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/*
* Copyright (c) 2011, PostgreSQL Global Development Group
* See the LICENSE file in the project root for more information.
*/
package org.postgresql.util;
import java.math.BigDecimal;
import java.nio.CharBuffer;
/**
* Helper methods to parse java base types from byte arrays.
*
* @author Mikko Tiihonen
*/
public class ByteConverter {
private static final int NBASE = 10000;
private static final int NUMERIC_DSCALE_MASK = 0x00003FFF;
private static final short NUMERIC_POS = 0x0000;
private static final short NUMERIC_NEG = 0x4000;
private static final short NUMERIC_NAN = (short) 0xC000;
private static final int DEC_DIGITS = 4;
private static final int[] round_powers = {0, 1000, 100, 10};
private static final int SHORT_BYTES = 2;
private static final int LONG_BYTES = 4;
private ByteConverter() {
// prevent instantiation of static helper class
}
/**
* Convert a variable length array of bytes to an integer
* @param bytes array of bytes that can be decoded as an integer
* @return integer
*/
public static int bytesToInt(byte []bytes) {
if ( bytes.length == 1 ) {
return (int)bytes[0];
}
if ( bytes.length == SHORT_BYTES ) {
return int2(bytes, 0);
}
if ( bytes.length == LONG_BYTES ) {
return int4(bytes, 0);
} else {
throw new IllegalArgumentException("Argument bytes is empty");
}
}
/**
* Convert a number from binary representation to text representation.
* @param idx index of the digit to be converted in the digits array
* @param digits array of shorts that can be decoded as the number String
* @param buffer the character buffer to put the text representation in
* @param alwaysPutIt a flag that indicate whether or not to put the digit char even if it is zero
* @return String the number as String
*/
private static void digitToString(int idx, short[] digits, CharBuffer buffer, boolean alwaysPutIt) {
short dig = (idx >= 0 && idx < digits.length) ? digits[idx] : 0;
// Each dig represents 4 decimal digits (e.g. 9999)
// If we continue the number, then we need to print 0 as 0000 (alwaysPutIt parameter is true)
for (int p = 1; p < round_powers.length; p++) {
int pow = round_powers[p];
short d1 = (short)(dig / pow);
dig -= d1 * pow;
boolean putit = (d1 > 0);
if (putit || alwaysPutIt) {
buffer.put((char)(d1 + '0'));
// We printed a character, so we need to print the rest of the current digits in dig
// For instance, we need to keep printing 000 from 1000 even if idx==0 (== it is the very
// beginning)
alwaysPutIt = true;
}
}
buffer.put((char)(dig + '0'));
}
/**
* Convert a number from binary representation to text representation.
* @param digits array of shorts that can be decoded as the number String
* @param scale the scale of the number binary representation
* @param weight the weight of the number binary representation
* @param sign the sign of the number
* @return String the number as String
*/
private static String numberBytesToString(short[] digits, int scale, int weight, int sign) {
CharBuffer buffer;
int i;
int d;
/*
* Allocate space for the result.
*
* i is set to the # of decimal digits before decimal point. dscale is the
* # of decimal digits we will print after decimal point. We may generate
* as many as DEC_DIGITS-1 excess digits at the end, and in addition we
* need room for sign, decimal point, null terminator.
*/
i = (weight + 1) * DEC_DIGITS;
if (i <= 0) {
i = 1;
}
buffer = CharBuffer.allocate((i + scale + DEC_DIGITS + 2));
/*
* Output a dash for negative values
*/
if (sign == NUMERIC_NEG) {
buffer.put('-');
}
/*
* Output all digits before the decimal point
*/
if (weight < 0) {
d = weight + 1;
buffer.put('0');
} else {
for (d = 0; d <= weight; d++) {
/* In the first digit, suppress extra leading decimal zeroes */
digitToString(d, digits, buffer, d != 0);
}
}
/*
* If requested, output a decimal point and all the digits that follow it.
* We initially put out a multiple of DEC_DIGITS digits, then truncate if
* needed.
*/
if (scale > 0) {
buffer.put('.');
for (i = 0; i < scale; d++, i += DEC_DIGITS) {
digitToString(d, digits, buffer, true);
}
}
/*
* terminate the string and return it
*/
int extra = (i - scale) % DEC_DIGITS;
return new String(buffer.array(), 0, buffer.position() - extra);
}
/**
* Convert a variable length array of bytes to an integer
* @param bytes array of bytes that can be decoded as an integer
* @return integer
*/
public static Number numeric(byte [] bytes) {
return numeric(bytes, 0, bytes.length);
}
/**
* Convert a variable length array of bytes to an integer
* @param bytes array of bytes that can be decoded as an integer
* @param pos index of the start position of the bytes array for number
* @param numBytes number of bytes to use, length is already encoded
* in the binary format but this is used for double checking
* @return integer
*/
public static Number numeric(byte [] bytes, int pos, int numBytes) {
if (numBytes < 8) {
throw new IllegalArgumentException("number of bytes should be at-least 8");
}
short len = ByteConverter.int2(bytes, pos);
short weight = ByteConverter.int2(bytes, pos + 2);
short sign = ByteConverter.int2(bytes, pos + 4);
short scale = ByteConverter.int2(bytes, pos + 6);
if (numBytes != (len * SHORT_BYTES + 8)) {
throw new IllegalArgumentException("invalid length of bytes \"numeric\" value");
}
if (!(sign == NUMERIC_POS
|| sign == NUMERIC_NEG
|| sign == NUMERIC_NAN)) {
throw new IllegalArgumentException("invalid sign in \"numeric\" value");
}
if (sign == NUMERIC_NAN) {
return Double.NaN;
}
if ((scale & NUMERIC_DSCALE_MASK) != scale) {
throw new IllegalArgumentException("invalid scale in \"numeric\" value");
}
short[] digits = new short[len];
int idx = pos + 8;
for (int i = 0; i < len; i++) {
short d = ByteConverter.int2(bytes, idx);
idx += 2;
if (d < 0 || d >= NBASE) {
throw new IllegalArgumentException("invalid digit in \"numeric\" value");
}
digits[i] = d;
}
String numString = numberBytesToString(digits, scale, weight, sign);
return new BigDecimal(numString);
}
/**
* Parses a long value from the byte array.
*
* @param bytes The byte array to parse.
* @param idx The starting index of the parse in the byte array.
* @return parsed long value.
*/
public static long int8(byte[] bytes, int idx) {
return
((long) (bytes[idx + 0] & 255) << 56)
+ ((long) (bytes[idx + 1] & 255) << 48)
+ ((long) (bytes[idx + 2] & 255) << 40)
+ ((long) (bytes[idx + 3] & 255) << 32)
+ ((long) (bytes[idx + 4] & 255) << 24)
+ ((long) (bytes[idx + 5] & 255) << 16)
+ ((long) (bytes[idx + 6] & 255) << 8)
+ (bytes[idx + 7] & 255);
}
/**
* Parses an int value from the byte array.
*
* @param bytes The byte array to parse.
* @param idx The starting index of the parse in the byte array.
* @return parsed int value.
*/
public static int int4(byte[] bytes, int idx) {
return
((bytes[idx] & 255) << 24)
+ ((bytes[idx + 1] & 255) << 16)
+ ((bytes[idx + 2] & 255) << 8)
+ ((bytes[idx + 3] & 255));
}
/**
* Parses a short value from the byte array.
*
* @param bytes The byte array to parse.
* @param idx The starting index of the parse in the byte array.
* @return parsed short value.
*/
public static short int2(byte[] bytes, int idx) {
return (short) (((bytes[idx] & 255) << 8) + ((bytes[idx + 1] & 255)));
}
/**
* Parses a boolean value from the byte array.
*
* @param bytes
* The byte array to parse.
* @param idx
* The starting index to read from bytes.
* @return parsed boolean value.
*/
public static boolean bool(byte[] bytes, int idx) {
return bytes[idx] == 1;
}
/**
* Parses a float value from the byte array.
*
* @param bytes The byte array to parse.
* @param idx The starting index of the parse in the byte array.
* @return parsed float value.
*/
public static float float4(byte[] bytes, int idx) {
return Float.intBitsToFloat(int4(bytes, idx));
}
/**
* Parses a double value from the byte array.
*
* @param bytes The byte array to parse.
* @param idx The starting index of the parse in the byte array.
* @return parsed double value.
*/
public static double float8(byte[] bytes, int idx) {
return Double.longBitsToDouble(int8(bytes, idx));
}
/**
* Encodes a long value to the byte array.
*
* @param target The byte array to encode to.
* @param idx The starting index in the byte array.
* @param value The value to encode.
*/
public static void int8(byte[] target, int idx, long value) {
target[idx + 0] = (byte) (value >>> 56);
target[idx + 1] = (byte) (value >>> 48);
target[idx + 2] = (byte) (value >>> 40);
target[idx + 3] = (byte) (value >>> 32);
target[idx + 4] = (byte) (value >>> 24);
target[idx + 5] = (byte) (value >>> 16);
target[idx + 6] = (byte) (value >>> 8);
target[idx + 7] = (byte) value;
}
/**
* Encodes a int value to the byte array.
*
* @param target The byte array to encode to.
* @param idx The starting index in the byte array.
* @param value The value to encode.
*/
public static void int4(byte[] target, int idx, int value) {
target[idx + 0] = (byte) (value >>> 24);
target[idx + 1] = (byte) (value >>> 16);
target[idx + 2] = (byte) (value >>> 8);
target[idx + 3] = (byte) value;
}
/**
* Encodes a int value to the byte array.
*
* @param target The byte array to encode to.
* @param idx The starting index in the byte array.
* @param value The value to encode.
*/
public static void int2(byte[] target, int idx, int value) {
target[idx + 0] = (byte) (value >>> 8);
target[idx + 1] = (byte) value;
}
/**
* Encodes a boolean value to the byte array.
*
* @param target
* The byte array to encode to.
* @param idx
* The starting index in the byte array.
* @param value
* The value to encode.
*/
public static void bool(byte[] target, int idx, boolean value) {
target[idx] = value ? (byte) 1 : (byte) 0;
}
/**
* Encodes a int value to the byte array.
*
* @param target The byte array to encode to.
* @param idx The starting index in the byte array.
* @param value The value to encode.
*/
public static void float4(byte[] target, int idx, float value) {
int4(target, idx, Float.floatToRawIntBits(value));
}
/**
* Encodes a int value to the byte array.
*
* @param target The byte array to encode to.
* @param idx The starting index in the byte array.
* @param value The value to encode.
*/
public static void float8(byte[] target, int idx, double value) {
int8(target, idx, Double.doubleToRawLongBits(value));
}
}