ancillaryFile.py

#!/usr/local/bin/python
#
#                               Copyright 2006
#                                     by
#                        The Board of Trustees of the
#                     Leland Stanford Junior University.
#                            All rights reserved.
#

__facility__ = "Online"
__abstract__ = "Read ancillary event contributions from a file"
__author__   = "R. Claus <Claus@SLAC.Stanford.edu> SLAC - GLAST LAT I&T/Online"
__date__     = "3/30/2006"
__updated__  = ("$Date: 2006/07/19 16:08:33 $").split(' ')[1]
__version__  = "$Revision: 1.2 $"
__release__  = "$Name: R04-12-00 $"
__credits__  = "SLAC"

import LATTE.copyright_SLAC

import struct
from   array   import array
import logging as     log

import LATTE.merger.geb                   as     geb
from   LATTE.merger.ancillaryContribution import AncillaryContribution


class AncillaryContributor(geb.GebContributor):
  __typeIds = [AncillaryContribution.EventId,
               AncillaryContribution.HeaderId,
               AncillaryContribution.TrailerId]
  def __init__(self, filename, offset = 0):
    geb.GebContributor.__init__(self)
    self.__filename  = filename
    self.__fakeEvent = struct.pack("<3L", AncillaryContribution.EventId, 3*4, 0xdeadbeefL)
    self.__offset = offset

  def name(self):
    return "Anc"

  def offset(self):
    return self.__offset

  def open(self):
    self.__file = file(self.__filename, 'rb')
    print "AncContrib.open: %s opened" % (self.__filename)

  def close(self):
    self.__file.close()

  def read(self):
    """!\brief Method to read an ancillary contribution from a file.
    """
    data = self.__file.read(8)
    if len(data) == 0:  raise EOFError, "AncContrib.read: End of file on %s" % (self.__filename)
    (vTypeId, length) = struct.unpack('<2L', data)
    typeId = vTypeId & 0x000fffff
    if typeId not in AncillaryContributor.__typeIds:
      raise KeyError, "AncContrib.read: Unrecognized contribution %08x" % (vTypeId)
    length &= 0x0fffffff
    #print "AncContrib.read:   id = %08x, len = %08x" % (typeId,length)
    #data  += self.__file.read(length - 8)
    #data = array('I', data)

    #!\todo Improve the swapping if possible, i.e. avoid a copy
    data = array('I', (vTypeId, length))
    data.fromfile(self.__file, (length - 8) / 4)
    data.byteswap()
    data = data.tostring()

    status = 0
    if typeId == AncillaryContribution.EventId:
      return geb.Geb.Build,     status, AncillaryContribution(self, data)
    else:
      return geb.Geb.DontBuild, status, AncillaryContribution(self, data)

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