fix predefines for bswap for old compilers (#99)

awslabs · Nov 12, 2024 · 3e4101b · 3e4101b
1 parent b23b2e2
commit 3e4101b
Showing 1 changed file with 7 additions and 2 deletions.
diff --git a/include/aws/checksums/private/crc_util.h b/include/aws/checksums/private/crc_util.h
@@ -31,7 +31,9 @@ static inline uint32_t aws_bswap32_if_be(uint32_t x) {
 
 #if _MSC_VER
     return _byteswap_ulong(x);
-#elif defined(__GNUC__) || defined(__clang__)
+#elif defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8))
+    return __builtin_bswap32(x);
+#elif defined(__clang__) && __clang_major__ >= 3
     return __builtin_bswap32(x);
 #else
     return (
@@ -47,7 +49,10 @@ static inline uint64_t aws_bswap64_if_be(uint64_t x) {
 
 #if _MSC_VER
     return _byteswap_uint64(x);
-#elif defined(__GNUC__) || defined(__clang__)
+#elif defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8))
+    /* Note: gcc supports it starting with 4.2. here its just picking the lowest version we run test on. */
+    return __builtin_bswap64(x);
+#elif defined(__clang__) && __clang_major__ >= 3
     return __builtin_bswap64(x);
 #else
     return ((x << 56) & 0xff00000000000000ULL) | ((x << 40) & 0x00ff000000000000ULL) |