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83 lines
2.3 KiB
83 lines
2.3 KiB
#pragma once
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#include <includes.hpp>
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// joshua's compression :D
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namespace jcmp {
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typedef uint32_t uint;
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struct __attribute__ ((__packed__)) header {
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const char signature[4];
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uint width;
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uint height;
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uint length;
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header(uint width = 0, uint height = 0, uint length = 0)
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: signature{'J', 'C', 'M', 'P'}
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, width(width)
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, height(height)
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, length(length)
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{}
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};
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struct __attribute__ ((__packed__)) coefficient {
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double c;
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uint x;
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uint y;
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};
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struct image {
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header header;
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std::vector<coefficient> data;
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image() = default;
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image(uint width, uint height, std::vector<coefficient> const & data_in)
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: header(width, height, data_in.size())
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, data(data_in)
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{}
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void clear(){
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header.length = header.height = header.width = 0;
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data.clear();
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}
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};
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// Way of writing does not matter for performance
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// timings: http://i.imgur.com/cskC43O.png (300 points per method)
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// It's not surprising as filebuf is already a buffer
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inline void write_to_file(image const & image, std::string filename){
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std::filebuf file;
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file.open(filename, std::ios_base::out|std::ios_base::trunc);
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file.sputn(reinterpret_cast<const char*>(&image.header), sizeof(header));
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file.sputn(reinterpret_cast<const char*>(image.data.data()), image.data.size() * sizeof(coefficient));
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}
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// Assumes Iterator points to a coefficient]
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// length in header is not used
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template <typename Iterator>
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inline void write_to_file(header h, Iterator begin, Iterator end, std::string filename){
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h.length = 0;
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std::filebuf file;
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file.open(filename, std::ios_base::out|std::ios_base::trunc);
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file.sputn(reinterpret_cast<const char*>(&h), sizeof(header));
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while(begin != end){
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file.sputn(reinterpret_cast<const char*>(&*begin++), sizeof(coefficient));
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h.length++;
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}
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// http://stackoverflow.com/questions/2530274/how-to-overwrite-only-part-of-a-file-in-c
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file.pubseekpos(0);
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file.sputn(reinterpret_cast<const char*>(&h), sizeof(header));
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}
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inline image read_from_file(std::string const& filename){
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std::filebuf file;
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file.open(filename, std::ios_base::in);
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image image;
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file.sgetn(reinterpret_cast<char*>(&image.header), sizeof(header));
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assert(strncmp("JCMP", image.header.signature, 4) == 0);
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image.data.resize(image.header.length);
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file.sgetn(reinterpret_cast<char*>(image.data.data()), image.data.size() * sizeof(coefficient));
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return image;
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}
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}
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