forked from Github_Repos/cvw
102 lines
1.9 KiB
C
102 lines
1.9 KiB
C
/*
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* Filename:
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*
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* sieve.c
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*
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* Description:
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*
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* The Sieve of Eratosthenes benchmark, from Byte Magazine
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* early 1980s, when a PC would do well to run this in 10
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* seconds. This version really does count prime numbers
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* but omits the numbers 1, 3 and all even numbers. The
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* expected count is 1899.
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*
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*/
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#include <sys/time.h>
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#include <stdio.h>
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#define SIZE 8190
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//#define SIZE 8388608
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double time_diff(struct timeval x , struct timeval y);
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int sieve () {
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unsigned char flags [SIZE + 1];
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int iter;
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int count;
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for (iter = 1; iter <= 10; iter++)
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{
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int i, prime, k;
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count = 0;
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for (i = 0; i <= SIZE; i++)
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flags [i] = 1;
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for (i = 0; i <= SIZE; i++)
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{
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if (flags [i])
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{
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prime = i + i + 3;
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k = i + prime;
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while (k <= SIZE)
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{
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flags [k] = 0;
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k += prime;
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}
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count++;
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}
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}
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}
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return count;
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}
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int main () {
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int ans;
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struct timeval before , after;
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gettimeofday(&before , NULL);
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ans = sieve ();
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gettimeofday(&after , NULL);
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if (ans != 1899)
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printf ("Sieve result wrong, ans = %d, expected 1899", ans);
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printf("Total time elapsed : %.0lf us\n" , time_diff(before , after) );
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printf("Round 2\n");
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gettimeofday(&before , NULL);
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ans = sieve ();
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gettimeofday(&after , NULL);
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if (ans != 1899)
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printf ("Sieve result wrong, ans = %d, expected 1899", ans);
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printf("Total time elapsed : %.0lf us\n" , time_diff(before , after) );
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return 0;
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}
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double time_diff(struct timeval x , struct timeval y)
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{
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double x_ms , y_ms , diff;
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x_ms = (double)x.tv_sec*1000000 + (double)x.tv_usec;
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y_ms = (double)y.tv_sec*1000000 + (double)y.tv_usec;
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diff = (double)y_ms - (double)x_ms;
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return diff;
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}
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