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The AWS SDK for Java with support for OSGi. The AWS SDK for Java provides Java APIs for building software on AWS' cost-effective, scalable, and reliable infrastructure products. The AWS Java SDK allows developers to code against APIs for all of Amazon's infrastructure web services (Amazon S3, Amazon EC2, Amazon SQS, Amazon Relational Database Service, Amazon AutoScaling, etc).
/*
* Copyright 2013-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file is distributed
* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
* express or implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
package com.amazonaws.util;
import static com.amazonaws.util.CodecUtils.sanityCheckLastPos;
/**
* Common base class for Base 32 like codec implementation.
*
* @author Hanson Char
*/
abstract class AbstractBase32Codec implements Codec {
private static final int MASK_2BITS = (1 << 2) - 1;
private static final int MASK_3BITS = (1 << 3) - 1;
private static final int MASK_4BITS = (1 << 4) - 1;
private static final int MASK_5BITS = (1 << 5) - 1;
// Base 32 alphabet as defined at http://www.ietf.org/rfc/rfc4648.txt
private static final byte PAD = '=';
private final byte[] alphabets;
protected AbstractBase32Codec(byte[] alphabets) {
this.alphabets = alphabets;
}
@Override
public final byte[] encode(byte[] src) {
final int num5bytes = src.length / 5;
final int remainder = src.length % 5;
if (remainder == 0)
{
byte[] dest = new byte[num5bytes * 8];
for (int s=0,d=0; s < src.length; s+=5, d+=8)
encode5bytes(src, s, dest, d);
return dest;
}
byte[] dest = new byte[(num5bytes+1) * 8];
int s=0, d=0;
for (; s < src.length-remainder; s+=5, d+=8)
encode5bytes(src, s, dest, d);
switch(remainder) {
case 1:
encode1byte(src, s, dest, d);
break;
case 2:
encode2bytes(src, s, dest, d);
break;
case 3:
encode3bytes(src, s, dest, d);
break;
case 4:
encode4bytes(src, s, dest, d);
break;
default:
throw new IllegalStateException();
}
return dest;
}
private final void encode5bytes(byte[] src, int s, byte[] dest, int d) {
// operator precedence in descending order: >>> or <<, &, |
byte p;
dest[d++] = (byte)alphabets[(p=src[s++]) >>> 3 & MASK_5BITS]; // 5
dest[d++] = (byte)alphabets[(p & MASK_3BITS) << 2 | (p=src[s++]) >>> 6 & MASK_2BITS]; // 3 2
dest[d++] = (byte)alphabets[p >>> 1 & MASK_5BITS]; // 5
dest[d++] = (byte)alphabets[(p & 1) << 4 | (p=src[s++]) >>> 4 & MASK_4BITS]; // 1 4
dest[d++] = (byte)alphabets[(p & MASK_4BITS) << 1 | (p=src[s++]) >>> 7 & 1]; // 4 1
dest[d++] = (byte)alphabets[p >>> 2 & MASK_5BITS]; // 5
dest[d++] = (byte)alphabets[(p & MASK_2BITS) << 3 | (p=src[s]) >>> 5 & MASK_3BITS]; // 2 3
dest[d] = (byte)alphabets[p & MASK_5BITS]; // 5
return;
}
private final void encode4bytes(byte[] src, int s, byte[] dest, int d) {
// operator precedence in descending order: >>> or <<, &, |
byte p;
dest[d++] = (byte)alphabets[(p=src[s++]) >>> 3 & MASK_5BITS]; // 5
dest[d++] = (byte)alphabets[(p & MASK_3BITS) << 2 | (p=src[s++]) >>> 6 & MASK_2BITS]; // 3 2
dest[d++] = (byte)alphabets[p >>> 1 & MASK_5BITS]; // 5
dest[d++] = (byte)alphabets[(p & 1) << 4 | (p=src[s++]) >>> 4 & MASK_4BITS]; // 1 4
dest[d++] = (byte)alphabets[(p & MASK_4BITS) << 1 | (p=src[s]) >>> 7 & 1]; // 4 1
dest[d++] = (byte)alphabets[p >>> 2 & MASK_5BITS]; // 5
dest[d++] = (byte)alphabets[(p & MASK_2BITS) << 3]; // 2
dest[d] = PAD;
return;
}
private final void encode3bytes(byte[] src, int s, byte[] dest, int d) {
// operator precedence in descending order: >>> or <<, &, |
byte p;
dest[d++] = (byte)alphabets[(p=src[s++]) >>> 3 & MASK_5BITS]; // 5
dest[d++] = (byte)alphabets[(p & MASK_3BITS) << 2 | (p=src[s++]) >>> 6 & MASK_2BITS]; // 3 2
dest[d++] = (byte)alphabets[p >>> 1 & MASK_5BITS]; // 5
dest[d++] = (byte)alphabets[(p & 1) << 4 | (p=src[s]) >>> 4 & MASK_4BITS]; // 1 4
dest[d++] = (byte)alphabets[(p & MASK_4BITS) << 1]; // 4
for (int i=0; i < 3; i++)
dest[d++] = PAD;
return;
}
private final void encode2bytes(byte[] src, int s, byte[] dest, int d) {
// operator precedence in descending order: >>> or <<, &, |
byte p;
dest[d++] = (byte)alphabets[(p=src[s++]) >>> 3 & MASK_5BITS]; // 5
dest[d++] = (byte)alphabets[(p & MASK_3BITS) << 2 | (p=src[s]) >>> 6 & MASK_2BITS]; // 3 2
dest[d++] = (byte)alphabets[p >>> 1 & MASK_5BITS]; // 5
dest[d++] = (byte)alphabets[(p & 1) << 4]; // 1
for (int i=0; i < 4; i++)
dest[d++] = PAD;
return;
}
private final void encode1byte(byte[] src, int s, byte[] dest, int d) {
// operator precedence in descending order: >>> or <<, &, |
byte p;
dest[d++] = (byte)alphabets[(p=src[s]) >>> 3 & MASK_5BITS]; // 5
dest[d++] = (byte)alphabets[(p & MASK_3BITS) << 2]; // 3
for (int i=0; i < 6; i++)
dest[d++] = PAD;
return;
}
private final void decode5bytes(byte[] src, int s, byte[] dest, int d) {
int p=0;
// operator precedence in descending order: >>> or <<, &, |
dest[d++] = (byte)
(
pos(src[s++]) << 3
| (p=pos(src[s++])) >>> 2 & MASK_3BITS
)
; // 5 3
dest[d++] = (byte)
(
(p & MASK_2BITS) << 6
| pos(src[s++]) << 1
| (p=pos(src[s++])) >>> 4 & 1
)
; // 2 5 1
dest[d++] = (byte)
(
(p & MASK_4BITS) << 4
| (p=pos(src[s++])) >>> 1 & MASK_4BITS
)
; // 4 4
dest[d++] = (byte)
(
(p & 1) << 7
| pos(src[s++]) << 2
| (p=pos(src[s++])) >>> 3 & MASK_2BITS
)
; // 1 5 2
dest[d] = (byte)
(
(p & MASK_3BITS) << 5
| pos(src[s])
); // 3 5
return;
}
/**
* @param n the number of final quantum in bytes to decode into. Ranges from 1 to 4, inclusive.
*/
private final void decode1to4bytes(int n, byte[] src, int s, byte[] dest, int d) {
int p=0;
// operator precedence in descending order: >>> or <<, &, |
dest[d++] = (byte)
(
pos(src[s++]) << 3
| (p=pos(src[s++])) >>> 2 & MASK_3BITS
)
; // 5 3
if (n == 1) {
sanityCheckLastPos(p, MASK_2BITS);
return;
}
dest[d++] = (byte)
(
(p & MASK_2BITS) << 6
| (pos(src[s++])) << 1
| (p=pos(src[s++])) >>> 4 & 1
)
; // 2 5 1
if (n == 2) {
sanityCheckLastPos(p, MASK_4BITS);
return;
}
dest[d++] = (byte)
(
(p & MASK_4BITS) << 4
| (p=pos(src[s++])) >>> 1 & MASK_4BITS
)
; // 4 4
if (n == 3) {
sanityCheckLastPos(p, 1);
return;
}
dest[d] = (byte)
(
(p & 1) << 7
| pos(src[s++]) << 2
| (p=pos(src[s])) >>> 3 & MASK_2BITS
)
; // 1 5 2
sanityCheckLastPos(p, MASK_3BITS);
return;
}
@Override
public final byte[] decode(byte[] src, final int length)
{
if (length % 8 != 0)
throw new IllegalArgumentException
("Input is expected to be encoded in multiple of 8 bytes but found: " + length);
int pads=0;
int last = length-1;
// max possible padding in b32 encoding is 6
for (; pads < 6 && last > -1; last--, pads++) {
if (src[last] != PAD)
break;
}
final int fq; // final quantum in unit of bytes
switch(pads) {
case 0:
fq=5;
break; // final quantum of encoding input is an integral multiple of 40 bits
case 1:
fq=4;
break; // final quantum of encoding input is exactly 32 bits
case 3:
fq=3;
break; // final quantum of encoding input is exactly 24 bits
case 4:
fq=2;
break; // final quantum of encoding input is exactly 16 bits
case 6:
fq=1;
break; // final quantum of encoding input is exactly 8 bits
default:
throw new IllegalArgumentException("Invalid number of paddings " + pads);
}
final byte[] dest = new byte[length / 8 * 5 - (5-fq)];
int s=0, d=0;
// % has a higher precedence than - than <
for (; d < dest.length - fq%5; s+=8,d+=5)
decode5bytes(src, s, dest, d);
if (fq < 5)
decode1to4bytes(fq, src, s, dest, d);
return dest;
}
protected abstract int pos(byte in);
}
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