Changed I/O, compression behavior, removed threads
This commit is contained in:
Phuntsok Drak-pa
parent
2cfb560153
commit
72c71c306f
122
src/compress.cc
122
src/compress.cc
@ -4,39 +4,39 @@
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*/
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#include "compress.hh"
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#include "utf8.hh"
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#include <cassert>
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#include <cstdlib>
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#include <fstream>
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#include <iostream>
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#include "io.hh"
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using std::vector;
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using std::uint8_t;
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using std::uint32_t;
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using std::string;
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using vuint32 = vector<uint32_t>;
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using vvuint32 = vector<vuint32>;
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using std::string;
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using dict_t = std::map<std::pair<uint32_t, uint8_t>, uint32_t>;
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using ustring = std::basic_string<uint8_t>; // chaîne non encodée
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using uvec = std::vector<std::uint32_t>; // chaîne encodée
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using std::printf;
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constexpr size_t CHUNK_SIZE = 32768;
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// constexpr size_t CHUNK_SIZE = 32768;
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/**
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*
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* Reçoit une liste de paires std::thread/vecteurs, le premier étant le
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* processus dont sa sortie est stockée dans le second. La sortie, une liste
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* de caractères uint32_t, est écrite dans le fichier de sortie \p out.
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*
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* \param[in] t_threads
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* \param[out] t_out
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*/
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void join_and_write(
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std::vector<std::pair<std::unique_ptr<std::thread>, uvec>> &t_threads,
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std::vector<std::vector<std::uint32_t>> &compressed_text) {
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for (auto &elem : t_threads) {
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(*elem.first).join();
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constexpr 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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for (auto &elem : t_threads) {
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compressed_text.push_back(std::move(elem.second));
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}
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t_threads.clear();
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return result;
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}
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/**
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@ -49,26 +49,36 @@ void join_and_write(
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* \param[in] t_text Chaîne de caractères uint8_t représentant le fichier d'entrée
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* \param[out] t_res Chaîne de caractères de sortie
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*/
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void lzw_compress(const std::vector<char> &t_text, uvec &t_res) {
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dict_t dictionary{};
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vvuint32 lzw_compress(string &&t_text) {
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std::puts("Compressing...");
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uint32_t w = 0xFFFF;
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vuint32 chunk{};
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vvuint32 res{};
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dict_t dict{};
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constexpr size_t DICT_MAX = 7936; /* 12 bits */
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constexpr size_t DICT_MAX = ipow(2, 13) - 256; /* 12 bits */
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for (const auto &c : t_text) {
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if (dictionary.size() >= DICT_MAX) {
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t_res.push_back(static_cast<uint32_t>(w));
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w = static_cast<uint32_t>(c);
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} else if (const auto &[exists, pos] =
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dico(dictionary, w, static_cast<std::uint8_t>(c));
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exists) {
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for(const auto c : t_text) {
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if(dict.size() >= DICT_MAX) {
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// Dictionary full -> chunk pushed, dict emptied
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res.push_back(std::move(chunk));
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chunk = vuint32{};
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dict = dict_t{};
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w = 0xFFFF;
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}
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if (const auto &[yes, pos] = dico(dict, w, static_cast<uint8_t>(c)); yes) {
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w = pos;
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} else {
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t_res.push_back(static_cast<uint32_t>(w));
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w = static_cast<std::uint8_t>(c);
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chunk.push_back(static_cast<uint32_t>(w));
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w = static_cast<uint32_t>(c);
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}
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}
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if(w != 0xFFFF) {
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chunk.push_back(w);
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res.push_back(std::move(chunk));
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}
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return res;
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}
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/**
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@ -91,8 +101,10 @@ void compress(const std::string &t_in_file, const char *t_out_file) {
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}
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// Fichier de sortie
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FILE *out =
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FILE *const out =
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(t_out_file != nullptr) ? fopen(t_out_file, "wb") : fopen("output.lzw", "wb");
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// std::ofstream out{(t_out_file != nullptr) ? t_out_file : "output.lzw",
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// std::ios::binary};
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if (out == nullptr) {
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std::cerr << "Error at " << __FILE__ << ":" << __LINE__ - 4
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<< ": could not open output file. Aborting...\n";
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@ -100,47 +112,9 @@ void compress(const std::string &t_in_file, const char *t_out_file) {
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exit(1);
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}
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// collection of chunks
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std::vector<std::vector<std::uint32_t>> compressed_text{};
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// thread pool
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std::vector<std::pair<std::unique_ptr<std::thread>, uvec>> threads{};
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// chunk chars
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std::vector<char> chunk(CHUNK_SIZE, 0);
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while (input_file.read(chunk.data(),
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static_cast<std::streamsize>(chunk.size()))) {
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threads.emplace_back(nullptr, uvec{});
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threads.back().second.reserve(CHUNK_SIZE);
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threads.back().first = std::make_unique<std::thread>(
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std::thread{lzw_compress, chunk, ref(threads.back().second)});
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assert(threads.back().first);
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if (threads.size() >= 8) {
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join_and_write(threads, compressed_text);
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}
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}
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if (!threads.empty()) {
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join_and_write(threads, compressed_text);
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}
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if (input_file.tellg() != std::ios::end) {
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std::puts("Leftovers, compressing...");
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{
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const auto prev_pos = input_file.tellg();
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input_file.seekg(0, std::ios::end);
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chunk.reserve(static_cast<size_t>(input_file.tellg() - prev_pos));
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input_file.seekg(prev_pos, std::ios::beg);
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std::istreambuf_iterator<char> itr(input_file);
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for (std::streamoff i = 0; i < prev_pos; ++i, ++itr){
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;
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}
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chunk.assign((itr), std::istreambuf_iterator<char>());
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}
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uvec ret{};
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lzw_compress(chunk, ret);
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compressed_text.push_back(std::move(ret));
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}
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const auto compressed_text{
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lzw_compress(std::string{std::istreambuf_iterator<char>(input_file),
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std::istreambuf_iterator<char>()})};
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write_file(out, compressed_text);
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@ -10,14 +10,14 @@
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#include <vector>
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#include <iostream>
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#include <thread>
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/// \brief Exécution des threads et écriture de leur résultat dans le fichier de sortie
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void join_and_write(std::vector<std::pair<std::unique_ptr<std::thread>,
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std::vector<std::uint32_t>>> &,
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std::vector<std::vector<std::uint32_t>> &);
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#include <optional>
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/// \brief Compression d'une chaine de caractères
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void lzw_compress(const std::vector<char> &, std::vector<std::uint32_t> &);
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std::vector<std::vector<std::uint32_t>> lzw_compress(std::string &&);
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std::optional<std::uint32_t>
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lzw_compress_char(std::vector<std::vector<std::uint32_t>> &,
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std::vector<std::uint32_t> &, const char);
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/// \brief Wrapper de \ref lzw_compress
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void compress(const std::string &, const char *);
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100
src/io.cc
100
src/io.cc
@ -4,13 +4,24 @@
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*/
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#include "io.hh"
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#include <array>
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#ifdef Debug
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constexpr bool debug_mode = true;
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#include <algorithm>
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#else
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constexpr bool debug_mode = false;
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#endif
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using std::vector;
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using std::uint32_t;
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using vuint32 = vector<uint32_t>;
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using vvuint32 = vector<vuint32>;
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constexpr unsigned char char_size = 12;
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/**
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* Écrit dans le fichier \p t_out les chunks passés en paramètre. Le fichier de
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* sortie est composé des éléments suivants :\n
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@ -35,61 +46,42 @@ constexpr bool debug_mode = false;
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* \param[out] t_out Fichier de sortie
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* \param[in] t_text Collection ordonnée des chunks à écrire dans \p t_out
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*/
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void write_file(FILE *t_out, std::vector<std::vector<std::uint32_t>> &t_text) {
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{
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uint32_t char_size = 12;
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if constexpr (debug_mode) {
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std::printf("Char size: %u\n", char_size);
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}
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fwrite(&char_size, sizeof(uint32_t), 1, t_out);
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auto size = static_cast<uint32_t>(t_text.size());
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if constexpr (debug_mode) {
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std::printf("Number of chunks: %u\n", size);
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}
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fwrite(&size, sizeof(uint32_t), 1, t_out);
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void write_file(FILE *const t_out, const vvuint32 &t_text) {
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const auto size = static_cast<uint32_t>(t_text.size());
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if constexpr (debug_mode) {
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std::printf("Char size: %u\n", char_size);
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std::printf("Number of chunks: %u\n", size);
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}
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for(const auto &chunk : t_text) {
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// write size of chunk in uint32_t
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{
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auto size = static_cast<uint32_t>(chunk.size());
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if constexpr (debug_mode) {
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std::printf("Size of chunk: %u\n", size);
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}
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fwrite(&size, sizeof(uint32_t), 1, t_out);
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}
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uint8_t remainder = 0x00;
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for(size_t i = 0; i < chunk.size(); ++i) {
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if(i % 2 == 0) {
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// char = xxxx xxxx xxxx
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// ^^^^^^^^^ ^^^^
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// write keep in remainder as xxxx0000
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auto temp = static_cast<unsigned char>(chunk[i] >> 4);
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fwrite(&temp, sizeof(temp), 1, t_out);
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if constexpr (debug_mode) {
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std::printf("writing: %x\t\t", temp);
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}
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remainder = static_cast<uint8_t>(chunk[i] << 4);
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} else {
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// already have `remainder = yyyy0000`
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// char = xxxx xxxx xxxx
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// ^^^^ ^^^^^^^^^
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// remainder = yyyyxxxx write after remainder
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// remainder = 00000000
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remainder &= static_cast<unsigned char>(chunk[i]) >> 8 & 0xF0;
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fwrite(&remainder, sizeof(remainder), 1, t_out);
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if constexpr (debug_mode) {
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std::printf("writing remainder: %x\t\t", remainder);
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}
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auto temp = static_cast<unsigned char>(chunk[i]);
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fwrite(&temp, sizeof(temp), 1, t_out);
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if constexpr (debug_mode) {
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std::printf("writing: %x\n", temp);
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}
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remainder = 0x00;
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}
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}
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if(remainder != 0) {
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fwrite(&remainder, sizeof(remainder), 1, t_out);
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fwrite(&char_size, sizeof(char_size), 1, t_out);
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fwrite(&size, sizeof(size), 1, t_out);
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for (const auto &chunk : t_text) {
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if constexpr (debug_mode) {
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std::printf("Size of chunk: %zu\n", chunk.size());
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}
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write_chunk(t_out, chunk);
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}
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}
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/**
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* \param t_out Output file
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* \param t_chunk Chunk to be written to \p t_out
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*/
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void write_chunk(FILE *const t_out, const vuint32 &t_chunk) {
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const auto chunk_size = static_cast<uint32_t>(t_chunk.size());
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fwrite(&chunk_size, sizeof(chunk_size), 1, t_out);
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std::array<unsigned char, 3> data{};
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for (size_t i = 0; i < t_chunk.size(); ++i) {
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data.fill(0);
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if (i % 2 == 0) {
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data[0] = static_cast<unsigned char>(t_chunk[i] >> 4);
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data[1] = static_cast<unsigned char>(t_chunk[i] << 4);
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} else {
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data[1] |= static_cast<unsigned char>(t_chunk[i] >> 8) & 0x0F;
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data[2] = static_cast<unsigned char>(t_chunk[i]);
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fwrite(data.data(), sizeof(data[0]), 3, t_out);
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}
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}
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if (t_chunk.size() % 2 != 0) {
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fwrite(data.data(), sizeof(data[0]), 3, t_out);
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}
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}
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@ -8,6 +8,7 @@
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#include <cstdio>
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#include <cstdint>
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#include <iostream>
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#include <vector>
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/*
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@ -26,6 +27,9 @@
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/// \brief Écrit dans le fichier le texte compressé
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void write_file(FILE *, std::vector<std::vector<std::uint32_t>> &);
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void write_file(FILE *const, const std::vector<std::vector<std::uint32_t>> &);
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/// \brief Écrit un chunk dans le fichier de sortie
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void write_chunk(FILE *const, const std::vector<std::uint32_t> &);
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#endif /* LZW_SRC_IO_H_ */
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52
src/utf8.cc
52
src/utf8.cc
@ -1,52 +0,0 @@
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/**
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* \file utf8.cc
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* \brief Implementation for UTF-8 related functions
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*/
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#include "utf8.hh"
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#include <string>
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using FILE = std::FILE;
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using uint8_t = std::uint8_t;
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using uint32_t = std::uint32_t;
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using ustring = std::basic_string<uint8_t>; // chaine non encodée
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/**
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* Les caractères \c passés en argument sont écrit dans le fichier de sortie au
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* format UTF-8
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*
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* \param[in] out Fichier de sortie
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* \param[in] c Caractères à écrire dans \p out
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*/
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void write_utf8(FILE* t_out, uint32_t t_c) {
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if(t_c < 128) {
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fwrite(&t_c, sizeof(unsigned char), 1, t_out);
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return;
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}
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size_t loops = 0;
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unsigned char header = 0;
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if (t_c < 2048) {
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loops = 1;
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header = 0xC0;
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} else if (t_c < 65536) {
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loops = 2;
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header = 0xE0;
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} else if (t_c < 2097152) {
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loops = 3;
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header = 0xF0;
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} else if (t_c < 67108864) {
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loops = 4;
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header = 0xF8;
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} else {
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loops = 5;
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header = 0xFC;
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}
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ustring str(loops + 1, 0);
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for (size_t i = 0; i <= loops; ++i) {
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str[i] = static_cast<unsigned char>(
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((t_c & ((i == loops) ? 0x3F : 0xFF)) >> ((loops - i) * 6)) +
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((i == 0) ? header : 0x80));
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}
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fwrite(str.data(), sizeof(unsigned char), str.size(), t_out);
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}
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26
src/utf8.hh
26
src/utf8.hh
@ -1,26 +0,0 @@
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/**
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* \file utf8.hh
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* \brief Header for UTF-8 related functions
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*/
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#ifndef LZW_SRC_UTF8_H_
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#define LZW_SRC_UTF8_H_
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#include <cstdio>
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#include <cstdint>
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/*
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L’encodage des caractères se fait en UTF-8
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char < 128 => "0xxxxxxx" 7bits
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char < 2,048 => "110xxxxx 10xxxxxx" 11bits
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char < 65,536 => "1110xxxx 10xxxxxx 10xxxxxx" 16bits
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char < 2,097,152 => "11110xxx 10xxxxxx 10xxxxxx 10xxxxxx" 21bits
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char < 67,108,864 => "111110xx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx" 26bits
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char < 2,147,483,648 => "1111110x 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx" 31bits
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*/
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/// \brief Écrit les caractères au format UTF-8
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void write_utf8(std::FILE* t_out, std::uint32_t t_c);
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#endif /* LZW_SRC_UTF8_H_ */
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