70 lines
1.9 KiB
C++
70 lines
1.9 KiB
C++
#include "common.hh"
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using std::uint16_t;
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using std::uint8_t;
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using dic_comp_t = std::map<std::pair<uint16_t, uint8_t>, uint16_t>;
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using ustring = std::basic_string<unsigned char>;
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using p_ustring = std::shared_ptr<ustring>;
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[[nodiscard]] int ipow(int base, int exp) {
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int result = 1;
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for (;;) {
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if (exp & 1) {
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result *= base;
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}
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exp >>= 1;
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if (exp == 0) {
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break;
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}
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base *= base;
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}
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return result;
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}
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[[nodiscard]] std::pair<bool, uint16_t>
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dico(dic_comp_t &t_dictionary, const uint16_t t_nr_chaine, const uint8_t t_c) {
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if (t_nr_chaine == 0xFFFF) {
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return std::make_pair(true, t_c);
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}
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auto &e = t_dictionary[std::make_pair(t_nr_chaine, t_c)];
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if (e != 0)
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return std::make_pair(true, e);
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e = static_cast<uint16_t>(t_dictionary.size() + 255);
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return std::make_pair(false, e);
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}
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[[nodiscard]] ustring dico_uncompress(std::map<uint16_t, ustring> &t_dict,
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const uint16_t t_code,
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const uint16_t t_old) {
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// le code existe dans le dictionnaire s’il est < 256
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if (t_code < 256) {
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ustring e{static_cast<unsigned char>(t_code)};
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// 256 car on n'a pas encore tenté d'insérer de nouveau caractère
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if (t_old < 256) {
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t_dict[static_cast<uint16_t>(t_dict.size() + 256)] =
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static_cast<unsigned char>(t_old) + e;
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} else {
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t_dict[static_cast<uint16_t>(t_dict.size() + 256)] = t_dict[t_old] + e;
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}
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return e;
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}
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auto &e = t_dict[t_code];
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auto str = (t_old < 256) ? ustring{static_cast<unsigned char>(t_old)}
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: t_dict[t_old];
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// le code existe dans le dictionnaire
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if (!e.empty()) {
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str += e[0];
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const auto index = static_cast<uint16_t>(t_dict.size() + 256);
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t_dict[index] = str;
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return e;
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}
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// le code n'existe pas encore dans le dictionnaire
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str += str[0];
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e = str;
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t_dict[t_code] = e;
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return e;
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}
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