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97
03-CRC.md
97
03-CRC.md
@ -1,97 +0,0 @@
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## Zadanie
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Napisać program, który dla wiadomości `M` w formie tekstowej ASCII (tj. `8` bitów na znak):
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1. utworzy FCS (*Frame Check Sequence*) długości `16` bitów zgodnie z algorytmem **D-1.1**;
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- INPUT: `M` - tablica znaków ASCII długości `n-2`;
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- OUTPUT: `N` - tablica 8-bitowych liczb (`unsigned char`) długości `n`, która zawiera oryginalną wiadomość `M` na pierwszych `n-2` miejscach, zaś ostatnie dwa zawierają FCS.
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2. pozwoli sprawdzić, czy dana ramka (tj. wiadomość + FCS) zawiera poprawną treść (zgodnie z **D-1.2**;
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- INPUT: `N` - tablica 8-bitowych liczb (`unsigned char`) długości `n` (np. w formacie hex)
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- OUTPUT: `true` jeśli dwie ostatnie liczby tablicy `N` odpowiadają FCS wiadomości `M = N[0:n-2]` (interpretowanej jako tablica typu `char`), `false` w przeciwnym wypadku;
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UWAGA: Program w punkcie **2** powinien być w stanie zweryfikować output z punktu **1**!
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Źródło: [Report: Telemetry Summary of Concept and Rationale](http://mtc-m16c.sid.inpe.br/col/sid.inpe.br/mtc-m18@80/2009/07.15.17.25/doc/CCSDS%20100.0-G-1.pdf), CCSDS 100.0-G-1 Report Concerning Space.
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### Warunki punktacji
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* program musi być typu wsadowego, tj. uruchamiany z linii komend;
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* program musi się działać (i kompilować) na serwerze [LTS](https://laboratoria.wmi.amu.edu.pl/en/uslugi/serwer-terminalowy/lts)
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* implementacja bazowa (korzystająca z dzielenia wielomianów) jest warta 1 punkt;
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* każda zmiana która wpływa na szybkość musi być skomentowana i opisana bardzo dokładnie (co zrobiliśmy, dlaczego (i jak) wpływa to na szybkość i dlaczego wynik matematycznie jest taki sam);
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* najszybsza implementacja dostaje 2 pkt; najwolniejsza 1; reszta rozłożona liniowo;
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* dwie kategorie szybkości:
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- języki statycznie kompilowane (C, C++, java,...) oraz języki JIT;
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- języki interpretowane (python, lua,...);
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UWAGA: **NIE** przyjmuję squashed pulls (z jednym commitem), zwłaszcza jeśli chodzi o wersję działającą szybko.
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### Termin
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21.06.2018
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### Dodatkowe informacje
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Funkcja, którą omawialiśmy, to tzw. CRC-16-CCITT, czyli [16-bit Cyclic Redundancy Check](https://en.wikipedia.org/wiki/Cyclic_redundancy_check). Funkcje tego typu , są uzywane we wszystkich ramkach [komunikacji](https://en.wikipedia.org/wiki/Cyclic_redundancy_check#Polynomial_representations_of_cyclic_redundancy_checks), od USB, przez Ethernet, Bluetooth, Wifi, GSM, na standardach dźwięku i obrazu (MPEG, PNG) i dyskach twadrdych (SATA) kończąc.
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#### Implementacja referencyjna
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```c
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static unsigned short crc_table[256] = {
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0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5,
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0x60c6, 0x70e7, 0x8108, 0x9129, 0xa14a, 0xb16b,
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0xc18c, 0xd1ad, 0xe1ce, 0xf1ef, 0x1231, 0x0210,
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0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6,
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0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c,
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0xf3ff, 0xe3de, 0x2462, 0x3443, 0x0420, 0x1401,
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0x64e6, 0x74c7, 0x44a4, 0x5485, 0xa56a, 0xb54b,
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0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d,
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0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6,
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0x5695, 0x46b4, 0xb75b, 0xa77a, 0x9719, 0x8738,
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0xf7df, 0xe7fe, 0xd79d, 0xc7bc, 0x48c4, 0x58e5,
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0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823,
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0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969,
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0xa90a, 0xb92b, 0x5af5, 0x4ad4, 0x7ab7, 0x6a96,
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0x1a71, 0x0a50, 0x3a33, 0x2a12, 0xdbfd, 0xcbdc,
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0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a,
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0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03,
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0x0c60, 0x1c41, 0xedae, 0xfd8f, 0xcdec, 0xddcd,
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0xad2a, 0xbd0b, 0x8d68, 0x9d49, 0x7e97, 0x6eb6,
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0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70,
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0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a,
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0x9f59, 0x8f78, 0x9188, 0x81a9, 0xb1ca, 0xa1eb,
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0xd10c, 0xc12d, 0xf14e, 0xe16f, 0x1080, 0x00a1,
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0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,
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0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c,
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0xe37f, 0xf35e, 0x02b1, 0x1290, 0x22f3, 0x32d2,
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0x4235, 0x5214, 0x6277, 0x7256, 0xb5ea, 0xa5cb,
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0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d,
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0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447,
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0x5424, 0x4405, 0xa7db, 0xb7fa, 0x8799, 0x97b8,
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0xe75f, 0xf77e, 0xc71d, 0xd73c, 0x26d3, 0x36f2,
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0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634,
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0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9,
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0xb98a, 0xa9ab, 0x5844, 0x4865, 0x7806, 0x6827,
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0x18c0, 0x08e1, 0x3882, 0x28a3, 0xcb7d, 0xdb5c,
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0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,
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0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0,
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0x2ab3, 0x3a92, 0xfd2e, 0xed0f, 0xdd6c, 0xcd4d,
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0xbdaa, 0xad8b, 0x9de8, 0x8dc9, 0x7c26, 0x6c07,
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0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1,
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0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba,
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0x8fd9, 0x9ff8, 0x6e17, 0x7e36, 0x4e55, 0x5e74,
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0x2e93, 0x3eb2, 0x0ed1, 0x1ef0
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};
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unsigned short CRCCCITT(unsigned char *data, size_t length)
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{
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size_t count;
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unsigned int crc = 0xffff;
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unsigned int temp;
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for (count = 0; count < length; ++count)
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{
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temp = (*data++ ^ (crc >> 8)) & 0xff;
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crc = crc_table[temp] ^ (crc << 8);
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}
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return (unsigned short)(crc);
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}
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```
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@ -1,48 +0,0 @@
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## Zadanie
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Napisać program, który dla pierścienia `ℤ/nℤ[x]/(f = a₀ + a₁x¹+ ...+ aₖxᵏ)` znajdzie wszystkie
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1. elementy odwracalne,
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2. dzielniki zera,
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3. elementy nilpotentne,
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4. elementy idempotentne.
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- INPUT: `n [a₀,a₁,...,aₖ]`
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- OUTPUT: lista zawierająca cztery powyższe listy elementów (wielomianów, podanych jako listy współczynników)
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### Przykłady:
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1. `ℤ/2ℤ[x]/(x² + x + 1)`, który jest ciałem, tzn. `0` jest jedynym elementem nilpotentnym i jedynym dzielnikiem zera:
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* INPUT: `2 [1,1,1]`
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* OUTPUT:
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```shell
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[
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[[1], [0,1], [0,1], [1,1]], # odwracalne
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[[0]], # dzielniki zera
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[[0]], # nilpotenty
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[[1]] # idempotenty
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]
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```
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1. `ℤ/5ℤ[x]/(2x³ + 2x² + x + 1)`
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* INPUT: `3, [1,1,2,2]`
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* OUTPUT:
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```sh
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[
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[[1], [2], [0, 1], [0, 2], [0, 0, 1], [1, 0, 1], [2, 1, 1], [2, 2, 1], [0, 0, 2], [2, 0, 2], [1, 1, 2], [1, 2, 2]], # odwracalne
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[[0], [1, 1], [2, 1], [1, 2], [2, 2], [2, 0, 1], [0, 1, 1], [1, 1, 1], [0, 2, 1], [1, 2, 1], [1, 0, 2], [0, 1, 2], [2, 1, 2], [0, 2, 2], [2, 2, 2]], # dzielniki zera
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[[0], [2, 0, 1], [1, 0, 2]], # nilpotenty
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[[0], [1], [1, 2, 1], [0, 1, 2]] # idempotenty
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]
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```
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### Warunki punktacji
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* program musi być typu wsadowego, tj. uruchamiany z linii komend;
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* program musi się działać (i kompilować) na serwerze [LTS](https://laboratoria.wmi.amu.edu.pl/en/uslugi/serwer-terminalowy/lts)
|
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|
||||
UWAGA: **NIE** przyjmuję squashed pulls (z jednym commitem)
|
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### Termin
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28.06.2018
|
48
Ring.py
Normal file
48
Ring.py
Normal file
@ -0,0 +1,48 @@
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from fractions import gcd
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class Modulo:
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def __init__(self, n):
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self.n = int(n)
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self.modulo_set = list(range(self.n))
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self.answer = []
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def get_inverse_elements(self):
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self.inverse_elements = []
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for i in self.modulo_set:
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if gcd(i, self.n) == 1:
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self.inverse_elements.append(i)
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self.answer.append(self.inverse_elements)
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def get_zero_divisors(self):
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self.zero_divisors = []
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for i in self.modulo_set:
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for j in self.modulo_set:
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if (i * j) % self.n == 0 and i != 0 and j != 0:
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self.zero_divisors.append(i)
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self.answer.append(list(set(self.zero_divisors)))
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def get_nilpotent_elements(self):
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self.nilpotent_elements = []
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for i in self.modulo_set:
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for j in range(1, len(self.inverse_elements) + 1):
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if (i**j) % self.n == 0 and i != 0:
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self.nilpotent_elements.append(i)
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self.answer.append(list(set(self.nilpotent_elements)))
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def get_idempotent_elements(self):
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self.idempotent_elements = []
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for i in self.modulo_set:
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if (i*i) % self.n == i:
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self.idempotent_elements.append(i)
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self.answer.append(self.idempotent_elements)
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def get_all(self):
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self.get_inverse_elements()
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self.get_zero_divisors()
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self.get_nilpotent_elements()
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self.get_idempotent_elements()
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return self.answer
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s = Modulo(input("Enter n: "))
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print(s.get_all())
|
85
crc16.py
Normal file
85
crc16.py
Normal file
@ -0,0 +1,85 @@
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from poly import Polynomial
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import sys
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import ast
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Polynomial.n = 2
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def normalize_byte(data):
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while len(data) != 8:
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if len(data) < 8:
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data = str(0) + data
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else:
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data = data[1:]
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return data
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def encode(in_data):
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data = in_data
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data = list(data)
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data_binary = [bin(ord(char)).replace('b', '') for char in data]
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data_binary = [normalize_byte(byte) for byte in data_binary]
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data_binary = [int(bit) for bit in list(''.join(data_binary))]
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data_binary.reverse()
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M = [0] * 16 + data_binary
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L = [0] * (len(data_binary)) + [1] * 16
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G = [1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1]
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result_poly = Polynomial.divide(Polynomial.add(Polynomial(M), Polynomial(L)), Polynomial(G))
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result = result_poly.coefficients + [0] * (16 - len(result_poly.coefficients))
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result.reverse()
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data_binary.reverse()
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data_binary = data_binary + result
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data_binary = [data_binary[i:i+8] for i in range(0, len(data_binary), 8)]
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data_binary = [int(''.join(map(str, byte)), 2) for byte in data_binary]
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fcs = [hex(byte) for byte in data_binary]
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fcs = fcs[-2:]
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data = [chr(byte) for byte in data_binary]
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data = ''.join(data[0:-2])
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return data, fcs
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def check_fcs(in_data, fcs):
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data = in_data
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data = list(data)
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data_binary = [bin(ord(char)).replace('b', '') for char in data]
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data_binary = [normalize_byte(byte) for byte in data_binary]
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data_binary = [int(bit) for bit in list(''.join(data_binary))]
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fcs_binary = [bin(int(in_hex, 16)).replace('b', '') for in_hex in fcs]
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fcs_binary = [normalize_byte(byte) for byte in fcs_binary]
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fcs_binary = [int(bit) for bit in list(''.join(fcs_binary))]
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data_binary += fcs_binary
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data_binary.reverse()
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C = [0] * 16 + data_binary
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L = [0] * len(data_binary) + [1] * 16
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G = [1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1]
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S = Polynomial.divide(Polynomial.add(Polynomial(C), Polynomial(L)), Polynomial(G))
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if S.coefficients == []:
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return True
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return False
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||||
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def main():
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try:
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if sys.argv[1] == '-e' or sys.argv[1] == '-encode':
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arg, fcs = encode(sys.argv[2])
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print(arg, fcs)
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print(check_fcs(arg, fcs)) # powinno zawsze zwracać true
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elif sys.argv[1] == '-c' or sys.argv[1] == '-check':
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arg = sys.argv[2]
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fcs = ast.literal_eval(sys.argv[3])
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print(check_fcs(arg, fcs))
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else:
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raise IndexError
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except IndexError:
|
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print("To encode: python3 CRC16.py -e [argument]\nTo check result: python3 CRC16.py -c [argument] [fcs]")
|
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|
||||
|
||||
if __name__ == "__main__":
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main()
|
75
poly.py
Normal file
75
poly.py
Normal file
@ -0,0 +1,75 @@
|
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import sys
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import ast
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|
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class Polynomial:
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|
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n = 0
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|
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def __init__(self, coef_list):
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self.degree = len(coef_list) - 1
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||||
self.coefficients = [x % Polynomial.n for x in coef_list]
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@staticmethod
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def add(p1, p2):
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result = []
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f = p1.coefficients
|
||||
g = p2.coefficients
|
||||
if len(f) >= len(g):
|
||||
result = f
|
||||
for i in range(0, len(g)):
|
||||
result[i] = f[i] + g[i]
|
||||
else:
|
||||
result = g
|
||||
for i in range(0, len(f)):
|
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result[i] = f[i] + g[i]
|
||||
result = [x % int(Polynomial.n) for x in result]
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return Polynomial(result)
|
||||
|
||||
@staticmethod
|
||||
def multiply(p1, p2):
|
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result = [0] * (p1.degree + p2.degree + 1)
|
||||
f = p1.coefficients
|
||||
g = p2.coefficients
|
||||
for i in range(0, len(f)):
|
||||
for j in range(0, len(g)):
|
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result[i+j] += f[i] * g[j]
|
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result = [x % int(Polynomial.n) for x in result]
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return Polynomial(result)
|
||||
|
||||
@staticmethod
|
||||
def divide(p1, p2):
|
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def inverse(x):
|
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for i in range(1, int(Polynomial.n)):
|
||||
r = (i * x) % int(Polynomial.n)
|
||||
if r == 1:
|
||||
break
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||||
else:
|
||||
raise ZeroDivisionError
|
||||
return i
|
||||
if p1.degree < p2.degree:
|
||||
return p1
|
||||
f = p1.coefficients
|
||||
g = p2.coefficients
|
||||
g_lead_coef = g[-1]
|
||||
g_deg = p2.degree
|
||||
while len(f) >= len(g):
|
||||
f_lead_coef = f[-1]
|
||||
tmp_coef = f_lead_coef * inverse(g_lead_coef)
|
||||
tmp_exp = len(f) - 1 - g_deg
|
||||
tmp = []
|
||||
for _ in range(tmp_exp):
|
||||
tmp.append(0)
|
||||
tmp.append(tmp_coef)
|
||||
tmp_poly = Polynomial(tmp)
|
||||
sub = Polynomial.multiply(p2, tmp_poly)
|
||||
f = [x - y for x, y in zip(f, sub.coefficients)]
|
||||
f = [x % int(Polynomial.n) for x in f]
|
||||
while f and f[-1] == 0:
|
||||
f.pop()
|
||||
return Polynomial(f)
|
||||
|
||||
@staticmethod
|
||||
def gcd(p1, p2):
|
||||
if len(p2.coefficients) == 0:
|
||||
return p1
|
||||
return Polynomial.gcd(p2, Polynomial.divide(p1, p2))
|
Loading…
Reference in New Issue
Block a user