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60 lines
1.5 KiB
60 lines
1.5 KiB
2 months ago
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/*
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* The UCW Library -- Prime numbers
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*
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* (c) 2008 Michal Vaner <vorner@ucw.cz>
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*
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* Code taken from ucw/lib.h by:
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*
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* (c) 1997--2008 Martin Mares <mj@ucw.cz>
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* (c) 2005 Tomas Valla <tom@ucw.cz>
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* (c) 2006 Robert Spalek <robert@ucw.cz>
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* (c) 2007 Pavel Charvat <pchar@ucw.cz>
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*
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* This software may be freely distributed and used according to the terms
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* of the GNU Lesser General Public License.
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*/
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#ifndef _UCW_PRIME_H
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#define _UCW_PRIME_H
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#include <ucw/lib.h>
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#ifdef CONFIG_UCW_CLEAN_ABI
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#define isprime ucw_isprime
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#define next_table_prime ucw_next_table_prime
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#define nextprime ucw_nextprime
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#define prev_table_prime ucw_prev_table_prime
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#endif
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/* prime.c */
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/**
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* Return a non-zero value iff @x is a prime number.
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* The time complexity is `O(sqrt(x))`.
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**/
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int isprime(uint x);
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/**
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* Return some prime greater than @x. The function does not checks overflows, but it should
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* be safe at least for @x lower than `1U << 31`.
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* If the Cramer's conjecture is true, it should have complexity `O(sqrt(x) * log(x)^2)`.
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**/
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uint nextprime(uint x);
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/* primetable.c */
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/**
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* Quickly lookup a precomputed table to return a prime number greater than @x.
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* Returns zero if there is no such prime (we guarantee the existance of at
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* least one prime greater than `1U << 31` in the table).
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**/
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uint next_table_prime(uint x);
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/**
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* Quickly lookup a precomputed table to return a prime number smaller than @x.
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* Returns zero if @x is smaller than `7`.
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**/
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uint prev_table_prime(uint x);
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#endif // _UCW_PRIME_H
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