Added an object to mangle byte arrays into Java...

Added an object to mangle byte arrays into Java classfile's version of
UTF8.

1 files changed, 269 insertions, 0 deletions

diff --git a/src/library/scala/reflect/generic/ByteCodecs.scala b/src/library/scala/reflect/generic/ByteCodecs.scala
new file mode 100644
index 0000000000..a172e425ef
--- /dev/null
+++ b/src/library/scala/reflect/generic/ByteCodecs.scala
@@ -0,0 +1,269 @@
+/*                     __                                               *\
+**     ________ ___   / /  ___     Scala API                            **
+**    / __/ __// _ | / /  / _ |    (c) 2007-2010, LAMP/EPFL             **
+**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
+** /____/\___/_/ |_/____/_/ | |                                         **
+**                          |/                                          **
+\*                                                                      */
+package scala.reflect.generic
+
+object ByteCodecs {
+
+  def bump(src: Array[Byte], len: Int, delta: Int) {
+    var i = 0
+    while (i < len) {
+      val in: Int = src(i) & 0xff
+      src(i) = (in + delta).toByte
+      i += 1
+    }
+  }
+
+  def encodeZeroes(src: Array[Byte]): Array[Byte] = {
+    var i = 0
+    val srclen = src.length
+    var count = 0
+    while (i < srclen) {
+      if (src(i) == 0) 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 == 0) {
+        dst(j) = (0xc0).toByte
+        dst(j + 1) = (0x80).toByte
+        j += 2
+      } else {
+        dst(j) = in
+        j += 1
+      }
+      i += 1
+    }
+    dst
+  }
+
+  def decodeZeroes(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) = 0
+        i += 2
+      } else {
+        src(j) = in.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, dstlen: Int) {
+    var i = 0
+    var j = 0
+    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
+    }
+  }
+
+  def encode(xs: Array[Byte]): Array[Byte] = {
+    val ys = xs.clone()
+    bump(ys, ys.length, 1)
+    encodeZeroes(encode8to7(ys))
+  }
+
+  /** Destructively decode array xs */
+  def decode(xs: Array[Byte], dstlen: Int) {
+    val len = decodeZeroes(xs)
+    decode7to8(xs, len, dstlen)
+    bump(xs, dstlen, -1)
+  }
+
+// test & debug, preliminary ----------------------------------
+
+  def testBump(xs: Array[Byte]) {
+    val xs0 = xs.clone()
+    bump(xs, xs.length, 1)
+    bump(xs, xs.length, -1)
+    assert(xs.deep == xs0.deep, xs0.deep)
+  }
+
+  def testZeroes(xs: Array[Byte]) {
+    val ys = encodeZeroes(xs)
+    val len = decodeZeroes(ys)
+    assert(len == xs.length && ys.take(len).deep == xs.deep,
+           "testZeroes("+xs.deep+") failed; len = "+len+", result = "+ys.take(len).deep)
+  }
+
+  def test8to7(xs: Array[Byte]) {
+    val ys = encode8to7(xs)
+    decode7to8(ys, ys.length, xs.length)
+    assert(ys.take(xs.length).deep == xs.deep,
+           "test8to7("+xs.deep+") failed, result = "+ys.take(xs.length).deep)
+  }
+
+  def testAll(xs: Array[Byte]) {
+    val ys = encode(xs)
+    decode(ys, xs.length)
+    assert(ys.take(xs.length).deep == xs.deep,
+           "testAll("+xs.deep+") failed, result = "+ys.take(xs.length).deep)
+  }
+
+  def test(inputs: Array[Byte]*) {
+    for (input <- inputs) {
+      testBump(input)
+      test8to7(input)
+      testAll(input)
+    }
+  }
+
+  def main(args: Array[String]) {
+    test(
+      Array(1, 2, 3),
+      Array(1, 2, 3, 4, 5, 6, 7),
+      Array(1, -2, 0, -3, -5, -6, -7),
+      Array(1, 3, -1, -128, 0, 0, -128, 1, 2, 3))
+    val rand = new scala.util.Random()
+    for (i <- 1 until 50000) {
+      if (i % 100 == 0) println("tested "+i)
+      var xs = new Array[Byte](i)
+      rand.nextBytes(xs)
+      test(xs)
+    }
+    println("tested OK")
+  }
+}
+
+
+
+
+
+
+
+