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Scala example source code file (ByteCodecs.scala)

This example Scala source code file (ByteCodecs.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Scala source code examples by using tags.

All credit for the original source code belongs to scala-lang.org; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Scala tags/keywords

array, byte, bytecodecs, int

The ByteCodecs.scala Scala example source code

/*                     __                                               *\
**     ________ ___   / /  ___     Scala API                            **
**    / __/ __// _ | / /  / _ |    (c) 2007-2013, LAMP/EPFL             **
**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
** /____/\___/_/ |_/____/_/ | |                                         **
**                          |/                                          **
\*                                                                      */
package scala
package reflect.internal.pickling

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 if (in == 0) {
        src(j) = 0x7f
        i += 1
      } 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
  }

  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).toInt
      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).toInt
      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))

  /**
   * Destructively decodes array xs and returns the length of the decoded array.
   *
   * Sometimes returns (length+1) of the decoded array. Example:
   *
   *   scala> val enc = scala.reflect.generic.ByteCodecs.encode(Array(1,2,3))
   *   enc: Array[Byte] = Array(2, 5, 13, 1)
   *
   *   scala> 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)
  }
}

Other Scala source code examples

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