forked from GNUsocial/gnu-social
221 lines
7.2 KiB
PHP
221 lines
7.2 KiB
PHP
<?php
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namespace ParagonIE\ConstantTime;
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/**
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* Copyright (c) 2016 Paragon Initiative Enterprises.
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* Copyright (c) 2014 Steve "Sc00bz" Thomas (steve at tobtu dot com)
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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/**
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* Class Base64
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* [A-Z][a-z][0-9]+/
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*
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* @package ParagonIE\ConstantTime
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*/
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abstract class Base64 implements EncoderInterface
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{
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/**
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* Encode into Base64
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*
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* Base64 character set "[A-Z][a-z][0-9]+/"
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*
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* @param string $src
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* @return string
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*/
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public static function encode($src)
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{
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$dest = '';
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$srcLen = Binary::safeStrlen($src);
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// Main loop (no padding):
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for ($i = 0; $i + 3 <= $srcLen; $i += 3) {
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$chunk = \unpack('C*', Binary::safeSubstr($src, $i, 3));
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$b0 = $chunk[1];
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$b1 = $chunk[2];
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$b2 = $chunk[3];
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$dest .=
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static::encode6Bits( $b0 >> 2 ) .
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static::encode6Bits((($b0 << 4) | ($b1 >> 4)) & 63) .
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static::encode6Bits((($b1 << 2) | ($b2 >> 6)) & 63) .
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static::encode6Bits( $b2 & 63);
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}
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// The last chunk, which may have padding:
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if ($i < $srcLen) {
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$chunk = \unpack('C*', Binary::safeSubstr($src, $i, $srcLen - $i));
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$b0 = $chunk[1];
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if ($i + 1 < $srcLen) {
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$b1 = $chunk[2];
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$dest .=
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static::encode6Bits( $b0 >> 2 ) .
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static::encode6Bits((($b0 << 4) | ($b1 >> 4)) & 63) .
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static::encode6Bits( ($b1 << 2) & 63) . '=';
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} else {
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$dest .=
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static::encode6Bits( $b0 >> 2) .
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static::encode6Bits(($b0 << 4) & 63) . '==';
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}
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}
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return $dest;
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}
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/**
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* decode from base64 into binary
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*
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* Base64 character set "./[A-Z][a-z][0-9]"
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*
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* @param string $src
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* @return string|bool
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* @throws \RangeException
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*/
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public static function decode($src, $strictPadding = false)
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{
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// Remove padding
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$srcLen = Binary::safeStrlen($src);
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if ($srcLen === 0) {
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return '';
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}
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if ($strictPadding) {
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if (($srcLen & 3) === 0) {
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if ($src[$srcLen - 1] === '=') {
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$srcLen--;
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if ($src[$srcLen - 1] === '=') {
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$srcLen--;
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}
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}
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}
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if (($srcLen & 3) === 1) {
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throw new \RangeException(
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'Incorrect padding'
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);
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}
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} else {
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$src = \rtrim($src, '=');
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$srcLen = Binary::safeStrlen($src);
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}
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$err = 0;
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$dest = '';
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// Main loop (no padding):
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for ($i = 0; $i + 4 <= $srcLen; $i += 4) {
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$chunk = \unpack('C*', Binary::safeSubstr($src, $i, 4));
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$c0 = static::decode6Bits($chunk[1]);
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$c1 = static::decode6Bits($chunk[2]);
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$c2 = static::decode6Bits($chunk[3]);
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$c3 = static::decode6Bits($chunk[4]);
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$dest .= \pack(
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'CCC',
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((($c0 << 2) | ($c1 >> 4)) & 0xff),
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((($c1 << 4) | ($c2 >> 2)) & 0xff),
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((($c2 << 6) | $c3 ) & 0xff)
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);
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$err |= ($c0 | $c1 | $c2 | $c3) >> 8;
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}
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// The last chunk, which may have padding:
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if ($i < $srcLen) {
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$chunk = \unpack('C*', Binary::safeSubstr($src, $i, $srcLen - $i));
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$c0 = static::decode6Bits($chunk[1]);
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if ($i + 2 < $srcLen) {
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$c1 = static::decode6Bits($chunk[2]);
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$c2 = static::decode6Bits($chunk[3]);
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$dest .= \pack(
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'CC',
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((($c0 << 2) | ($c1 >> 4)) & 0xff),
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((($c1 << 4) | ($c2 >> 2)) & 0xff)
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);
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$err |= ($c0 | $c1 | $c2) >> 8;
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} elseif($i + 1 < $srcLen) {
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$c1 = static::decode6Bits($chunk[2]);
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$dest .= \pack(
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'C',
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((($c0 << 2) | ($c1 >> 4)) & 0xff)
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);
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$err |= ($c0 | $c1) >> 8;
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} elseif ($i < $srcLen && $strictPadding) {
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$err |= 1;
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}
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}
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if ($err !== 0) {
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return false;
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}
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return $dest;
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}
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/**
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* Uses bitwise operators instead of table-lookups to turn 6-bit integers
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* into 8-bit integers.
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*
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* Base64 character set:
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* [A-Z] [a-z] [0-9] + /
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* 0x41-0x5a, 0x61-0x7a, 0x30-0x39, 0x2b, 0x2f
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*
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* @param int $src
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* @return int
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*/
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protected static function decode6Bits($src)
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{
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$ret = -1;
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// if ($src > 0x40 && $src < 0x5b) $ret += $src - 0x41 + 1; // -64
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$ret += (((0x40 - $src) & ($src - 0x5b)) >> 8) & ($src - 64);
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// if ($src > 0x60 && $src < 0x7b) $ret += $src - 0x61 + 26 + 1; // -70
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$ret += (((0x60 - $src) & ($src - 0x7b)) >> 8) & ($src - 70);
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// if ($src > 0x2f && $src < 0x3a) $ret += $src - 0x30 + 52 + 1; // 5
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$ret += (((0x2f - $src) & ($src - 0x3a)) >> 8) & ($src + 5);
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// if ($src == 0x2b) $ret += 62 + 1;
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$ret += (((0x2a - $src) & ($src - 0x2c)) >> 8) & 63;
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// if ($src == 0x2f) ret += 63 + 1;
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$ret += (((0x2e - $src) & ($src - 0x30)) >> 8) & 64;
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return $ret;
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}
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/**
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* Uses bitwise operators instead of table-lookups to turn 8-bit integers
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* into 6-bit integers.
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*
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* @param int $src
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* @return string
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*/
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protected static function encode6Bits($src)
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{
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$diff = 0x41;
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// if ($src > 25) $diff += 0x61 - 0x41 - 26; // 6
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$diff += ((25 - $src) >> 8) & 6;
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// if ($src > 51) $diff += 0x30 - 0x61 - 26; // -75
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$diff -= ((51 - $src) >> 8) & 75;
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// if ($src > 61) $diff += 0x2b - 0x30 - 10; // -15
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$diff -= ((61 - $src) >> 8) & 15;
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// if ($src > 62) $diff += 0x2f - 0x2b - 1; // 3
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$diff += ((62 - $src) >> 8) & 3;
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return \pack('C', $src + $diff);
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}
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}
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