Module: Wardite::Leb128Helper

Included in:
BinaryLoader
Defined in:
lib/wardite/leb128.rb

Class Method Summary collapse

Class Method Details

.fetch_sleb128(buf, max_level: 8) ⇒ Object 



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# File 'lib/wardite/leb128.rb', line 32

def fetch_sleb128(buf, max_level: 8)
  dest = 0
  level = 0
  while b = buf.read(1)
    raise LoadError, "buffer too short" unless b
    c = b.ord

    upper, lower = (c >> 7), (c & (1 << 7) - 1)
    dest |= lower << (7 * level)
    if upper == 0
      break
    end

    if level > max_level
      raise "unreachable! debug: dest = #{dest} level = #{level}"
    end
    level += 1
  end
  shift = 7 * (level + 1) - 1
  return dest | -(dest & (1 << shift))   
end

.fetch_uleb128(buf, max_level: 8) ⇒ Object 



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# File 'lib/wardite/leb128.rb', line 7

def fetch_uleb128(buf, max_level: 8)
  dest = 0
  level = 0
  while b = buf.read(1)
    raise LoadError, "buffer too short" unless b
    c = b.ord
    return c if c < 0x80 && level.zero?

    upper, lower = (c >> 7), (c & (1 << 7) - 1)
    dest |= lower << (7 * level)
    if upper == 0
      return dest
    end

    if level > max_level
      break
    end
    level += 1
  end
  # unreachable but...
  raise "unreachable! debug: dest = #{dest} level = #{level}"
end