/*
* Copyright 1998-2014 University Corporation for Atmospheric Research/Unidata
*
* Portions of this software were developed by the Unidata Program at the
* University Corporation for Atmospheric Research.
*
* Access and use of this software shall impose the following obligations
* and understandings on the user. The user is granted the right, without
* any fee or cost, to use, copy, modify, alter, enhance and distribute
* this software, and any derivative works thereof, and its supporting
* documentation for any purpose whatsoever, provided that this entire
* notice appears in all copies of the software, derivative works and
* supporting documentation. Further, UCAR requests that the user credit
* UCAR/Unidata in any publications that result from the use of this
* software or in any product that includes this software. The names UCAR
* and/or Unidata, however, may not be used in any advertising or publicity
* to endorse or promote any products or commercial entity unless specific
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* understands that UCAR/Unidata is not obligated to provide the user with
* any support, consulting, training or assistance of any kind with regard
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*
* THIS SOFTWARE IS PROVIDED BY UCAR/UNIDATA "AS IS" AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL UCAR/UNIDATA BE LIABLE FOR ANY SPECIAL,
* INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
* FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
* NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
* WITH THE ACCESS, USE OR PERFORMANCE OF THIS SOFTWARE.
*/
package ucar.unidata.io;
/**
* The Swap class provides static methods for swapping the bytes of chars,
* shorts, ints, longs, floats, and doubles.
*
* @author Kirk Waters
* @author Russ Rew, 1998, added documentation
*/
public class Swap {
/**
* Returns the short resulting from swapping 2 bytes at a specified
* offset in a byte array.
*
* @param b the byte array
* @param offset the offset of the first byte
* @return the short represented by the bytes
* <code>b[offset+1], b[offset]</code>
*/
static public short swapShort(byte[] b, int offset) {
// 2 bytes
int low = b[offset] & 0xff;
int high = b[offset + 1] & 0xff;
return (short) (high << 8 | low);
}
/**
* Returns the int resulting from reversing 4 bytes at a specified
* offset in a byte array.
*
* @param b the byte array
* @param offset the offset of the first byte
* @return the int represented by the bytes
* <code>b[offset+3], b[offset+2], ..., b[offset]</code>
*/
static public int swapInt(byte[] b, int offset) {
// 4 bytes
int accum = 0;
for (int shiftBy = 0, i = offset; shiftBy < 32; shiftBy += 8, i++) {
accum |= (b[i] & 0xff) << shiftBy;
}
return accum;
}
/**
* Returns the long resulting from reversing 8 bytes at a specified
* offset in a byte array.
*
* @param b the byte array
* @param offset the offset of the first byte
* @return the long represented by the bytes
* <code>b[offset+7], b[offset+6], ..., b[offset]</code>
*/
static public long swapLong(byte[] b, int offset) {
// 8 bytes
long accum = 0;
long shiftedval;
for (int shiftBy = 0, i = offset; shiftBy < 64; shiftBy += 8, i++) {
shiftedval = ((long) (b[i] & 0xff)) << shiftBy;
accum |= shiftedval;
}
return accum;
}
/**
* Returns the float resulting from reversing 4 bytes at a specified
* offset in a byte array.
*
* @param b the byte array
* @param offset the offset of the first byte
* @return the float represented by the bytes
* <code>b[offset+3], b[offset+2], ..., b[offset]</code>
*/
static public float swapFloat(byte[] b, int offset) {
int accum = 0;
for (int shiftBy = 0, i = offset; shiftBy < 32; shiftBy += 8, i++) {
accum |= (b[i] & 0xff) << shiftBy;
}
return Float.intBitsToFloat(accum);
}
/**
* Returns the double resulting from reversing 8 bytes at a specified
* offset in a byte array.
*
* @param b the byte array
* @param offset the offset of the first byte
* @return the double represented by the bytes
* <code>b[offset+7], b[offset+6], ..., b[offset]</code>
*/
static public double swapDouble(byte[] b, int offset) {
long accum = 0;
long shiftedval;
for (int shiftBy = 0, i = offset; shiftBy < 64; shiftBy += 8, i++) {
shiftedval = ((long) (b[i] & 0xff)) << shiftBy;
accum |= shiftedval;
}
return Double.longBitsToDouble(accum);
}
/**
* Returns the char resulting from swapping 2 bytes at a specified
* offset in a byte array.
*
* @param b the byte array
* @param offset the offset of the first byte
* @return the char represented by the bytes
* <code>b[offset+1], b[offset]</code>
*/
static public char swapChar(byte[] b, int offset) {
// 2 bytes
int low = b[offset] & 0xff;
int high = b[offset + 1] & 0xff;
return (char) (high << 8 | low);
}
/**
* Returns the short resulting from swapping 2 bytes of a specified
* short.
*
* @param s input value for which byte reversal is desired
* @return the value represented by the bytes of <code>s</code>
* reversed
*/
static public short swapShort(short s) {
return (swapShort(shortToBytes(s), 0));
}
/**
* Returns the int resulting from reversing 4 bytes of a specified
* int.
*
* @param v input value for which byte reversal is desired
* @return the value represented by the bytes of <code>v</code>
* reversed
*/
static public int swapInt(int v) {
return (swapInt(intToBytes(v), 0));
}
/**
* Returns the long resulting from reversing 8 bytes of a specified
* long.
*
* @param l input value for which byte reversal is desired
* @return the value represented by the bytes of <code>l</code>
* reversed
*/
static public long swapLong(long l) {
return (swapLong(longToBytes(l), 0));
}
/**
* Returns the float resulting from reversing 4 bytes of a specified
* float.
*
* @param v input value for which byte reversal is desired
* @return the value represented by the bytes of <code>v</code>
* reversed
*/
static public float swapFloat(float v) {
int l = swapInt(Float.floatToIntBits(v));
return (Float.intBitsToFloat(l));
}
/**
* Returns the double resulting from reversing 8 bytes of a specified
* double.
*
* @param v input value for which byte reversal is desired
* @return the value represented by the bytes of <code>v</code>
* reversed
*/
static public double swapDouble(double v) {
long l = swapLong(Double.doubleToLongBits(v));
return (Double.longBitsToDouble(l));
}
/**
* Convert a short to an array of 2 bytes.
*
* @param v input value
* @return the corresponding array of bytes
*/
static public byte[] shortToBytes(short v) {
byte[] b = new byte[2];
int allbits = 255;
for (int i = 0; i < 2; i++) {
b[1 - i] = (byte) ((v & (allbits << i * 8)) >> i * 8);
}
return b;
}
/**
* Convert an int to an array of 4 bytes.
*
* @param v input value
* @return the corresponding array of bytes
*/
static public byte[] intToBytes(int v) {
byte[] b = new byte[4];
int allbits = 255;
for (int i = 0; i < 4; i++) {
b[3 - i] = (byte) ((v & (allbits << i * 8)) >> i * 8);
}
return b;
}
/**
* Convert a long to an array of 8 bytes.
*
* @param v input value
* @return the corresponding array of bytes
*/
static public byte[] longToBytes(long v) {
byte[] b = new byte[8];
long allbits = 255;
for (int i = 0; i < 8; i++) {
b[7 - i] = (byte) ((v & (allbits << i * 8)) >> i * 8);
}
return b;
}
}