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/*
* 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
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "SignedBigInteger.h"
#include <AK/StringBuilder.h>
namespace Crypto {
SignedBigInteger SignedBigInteger::import_data(const u8* ptr, size_t length)
{
bool sign = *ptr;
auto unsigned_data = UnsignedBigInteger::import_data(ptr + 1, length - 1);
return { move(unsigned_data), sign };
}
size_t SignedBigInteger::export_data(AK::ByteBuffer& data) const
{
data[0] = m_sign;
auto bytes_view = data.slice_view(1, data.size() - 1);
return m_unsigned_data.export_data(bytes_view) + 1;
}
SignedBigInteger SignedBigInteger::from_base10(StringView str)
{
bool sign = false;
if (str.length() > 1) {
auto maybe_sign = str[0];
if (maybe_sign == '-') {
str = str.substring_view(1, str.length() - 1);
sign = true;
}
if (maybe_sign == '+')
str = str.substring_view(1, str.length() - 1);
}
auto unsigned_data = UnsignedBigInteger::from_base10(str);
return { move(unsigned_data), sign };
}
String SignedBigInteger::to_base10() const
{
StringBuilder builder;
if (m_sign)
builder.append('-');
builder.append(m_unsigned_data.to_base10());
return builder.to_string();
}
FLATTEN SignedBigInteger SignedBigInteger::plus(const SignedBigInteger& other) const
{
// If both are of the same sign, just add the unsigned data and return.
if (m_sign == other.m_sign)
return { other.m_unsigned_data.plus(m_unsigned_data), m_sign };
// One value is signed while the other is not.
return m_sign ? other.minus(this->m_unsigned_data) : minus(other.m_unsigned_data);
}
FLATTEN SignedBigInteger SignedBigInteger::minus(const SignedBigInteger& other) const
{
// If the signs are different, convert the op to an addition.
if (m_sign != other.m_sign) {
// -x - y = - (x + y)
// x - -y = (x + y)
SignedBigInteger result { other.m_unsigned_data.plus(this->m_unsigned_data) };
if (m_sign)
result.negate();
return result;
}
if (!m_sign) {
// Both operands are positive.
// x - y = - (y - x)
if (m_unsigned_data < other.m_unsigned_data) {
// The result will be negative.
return { other.m_unsigned_data.minus(m_unsigned_data), true };
}
// The result will be either zero, or positive.
return SignedBigInteger { m_unsigned_data.minus(other.m_unsigned_data) };
}
// Both operands are negative.
// -x - -y = y - x
if (m_unsigned_data < other.m_unsigned_data) {
// The result will be positive.
return SignedBigInteger { m_unsigned_data.minus(other.m_unsigned_data) };
}
// The result will be either zero, or negative.
// y - x = - (x - y)
return { other.m_unsigned_data.minus(m_unsigned_data), true };
}
FLATTEN SignedBigInteger SignedBigInteger::plus(const UnsignedBigInteger& other) const
{
if (m_sign) {
if (other < m_unsigned_data)
return { m_unsigned_data.minus(other), true };
return { other.minus(m_unsigned_data), false };
}
return { m_unsigned_data.plus(other), false };
}
FLATTEN SignedBigInteger SignedBigInteger::minus(const UnsignedBigInteger& other) const
{
if (m_sign)
return { m_unsigned_data.plus(m_unsigned_data), true };
if (other < m_unsigned_data)
return { m_unsigned_data.minus(other), false };
return { other.minus(m_unsigned_data), true };
}
bool SignedBigInteger::operator==(const UnsignedBigInteger& other) const
{
if (m_sign)
return false;
return m_unsigned_data == other;
}
bool SignedBigInteger::operator!=(const UnsignedBigInteger& other) const
{
if (m_sign)
return true;
return m_unsigned_data != other;
}
bool SignedBigInteger::operator<(const UnsignedBigInteger& other) const
{
if (m_sign)
return true;
return m_unsigned_data < other;
}
FLATTEN SignedBigInteger SignedBigInteger::shift_left(size_t num_bits) const
{
return SignedBigInteger { m_unsigned_data.shift_left(num_bits), m_sign };
}
FLATTEN SignedBigInteger SignedBigInteger::multiplied_by(const SignedBigInteger& other) const
{
bool result_sign = m_sign ^ other.m_sign;
return { m_unsigned_data.multiplied_by(other.m_unsigned_data), result_sign };
}
FLATTEN SignedDivisionResult SignedBigInteger::divided_by(const SignedBigInteger& divisor) const
{
// Aa / Bb -> (A^B)q, Ar
bool result_sign = m_sign ^ divisor.m_sign;
auto unsigned_division_result = m_unsigned_data.divided_by(divisor.m_unsigned_data);
return {
{ move(unsigned_division_result.quotient), result_sign },
{ move(unsigned_division_result.remainder), m_sign }
};
}
void SignedBigInteger::set_bit_inplace(size_t bit_index)
{
m_unsigned_data.set_bit_inplace(bit_index);
}
bool SignedBigInteger::operator==(const SignedBigInteger& other) const
{
if (is_invalid() != other.is_invalid())
return false;
if (m_unsigned_data == 0 && other.m_unsigned_data == 0)
return true;
return m_sign == other.m_sign && m_unsigned_data == other.m_unsigned_data;
}
bool SignedBigInteger::operator!=(const SignedBigInteger& other) const
{
return !(*this == other);
}
bool SignedBigInteger::operator<(const SignedBigInteger& other) const
{
if (m_sign ^ other.m_sign)
return m_sign;
if (m_sign)
return other.m_unsigned_data < m_unsigned_data;
return m_unsigned_data < other.m_unsigned_data;
}
}
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