LEB128.scala

import java.nio.ByteBuffer

object LEB128 {
  def write(buffer: ByteBuffer, offset: Int, longValue: Long): Int = {
    var writtenBytes: Int = 0
    var value = longValue

    if (value.abs <= 63) {
      if (value < 0) {
        value = value.abs
        buffer.put(offset, (64 | value).toByte)
      } else {
        buffer.put(offset, value.toByte)
      }
      writtenBytes = 1
    } else {
      if (value < 0) {
        value = value.abs
        buffer.put(offset + writtenBytes, (192 | (value & 63)).toByte)
      } else {
        buffer.put(offset + writtenBytes, (128 | (value & 63)).toByte)
      }
      writtenBytes = 1

      value >>= 6
      while (0 != value) {
        if (value > 127) {
          buffer.put(offset + writtenBytes, (128 | value & 127).toByte)
        } else {
          buffer.put(offset + writtenBytes, (value & 127).toByte)
        }
        writtenBytes += 1

        value >>= 7
      }
    }

    writtenBytes
  }

  def read(buffer: ByteBuffer, offset: Int): (Long, Int) = {
    var readBytes: Int = 0
    var value = 0L
    var negative = false
    if ((64 & buffer.get(offset)) > 0) {
      negative = true
    }

    value += (buffer.get(offset) & 63)
    readBytes = 1

    if (128.toByte == (buffer.get(offset) & 128.toByte)) {
      var j = 6
      while (128.toByte == (buffer.get(offset + readBytes) & 128.toByte)) {
        value += ((buffer.get(offset + readBytes) & 127L) << j)
        readBytes += 1
        j += 7
      }
      value += (buffer.get(offset + readBytes).toLong << j)
      readBytes += 1
    }

    if (negative) {
      value = -value
    }

    (value, readBytes)
  }
}