From 2a8e7aeeef99161b6f0378ac14e297c23ca6227b Mon Sep 17 00:00:00 2001 From: Sebastiano Tronto Date: Wed, 4 Jun 2025 11:55:34 +0200 Subject: First 4 examples --- 03_threads/primes.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+) create mode 100644 03_threads/primes.c (limited to '03_threads/primes.c') diff --git a/03_threads/primes.c b/03_threads/primes.c new file mode 100644 index 0000000..a5076c6 --- /dev/null +++ b/03_threads/primes.c @@ -0,0 +1,53 @@ +#include +#include + +#define NTHREADS 16 + +bool isprime(int); +void *pthread_routine(void *); + +struct interval { int low; int high; int count; }; + +int primes_in_range(int low, int high) { + pthread_t threads[NTHREADS]; + struct interval args[NTHREADS]; + + if (low < 0 || high < low) + return 0; + + int interval_size = (high-low)/NTHREADS + 1; + for (int i = 0; i < NTHREADS; i++) { + args[i].low = low + i*interval_size; + args[i].high = args[i].low + interval_size; + pthread_create(&threads[i], NULL, pthread_routine, &args[i]); + } + + int result = 0; + for (int i = 0; i < NTHREADS; i++) { + pthread_join(threads[i], NULL); + result += args[i].count; + } + + return result; +} + +bool isprime(int n) { + if (n < 2) + return false; + + for (int i = 2; i*i <= n; i++) + if (n % i == 0) + return false; + return true; +} + +void *pthread_routine(void *arg) { + struct interval *interval = arg; + + interval->count = 0; + for (int i = interval->low; i < interval->high; i++) + if (isprime(i)) + interval->count++; + + return NULL; +} -- cgit v1.3