Class: Kiwi::ByteBuffer

Inherits:
Object
  • Object
show all
Defined in:
lib/kiwi/byte_buffer.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(data = []) ⇒ ByteBuffer

Returns a new instance of ByteBuffer.



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# File 'lib/kiwi/byte_buffer.rb', line 10

def initialize(data = [])
  @data = data
  @index = 0
end

Instance Attribute Details

#data ⇒ Object (readonly) Also known as: bytes

Returns the value of attribute data.



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# File 'lib/kiwi/byte_buffer.rb', line 5

def data
  @data
end

#index ⇒ Object (readonly)

Returns the value of attribute index.



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# File 'lib/kiwi/byte_buffer.rb', line 6

def index
  @index
end

Instance Method Details

#read_bool ⇒ Object 



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# File 'lib/kiwi/byte_buffer.rb', line 39

def read_bool
  read_byte == 0x1
end

#read_byte ⇒ Object 



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# File 'lib/kiwi/byte_buffer.rb', line 15

def read_byte
  if index >= data.length
    raise RangeError, "Index out of bounds"
  else
    value = data[index]
    @index += 1
    value
  end
end

#read_byte_array ⇒ Object 



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# File 'lib/kiwi/byte_buffer.rb', line 25

def read_byte_array
  read_bytes(read_var_uint)
end

#read_bytes(len) ⇒ Object 



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# File 'lib/kiwi/byte_buffer.rb', line 29

def read_bytes(len)
  if index + len > data.length
    raise RangeError, "Read bytes out of bounds"
  else
    value = data[index..(index + len)]
    @index += len
    value
  end
end

#read_string ⇒ Object 



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# File 'lib/kiwi/byte_buffer.rb', line 79

def read_string
  result = []

  loop do
    char = read_byte
    break if char == 0
    result << char
  end

  result.pack("C*").force_encoding("UTF-8")
end

#read_var_float ⇒ Object

Raises:

  • (RangeError) 


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# File 'lib/kiwi/byte_buffer.rb', line 68

def read_var_float
  first = read_byte
  return 0.0 if first == 0
  raise RangeError, "Index out of bounds" if index + 3 > data.length
  bits = first | (data[index] << 8) | (data[index + 1] << 16) | (data[index + 2] << 24)
  bits = (bits << 23) | (bits >> 9) # Move the exponent back into place
  value = [bits].pack("L").unpack("F*")[0]
  @index += 3
  value
end

#read_var_int ⇒ Object 



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# File 'lib/kiwi/byte_buffer.rb', line 43

def read_var_int
  value = read_var_uint

  if (value & 1) != 0
    ~(value >> 1)
  else
    value >> 1
  end
end

#read_var_uint ⇒ Object 



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# File 'lib/kiwi/byte_buffer.rb', line 53

def read_var_uint
  shift = 0
  result = 0

  loop do
    byte = read_byte
    result |= (byte & 127) << shift
    shift += 7

    break if (byte & 128) == 0 || shift >= 35
  end

  result
end

#write_bool(value) ⇒ Object 



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# File 'lib/kiwi/byte_buffer.rb', line 91

def write_bool(value)
  data.push(value ? 0x1 : 0x0)
end

#write_byte(value) ⇒ Object 



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# File 'lib/kiwi/byte_buffer.rb', line 95

def write_byte(value)
  data.push(value & 255)
end

#write_byte_array(value) ⇒ Object 



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# File 'lib/kiwi/byte_buffer.rb', line 99

def write_byte_array(value)
  write_var_uint(value.length)
  data.push(*value)
end

#write_string(value) ⇒ Object 



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# File 'lib/kiwi/byte_buffer.rb', line 135

def write_string(value)
  data.push(*value.bytes)
  data.push(0)
end

#write_var_float(value) ⇒ Object 



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# File 'lib/kiwi/byte_buffer.rb', line 123

def write_var_float(value)
  bits = [value].pack("F*").unpack("L")[0]
  bits = (bits >> 23) | (bits << 9)
  bytes = [bits].pack("L").unpack("C*")

  if (bytes[0] & 255) == 0
    data.push(0)
  else
    data.push(*bytes)
  end
end

#write_var_int(value) ⇒ Object

Write a variable-length signed 32-bit integer to the end of the buffer.



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# File 'lib/kiwi/byte_buffer.rb', line 105

def write_var_int(value)
  write_var_uint((value << 1) ^ (value >> 31))
end

#write_var_uint(value) ⇒ Object 



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# File 'lib/kiwi/byte_buffer.rb', line 109

def write_var_uint(value)
  loop do
    byte = value & 127
    value = value >> 7

    if value == 0
      write_byte(byte)
      return
    end

    write_byte(byte | 128)
  end
end