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Scala example source code file (ByteCodecs.scala)

This example Scala source code file (ByteCodecs.scala) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Scala tags/keywords

array, array, byte, byte, bytecodecs, bytecodecs, int, int

The Scala ByteCodecs.scala source code

/*                     __                                               *\
**     ________ ___   / /  ___     Scala API                            **
**    / __/ __// _ | / /  / _ |    (c) 2007-2011, LAMP/EPFL             **
**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
** /____/\___/_/ |_/____/_/ | |                                         **
**                          |/                                          **
\*                                                                      */
package scala.reflect.generic

object ByteCodecs { 

  def avoidZero(src: Array[Byte]): Array[Byte] = {
    var i = 0
    val srclen = src.length
    var count = 0
    while (i < srclen) {
      if (src(i) == 0x7f) count += 1
      i += 1
    }
    val dst = new Array[Byte](srclen + count)
    i = 0
    var j = 0
    while (i < srclen) {
      val in = src(i)
      if (in == 0x7f) {
        dst(j) = (0xc0).toByte
        dst(j + 1) = (0x80).toByte
        j += 2
      } else {
        dst(j) = (in + 1).toByte
        j += 1
      }
      i += 1
    }
    dst
  }

  def regenerateZero(src: Array[Byte]): Int = {
    var i = 0
    val srclen = src.length
    var j = 0
    while (i < srclen) {
      val in: Int = src(i) & 0xff
      if (in == 0xc0 && (src(i + 1) & 0xff) == 0x80) {
        src(j) = 0x7f
        i += 2
      } else {
        src(j) = (in - 1).toByte
        i += 1
      }
      j += 1
    }
    j
  }

  def encode8to7(src: Array[Byte]): Array[Byte] = {
    val srclen = src.length
    val dstlen = (srclen * 8 + 6) / 7
    val dst = new Array[Byte](dstlen)
    var i = 0
    var j = 0
    while (i + 6 < srclen) {
      var in: Int = src(i) & 0xff
      dst(j) = (in & 0x7f).toByte
      var out: Int = in >>> 7
      in = src(i + 1) & 0xff
      dst(j + 1) = (out | (in << 1) & 0x7f).toByte
      out = in >>> 6
      in = src(i + 2) & 0xff
      dst(j + 2) = (out | (in << 2) & 0x7f).toByte
      out = in >>> 5
      in = src(i + 3) & 0xff
      dst(j + 3) = (out | (in << 3) & 0x7f).toByte
      out = in >>> 4
      in = src(i + 4) & 0xff
      dst(j + 4) = (out | (in << 4) & 0x7f).toByte
      out = in >>> 3
      in = src(i + 5) & 0xff
      dst(j + 5) = (out | (in << 5) & 0x7f).toByte
      out = in >>> 2
      in = src(i + 6) & 0xff
      dst(j + 6) = (out | (in << 6) & 0x7f).toByte
      out = in >>> 1
      dst(j + 7) = out.toByte
      i += 7
      j += 8
    }
    if (i < srclen) {
      var in: Int = src(i) & 0xff
      dst(j) = (in & 0x7f).toByte; j += 1
      var out: Int = in >>> 7
      if (i + 1 < srclen) {
        in = src(i + 1) & 0xff
        dst(j) = (out | (in << 1) & 0x7f).toByte; j += 1
        out = in >>> 6
        if (i + 2 < srclen) {
          in = src(i + 2) & 0xff
          dst(j) = (out | (in << 2) & 0x7f).toByte; j += 1
          out = in >>> 5
          if (i + 3 < srclen) {
            in = src(i + 3) & 0xff
            dst(j) = (out | (in << 3) & 0x7f).toByte; j += 1
            out = in >>> 4
            if (i + 4 < srclen) {
              in = src(i + 4) & 0xff
              dst(j) = (out | (in << 4) & 0x7f).toByte; j += 1
              out = in >>> 3
              if (i + 5 < srclen) {
                in = src(i + 5) & 0xff
                dst(j) = (out | (in << 5) & 0x7f).toByte; j += 1
                out = in >>> 2
              }
            }
          }
        }
      }
      if (j < dstlen) dst(j) = out.toByte
    }
    dst
  }

  @deprecated("use 2-argument version instead", "2.8.0")
  def decode7to8(src: Array[Byte], srclen: Int, dstlen: Int) { decode7to8(src, srclen) }

  def decode7to8(src: Array[Byte], srclen: Int): Int = {
    var i = 0
    var j = 0
    val dstlen = (srclen * 7 + 7) / 8
    while (i + 7 < srclen) {
      var out: Int = src(i)
      var in: Byte = src(i + 1)
      src(j) = (out | (in & 0x01) << 7).toByte
      out = in >>> 1
      in = src(i + 2)
      src(j + 1) = (out | (in & 0x03) << 6).toByte
      out = in >>> 2
      in = src(i + 3)
      src(j + 2) = (out | (in & 0x07) << 5).toByte
      out = in >>> 3
      in = src(i + 4)
      src(j + 3) = (out | (in & 0x0f) << 4).toByte
      out = in >>> 4
      in = src(i + 5)
      src(j + 4) = (out | (in & 0x1f) << 3).toByte
      out = in >>> 5
      in = src(i + 6)
      src(j + 5) = (out | (in & 0x3f) << 2).toByte
      out = in >>> 6
      in = src(i + 7)
      src(j + 6) = (out | in << 1).toByte
      i += 8
      j += 7
    }
    if (i < srclen) {
      var out: Int = src(i)
      if (i + 1 < srclen) {
        var in: Byte = src(i + 1)
        src(j) = (out | (in & 0x01) << 7).toByte; j += 1
        out = in >>> 1
        if (i + 2 < srclen) {
          in = src(i + 2)
          src(j) = (out | (in & 0x03) << 6).toByte; j += 1
          out = in >>> 2
          if (i + 3 < srclen) {
            in = src(i + 3)
            src(j) = (out | (in & 0x07) << 5).toByte; j += 1
            out = in >>> 3
            if (i + 4 < srclen) {
              in = src(i + 4)
              src(j) = (out | (in & 0x0f) << 4).toByte; j += 1
              out = in >>> 4
              if (i + 5 < srclen) {
                in = src(i + 5)
                src(j) = (out | (in & 0x1f) << 3).toByte; j += 1
                out = in >>> 5
                if (i + 6 < srclen) {
                  in = src(i + 6)
                  src(j) = (out | (in & 0x3f) << 2).toByte; j += 1
                  out = in >>> 6
                }
              }
            }
          }
        }
      }
      if (j < dstlen) src(j) = out.toByte
    }
    dstlen
  }

  def encode(xs: Array[Byte]): Array[Byte] = avoidZero(encode8to7(xs))

  @deprecated("use 1-argument version instead", "2.8.0")
  def decode(xs: Array[Byte], dstlen: Int) { decode(xs) }

  /**
   * Destructively decodes array xs and returns the length of the decoded array.
   *
   * Sometimes returns (length+1) of the decoded array. Example:
   *
   *   scala> val enc = reflect.generic.ByteCodecs.encode(Array(1,2,3))
   *   enc: Array[Byte] = Array(2, 5, 13, 1)
   *
   *   scala> reflect.generic.ByteCodecs.decode(enc)
   *   res43: Int = 4
   *
   *   scala> enc
   *   res44: Array[Byte] = Array(1, 2, 3, 0)
   *
   * However, this does not always happen.
   */
  def decode(xs: Array[Byte]): Int = {
    val len = regenerateZero(xs)
    decode7to8(xs, len)
  }
}

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