Helper classes for array optimized byte character set encoding/decoding

2 files changed, 325 insertions, 0 deletions

diff --git a/gnu/java/nio/charset/ByteDecodeLoopHelper.java b/gnu/java/nio/charset/ByteDecodeLoopHelper.java
new file mode 100644
index 000000000..33dfa0263
--- /dev/null
+++ b/gnu/java/nio/charset/ByteDecodeLoopHelper.java
@@ -0,0 +1,162 @@
+/* ByteCharset.java -- Abstract class for generic 1-byte encodings.
+   Copyright (C) 2005 Free Software Foundation, Inc.
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING.  If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library.  Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module.  An independent module is a module which is not derived from
+or based on this library.  If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so.  If you do not wish to do so, delete this
+exception statement from your version. */
+
+package gnu.java.nio.charset;
+
+import java.nio.ByteBuffer;
+import java.nio.CharBuffer;
+import java.nio.charset.CoderResult;
+
+/**
+ * Helper class to deal with decoding loops that read a byte at a time
+ * 
+ * @author Ian Rogers
+ */
+public abstract class ByteDecodeLoopHelper
+{
+  /**
+   * @return can the given byte be encoded
+   */
+  protected abstract boolean isMappable(byte b);
+
+  /**
+   * Map the given byte to a char, the given byte is guaranteed to be mappable
+   */
+  protected abstract char mapToChar(byte b);
+
+  /**
+   * Encodes one or more characters into one or more bytes, mapping each
+   * character to only one byte
+   * 
+   * @param in character buffer to read from
+   * @param out byte buffer to write to
+   * @return the result state of the encoder
+   */
+  CoderResult decodeLoop(ByteBuffer in, CharBuffer out)
+  {
+    if (in.hasArray() && out.hasArray())
+      {
+        return arrayDecodeLoop(in, out);
+      } else
+      {
+        return normalDecodeLoop(in, out);
+      }
+  }
+
+  /**
+   * Encode loop using get and put operations
+   */
+  private CoderResult normalDecodeLoop(ByteBuffer in, CharBuffer out)
+  {
+    int outRemaining = out.remaining();
+    int inRemaining = in.remaining();
+    while (inRemaining > 0 && outRemaining > 0)
+      {
+        byte b = in.get();
+        inRemaining--;
+
+        if (!isMappable(b))
+          {
+            in.position(in.position() - 1);
+            return CoderResult.unmappableForLength(1);
+          }
+        char c = mapToChar(b);
+        out.put(c);
+        outRemaining--;
+      }
+    if (inRemaining > 0)
+      {
+        return CoderResult.OVERFLOW;
+      } else
+      {
+        return CoderResult.UNDERFLOW;
+      }
+  }
+
+  /**
+   * Encode loop using array read and write operations
+   */
+  private CoderResult arrayDecodeLoop(ByteBuffer in, CharBuffer out)
+  {
+    byte[] inArray = in.array();
+    char[] outArray = out.array();
+    int inPos = in.arrayOffset() + in.position();
+    int outPos = out.arrayOffset() + out.position();
+    int inRemaining = in.remaining();
+    int outRemaining = out.remaining();
+    CoderResult result;
+    if (inRemaining <= outRemaining)
+      {
+        for (int i = 0; i < inRemaining; i++)
+          {
+            byte b = inArray[inPos];
+            inPos++;
+            if (!isMappable(b))
+              {
+                inPos--;
+                result = CoderResult.unmappableForLength(1);
+                break;
+              }
+            char c = mapToChar(b);
+            outArray[outPos] = c;
+            outPos++;
+          }
+        result = CoderResult.UNDERFLOW;
+      }
+    else
+      {
+        for (int i = 0; i < outRemaining; i++)
+          {
+            byte b = inArray[inPos];
+            inPos++;
+            if (!isMappable(b))
+              {
+                inPos--;
+                result = CoderResult.unmappableForLength(1);
+                break;
+              }
+            char c = mapToChar(b);
+            outArray[outPos] = c;
+            outPos++;
+          }
+        result = CoderResult.OVERFLOW;
+      }
+    in.position(inPos - in.arrayOffset());
+    out.position(outPos - out.arrayOffset());
+    return result;
+  }
+}
diff --git a/gnu/java/nio/charset/ByteEncodeLoopHelper.java b/gnu/java/nio/charset/ByteEncodeLoopHelper.java
new file mode 100644
index 000000000..5f703b195
--- /dev/null
+++ b/gnu/java/nio/charset/ByteEncodeLoopHelper.java
@@ -0,0 +1,163 @@
+/* ByteCharset.java -- Abstract class for generic 1-byte encodings.
+   Copyright (C) 2005 Free Software Foundation, Inc.
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING.  If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library.  Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module.  An independent module is a module which is not derived from
+or based on this library.  If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so.  If you do not wish to do so, delete this
+exception statement from your version. */
+
+package gnu.java.nio.charset;
+
+import java.nio.ByteBuffer;
+import java.nio.CharBuffer;
+import java.nio.charset.CoderResult;
+
+/**
+ * Helper class to deal with encoding loops that write a byte at a time
+ * 
+ * @author Ian Rogers
+ */
+public abstract class ByteEncodeLoopHelper
+{
+  /**
+   * @return can the given character be encoded
+   */
+  protected abstract boolean isMappable(char c);
+
+  /**
+   * Map the given character to a byte, the given character is guaranteed to be
+   * mappable
+   */
+  protected abstract byte mapToByte(char c);
+
+  /**
+   * Encodes one or more characters into one or more bytes, mapping each
+   * character to only one byte
+   * 
+   * @param in character buffer to read from
+   * @param out byte buffer to write to
+   * @return the result state of the encoder
+   */
+  CoderResult encodeLoop(CharBuffer in, ByteBuffer out)
+  {
+    if (in.hasArray() && out.hasArray())
+      {
+        return arrayEncodeLoop(in, out);
+      } else
+      {
+        return normalEncodeLoop(in, out);
+      }
+  }
+
+  /**
+   * Encode loop using get and put operations
+   */
+  private CoderResult normalEncodeLoop(CharBuffer in, ByteBuffer out)
+  {
+    int outRemaining = out.remaining();
+    int inRemaining = in.remaining();
+    while (inRemaining > 0 && outRemaining > 0)
+      {
+        char c = in.get();
+        inRemaining--;
+
+        if (!isMappable(c))
+          {
+            in.position(in.position() - 1);
+            return CoderResult.unmappableForLength(1);
+          }
+        byte b = mapToByte(c);
+        out.put(b);
+        outRemaining--;
+      }
+    if (inRemaining > 0)
+      {
+        return CoderResult.OVERFLOW;
+      } else
+      {
+        return CoderResult.UNDERFLOW;
+      }
+  }
+
+  /**
+   * Encode loop using array read and write operations
+   */
+  private CoderResult arrayEncodeLoop(CharBuffer in, ByteBuffer out)
+  {
+    char[] inArray = in.array();
+    byte[] outArray = out.array();
+    int inPos = in.arrayOffset() + in.position();
+    int outPos = out.arrayOffset() + out.position();
+    int inRemaining = in.remaining();
+    int outRemaining = out.remaining();
+    CoderResult result;
+    if (inRemaining <= outRemaining)
+      {
+        for (int i = 0; i < inRemaining; i++)
+          {
+            char inChar = inArray[inPos];
+            inPos++;
+            if (!isMappable(inChar))
+              {
+                inPos--;
+                result = CoderResult.unmappableForLength(1);
+                break;
+              }
+            byte b = mapToByte(inChar);
+            outArray[outPos] = b;
+            outPos++;
+          }
+        result = CoderResult.UNDERFLOW;
+      }
+    else
+      {
+        for (int i = 0; i < outRemaining; i++)
+          {
+            char inChar = inArray[inPos];
+            inPos++;
+            if (!isMappable(inChar))
+              {
+                inPos--;
+                result = CoderResult.unmappableForLength(1);
+                break;
+              }
+            byte b = mapToByte(inChar);
+            outArray[outPos] = b;
+            outPos++;
+          }
+        result = CoderResult.OVERFLOW;
+      }
+    in.position(inPos - in.arrayOffset());
+    out.position(outPos - out.arrayOffset());
+    return result;
+  }
+}