More math opcode Fun. (0.37.44)

src/vm/math/isqrt.c

@@ -0,0 +1,47 @@
+/**
+ * This file is part of the Fun programming language.
+ * https://fun-lang.xyz/
+ *
+ * Copyright 2026 Johannes Findeisen <you@hanez.org>
+ * Licensed under the terms of the Apache-2.0 license.
+ * https://opensource.org/license/apache-2-0
+ *
+ *  Added: 2026-01-03
+ */
+
+/**
+* @file isqrt.c
+ * @brief Implements the OP_ISQRT opcode for integer square root (floor).
+ */
+
+case OP_ISQRT: {
+    Value v = pop_value(vm);
+    if (!((v.type == VAL_INT) || (v.type == VAL_FLOAT))) {
+        fprintf(stderr, "Runtime type error: ISQRT expects number, got %s\n", value_type_name(v.type));
+        exit(1);
+    }
+    int64_t a = (v.type == VAL_INT) ? v.i : (int64_t)v.d;
+    if (a <= 0) {
+        free_value(v);
+        push_value(vm, make_int(0));
+        break;
+    }
+    /* Binary isqrt inline */
+    uint64_t n = (uint64_t)a;
+    uint64_t x = 0;
+    uint64_t bit = (uint64_t)1 << 62; /* highest even bit set */
+    while (bit > n) bit >>= 2;
+    while (bit != 0) {
+        if (n >= x + bit) {
+            n -= x + bit;
+            x = (x >> 1) + bit;
+        } else {
+            x >>= 1;
+        }
+        bit >>= 2;
+    }
+    int64_t r = (int64_t)x;
+    free_value(v);
+    push_value(vm, make_int(r));
+    break;
+}