From 100eabbc0824488c9cd148d9c90d053ee69022e4 Mon Sep 17 00:00:00 2001
From: Rosen Penev <rosenp@gmail.com>
Date: Wed, 12 Jul 2023 09:05:59 -0700
Subject: [PATCH] add std::byteswap support

Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
 src/image.cpp    | 12 ++++++++++++
 src/pgfimage.cpp |  4 ++++
 2 files changed, 16 insertions(+)

diff --git a/src/image.cpp b/src/image.cpp
index a439ee15..eee9720a 100644
--- a/src/image.cpp
+++ b/src/image.cpp
@@ -196,6 +196,9 @@ bool Image::isLittleEndianPlatform() {
 }
 
 uint64_t Image::byteSwap(uint64_t value, bool bSwap) {
+#ifdef __cpp_lib_byteswap
+  return bSwap ? std::byteswap(value) : value;
+#else
   uint64_t result = 0;
   auto source_value = reinterpret_cast<byte*>(&value);
   auto destination_value = reinterpret_cast<byte*>(&result);
@@ -204,22 +207,31 @@ uint64_t Image::byteSwap(uint64_t value, bool bSwap) {
     destination_value[i] = source_value[8 - i - 1];
 
   return bSwap ? result : value;
+#endif
 }
 
 uint32_t Image::byteSwap(uint32_t value, bool bSwap) {
+#ifdef __cpp_lib_byteswap
+  return bSwap ? std::byteswap(value) : value;
+#else
   uint32_t result = 0;
   result |= (value & 0x000000FFU) << 24;
   result |= (value & 0x0000FF00U) << 8;
   result |= (value & 0x00FF0000U) >> 8;
   result |= (value & 0xFF000000U) >> 24;
   return bSwap ? result : value;
+#endif
 }
 
 uint16_t Image::byteSwap(uint16_t value, bool bSwap) {
+#ifdef __cpp_lib_byteswap
+  return bSwap ? std::byteswap(value) : value;
+#else
   uint16_t result = 0;
   result |= (value & 0x00FFU) << 8;
   result |= (value & 0xFF00U) >> 8;
   return bSwap ? result : value;
+#endif
 }
 
 uint16_t Image::byteSwap2(const DataBuf& buf, size_t offset, bool bSwap) {
diff --git a/src/pgfimage.cpp b/src/pgfimage.cpp
index 5c5c2c12..538b5bd9 100644
--- a/src/pgfimage.cpp
+++ b/src/pgfimage.cpp
@@ -28,12 +28,16 @@ const unsigned char pgfBlank[] = {
 
 namespace Exiv2 {
 static uint32_t byteSwap_(uint32_t value, bool bSwap) {
+#ifdef __cpp_lib_byteswap
+  return bSwap ? std::byteswap(value) : value;
+#else
   uint32_t result = 0;
   result |= (value & 0x000000FF) << 24;
   result |= (value & 0x0000FF00) << 8;
   result |= (value & 0x00FF0000) >> 8;
   result |= (value & 0xFF000000) >> 24;
   return bSwap ? result : value;
+#endif
 }
 
 static uint32_t byteSwap_(Exiv2::DataBuf& buf, size_t offset, bool bSwap) {