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/** @file 410user/progs/ack.c
* @author acrichto
* @brief Computes Ackermann function in multiple threads
* @public yes
* @for p4-smp
* @status done
*/
/* "Because not all total computable functions are primitive recursive" */
#include <thread.h>
#include <thrgrp.h>
#include <410_tests.h>
#include <stdio.h>
#include <syscall.h>
DEF_TEST_NAME("ack:");
#define ACKN 8
#define THREADS 8
typedef void*(thr_func)(void*);
int ack(int m, int n) {
if (m == 0) return n + 1;
if (n == 0) return ack(m - 1, 1);
return ack(m - 1, ack(m, n - 1));
}
void* ackstart(void *n) {
return (void*) ack(3, (int) n);
}
int main() {
thr_init(1024 * 128);
int ticks = get_ticks();
int i, answer, guess;
thrgrp_group_t group;
REPORT_ON_ERR(thrgrp_init_group(&group));
for (i = 0; i < THREADS; i++) {
REPORT_ON_ERR(thrgrp_create(&group, (thr_func*) ackstart, (void*) ACKN));
}
REPORT_ON_ERR(thrgrp_join(&group, (void*) &answer));
for (i = 1; i < THREADS; i++) {
REPORT_ON_ERR(thrgrp_join(&group, (void*) &guess));
if (guess != answer) {
REPORT_END_FAIL;
}
}
printf("ack(3, %d) = %d\n", ACKN, answer);
printf("ticks taken: %d\n", get_ticks() - ticks);
thr_exit(0);
}
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