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feat(baseN): decode

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This commit is contained in:
SEK1RO
2024-09-18 23:29:21 +03:00
parent 61c0ae3a72
commit 961e54c08b
2 changed files with 56 additions and 13 deletions
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42
src/baseN.cpp
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@ -84,4 +84,46 @@ namespace baseN
{ return ch != ' '; }));
return str;
}
void decode(const char *str, uint64_t str_size, uint8_t *data, uint64_t data_size, uint8_t base, const char *digits, const int8_t *map)
{
std::string_view sv(std::find_if(str, str + str_size, [digits](char ch)
{ return ch != digits[0]; }),
str_size);
if (sv.size() == 0)
{
return;
}
if (!baseN::isValid(sv, map))
{
throw std::logic_error("baseN::decode: out of digits map");
}
std::span<uint8_t> dv(data, data_size);
auto sv_it = sv.begin();
auto quo_it = dv.rbegin();
auto quo_it_last = dv.rbegin() + 1;
uint16_t div;
*quo_it = map[(int8_t)*sv_it++];
while (sv_it < sv.end())
{
div = map[(int8_t)*sv_it++];
while (quo_it < quo_it_last && quo_it < dv.rend() - 1)
{
div += *quo_it * base;
*quo_it++ = div;
div >>= 8;
}
*quo_it++ = div;
quo_it_last = quo_it;
quo_it = dv.rbegin();
}
}
std::vector<uint8_t> decode(std::string_view str, uint8_t base, const char *digits, const int8_t *map) noexcept
{
std::vector<uint8_t> data(baseN::sizeDecoded(str, base));
baseN::decode(str.data(), str.size(), data.data(), data.size(), base, digits, map);
data.erase(data.begin(), std::find_if(data.begin(), data.end(), [](uint8_t item)
{ return item != 0; }));
return data;
}
}

27
test/test-baseN.cpp
View File

@ -47,19 +47,20 @@ TEST(baseN, encode_1e3)
std::fill(data.begin(), data.end(), 1);
encode(data, 58, b58digits);
}
// TEST(baseN, decode)
// {
// EXPECT_EQ(hex::encode(decode("Ky", 58, b58digits, b58map)), "044c");
// EXPECT_EQ(hex::encode(decode("KyK", 58, b58digits, b58map)), "f94a");
// EXPECT_EQ(hex::encode(decode("KyKX", 58, b58digits, b58map)), "387ae2");
// EXPECT_EQ(hex::encode(decode("KyKXa", 58, b58digits, b58map)), "0ccbd755");
// EXPECT_EQ(hex::encode(decode("KyKXaa", 58, b58digits, b58map)), "02e62ec963");
// }
// TEST(baseN, decode_1e4)
// {
// std::string str(1e4, '1');
// decode(str, 58, b58digits, b58map, str.size() * 733 / 1000 + 1);
// }
TEST(baseN, decode)
{
EXPECT_EQ(hex::encode(decode("", 58, b58digits, b58map)), "");
EXPECT_EQ(hex::encode(decode("Ky", 58, b58digits, b58map)), "044c");
EXPECT_EQ(hex::encode(decode("KyK", 58, b58digits, b58map)), "f94a");
EXPECT_EQ(hex::encode(decode("KyKX", 58, b58digits, b58map)), "387ae2");
EXPECT_EQ(hex::encode(decode("KyKXa", 58, b58digits, b58map)), "0ccbd755");
EXPECT_EQ(hex::encode(decode("KyKXaa", 58, b58digits, b58map)), "02e62ec963");
}
TEST(baseN, decode_1e3)
{
std::string str(1e3, '2');
decode(str, 58, b58digits, b58map);
}
int main(int argc, char **argv)
{