Bachelors_Thesis_Code/processes.cpp

#include "processes.hpp"

Rabin_fingerprint_process::Rabin_fingerprint_process(uint32_t irr_poly, size_t window_size_in_bits)
    : window_size_in_bits(window_size_in_bits),
      phi(irr_poly, window_size_in_bits)
{}

void Rabin_fingerprint_process::stream_char(char c) {
    std::bitset<8> b(c);
    for (char i = 7; i >= 0; i--) {
        stream_bit((bool)b[i]);
    }
}

void Rabin_fingerprint_process::stream_bit(bool b) {
    if (window.size() == window_size_in_bits) {
        window.push(b);
        bool b_out = window.front();
        window.pop();
        phi.slide_bit(b, b_out);
    } else {
        window.push(b);
        phi.push_bit(b);
    }
}

uint32_t Rabin_fingerprint_process::get_fingerprint() {
    return phi.get_fingerprint();
}

std::string Rabin_fingerprint_process::get_string_in_window() {
    // check if window contains a whole number of chars
    if ((window_size_in_bits & 0b111) != 0)
        throw std::logic_error("The fingerprinting window doesn't contain a whole number of chars (counting the bits), so it doesn't make sense to return it as a string.");

    #ifndef NDEBUG
    if (window.size() != window_size_in_bits)
        throw std::logic_error("False match! The sliding window isn't even filled yet, which means you matched the pattern of a substring shorter than the pattern. This case should be handled/avoided elsewhere, so we throw an error.");
    #endif

    std::ostringstream os;
    for (size_t i = 0; i < window.size()>>3; i++) {
        // cycle the char
        char c = 0;
        for (size_t j = 0; j < 8; j++) {
            bool b = window.front();
            window.pop();
            window.push(b);
            c <<= 1;
            c |= b;
        }

        os << c;
    }

    std::string s = os.str();

    return s;
}