From: Markus Scherer <markus.icu@gmail.com>
Date: Tue, 5 Jul 2011 06:12:51 +0000 (+0000)
Subject: ICU-8657 fix mis-named LESwaps methods
X-Git-Tag: milestone-59-0-1~4684
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=08e1d54eab8d13cb580a13a41e40542acb82e98e;p=icu

ICU-8657 fix mis-named LESwaps methods

X-SVN-Rev: 30274
---

diff --git a/icu4c/source/layout/LESwaps.h b/icu4c/source/layout/LESwaps.h
index 489a9ae449d..03c7d42c6e6 100644
--- a/icu4c/source/layout/LESwaps.h
+++ b/icu4c/source/layout/LESwaps.h
@@ -1,6 +1,6 @@
 /*
  *
- * (C) Copyright IBM Corp. 1998-2010 - All Rights Reserved
+ * (C) Copyright IBM Corp. 1998-2011 - All Rights Reserved
  *
  */
 
@@ -45,8 +45,8 @@ class U_LAYOUT_API LESwaps /* not : public UObject because all methods are stati
 public:
 
     /**
-     * This method does the byte swap required on little endian platforms
-     * to correctly access a (16-bit) word.
+     * Reads a big-endian 16-bit word and returns a native-endian value.
+     * No-op on a big-endian platform, byte-swaps on a little-endian platform.
      *
      * @param value - the word to be byte swapped
      *
@@ -56,12 +56,19 @@ public:
      */
     static le_uint16 swapWord(le_uint16 value)
     {
-        return (le_uint16)((value << 8) | (value >> 8));
+#if (defined(U_IS_BIG_ENDIAN) && U_IS_BIG_ENDIAN) || (defined(BYTE_ORDER) && defined(BIG_ENDIAN)) || defined(__BIG_ENDIAN__)
+        // Fastpath when we know that the platform is big-endian.
+        return value;
+#else
+        // Reads a big-endian value on any platform.
+        const le_uint8 *p = reinterpret_cast<const le_uint8 *>(&value);
+        return (le_uint16)((p[0] << 8) | p[1]);
+#endif
     };
 
     /**
-     * This method does the byte swapping required on little endian platforms
-     * to correctly access a (32-bit) long.
+     * Reads a big-endian 32-bit word and returns a native-endian value.
+     * No-op on a big-endian platform, byte-swaps on a little-endian platform.
      *
      * @param value - the long to be byte swapped
      *
@@ -71,11 +78,14 @@ public:
      */
     static le_uint32 swapLong(le_uint32 value)
     {
-        return (le_uint32)(
-            (value << 24) |
-            ((value << 8) & 0xff0000) |
-            ((value >> 8) & 0xff00) |
-            (value >> 24));
+#if (defined(U_IS_BIG_ENDIAN) && U_IS_BIG_ENDIAN) || (defined(BYTE_ORDER) && defined(BIG_ENDIAN)) || defined(__BIG_ENDIAN__)
+        // Fastpath when we know that the platform is big-endian.
+        return value;
+#else
+        // Reads a big-endian value on any platform.
+        const le_uint8 *p = reinterpret_cast<const le_uint8 *>(&value);
+        return (le_uint32)((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]);
+#endif
     };
 
 private: