168 lines
3.4 KiB
Ruby
168 lines
3.4 KiB
Ruby
# --
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# Copyright (C) 2008-2009 10gen Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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# ++
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# A byte buffer.
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class ByteBuffer
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attr_reader :order
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def initialize(initial_data=[])
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@buf = initial_data
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@cursor = 0
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self.order = :little_endian
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end
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# +endianness+ should be :little_endian or :big_endian. Default is :little_endian
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def order=(endianness)
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@order = endianness
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@int_pack_order = endianness == :little_endian ? 'V' : 'N'
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@double_pack_order = endianness == :little_endian ? 'E' : 'G'
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end
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def rewind
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@cursor = 0
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end
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def position
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@cursor
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end
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def position=(val)
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@cursor = val
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end
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def clear
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@buf = []
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rewind
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end
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def size
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@buf.size
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end
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alias_method :length, :size
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def put(byte, offset=nil)
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@cursor = offset if offset
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@buf[@cursor] = byte
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@cursor += 1
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end
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def put_array(array, offset=nil)
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@cursor = offset if offset
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@buf[@cursor, array.length] = array
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@cursor += array.length
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end
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def put_int(i, offset=nil)
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a = []
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[i].pack(@int_pack_order).each_byte { |b| a << b }
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put_array(a, offset)
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end
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def put_long(i, offset=nil)
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offset = @cursor unless offset
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if @int_pack_order == 'N'
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put_int(i >> 32, offset)
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put_int(i & 0xffffffff, offset + 4)
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else
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put_int(i & 0xffffffff, offset)
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put_int(i >> 32, offset + 4)
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end
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end
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def put_double(d, offset=nil)
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a = []
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[d].pack(@double_pack_order).each_byte { |b| a << b }
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put_array(a, offset)
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end
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# If +size+ == nil, returns one byte. Else returns array of bytes of length
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# # +size+.
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def get(len=nil)
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one_byte = len.nil?
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len ||= 1
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check_read_length(len)
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start = @cursor
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@cursor += len
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if one_byte
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@buf[start]
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else
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if @buf.respond_to? "unpack"
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@buf[start, len].unpack("C*")
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else
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@buf[start, len]
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end
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end
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end
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def get_int
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check_read_length(4)
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vals = ""
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(@cursor..@cursor+3).each { |i| vals << @buf[i].chr }
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@cursor += 4
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vals.unpack(@int_pack_order)[0]
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end
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def get_long
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i1 = get_int
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i2 = get_int
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if @int_pack_order == 'N'
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(i1 << 32) + i2
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else
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(i2 << 32) + i1
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end
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end
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def get_double
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check_read_length(8)
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vals = ""
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(@cursor..@cursor+7).each { |i| vals << @buf[i].chr }
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@cursor += 8
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vals.unpack(@double_pack_order)[0]
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end
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def more?
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@cursor < @buf.size
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end
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def to_a
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if @buf.respond_to? "unpack"
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@buf.unpack("C*")
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else
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@buf
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end
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end
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def to_s
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if @buf.respond_to? "pack"
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@buf.pack("C*")
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else
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@buf
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end
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end
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def dump
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@buf.each_with_index { |c, i| $stderr.puts "#{'%04d' % i}: #{'%02x' % c} #{'%03o' % c} #{'%s' % c.chr} #{'%3d' % c}" }
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end
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private
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def check_read_length(len)
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raise "attempt to read past end of buffer" if @cursor + len > @buf.length
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end
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end
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