From 8a9f064ede7177956c2180589fabf72a23bd67df Mon Sep 17 00:00:00 2001
From: Ivailo Monev <xakepa10@gmail.com>
Date: Wed, 6 Jan 2021 09:12:40 +0200
Subject: [PATCH] use compiler built-ins for byte swapping

for reference:
https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html
https://clang.llvm.org/docs/LanguageExtensions.html

Signed-off-by: Ivailo Monev <xakepa10@gmail.com>
---
 src/core/global/qendian.h | 41 +++--------------------------------------
 1 file changed, 3 insertions(+), 38 deletions(-)

diff --git a/src/core/global/qendian.h b/src/core/global/qendian.h
index 5024859f3..af05b095a 100644
--- a/src/core/global/qendian.h
+++ b/src/core/global/qendian.h
@@ -36,10 +36,6 @@
 
 #include <QtCore/qglobal.h>
 
-#ifdef __GLIBC__
-#include <byteswap.h>
-#endif
-
 QT_BEGIN_HEADER
 
 QT_BEGIN_NAMESPACE
@@ -165,49 +161,18 @@ template <> inline qint16 qFromBigEndian<qint16>(const uchar *src)
 */
 template <typename T> T qbswap(const T source);
 
-#ifdef __GLIBC__
 template <> inline quint64 qbswap<quint64>(const quint64 source)
 {
-    return bswap_64(source);
+    return __builtin_bswap64(source);
 }
 template <> inline quint32 qbswap<quint32>(const quint32 source)
 {
-    return bswap_32(source);
+    return __builtin_bswap32(source);
 }
 template <> inline quint16 qbswap<quint16>(const quint16 source)
 {
-    return bswap_16(source);
-}
-#else
-template <> inline quint64 qbswap<quint64>(const quint64 source)
-{
-    return 0
-        | ((source & Q_UINT64_C(0x00000000000000ff)) << 56)
-        | ((source & Q_UINT64_C(0x000000000000ff00)) << 40)
-        | ((source & Q_UINT64_C(0x0000000000ff0000)) << 24)
-        | ((source & Q_UINT64_C(0x00000000ff000000)) << 8)
-        | ((source & Q_UINT64_C(0x000000ff00000000)) >> 8)
-        | ((source & Q_UINT64_C(0x0000ff0000000000)) >> 24)
-        | ((source & Q_UINT64_C(0x00ff000000000000)) >> 40)
-        | ((source & Q_UINT64_C(0xff00000000000000)) >> 56);
-}
-
-template <> inline quint32 qbswap<quint32>(const quint32 source)
-{
-    return 0
-        | ((source & 0x000000ff) << 24)
-        | ((source & 0x0000ff00) << 8)
-        | ((source & 0x00ff0000) >> 8)
-        | ((source & 0xff000000) >> 24);
-}
-
-template <> inline quint16 qbswap<quint16>(const quint16 source)
-{
-    return quint16( 0
-                    | ((source & 0x00ff) << 8)
-                    | ((source & 0xff00) >> 8) );
+    return __builtin_bswap16(source);
 }
-#endif // __GLIBC__
 
 // signed specializations
 template <> inline qint64 qbswap<qint64>(const qint64 source)
-- 
2.11.0