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68 lines
1.2 KiB
C
68 lines
1.2 KiB
C
#include "miller_rabin.h"
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static inline cmph_uint64 int_pow(cmph_uint64 a, cmph_uint64 d, cmph_uint64 n)
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{
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cmph_uint64 a_pow = a;
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cmph_uint64 res = 1;
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while(d > 0)
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{
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if((d & 1) == 1)
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res =(((cmph_uint64)res) * a_pow) % n;
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a_pow = (((cmph_uint64)a_pow) * a_pow) % n;
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d /= 2;
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};
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return res;
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};
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static inline cmph_uint8 check_witness(cmph_uint64 a_exp_d, cmph_uint64 n, cmph_uint64 s)
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{
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cmph_uint64 i;
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cmph_uint64 a_exp = a_exp_d;
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if(a_exp == 1 || a_exp == (n - 1))
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return 1;
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for(i = 1; i < s; i++)
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{
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a_exp = (((cmph_uint64)a_exp) * a_exp) % n;
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if(a_exp == (n - 1))
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return 1;
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};
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return 0;
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};
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cmph_uint8 check_primality(cmph_uint64 n)
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{
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cmph_uint64 a, d, s, a_exp_d;
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if((n % 2) == 0)
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return 0;
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if((n % 3) == 0)
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return 0;
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if((n % 5) == 0)
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return 0;
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if((n % 7 ) == 0)
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return 0;
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//we decompoe the number n - 1 into 2^s*d
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s = 0;
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d = n - 1;
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do
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{
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s++;
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d /= 2;
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}while((d % 2) == 0);
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a = 2;
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a_exp_d = int_pow(a, d, n);
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if(check_witness(a_exp_d, n, s) == 0)
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return 0;
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a = 7;
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a_exp_d = int_pow(a, d, n);
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if(check_witness(a_exp_d, n, s) == 0)
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return 0;
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a = 61;
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a_exp_d = int_pow(a, d, n);
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if(check_witness(a_exp_d, n, s) == 0)
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return 0;
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return 1;
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};
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