StdLib/LibC: Provide missing ARM symbols

Provide missing functionality by using files from LLVM.

Changes made:
- Formatting changes (tabs to spaces, DOS line endings etc).
- Simplified 'int_endianness.h' to work for our case.
- Added LLVM licence to the individual files.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Harry Liebel <Harry.Liebel@arm.com>
Reviewed-by: Olivier Martin <Olivier.Martin@arm.com>
Reviewed-by: Daryl McDaniel <edk2-lists@mc2research.org>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18117 6f19259b-4bc3-4df7-8a09-765794883524

StdLib/LibC/Main/Arm/floatunsidf.c

@@ -0,0 +1,71 @@
+/**
+University of Illinois/NCSA
+Open Source License
+
+Copyright (c) 2009-2014 by the contributors listed in CREDITS.TXT
+
+All rights reserved.
+
+Developed by:
+
+    LLVM Team
+
+    University of Illinois at Urbana-Champaign
+
+    http://llvm.org
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal with
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions:
+
+    * Redistributions of source code must retain the above copyright notice,
+      this list of conditions and the following disclaimers.
+
+    * Redistributions in binary form must reproduce the above copyright notice,
+      this list of conditions and the following disclaimers in the
+      documentation and/or other materials provided with the distribution.
+
+    * Neither the names of the LLVM Team, University of Illinois at
+      Urbana-Champaign, nor the names of its contributors may be used to
+      endorse or promote products derived from this Software without specific
+      prior written permission.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE
+SOFTWARE.
+**/
+
+#define DOUBLE_PRECISION
+#include "fp_lib.h"
+
+#include "int_lib.h"
+
+ARM_EABI_FNALIAS(ui2d, floatunsidf)
+
+COMPILER_RT_ABI fp_t
+__floatunsidf(unsigned int a) {
+
+    const int aWidth = sizeof a * CHAR_BIT;
+
+    // Handle zero as a special case to protect clz
+    if (a == 0) return fromRep(0);
+
+    // Exponent of (fp_t)a is the width of abs(a).
+    const int exponent = (aWidth - 1) - __builtin_clz(a);
+    rep_t result;
+
+    // Shift a into the significand field and clear the implicit bit.
+    const int shift = significandBits - exponent;
+    result = (rep_t)a << shift ^ implicitBit;
+
+    // Insert the exponent
+    result += (rep_t)(exponent + exponentBias) << significandBits;
+    return fromRep(result);
+}