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##
# Ber extensions to the Fixnum class.
module Net::BER::Extensions::Fixnum
##
# Converts the fixnum to BER format.
def to_ber
"\002#{to_ber_internal}"
end
##
# Converts the fixnum to BER enumerated format.
def to_ber_enumerated
"\012#{to_ber_internal}"
end
##
# Converts the fixnum to BER length encodining format.
def to_ber_length_encoding
if self <= 127
[self].pack('C')
else
i = [self].pack('N').sub(/^[\0]+/,"")
[0x80 + i.length].pack('C') + i
end
end
##
# Generate a BER-encoding for an application-defined INTEGER. Examples of
# such integers are SNMP's Counter, Gauge, and TimeTick types.
def to_ber_application(tag)
[0x40 + tag].pack("C") + to_ber_internal
end
##
# Used to BER-encode the length and content bytes of a Fixnum. Callers
# must prepend the tag byte for the contained value.
def to_ber_internal
# CAUTION: Bit twiddling ahead. You might want to shield your eyes or
# something.
# Looks for the first byte in the fixnum that is not all zeroes. It does
# this by masking one byte after another, checking the result for bits
# that are left on.
size = Net::BER::MAX_FIXNUM_SIZE
while size > 1
break if (self & (0xff << (size - 1) * 8)) > 0
size -= 1
end
# Store the size of the fixnum in the result
result = [size]
# Appends bytes to result, starting with higher orders first. Extraction
# of bytes is done by right shifting the original fixnum by an amount
# and then masking that with 0xff.
while size > 0
# right shift size - 1 bytes, mask with 0xff
result << ((self >> ((size - 1) * 8)) & 0xff)
size -= 1
end
result.pack('C*')
end
private :to_ber_internal
end
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