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author | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
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committer | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
commit | 554fd8c5195424bdbcabf5de30fdc183aba391bd (patch) | |
tree | 976dc5ab7fddf506dadce60ae936f43f58787092 /libjava/classpath/gnu/java/security/prng/BasePRNG.java | |
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Diffstat (limited to 'libjava/classpath/gnu/java/security/prng/BasePRNG.java')
-rw-r--r-- | libjava/classpath/gnu/java/security/prng/BasePRNG.java | 178 |
1 files changed, 178 insertions, 0 deletions
diff --git a/libjava/classpath/gnu/java/security/prng/BasePRNG.java b/libjava/classpath/gnu/java/security/prng/BasePRNG.java new file mode 100644 index 000000000..eb5ada71c --- /dev/null +++ b/libjava/classpath/gnu/java/security/prng/BasePRNG.java @@ -0,0 +1,178 @@ +/* BasePRNG.java -- + Copyright (C) 2001, 2002, 2006 Free Software Foundation, Inc. + +This file is a 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 of the License, 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; if not, write to the Free Software +Foundation, Inc., 51 Franklin St, 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.security.prng; + +import java.util.Map; + +/** + * An abstract class to facilitate implementing PRNG algorithms. + */ +public abstract class BasePRNG + implements IRandom +{ + /** The canonical name prefix of the PRNG algorithm. */ + protected String name; + + /** Indicate if this instance has already been initialised or not. */ + protected boolean initialised; + + /** A temporary buffer to serve random bytes. */ + protected byte[] buffer; + + /** The index into buffer of where the next byte will come from. */ + protected int ndx; + + /** + * Trivial constructor for use by concrete subclasses. + * + * @param name the canonical name of this instance. + */ + protected BasePRNG(String name) + { + super(); + + this.name = name; + initialised = false; + buffer = new byte[0]; + } + + public String name() + { + return name; + } + + public void init(Map attributes) + { + this.setup(attributes); + + ndx = 0; + initialised = true; + } + + public byte nextByte() throws IllegalStateException, LimitReachedException + { + if (! initialised) + throw new IllegalStateException(); + + return nextByteInternal(); + } + + public void nextBytes(byte[] out) throws IllegalStateException, + LimitReachedException + { + nextBytes(out, 0, out.length); + } + + public void nextBytes(byte[] out, int offset, int length) + throws IllegalStateException, LimitReachedException + { + if (! initialised) + throw new IllegalStateException("not initialized"); + + if (length == 0) + return; + + if (offset < 0 || length < 0 || offset + length > out.length) + throw new ArrayIndexOutOfBoundsException("offset=" + offset + " length=" + + length + " limit=" + + out.length); + if (ndx >= buffer.length) + { + fillBlock(); + ndx = 0; + } + int count = 0; + while (count < length) + { + int amount = Math.min(buffer.length - ndx, length - count); + System.arraycopy(buffer, ndx, out, offset + count, amount); + count += amount; + ndx += amount; + if (ndx >= buffer.length) + { + fillBlock(); + ndx = 0; + } + } + } + + public void addRandomByte(byte b) + { + throw new UnsupportedOperationException("random state is non-modifiable"); + } + + public void addRandomBytes(byte[] buffer) + { + addRandomBytes(buffer, 0, buffer.length); + } + + public void addRandomBytes(byte[] buffer, int offset, int length) + { + throw new UnsupportedOperationException("random state is non-modifiable"); + } + + public boolean isInitialised() + { + return initialised; + } + + private byte nextByteInternal() throws LimitReachedException + { + if (ndx >= buffer.length) + { + this.fillBlock(); + ndx = 0; + } + + return buffer[ndx++]; + } + + public Object clone() throws CloneNotSupportedException + { + BasePRNG result = (BasePRNG) super.clone(); + if (this.buffer != null) + result.buffer = (byte[]) this.buffer.clone(); + + return result; + } + + public abstract void setup(Map attributes); + + public abstract void fillBlock() throws LimitReachedException; +} |