sends data (over USB) and I read
this data in my "read_event" function.

Everything is good until the end-of-run, at which time this happens:
0) mfe.c calls my read_event() to read the data (loop until the end-of-run
transition)
1) mfe.c calls my end_of_run()
2) here, I tell the device "please stop sending data"
3) all seems good, but wait!!!
4) there is all this data generated between step 0 and step 2 still sitting
inside the device and it has nowhere to go: the run is ended, the output file is
closed, my read_event() will never be called ever again (well, until the next run).

It seems to me mfe.c needs to have one more function, something like
"pre_end_of_run()" that works like this:
0) mfe.c calls my read_event() to read the data (loop until the end-of-run
transition)
1) mfe.c calls pre_end_of_run(), here I tell the device to stop sending data
2) mfe.c calls read_event() for the very last time, to give me the opportunity
to read and send away any data I still may have.
3) mfe.c calls the end_of_run(). The run is truely finished.

Any thoughts?

K.O.

> > I agree to make 32-bit and 64-bit compatible. In the long run, everything will be 64-bit, so I would suggest
> > in breaking the 32-bit ODB, add some padding there where needed, probably with some conditional compiling.
> 
> I now have the patches to implement this. Changes turned out to be minimal:
> 
> 1) midas.h: remove unused field "dispatch" from EVENT_REQUEST and bump DATABASE_VERSION from 2 to 3
> 2) msystem.h: add 32-bit padding to CHN_STATISTICS and CHN_SETTINGS

The padding of CHN_STATISTICS and CHN_SETTINGS is not working right - somehow mhttpd and mlogger keep recreating the
data in ODB and erasing the padding fields. I am looking into this.

K.O.

> I agree to make 32-bit and 64-bit compatible. In the long run, everything will be 64-bit, so I would suggest
> in breaking the 32-bit ODB, add some padding there where needed, probably with some conditional compiling.

I now have the patches to implement this. Changes turned out to be minimal:

1) midas.h: remove unused field "dispatch" from EVENT_REQUEST and bump DATABASE_VERSION from 2 to 3
2) msystem.h: add 32-bit padding to CHN_STATISTICS and CHN_SETTINGS

(Pedantic note: the C/C++ languages permit compilers to arbitrary pad data members inside structures and one is
not supposed to rely on the specific layout of "struct"s, they could changing from day to day depending on
compiler vendor, version, 32/64 bit, optimization level, etc. This is quite silly, but I guess it was the only way
"they" could agree on a standard)

In practice, compilers are will behaved and one can follow simple rules and stay out of trouble.
1) if all data members are of the same size -> no padding
2) do not use "double" (64-bit) and "short" (16-bit), make all char[] arrays divisible by 4 -> size of everything
is 32-bit, see rule 1
3) if you have to use "short", they have to come in pairs to keep everything else aligned to 32-bit
4) if you have to use "double" (or uint64_t), keep them aligned to 64-bit, i.e. struct { int a,b,c; double x;} is
*bad* (4-byte padding may be added between c and x). struct { int a,b,c,d; double x; } is good.

Below are is "svn diff include/midas.h include/msystem.h". These changes have been tested on SL4 32-bit and
64-bit, SL5 32/64, F7 32/64 and SL4/ICC (Intel compiler) 32 bit and 64 bit.

The testing was done by adding checks on sizes of all struct's kept on ODB, i.e.
   assert(sizeof(CHN_SETTINGS        ) ==    640); // ODB v3 with padding
   assert(sizeof(CHN_STATISTICS      ) ==     32); // ODB v3 with padding
   ... etc ...

K.O.

ladd03:midas$ svn diff include/midas.h include/msystem.h
Index: include/midas.h
===================================================================
--- include/midas.h     (revision 3798)
+++ include/midas.h     (working copy)
@@ -38,7 +38,7 @@
  *  @{  */

 /* has to be changed whenever binary ODB format changes */
-#define DATABASE_VERSION 2
+#define DATABASE_VERSION 3

 /* MIDAS version number which will be incremented for every release */
 #define MIDAS_VERSION "2.0.0"
@@ -810,8 +810,6 @@
    short int event_id;           /**< event ID                        */
    short int trigger_mask;       /**< trigger mask                    */
    INT sampling_type;            /**< GET_ALL, GET_SOME, GET_FARM     */
-                                 /**< dispatch function */
-   void (*dispatch) (HNDLE, HNDLE, EVENT_HEADER *, void *);
 } EVENT_REQUEST;

 typedef struct {
Index: include/msystem.h
===================================================================
--- include/msystem.h   (revision 3798)
+++ include/msystem.h   (working copy)
@@ -454,6 +454,7 @@
    INT event_id;
    INT trigger_mask;
    DWORD event_limit;
+   INT pad; // FIXME 64-bit "double" should be 64-bit aligned
    double byte_limit;
    double tape_capacity;
    char subdir_format[32];
@@ -465,6 +466,7 @@
    double bytes_written;
    double bytes_written_total;
    INT files_written;
+   INT pad; // FIXME pad data structure to be 64-bit aligned
 } CHN_STATISTICS;

 typedef struct {
ladd03:midas$

> I had to change the pointer type of mvme_read and mvme_write to (void *) instead
> to (mvme_locaddr_t *) to avoid warnings under 64-bit linux. Please adjust your
> VME drivers if necessary.

Updated: vmicvme.c (VMIVME-7750/7805) and gefvme.c (GEFANUC V7865)

K.O.

I had to change the pointer type of mvme_read and mvme_write to (void *) instead
to (mvme_locaddr_t *) to avoid warnings under 64-bit linux. Please adjust your
VME drivers if necessary.

- Stefan

> The biggest problem here is that making 32-bit ODB and 64-bit ODB compatible requires breaking one or
> the other (My proposed changes break the 64-bit version. Alternatively, one could add explicit padding
> to these data structures and break the 32-bit ODB).
> 
> I think it is important to make 32-bit and 64-bit code compatible: at TRIUMF we have to use a mixed
> environment because out latest host computers all run 64-bit Linux while all our VME processors and all
> older machines can only run 32-bit code; this incompatibility causes us weekly headaches.
> 
> Any thoughts?

I agree to make 32-bit and 64-bit compatible. In the long run, everything will be 64-bit, so I would suggest
in breaking the 32-bit ODB, add some padding there where needed, probably with some conditional compiling.
This ensures to keep the native 64-bit packing, which probably will be somehow optimized for 64-bit
architectures and therefore might be a bit faster in the long run, when most systems are 64-bit. After this
has been implemented and well tested, I would go with an official announcement of the 32-bit break in the ODB,
and release a new version, so people can update from a TAR file if necessary. Existing ODB's can be converted
to the new format by exporting them in XML form and importing them again after the upgrade.

> We run 64-bit MIDAS on RHEL4 with 64-bit ROOT and everything generally works,
> except for compatibility problems with 32-bit MIDAS.
> 
> The big problem is that 64-bit and 32-bit ODB turned out to be incompatible ...

I have now identified 3 data structures that change size when compiled with "-m64":

EVENT_REQUEST: stores a pointer to a function. Pointer size is 4 bytes with -m32 and 8 bytes with -m64.
This structure is part of an array inside BUFFER_HEADER, resulting in a sizable size mismatch between 32
bit and 64 bit shared memory data buffers.

The fix is simple: the function pointer is not used anywhere. Replace is with a "DWORD unused_filler"
makes -m32 and -m64 data buffers compatible. (But breaks compatibility with previous -m64 compiled midas).

CHN_SETTINGS and CHN_STATISTICS: apparently, -m32 and -m64 GCC has different packing rules and in -m64
mode, 4 bytes of padding are added to these data structures. Size size mismatch appears to be benign,
but will result in "size mismatch" complaints from ODB.

The fix is simple: adding "__attribute__ ((__packed__))" to the definition of the data structure makes
-m64 identical to -m32.

The "svn diff" of changes involved is attached below.

The biggest problem here is that making 32-bit ODB and 64-bit ODB compatible requires breaking one or
the other (My proposed changes break the 64-bit version. Alternatively, one could add explicit padding
to these data structures and break the 32-bit ODB).

I think it is important to make 32-bit and 64-bit code compatible: at TRIUMF we have to use a mixed
environment because out latest host computers all run 64-bit Linux while all our VME processors and all
older machines can only run 32-bit code; this incompatibility causes us weekly headaches.

Any thoughts?

K.O.

(this output of svn diff is doctored for clarity)

ladd00:midas$ svn diff
Index: include/midas.h
===================================================================
--- include/midas.h     (revision 3744)
+++ include/midas.h     (working copy)
-   void (*dispatch) (HNDLE, HNDLE, EVENT_HEADER *, void *);
+   INT unused; // was void (*dispatch) (HNDLE, HNDLE, EVENT_HEADER *, void *);
 } EVENT_REQUEST;
 
--- include/msystem.h   (revision 3744)
+++ include/msystem.h   (working copy)

+#define PACKED __attribute__ ((__packed__))  <--- this goes into midas.h inside the #ifdef "we use GCC"
 
-typedef struct {
+typedef struct PACKED { ... CHN_SETTINGS
 
-typedef struct {
+typedef struct PACKED { ... CHN_STATISTICS

> I commited a few minor changes to musbstd and mscb code...
>
> The basic functions work with the MSCB USB master, but I still need to
> investigate some cases where the connection hangs and usb communications do not
> work until the USB cable is unplugged and plugged back in. I see this problem
> both on MacOS and Linux.

I think I fixed the hangs we see on linux and macos - at the end all I had to do is
issue a usb reset to make mscb communicate again.

Also tested on Linux FC6 and SL4.5.

K.O.

#include <stdio.h>
  
int main(){
   int ii = 1;
   float* ff = (float*)&ii;
   *ff = 2;
   printf("%d\n", ii);
   return 0;
} 

warning: dereferencing type-punned pointer will break strict-aliasing rules

#include <stdio.h>

typedef struct xxx {int ii;} XX;
  
int main(){
   XX a;
   a.ii = 1;
   *(short*)&a.ii = 0;
   printf("%d\n", a.ii);
   return 0;
}

#include <stdio.h>
#include <string.h>
#include <malloc.h>
  
int main(){
   int *ii = (int*)malloc(8);
   ii[0] = 1;
   ii[1] = 2;
   float* ff = (float*)ii;
   ff[0] = 3;
   ff[1] = 4;
   printf("%d %d\n", ii[0], ii[1]);
   return 0;
}