87 lines
2.1 KiB
PHP
87 lines
2.1 KiB
PHP
<?php
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declare(strict_types=1);
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/*
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* The MIT License (MIT)
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*
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* Copyright (c) 2018-2020 Spomky-Labs
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*
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* This software may be modified and distributed under the terms
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* of the MIT license. See the LICENSE file for details.
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*/
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namespace CBOR\OtherObject;
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use Brick\Math\BigInteger;
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use CBOR\OtherObject as Base;
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use CBOR\Utils;
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use InvalidArgumentException;
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final class HalfPrecisionFloatObject extends Base
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{
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public static function supportedAdditionalInformation(): array
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{
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return [25];
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}
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public static function createFromLoadedData(int $additionalInformation, ?string $data): Base
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{
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return new self($additionalInformation, $data);
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}
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/**
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* @return HalfPrecisionFloatObject
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*/
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public static function create(string $value): self
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{
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if (4 !== mb_strlen($value, '8bit')) {
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throw new InvalidArgumentException('The value is not a valid half precision floating point');
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}
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return new self(25, $value);
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}
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public function getNormalizedData(bool $ignoreTags = false)
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{
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$exp = $this->getExponent();
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$mant = $this->getMantissa();
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$sign = $this->getSign();
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if (0 === $exp) {
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$val = $mant * 2 ** (-24);
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} elseif (0b11111 !== $exp) {
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$val = ($mant + (1 << 10)) * 2 ** ($exp - 25);
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} else {
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$val = 0 === $mant ? INF : NAN;
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}
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return $sign * $val;
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}
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public function getExponent(): int
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{
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$data = $this->data;
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Utils::assertString($data, 'Invalid data');
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return Utils::binToBigInteger($data)->shiftedRight(10)->and(Utils::hexToBigInteger('1f'))->toInt();
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}
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public function getMantissa(): int
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{
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$data = $this->data;
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Utils::assertString($data, 'Invalid data');
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return Utils::binToBigInteger($data)->and(Utils::hexToBigInteger('3ff'))->toInt();
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}
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public function getSign(): int
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{
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$data = $this->data;
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Utils::assertString($data, 'Invalid data');
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$sign = Utils::binToBigInteger($data)->shiftedRight(15);
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return $sign->isEqualTo(BigInteger::one()) ? -1 : 1;
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}
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}
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