1 files changed, 35 insertions, 0 deletions

diff --git a/fib.c b/fib.c
new file mode 100644
index 0000000..6f510c2
--- /dev/null
+++ b/fib.c
@@ -0,0 +1,35 @@
+#include <stdio.h>
+
+static long fib_internal(int n, long a, long b) {
+    if (n == 0) {
+        return a;
+    } else if (n == 1) {
+        return b;
+    } else {
+        __attribute__((musttail))
+        return fib_internal(n-1, b, a + b);
+    }
+}
+
+long fib(int n) {
+    return fib_internal(n, 0, 1);
+}
+
+void test(int n) {
+    printf("fib [%d] = [%ld]\n", n, fib(n));
+}
+
+// static long recursion_depth(long n, long max) {
+//     if (n >= max) {
+//         return n;
+//     }
+//     __attribute__((musttail))
+//     return recursion_depth(n+1, max);
+// }
+
+int main(void) {
+    for (int i=1; i<300; i++) {
+        test(i);
+    }
+    //printf("%ld\n", recursion_depth(0, 1000000000));
+}
\ No newline at end of file