/*
 * Copyright (c) 2006, 2016, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * questions.
 */

package sun.security.provider;

import static java.lang.Integer.reverseBytes;
import static java.lang.Long.reverseBytes;

import java.nio.ByteOrder;

import sun.misc.Unsafe;

Optimized methods for converting between byte[] and int[]/long[], both for
big endian and little endian byte orders.
Currently, it includes a default code path plus two optimized code paths.
One is for little endian architectures that support full speed int/long
access at unaligned addresses (i.e. x86/amd64). The second is for big endian
architectures (that only support correctly aligned access), such as SPARC.
These are the only platforms we currently support, but other optimized
variants could be added as needed.
NOTE that ArrayIndexOutOfBoundsException will be thrown if the bounds checks
failed.
This class may also be helpful in improving the performance of the
crypto code in the SunJCE provider. However, for now it is only accessible by
the message digest implementation in the SUN provider.
Author:
 Andreas Sterbenz
Since:
  1.6/**
 * Optimized methods for converting between byte[] and int[]/long[], both for
 * big endian and little endian byte orders.
 *
 * Currently, it includes a default code path plus two optimized code paths.
 * One is for little endian architectures that support full speed int/long
 * access at unaligned addresses (i.e. x86/amd64). The second is for big endian
 * architectures (that only support correctly aligned access), such as SPARC.
 * These are the only platforms we currently support, but other optimized
 * variants could be added as needed.
 *
 * NOTE that ArrayIndexOutOfBoundsException will be thrown if the bounds checks
 * failed.
 *
 * This class may also be helpful in improving the performance of the
 * crypto code in the SunJCE provider. However, for now it is only accessible by
 * the message digest implementation in the SUN provider.
 *
 * @since   1.6
 * @author  Andreas Sterbenz
 */
final class ByteArrayAccess {

    private ByteArrayAccess() {
        // empty
    }

    private static final Unsafe unsafe = Unsafe.getUnsafe();

    // whether to use the optimized path for little endian platforms that
    // support full speed unaligned memory access.
    private static final boolean littleEndianUnaligned;

    // whether to use the optimzied path for big endian platforms that
    // support only correctly aligned full speed memory access.
    // (Note that on SPARC unaligned memory access is possible, but it is
    // implemented using a software trap and therefore very slow)
    private static final boolean bigEndian;

    private final static int byteArrayOfs = unsafe.arrayBaseOffset(byte[].class);

    static {
        boolean scaleOK = ((unsafe.arrayIndexScale(byte[].class) == 1)
            && (unsafe.arrayIndexScale(int[].class) == 4)
            && (unsafe.arrayIndexScale(long[].class) == 8)
            && ((byteArrayOfs & 3) == 0));

        ByteOrder byteOrder = ByteOrder.nativeOrder();
        littleEndianUnaligned =
            scaleOK && unaligned() && (byteOrder == ByteOrder.LITTLE_ENDIAN);
        bigEndian =
            scaleOK && (byteOrder == ByteOrder.BIG_ENDIAN);
    }

    // Return whether this platform supports full speed int/long memory access
    // at unaligned addresses.
    // This code was copied from java.nio.Bits because there is no equivalent
    // public API.
    private static boolean unaligned() {
        String arch = java.security.AccessController.doPrivileged
            (new sun.security.action.GetPropertyAction("os.arch", ""));
        return arch.equals("i386") || arch.equals("x86") || arch.equals("amd64")
            || arch.equals("x86_64") || arch.equals("ppc64") || arch.equals("ppc64le");
    }

    
byte[] to int[] conversion, little endian byte order.
/**
     * byte[] to int[] conversion, little endian byte order.
     */
    static void b2iLittle(byte[] in, int inOfs, int[] out, int outOfs, int len) {
        if ((inOfs < 0) || ((in.length - inOfs) < len) ||
            (outOfs < 0) || ((out.length - outOfs) < len/4)) {
            throw new ArrayIndexOutOfBoundsException();
        }
        if (littleEndianUnaligned) {
            inOfs += byteArrayOfs;
            len += inOfs;
            while (inOfs < len) {
                out[outOfs++] = unsafe.getInt(in, (long)inOfs);
                inOfs += 4;
            }
        } else if (bigEndian && ((inOfs & 3) == 0)) {
            inOfs += byteArrayOfs;
            len += inOfs;
            while (inOfs < len) {
                out[outOfs++] = reverseBytes(unsafe.getInt(in, (long)inOfs));
                inOfs += 4;
            }
        } else {
            len += inOfs;
            while (inOfs < len) {
                out[outOfs++] = ((in[inOfs    ] & 0xff)      )
                              | ((in[inOfs + 1] & 0xff) <<  8)
                              | ((in[inOfs + 2] & 0xff) << 16)
                              | ((in[inOfs + 3]       ) << 24);
                inOfs += 4;
            }
        }
    }

    // Special optimization of b2iLittle(in, inOfs, out, 0, 64)
    static void b2iLittle64(byte[] in, int inOfs, int[] out) {
        if ((inOfs < 0) || ((in.length - inOfs) < 64) ||
            (out.length < 16)) {
            throw new ArrayIndexOutOfBoundsException();
        }
        if (littleEndianUnaligned) {
            inOfs += byteArrayOfs;
            out[ 0] = unsafe.getInt(in, (long)(inOfs     ));
            out[ 1] = unsafe.getInt(in, (long)(inOfs +  4));
            out[ 2] = unsafe.getInt(in, (long)(inOfs +  8));
            out[ 3] = unsafe.getInt(in, (long)(inOfs + 12));
            out[ 4] = unsafe.getInt(in, (long)(inOfs + 16));
            out[ 5] = unsafe.getInt(in, (long)(inOfs + 20));
            out[ 6] = unsafe.getInt(in, (long)(inOfs + 24));
            out[ 7] = unsafe.getInt(in, (long)(inOfs + 28));
            out[ 8] = unsafe.getInt(in, (long)(inOfs + 32));
            out[ 9] = unsafe.getInt(in, (long)(inOfs + 36));
            out[10] = unsafe.getInt(in, (long)(inOfs + 40));
            out[11] = unsafe.getInt(in, (long)(inOfs + 44));
            out[12] = unsafe.getInt(in, (long)(inOfs + 48));
            out[13] = unsafe.getInt(in, (long)(inOfs + 52));
            out[14] = unsafe.getInt(in, (long)(inOfs + 56));
            out[15] = unsafe.getInt(in, (long)(inOfs + 60));
        } else if (bigEndian && ((inOfs & 3) == 0)) {
            inOfs += byteArrayOfs;
            out[ 0] = reverseBytes(unsafe.getInt(in, (long)(inOfs     )));
            out[ 1] = reverseBytes(unsafe.getInt(in, (long)(inOfs +  4)));
            out[ 2] = reverseBytes(unsafe.getInt(in, (long)(inOfs +  8)));
            out[ 3] = reverseBytes(unsafe.getInt(in, (long)(inOfs + 12)));
            out[ 4] = reverseBytes(unsafe.getInt(in, (long)(inOfs + 16)));
            out[ 5] = reverseBytes(unsafe.getInt(in, (long)(inOfs + 20)));
            out[ 6] = reverseBytes(unsafe.getInt(in, (long)(inOfs + 24)));
            out[ 7] = reverseBytes(unsafe.getInt(in, (long)(inOfs + 28)));
            out[ 8] = reverseBytes(unsafe.getInt(in, (long)(inOfs + 32)));
            out[ 9] = reverseBytes(unsafe.getInt(in, (long)(inOfs + 36)));
            out[10] = reverseBytes(unsafe.getInt(in, (long)(inOfs + 40)));
            out[11] = reverseBytes(unsafe.getInt(in, (long)(inOfs + 44)));
            out[12] = reverseBytes(unsafe.getInt(in, (long)(inOfs + 48)));
            out[13] = reverseBytes(unsafe.getInt(in, (long)(inOfs + 52)));
            out[14] = reverseBytes(unsafe.getInt(in, (long)(inOfs + 56)));
            out[15] = reverseBytes(unsafe.getInt(in, (long)(inOfs + 60)));
        } else {
            b2iLittle(in, inOfs, out, 0, 64);
        }
    }

    
int[] to byte[] conversion, little endian byte order.
/**
     * int[] to byte[] conversion, little endian byte order.
     */
    static void i2bLittle(int[] in, int inOfs, byte[] out, int outOfs, int len) {
        if ((inOfs < 0) || ((in.length - inOfs) < len/4) ||
            (outOfs < 0) || ((out.length - outOfs) < len)) {
            throw new ArrayIndexOutOfBoundsException();
        }
        if (littleEndianUnaligned) {
            outOfs += byteArrayOfs;
            len += outOfs;
            while (outOfs < len) {
                unsafe.putInt(out, (long)outOfs, in[inOfs++]);
                outOfs += 4;
            }
        } else if (bigEndian && ((outOfs & 3) == 0)) {
            outOfs += byteArrayOfs;
            len += outOfs;
            while (outOfs < len) {
                unsafe.putInt(out, (long)outOfs, reverseBytes(in[inOfs++]));
                outOfs += 4;
            }
        } else {
            len += outOfs;
            while (outOfs < len) {
                int i = in[inOfs++];
                out[outOfs++] = (byte)(i      );
                out[outOfs++] = (byte)(i >>  8);
                out[outOfs++] = (byte)(i >> 16);
                out[outOfs++] = (byte)(i >> 24);
            }
        }
    }

    // Store one 32-bit value into out[outOfs..outOfs+3] in little endian order.
    static void i2bLittle4(int val, byte[] out, int outOfs) {
        if ((outOfs < 0) || ((out.length - outOfs) < 4)) {
            throw new ArrayIndexOutOfBoundsException();
        }
        if (littleEndianUnaligned) {
            unsafe.putInt(out, (long)(byteArrayOfs + outOfs), val);
        } else if (bigEndian && ((outOfs & 3) == 0)) {
            unsafe.putInt(out, (long)(byteArrayOfs + outOfs), reverseBytes(val));
        } else {
            out[outOfs    ] = (byte)(val      );
            out[outOfs + 1] = (byte)(val >>  8);
            out[outOfs + 2] = (byte)(val >> 16);
            out[outOfs + 3] = (byte)(val >> 24);
        }
    }

    
byte[] to int[] conversion, big endian byte order.
/**
     * byte[] to int[] conversion, big endian byte order.
     */
    static void b2iBig(byte[] in, int inOfs, int[] out, int outOfs, int len) {
        if ((inOfs < 0) || ((in.length - inOfs) < len) ||
            (outOfs < 0) || ((out.length - outOfs) < len/4)) {
            throw new ArrayIndexOutOfBoundsException();
        }
        if (littleEndianUnaligned) {
            inOfs += byteArrayOfs;
            len += inOfs;
            while (inOfs < len) {
                out[outOfs++] = reverseBytes(unsafe.getInt(in, (long)inOfs));
                inOfs += 4;
            }
        } else if (bigEndian && ((inOfs & 3) == 0)) {
            inOfs += byteArrayOfs;
            len += inOfs;
            while (inOfs < len) {
                out[outOfs++] = unsafe.getInt(in, (long)inOfs);
                inOfs += 4;
            }
        } else {
            len += inOfs;
            while (inOfs < len) {
                out[outOfs++] = ((in[inOfs + 3] & 0xff)      )
                              | ((in[inOfs + 2] & 0xff) <<  8)
                              | ((in[inOfs + 1] & 0xff) << 16)
                              | ((in[inOfs    ]       ) << 24);
                inOfs += 4;
            }
        }
    }

    // Special optimization of b2iBig(in, inOfs, out, 0, 64)
    static void b2iBig64(byte[] in, int inOfs, int[] out) {
        if ((inOfs < 0) || ((in.length - inOfs) < 64) ||
            (out.length < 16)) {
            throw new ArrayIndexOutOfBoundsException();
        }
        if (littleEndianUnaligned) {
            inOfs += byteArrayOfs;
            out[ 0] = reverseBytes(unsafe.getInt(in, (long)(inOfs     )));
            out[ 1] = reverseBytes(unsafe.getInt(in, (long)(inOfs +  4)));
            out[ 2] = reverseBytes(unsafe.getInt(in, (long)(inOfs +  8)));
            out[ 3] = reverseBytes(unsafe.getInt(in, (long)(inOfs + 12)));
            out[ 4] = reverseBytes(unsafe.getInt(in, (long)(inOfs + 16)));
            out[ 5] = reverseBytes(unsafe.getInt(in, (long)(inOfs + 20)));
            out[ 6] = reverseBytes(unsafe.getInt(in, (long)(inOfs + 24)));
            out[ 7] = reverseBytes(unsafe.getInt(in, (long)(inOfs + 28)));
            out[ 8] = reverseBytes(unsafe.getInt(in, (long)(inOfs + 32)));
            out[ 9] = reverseBytes(unsafe.getInt(in, (long)(inOfs + 36)));
            out[10] = reverseBytes(unsafe.getInt(in, (long)(inOfs + 40)));
            out[11] = reverseBytes(unsafe.getInt(in, (long)(inOfs + 44)));
            out[12] = reverseBytes(unsafe.getInt(in, (long)(inOfs + 48)));
            out[13] = reverseBytes(unsafe.getInt(in, (long)(inOfs + 52)));
            out[14] = reverseBytes(unsafe.getInt(in, (long)(inOfs + 56)));
            out[15] = reverseBytes(unsafe.getInt(in, (long)(inOfs + 60)));
        } else if (bigEndian && ((inOfs & 3) == 0)) {
            inOfs += byteArrayOfs;
            out[ 0] = unsafe.getInt(in, (long)(inOfs     ));
            out[ 1] = unsafe.getInt(in, (long)(inOfs +  4));
            out[ 2] = unsafe.getInt(in, (long)(inOfs +  8));
            out[ 3] = unsafe.getInt(in, (long)(inOfs + 12));
            out[ 4] = unsafe.getInt(in, (long)(inOfs + 16));
            out[ 5] = unsafe.getInt(in, (long)(inOfs + 20));
            out[ 6] = unsafe.getInt(in, (long)(inOfs + 24));
            out[ 7] = unsafe.getInt(in, (long)(inOfs + 28));
            out[ 8] = unsafe.getInt(in, (long)(inOfs + 32));
            out[ 9] = unsafe.getInt(in, (long)(inOfs + 36));
            out[10] = unsafe.getInt(in, (long)(inOfs + 40));
            out[11] = unsafe.getInt(in, (long)(inOfs + 44));
            out[12] = unsafe.getInt(in, (long)(inOfs + 48));
            out[13] = unsafe.getInt(in, (long)(inOfs + 52));
            out[14] = unsafe.getInt(in, (long)(inOfs + 56));
            out[15] = unsafe.getInt(in, (long)(inOfs + 60));
        } else {
            b2iBig(in, inOfs, out, 0, 64);
        }
    }

    
int[] to byte[] conversion, big endian byte order.
/**
     * int[] to byte[] conversion, big endian byte order.
     */
    static void i2bBig(int[] in, int inOfs, byte[] out, int outOfs, int len) {
        if ((inOfs < 0) || ((in.length - inOfs) < len/4) ||
            (outOfs < 0) || ((out.length - outOfs) < len)) {
            throw new ArrayIndexOutOfBoundsException();
        }
        if (littleEndianUnaligned) {
            outOfs += byteArrayOfs;
            len += outOfs;
            while (outOfs < len) {
                unsafe.putInt(out, (long)outOfs, reverseBytes(in[inOfs++]));
                outOfs += 4;
            }
        } else if (bigEndian && ((outOfs & 3) == 0)) {
            outOfs += byteArrayOfs;
            len += outOfs;
            while (outOfs < len) {
                unsafe.putInt(out, (long)outOfs, in[inOfs++]);
                outOfs += 4;
            }
        } else {
            len += outOfs;
            while (outOfs < len) {
                int i = in[inOfs++];
                out[outOfs++] = (byte)(i >> 24);
                out[outOfs++] = (byte)(i >> 16);
                out[outOfs++] = (byte)(i >>  8);
                out[outOfs++] = (byte)(i      );
            }
        }
    }

    // Store one 32-bit value into out[outOfs..outOfs+3] in big endian order.
    static void i2bBig4(int val, byte[] out, int outOfs) {
        if ((outOfs < 0) || ((out.length - outOfs) < 4)) {
            throw new ArrayIndexOutOfBoundsException();
        }
        if (littleEndianUnaligned) {
            unsafe.putInt(out, (long)(byteArrayOfs + outOfs), reverseBytes(val));
        } else if (bigEndian && ((outOfs & 3) == 0)) {
            unsafe.putInt(out, (long)(byteArrayOfs + outOfs), val);
        } else {
            out[outOfs    ] = (byte)(val >> 24);
            out[outOfs + 1] = (byte)(val >> 16);
            out[outOfs + 2] = (byte)(val >>  8);
            out[outOfs + 3] = (byte)(val      );
        }
    }

    
byte[] to long[] conversion, big endian byte order.
/**
     * byte[] to long[] conversion, big endian byte order.
     */
    static void b2lBig(byte[] in, int inOfs, long[] out, int outOfs, int len) {
        if ((inOfs < 0) || ((in.length - inOfs) < len) ||
            (outOfs < 0) || ((out.length - outOfs) < len/8)) {
            throw new ArrayIndexOutOfBoundsException();
        }
        if (littleEndianUnaligned) {
            inOfs += byteArrayOfs;
            len += inOfs;
            while (inOfs < len) {
                out[outOfs++] = reverseBytes(unsafe.getLong(in, (long)inOfs));
                inOfs += 8;
            }
        } else if (bigEndian && ((inOfs & 3) == 0)) {
            // In the current HotSpot memory layout, the first element of a
            // byte[] is only 32-bit aligned, not 64-bit.
            // That means we could use getLong() only for offset 4, 12, etc.,
            // which would rarely occur in practice. Instead, we use an
            // optimization that uses getInt() so that it works for offset 0.
            inOfs += byteArrayOfs;
            len += inOfs;
            while (inOfs < len) {
                out[outOfs++] =
                      ((long)unsafe.getInt(in, (long)inOfs) << 32)
                          | (unsafe.getInt(in, (long)(inOfs + 4)) & 0xffffffffL);
                inOfs += 8;
            }
        } else {
            len += inOfs;
            while (inOfs < len) {
                int i1 = ((in[inOfs + 3] & 0xff)      )
                       | ((in[inOfs + 2] & 0xff) <<  8)
                       | ((in[inOfs + 1] & 0xff) << 16)
                       | ((in[inOfs    ]       ) << 24);
                inOfs += 4;
                int i2 = ((in[inOfs + 3] & 0xff)      )
                       | ((in[inOfs + 2] & 0xff) <<  8)
                       | ((in[inOfs + 1] & 0xff) << 16)
                       | ((in[inOfs    ]       ) << 24);
                out[outOfs++] = ((long)i1 << 32) | (i2 & 0xffffffffL);
                inOfs += 4;
            }
        }
    }

    // Special optimization of b2lBig(in, inOfs, out, 0, 128)
    static void b2lBig128(byte[] in, int inOfs, long[] out) {
        if ((inOfs < 0) || ((in.length - inOfs) < 128) ||
            (out.length < 16)) {
            throw new ArrayIndexOutOfBoundsException();
        }
        if (littleEndianUnaligned) {
            inOfs += byteArrayOfs;
            out[ 0] = reverseBytes(unsafe.getLong(in, (long)(inOfs      )));
            out[ 1] = reverseBytes(unsafe.getLong(in, (long)(inOfs +   8)));
            out[ 2] = reverseBytes(unsafe.getLong(in, (long)(inOfs +  16)));
            out[ 3] = reverseBytes(unsafe.getLong(in, (long)(inOfs +  24)));
            out[ 4] = reverseBytes(unsafe.getLong(in, (long)(inOfs +  32)));
            out[ 5] = reverseBytes(unsafe.getLong(in, (long)(inOfs +  40)));
            out[ 6] = reverseBytes(unsafe.getLong(in, (long)(inOfs +  48)));
            out[ 7] = reverseBytes(unsafe.getLong(in, (long)(inOfs +  56)));
            out[ 8] = reverseBytes(unsafe.getLong(in, (long)(inOfs +  64)));
            out[ 9] = reverseBytes(unsafe.getLong(in, (long)(inOfs +  72)));
            out[10] = reverseBytes(unsafe.getLong(in, (long)(inOfs +  80)));
            out[11] = reverseBytes(unsafe.getLong(in, (long)(inOfs +  88)));
            out[12] = reverseBytes(unsafe.getLong(in, (long)(inOfs +  96)));
            out[13] = reverseBytes(unsafe.getLong(in, (long)(inOfs + 104)));
            out[14] = reverseBytes(unsafe.getLong(in, (long)(inOfs + 112)));
            out[15] = reverseBytes(unsafe.getLong(in, (long)(inOfs + 120)));
        } else {
            // no optimization for big endian, see comments in b2lBig
            b2lBig(in, inOfs, out, 0, 128);
        }
    }

    
long[] to byte[] conversion, big endian byte order.
/**
     * long[] to byte[] conversion, big endian byte order.
     */
    static void l2bBig(long[] in, int inOfs, byte[] out, int outOfs, int len) {
        if ((inOfs < 0) || ((in.length - inOfs) < len/8) ||
            (outOfs < 0) || ((out.length - outOfs) < len)) {
            throw new ArrayIndexOutOfBoundsException();
        }
        len += outOfs;
        while (outOfs < len) {
            long i = in[inOfs++];
            out[outOfs++] = (byte)(i >> 56);
            out[outOfs++] = (byte)(i >> 48);
            out[outOfs++] = (byte)(i >> 40);
            out[outOfs++] = (byte)(i >> 32);
            out[outOfs++] = (byte)(i >> 24);
            out[outOfs++] = (byte)(i >> 16);
            out[outOfs++] = (byte)(i >>  8);
            out[outOfs++] = (byte)(i      );
        }
    }
}