From 5f0f9f927328df9ccf463969c71b3a136c9825cf Mon Sep 17 00:00:00 2001
From: Hugues Delorme <delorme.hugues@fougsys.fr>
Date: Thu, 23 Jan 2014 17:28:59 +0100
Subject: [PATCH] global: improve byte swapping functions (endian.h)

Use platform's builtin byte swapping functions when available
---
 src/endian.c | 37 +++++++++++++++++++++++++------------
 src/endian.h |  6 ++----
 2 files changed, 27 insertions(+), 16 deletions(-)

diff --git a/src/endian.c b/src/endian.c
index 62b7245..a02535b 100644
--- a/src/endian.c
+++ b/src/endian.c
@@ -2,6 +2,9 @@
 
 #include "convert.h"
 
+#ifdef FOUG_HAVE_MSVC_BUILTIN_BSWAP_FUNC
+# include <stdlib.h>
+#endif
 #include <string.h>
 
 typedef union
@@ -26,14 +29,19 @@ foug_endianness_t foug_host_endianness()
     return FOUG_OTHER_ENDIAN;
 }
 
-uint16_t foug_uint16_swap(uint16_t val)
+/*! Returns \p val with the order of bytes reversed.
+ *
+ *  Uses compiler builtin functions if available
+ */
+uint16_t foug_uint16_bswap(uint16_t val)
 {
+#ifdef FOUG_HAVE_GCC_BUILTIN_BSWAP_FUNC
+  return __builtin_bswap16(val);
+#elif defined(FOUG_HAVE_MSVC_BUILTIN_BSWAP_FUNC)
+  return _byteswap_ushort(val);
+#else
   return ((val & 0x00FF) << 8) | ((val >> 8) & 0x00FF);
-}
-
-uint16_t foug_uint16_noswap(uint16_t val)
-{
-  return val;
+#endif
 }
 
 /*! Read a 16bit integer from memory-location \p bytes (little-endian byte order) */
@@ -59,18 +67,23 @@ void foug_encode_uint16_le(uint16_t val, uint8_t* bytes)
   bytes[1] = (val >> 8) & 0xFF;
 }
 
-uint32_t foug_uint32_swap(uint32_t val)
+/*! Returns \p val with the order of bytes reversed.
+ *
+ *  Uses compiler builtin functions if available
+ */
+uint32_t foug_uint32_bswap(uint32_t val)
 {
+#ifdef FOUG_HAVE_GCC_BUILTIN_BSWAP_FUNC
+  return __builtin_bswap32(val);
+#elif defined(FOUG_HAVE_MSVC_BUILTIN_BSWAP_FUNC)
+  return _byteswap_ulong(val);
+#else
   return
       ((val & 0x000000FF) << 24)
       | ((val & 0x0000FF00) << 8)
       | ((val >> 8) & 0x0000FF00)
       | ((val >> 24) & 0x000000FF);
-}
-
-uint32_t foug_uint32_noswap(uint32_t val)
-{
-  return val;
+#endif
 }
 
 /*! Read a 32bit integer from memory-location \p bytes (little-endian byte order) */
diff --git a/src/endian.h b/src/endian.h
index 5ec87a0..6302783 100644
--- a/src/endian.h
+++ b/src/endian.h
@@ -13,14 +13,12 @@ typedef enum
 
 FOUG_LIB_EXPORT foug_endianness_t foug_host_endianness();
 
-FOUG_LIB_EXPORT uint16_t foug_uint16_swap(uint16_t val);
-FOUG_LIB_EXPORT uint16_t foug_uint16_noswap(uint16_t val);
+FOUG_LIB_EXPORT uint16_t foug_uint16_bswap(uint16_t val);
 FOUG_LIB_EXPORT uint16_t foug_decode_uint16_le(const uint8_t* bytes);
 FOUG_LIB_EXPORT uint16_t foug_decode_uint16_be(const uint8_t* bytes);
 FOUG_LIB_EXPORT void foug_encode_uint16_le(uint16_t val, uint8_t* bytes);
 
-FOUG_LIB_EXPORT uint32_t foug_uint32_swap(uint32_t val);
-FOUG_LIB_EXPORT uint32_t foug_uint32_noswap(uint32_t val);
+FOUG_LIB_EXPORT uint32_t foug_uint32_bswap(uint32_t val);
 FOUG_LIB_EXPORT uint32_t foug_decode_uint32_le(const uint8_t* bytes);
 FOUG_LIB_EXPORT uint32_t foug_decode_uint32_me(const uint8_t* bytes);
 FOUG_LIB_EXPORT uint32_t foug_decode_uint32_be(const uint8_t* bytes);