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LibCrypto: Cache the "trimmed length" of UnsignedBigIntegers

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This avoids repeated traversals of the underlying words and gives a
30% speed-up on "test-crypto -t pk" :^)
This commit is contained in:
Andreas Kling 2020-05-07 12:23:09 +02:00
parent 57f68ac5d7
commit 444b6c8407
2 changed files with 24 additions and 9 deletions
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20
Libraries/LibCrypto/BigInt/UnsignedBigInteger.cpp
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@ -49,7 +49,7 @@ UnsignedBigInteger UnsignedBigInteger::import_data(const u8* ptr, size_t length)
return integer;
}
size_t UnsignedBigInteger::export_data(AK::ByteBuffer& data)
size_t UnsignedBigInteger::export_data(AK::ByteBuffer& data) const
{
UnsignedBigInteger copy { *this };
UnsignedBigInteger quotient;
@ -105,6 +105,7 @@ void UnsignedBigInteger::set_to_0()
{
m_words.clear_with_capacity();
m_is_invalid = false;
m_cached_trimmed_length = {};
}
void UnsignedBigInteger::set_to(u32 other)
@ -112,6 +113,7 @@ void UnsignedBigInteger::set_to(u32 other)
m_is_invalid = false;
m_words.resize_and_keep_capacity(1);
m_words[0] = other;
m_cached_trimmed_length = {};
}
void UnsignedBigInteger::set_to(const UnsignedBigInteger& other)
@ -119,16 +121,20 @@ void UnsignedBigInteger::set_to(const UnsignedBigInteger& other)
m_is_invalid = other.m_is_invalid;
m_words.resize_and_keep_capacity(other.m_words.size());
__builtin_memcpy(m_words.data(), other.m_words.data(), other.m_words.size() * sizeof(u32));
m_cached_trimmed_length = {};
}
size_t UnsignedBigInteger::trimmed_length() const
{
size_t num_leading_zeroes = 0;
for (int i = length() - 1; i >= 0; --i, ++num_leading_zeroes) {
if (m_words[i] != 0)
break;
if (!m_cached_trimmed_length.has_value()) {
size_t num_leading_zeroes = 0;
for (int i = length() - 1; i >= 0; --i, ++num_leading_zeroes) {
if (m_words[i] != 0)
break;
}
m_cached_trimmed_length = length() - num_leading_zeroes;
}
return length() - num_leading_zeroes;
return m_cached_trimmed_length.value();
}
FLATTEN UnsignedBigInteger UnsignedBigInteger::plus(const UnsignedBigInteger& other) const
@ -206,6 +212,8 @@ void UnsignedBigInteger::set_bit_inplace(size_t bit_index)
m_words.unchecked_append(0);
}
m_words[word_index] |= (1 << inner_word_index);
m_cached_trimmed_length = {};
}
bool UnsignedBigInteger::operator==(const UnsignedBigInteger& other) const