I2P_Developers/i2p.itoopie
3
0
Fork 0
Code Issues Pull Requests Actions 1 Packages Projects Releases Wiki Activity

dont be such a reuse zealot and just fscking optimize the use case

Browse Source 
(aka shift instead of creating heavyweight BigInteger objects)
plus some good ol' caching and gc churn reduction
This commit is contained in:
jrandom
2004-04-27 08:30:55 +00:00
committed by zzz
parent ea03637ec1
commit e766a00a12
1 changed files with 44 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

47
core/java/src/net/i2p/data/UnsignedInteger.java
View File

@ -57,8 +57,9 @@ public class UnsignedInteger {
* available immediately.
*
* @param value number to represent
* @throws IllegalArgumentException if the value is negative
*/
public UnsignedInteger(long value) {
public UnsignedInteger(long value) throws IllegalArgumentException {
_value = value;
_data = calculateBytes(value);
}
@ -86,9 +87,42 @@ public class UnsignedInteger {
}
/**
* Calculate the bytes as an unsigned integer with the most significant bit and byte in the first position
* Calculate the bytes as an unsigned integer with the most significant
* bit and byte in the first position. The return value always has at least
* one byte in it.
*
* @throws IllegalArgumentException if the value is negative
*/
private static byte[] calculateBytes(long value) {
private static byte[] calculateBytes(long value) throws IllegalArgumentException {
if (value < 0)
throw new IllegalArgumentException("unsigned integer, and you want a negative? " + value);
byte val[] = new byte[8];
val[0] = (byte)(value >>> 56);
val[1] = (byte)(value >>> 48);
val[2] = (byte)(value >>> 40);
val[3] = (byte)(value >>> 32);
val[4] = (byte)(value >>> 24);
val[5] = (byte)(value >>> 16);
val[6] = (byte)(value >>> 8);
val[7] = (byte)value;
int firstNonZero = -1;
for (int i = 0; i < val.length; i++) {
if (val[i] != 0x00) {
firstNonZero = i;
break;
}
}
if (firstNonZero == 0)
return val;
if (firstNonZero == -1)
return new byte[1]; // initialized as 0
byte rv[] = new byte[8-firstNonZero];
System.arraycopy(val, firstNonZero, rv, 0, rv.length);
return rv;
/*
BigInteger bi = new BigInteger("" + value);
byte buf[] = bi.toByteArray();
if ((buf == null) || (buf.length <= 0))
@ -99,6 +133,7 @@ public class UnsignedInteger {
byte rv[] = new byte[buf.length - trim];
System.arraycopy(buf, trim, rv, 0, rv.length);
return rv;
*/
}
/**
@ -120,6 +155,8 @@ public class UnsignedInteger {
throw new IllegalArgumentException("Value (" + _value + ") is greater than the requested number of bytes ("
+ numBytes + ")");
if (numBytes == _data.length) return _data;
byte[] data = new byte[numBytes];
System.arraycopy(_data, 0, data, numBytes - _data.length, _data.length);
return data;
@ -189,5 +226,9 @@ public class UnsignedInteger {
_log.debug(num + " turned into a byte array and back again: " + val2 + " (" + val2.getLong() + "/"
+ toString(val2.getBytes()) + ")");
_log.debug(num + " As an 8 byte array: " + toString(val2.getBytes(8)));
BigInteger bi = new BigInteger(num+"");
_log.debug(num + " As a bigInteger: 0x" + bi.toString(16));
BigInteger tbi = new BigInteger(1, calculateBytes(num));
_log.debug(num + " As a shifted : 0x" + tbi.toString(16));
}
}