Difference between revisions of "MIDAS Event Construction"

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==MIDAS event construction==
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{{Pagelinks}}
  
The  [[MIDAS Event Structure]] is a variable length event format.  
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== Introduction ==
It uses [[MIDAS Event Structure #MIDAS Data Bank |banks]] as
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The  [[MIDAS Event Structure]] is a variable length event format. It uses [[MIDAS Event Structure #MIDAS Data Bank |banks]] as subsets of an event.
subsets of an event.
 
  
Usually a bank contains an array of values that logically belong
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Usually a bank contains an array of values that logically belong together. For example, an experiment can generate an ADC bank, a TDC bank and a bank with trigger information. The length of a bank can vary from one event to another due to zero suppression from the hardware. Besides the variable data length support of the bank structure, another main advantage is the possibility for the analyzer to add more (calculated) banks during the analysis process to the event in process. After the first analysis stage, the event can contain in addition to the the raw ADC bank, a bank with calibrated ADC values called CADC for example. In this CADC bank the raw ADC values could be offset or gain-corrected.
together. For example, an experiment can generate an ADC bank, a TDC bank and a
 
bank with trigger information. The length of a bank can vary from one event to
 
another due to zero suppression from the hardware. Besides the variable data length
 
support of the bank structure, another main advantage is the possibility for the
 
analyzer to add more (calculated) banks during the analysis process to the event
 
in process. After the first analysis stage, the event can contain in addition to the
 
the raw ADC bank, a bank with calibrated ADC values called CADC for example.
 
In this CADC bank the raw ADC values could be offset or gain-corrected.
 
  
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==Creation of MIDAS banks==
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[[MIDAS Event Structure #MIDAS Data Bank |MIDAS banks]] may be created in the [[Frontend user code|Frontend User Code]] with calls to the MIDAS library.
  
[[Midas Data Types]]
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The following routines are available in the MIDAS package :
Midas defines its own <b> data types </b> for OS compatibility. It is suggested that you use them
 
in order to ensure correct compilation when moving code from one OS to another.
 
  
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* '''bk_init()'''  Initializes a bank structure in an event with a 16-bit word event size field
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* '''bk_init32()'''  Similar to '''bk_init()''' with a 32-bit word event size field
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* '''bk_init32a()'''  Similar to '''bk_init32()''' with a 64-bit bank alignment
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* '''bk_create()''' Creates a bank with a given name (exactly four characters)
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* '''bk_close()''' Closes a bank previously opened with bk_create()
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* '''bk_copy()''' Copy bank given by name into pointed event
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* '''bk_locate()''' Locates a bank within an event by its name
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* '''bk_iterate()''' Returns bank and data pointers to each bank in the event
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* '''bk_list()''' Constructs a string with all the banks' names in the event
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* '''bk_size()''' Returns the size in bytes of all banks including the bank headers in an event
  
\em float and \em double retain OS definition.
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The first four routines are for creation of banks (e.g. in a frontend), while the last four are used to process the banks (e.g. in an analyzer).
  
- BYTE      unsigned char
 
- WORD      unsigned short int (16bits word)
 
- DWORD    unsigned 32bits word
 
- INT      signed 32bits word
 
- BOOL      OS dependent.
 
  
When defining a data type either in the frontend code for bank definition or in user code
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An example of MIDAS bank construction in a frontend can be found in a [[Frontend user code#General readout function|frontend readout routine]]. Many more examples are available in the [[Frontend user code#Introduction|frontend templates provided]].
to define ODB variables, Midas requires the use of its own data type declaration. The list
 
below shows the main Type IDentification to be used (refer to @ref mdefineh
 
for complete listing):
 
  
- TID_BYTE      unsigned byte        0      255
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[[Category:Event]]
- TID_SBYTE    signed BYTE        -128      127
 
- TID_CHAR      single character      0      255
 
- TID_WORD      two BYTE            0      65535
 
- TID_SHORT    signed WORD        -32768    32767
 
- TID_DWORD    four bytes            0      2**32-1
 
- TID_INT      signed DWORD        -2**31    2**31-1
 
- TID_BOOL      four bytes bool      0        1 
 
- TID_FLOAT    four bytes float format   
 
- TID_DOUBLE    eight bytes float format               
 
 
 
<hr>
 
\anchor idx_Midas_bank
 
@subsection FE_creation_Midas_banks Creation of MIDAS banks
 
 
 
MIDAS banks are created in the frontend readout code with calls to the MIDAS library.
 
The following routines are available:
 
- bk_init() , bk_init32() Initializes a bank structure in an event.
 
    <br>Note that bk_init32 can be used to reduce the size of very large banks, where the
 
    data will fit into a 32-bit word
 
- bk_create() Creates a bank with a given name (exactly four characters)
 
- bk_close() Closes a bank previously opened with bk_create().
 
- bk_locate() Locates a bank within an event by its name.
 
- bk_iterate() Returns bank and data pointers to each bank in the event.
 
- bk_list() Constructs a string with all the banks' names in the event.
 
- bk_size() Returns the size in bytes of all banks including the bank
 
headers in an event.
 

Latest revision as of 11:46, 6 April 2020


Introduction

The MIDAS Event Structure is a variable length event format. It uses banks as subsets of an event.

Usually a bank contains an array of values that logically belong together. For example, an experiment can generate an ADC bank, a TDC bank and a bank with trigger information. The length of a bank can vary from one event to another due to zero suppression from the hardware. Besides the variable data length support of the bank structure, another main advantage is the possibility for the analyzer to add more (calculated) banks during the analysis process to the event in process. After the first analysis stage, the event can contain in addition to the the raw ADC bank, a bank with calibrated ADC values called CADC for example. In this CADC bank the raw ADC values could be offset or gain-corrected.

Creation of MIDAS banks

MIDAS banks may be created in the Frontend User Code with calls to the MIDAS library.

The following routines are available in the MIDAS package :

  • bk_init() Initializes a bank structure in an event with a 16-bit word event size field
  • bk_init32() Similar to bk_init() with a 32-bit word event size field
  • bk_init32a() Similar to bk_init32() with a 64-bit bank alignment
  • bk_create() Creates a bank with a given name (exactly four characters)
  • bk_close() Closes a bank previously opened with bk_create()
  • bk_copy() Copy bank given by name into pointed event
  • bk_locate() Locates a bank within an event by its name
  • bk_iterate() Returns bank and data pointers to each bank in the event
  • bk_list() Constructs a string with all the banks' names in the event
  • bk_size() Returns the size in bytes of all banks including the bank headers in an event

The first four routines are for creation of banks (e.g. in a frontend), while the last four are used to process the banks (e.g. in an analyzer).


An example of MIDAS bank construction in a frontend can be found in a frontend readout routine. Many more examples are available in the frontend templates provided.