serenity/Libraries/LibCrypto/BigInt/SignedBigInteger.h

/*
 * Copyright (c) 2020, the SerenityOS developers.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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#pragma once

#include <LibCrypto/BigInt/UnsignedBigInteger.h>

namespace Crypto {

struct SignedDivisionResult;

class SignedBigInteger {
public:
    SignedBigInteger(i32 x)
        : m_sign(x < 0)
        , m_unsigned_data(abs(x))
    {
    }

    SignedBigInteger(UnsignedBigInteger&& unsigned_data, bool sign)
        : m_sign(sign)
        , m_unsigned_data(move(unsigned_data))
    {
    }

    explicit SignedBigInteger(UnsignedBigInteger unsigned_data)
        : m_sign(false)
        , m_unsigned_data(move(unsigned_data))
    {
    }

    SignedBigInteger()
        : m_sign(false)
        , m_unsigned_data()
    {
    }

    static SignedBigInteger create_invalid()
    {
        return { UnsignedBigInteger::create_invalid(), false };
    }

    static SignedBigInteger import_data(const AK::StringView& data) { return import_data((const u8*)data.characters_without_null_termination(), data.length()); }
    static SignedBigInteger import_data(const u8* ptr, size_t length);

    size_t export_data(AK::ByteBuffer& data) const;
    size_t export_data(const u8* ptr, size_t length) const
    {
        auto buffer = ByteBuffer::wrap(ptr, length);
        return export_data(buffer);
    }

    static SignedBigInteger from_base10(StringView str);
    String to_base10() const;

    const UnsignedBigInteger& unsigned_value() const { return m_unsigned_data; }
    const Vector<u32, STARTING_WORD_SIZE> words() const { return m_unsigned_data.words(); }
    bool is_negative() const { return m_sign; }

    void negate() { m_sign = !m_sign; }

    void set_to_0() { m_unsigned_data.set_to_0(); }
    void set_to(i32 other)
    {
        m_unsigned_data.set_to((u32)other);
        m_sign = other < 0;
    }
    void set_to(const SignedBigInteger& other)
    {
        m_unsigned_data.set_to(other.m_unsigned_data);
        m_sign = other.m_sign;
    }

    void invalidate()
    {
        m_unsigned_data.invalidate();
    }

    bool is_invalid() const { return m_unsigned_data.is_invalid(); }

    // These get + 1 byte for the sign.
    size_t length() const { return m_unsigned_data.length() + 1; }
    size_t trimmed_length() const { return m_unsigned_data.trimmed_length() + 1; };

    SignedBigInteger plus(const SignedBigInteger& other) const;
    SignedBigInteger minus(const SignedBigInteger& other) const;
    SignedBigInteger shift_left(size_t num_bits) const;
    SignedBigInteger multiplied_by(const SignedBigInteger& other) const;
    SignedDivisionResult divided_by(const SignedBigInteger& divisor) const;

    SignedBigInteger plus(const UnsignedBigInteger& other) const;
    SignedBigInteger minus(const UnsignedBigInteger& other) const;
    SignedBigInteger multiplied_by(const UnsignedBigInteger& other) const;
    SignedDivisionResult divided_by(const UnsignedBigInteger& divisor) const;

    void set_bit_inplace(size_t bit_index);

    bool operator==(const SignedBigInteger& other) const;
    bool operator!=(const SignedBigInteger& other) const;
    bool operator<(const SignedBigInteger& other) const;

    bool operator==(const UnsignedBigInteger& other) const;
    bool operator!=(const UnsignedBigInteger& other) const;
    bool operator<(const UnsignedBigInteger& other) const;

private:
    bool m_sign { false };
    UnsignedBigInteger m_unsigned_data;
};

struct SignedDivisionResult {
    Crypto::SignedBigInteger quotient;
    Crypto::SignedBigInteger remainder;
};

}

inline const LogStream&
operator<<(const LogStream& stream, const Crypto::SignedBigInteger value)
{
    if (value.is_invalid()) {
        stream << "Invalid BigInt";
        return stream;
    }
    if (value.is_negative())
        stream << "-";

    stream << value.unsigned_value();
    return stream;
}

inline Crypto::SignedBigInteger
operator""_sbigint(const char* string, size_t length)
{
    return Crypto::SignedBigInteger::from_base10({ string, length });
}