From 66dfd956daf9f346b429868dc3a14e84eab9b9b0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Nils=20O=2E=20Sel=C3=A5sdal?= <nos@utel.tech>
Date: Wed, 20 May 2026 20:33:10 +0200
Subject: [PATCH] Fix 64 bit variants. Note undefined behavior

---
 include/ucore/math.h | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/include/ucore/math.h b/include/ucore/math.h
index 858af09..73e6172 100644
--- a/include/ucore/math.h
+++ b/include/ucore/math.h
@@ -25,6 +25,10 @@ uc_phi_64(uint64_t N);
 #  endif
 #endif
 
+
+// Note: the nextpow2 functions have undefined behavior if 
+// x > 2^(n-1) for n of the 32 or 64 bit variants
+
 #if HAVE_BUILTIN_CLZ
 
 static inline uint32_t
@@ -39,7 +43,7 @@ static inline uint64_t
 uc_nextpow2_64(uint64_t x)
 {
     if (x <= 1) return 1;
-    return 1u << (64 - __builtin_clzll(x - 1));
+    return (uint64_t)1 << (64 - __builtin_clzll(x - 1));
     return x;
 }
 #else
@@ -61,7 +65,7 @@ uc_nextpow2(uint32_t x)
 }
 
 static inline uint64_t
-uc_nextpow2(uint64_t x)
+uc_nextpow2_64(uint64_t x)
 {
     if (x == 0) {
         return 1;