:3HEADmain

Signed-off-by: Anna (navi) Figueiredo Gomes <navi@vlhl.dev>

1 files changed, 61 insertions, 0 deletions

diff --git a/fb.c b/fb.c
new file mode 100644
index 0000000..6c4665e
--- /dev/null
+++ b/fb.c
@@ -0,0 +1,61 @@
+#include <errno.h>
+#include <gmp.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(int argc, char **argv) {
+	if (argc != 2) {
+		fprintf(stderr, "usage: %s <count>\n", argv[0]);
+		exit(-1);
+	}
+
+	char *end = argv[1];
+	long count = strtol(argv[1], &end, 10);
+	if (argv[1] == end || *end) {
+		fprintf(stderr, "usage: %s <count>\n", argv[0]);
+		exit(-1);
+	} else if (errno == ERANGE) {
+		perror(argv[1]);
+		exit(-1);
+	}
+
+	mpz_t a, b, p, q;
+	mpz_t ta, tp, tmp;
+	mpz_init_set_ui(a, 1);
+	mpz_init_set_ui(b, 0);
+	mpz_init_set_ui(p, 0);
+	mpz_init_set_ui(q, 1);
+	mpz_init(tmp);
+	mpz_init(ta);
+	mpz_init(tp);
+
+	while (count > 0) {
+		if (count % 2 == 0) {
+			mpz_mul(tmp, p, p);
+			mpz_addmul(tp, q, q);
+
+			mpz_mul(tmp, p, q);
+			mpz_mul_ui(tmp, tmp, 2);
+			mpz_add(q, tmp, q);
+			mpz_set(p, tp);
+
+			count /= 2;
+		} else {
+			mpz_mul(tmp, b, q);
+			mpz_addmul(tmp, a, q);
+			mpz_addmul(tmp, a, p);
+			mpz_set(ta, tmp);
+
+			mpz_set_ui(tmp, 0);
+			mpz_addmul(tmp, b, p);
+			mpz_addmul(tmp, a, q);
+			mpz_set(a, ta);
+			mpz_set(b, tmp);
+
+			count -= 1;
+		}
+	}
+
+	//mpz_out_str(stdout, 10, b);
+	//printf("\n");
+}