112 lines
3.0 KiB
C++
112 lines
3.0 KiB
C++
#include <stdexcept>
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#include <base/baseN.hpp>
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namespace baseN
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{
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bool isValid(const std::string &str, const int8_t *map) noexcept
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{
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for (int64_t i = str.size() - 1; i >= 0; i--)
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{
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if (map[(int8_t)str[i]] == -1)
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{
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return false;
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}
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}
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return true;
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}
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std::string encode(std::vector<uint8_t> data, uint8_t base, uint64_t enc_size, const char *digits) noexcept
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{
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if (data.size() == 0)
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{
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return "";
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}
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std::string str(enc_size, ' ');
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int64_t
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zero_count = 0,
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idx_div = 0,
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idx_quo = 0,
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idx_quo_last = data.size(),
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idx_str = str.size() - 1;
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uint16_t div = data[idx_div++];
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while (data[zero_count] == 0)
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{
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zero_count++;
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}
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while (idx_quo_last > 1 || data[0] > base)
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{
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if (div < base)
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{
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div <<= 8;
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div += data[idx_div++];
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}
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data[idx_quo++] = div / base;
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div %= base;
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while (idx_div < idx_quo_last)
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{
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div <<= 8;
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div += data[idx_div++];
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data[idx_quo++] = div / base;
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div %= base;
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}
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idx_quo_last = idx_quo;
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idx_quo = 0;
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idx_div = 0;
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str[idx_str--] = digits[div];
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div = data[idx_div++];
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}
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str[idx_str--] = digits[div];
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while (zero_count > 0 && idx_str > 0)
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{
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str[idx_str--] = '1';
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zero_count--;
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}
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str.erase(0, idx_str + 1);
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return str;
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}
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std::vector<uint8_t> decode(const std::string &str, uint8_t base, uint64_t dec_size, const char *digits, const int8_t *map)
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{
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if (str.size() == 0)
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{
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return std::vector<uint8_t>();
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}
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if (!baseN::isValid(str, map))
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{
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throw std::logic_error("baseN::decode: out of digits map");
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}
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std::vector<uint8_t> data(dec_size);
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uint64_t idx_str = 0;
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int64_t
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zero_count = 0,
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idx_quo = data.size() - 1,
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idx_quo_last = data.size() - 2;
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uint16_t div;
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while (str[zero_count] == digits[0])
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{
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zero_count++;
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}
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data[idx_quo] = map[(int8_t)str[idx_str++]];
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while (idx_str < str.size())
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{
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div = map[(int8_t)str[idx_str++]];
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while (idx_quo > idx_quo_last && idx_quo > 0)
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{
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div += data[idx_quo] * base;
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data[idx_quo--] = div;
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div >>= 8;
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}
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data[idx_quo--] = div;
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idx_quo_last = idx_quo;
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idx_quo = data.size() - 1;
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}
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idx_quo = 0;
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while (data[idx_quo] == 0)
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{
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idx_quo++;
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}
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data.erase(data.begin(), data.begin() + idx_quo - zero_count);
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return data;
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}
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} |