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#include <iostream>
#include <fstream>
#include <cstring>
#include <array>
#include <list>
#include <vector>
#include <cstdint>
#include <sstream>
#include "huffman.hpp"
int show_usage()
{
std::cerr << "Usage: sound (compress|decompress) input_file output_file." << std::endl;
return 1;
}
std::array<char, 44> read_header(std::ifstream& input_file)
{
std::array<char, 44> wav_header;
input_file.read(wav_header.data(), wav_header.size());
return wav_header;
}
std::list<char> read_first_context(std::istreambuf_iterator<char>& input_iterator)
{
std::list<char> result;
result.push_back(*input_iterator);
++input_iterator;
result.push_back(*input_iterator);
++input_iterator;
return result;
}
int fc(const std::list<char>& context)
{
auto c1 = context.front();
auto c2 = context.back();
return c1 + (c1 - c2);
}
int archive(const char *input_name, const char *output_name)
{
std::ifstream input_file{ input_name, std::ios::binary | std::ios::in };
input_file.exceptions(std::ios::badbit | std::ios::failbit);
std::array<char, 44> wav_header = read_header(input_file);
if (input_file.gcount() != 44)
{
// Not enough bytes available to read the header.
return 2;
}
std::istreambuf_iterator<char> wav_iterator(input_file), input_end;
std::list<char> context = read_first_context(wav_iterator);
std::ofstream output_file{ output_name, std::ios::binary | std::ios::trunc | std::ios::in };
output_file.exceptions(std::ios::badbit | std::ios::failbit);
output_file.write(wav_header.data(), wav_header.size());
output_file.write(&context.front(), 1);
output_file.write(&context.back(), 1);
std::vector<std::uint8_t> encoding;
while (wav_iterator != input_end)
{
int guess = fc(context);
int error = *wav_iterator - guess;
// Update the context.
context.pop_back();
context.push_back(*wav_iterator);
encoding.push_back(error >> 8);
encoding.push_back(error);
++wav_iterator;
}
compress(encoding, output_file);
return 0;
}
int unarchive(const char *input_name, const char *output_name)
{
std::ifstream input_file{ input_name, std::ios::binary | std::ios::in };
input_file.exceptions(std::ios::badbit | std::ios::failbit);
std::array<char, 44> wav_header = read_header(input_file);
if (input_file.gcount() != 44)
{
// Not enough bytes available to read the header.
return 2;
}
std::istreambuf_iterator<char> wav_iterator(input_file), input_end;
std::list<char> context = read_first_context(wav_iterator);
std::stringstream encoding_stream;
std::vector<std::uint8_t> encoded_wav{ wav_iterator, input_end };
decompress(encoded_wav, encoding_stream);
std::ofstream output_file{ output_name, std::ios::binary | std::ios::trunc | std::ios::in };
output_file.exceptions(std::ios::badbit | std::ios::failbit);
output_file.write(wav_header.data(), wav_header.size());
output_file.write(&context.front(), 1);
output_file.write(&context.back(), 1);
std::string encoding = encoding_stream.str();
auto current_encoding = std::cbegin(encoding);
while (current_encoding != std::cend(encoding))
{
std::uint8_t first_byte = *current_encoding;
++current_encoding;
std::uint8_t second_byte = *current_encoding;
++current_encoding;
int error = (first_byte << 8) | second_byte;
int guess = fc(context);
char element = error + guess;
// Update the context.
context.pop_back();
context.push_back(element);
output_file.write(&element, 1);
}
return 0;
}
int main(int argc, char **argv)
{
if (argc != 4)
{
return show_usage();
}
if (std::strcmp(argv[1], "compress") == 0)
{
return archive(argv[2], argv[3]);
}
else if (std::strcmp(argv[1], "decompress") == 0)
{
return unarchive(argv[2], argv[3]);
}
else
{
return show_usage();
}
return 0;
}
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