diff options
Diffstat (limited to 'ArmPkg/Library/CompilerIntrinsicsLib/Arm/ctzsi2.c')
| -rw-r--r-- | ArmPkg/Library/CompilerIntrinsicsLib/Arm/ctzsi2.c | 196 |
1 files changed, 98 insertions, 98 deletions
diff --git a/ArmPkg/Library/CompilerIntrinsicsLib/Arm/ctzsi2.c b/ArmPkg/Library/CompilerIntrinsicsLib/Arm/ctzsi2.c index 425d8b9e44..71f303b344 100644 --- a/ArmPkg/Library/CompilerIntrinsicsLib/Arm/ctzsi2.c +++ b/ArmPkg/Library/CompilerIntrinsicsLib/Arm/ctzsi2.c @@ -1,98 +1,98 @@ -/** @file - Compiler intrinsic to return the number of trailing zeros, ported from LLVM code. - - Copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR> - This program and the accompanying materials - are licensed and made available under the terms and conditions of the BSD License - which accompanies this distribution. The full text of the license may be found at - http://opensource.org/licenses/bsd-license.php - - THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, - WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. - -**/ -/** - University of Illinois/NCSA - Open Source License - - Copyright (c) 2003-2008 University of Illinois at Urbana-Champaign. - 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. -**/ - - -#include "Llvm_int_lib.h" - -// Returns: the number of trailing 0-bits - -// Precondition: a != 0 - -INT32 -__ctzsi2(INT32 a) -{ - UINT32 x = (UINT32)a; - INT32 t = ((x & 0x0000FFFF) == 0) << 4; // if (x has no small bits) t = 16 else 0 - x >>= t; // x = [0 - 0xFFFF] + higher garbage bits - UINT32 r = t; // r = [0, 16] - // return r + ctz(x) - t = ((x & 0x00FF) == 0) << 3; - x >>= t; // x = [0 - 0xFF] + higher garbage bits - r += t; // r = [0, 8, 16, 24] - // return r + ctz(x) - t = ((x & 0x0F) == 0) << 2; - x >>= t; // x = [0 - 0xF] + higher garbage bits - r += t; // r = [0, 4, 8, 12, 16, 20, 24, 28] - // return r + ctz(x) - t = ((x & 0x3) == 0) << 1; - x >>= t; - x &= 3; // x = [0 - 3] - r += t; // r = [0 - 30] and is even - // return r + ctz(x) -// The branch-less return statement below is equivalent -// to the following switch statement: -// switch (x) -// { -// case 0: -// return r + 2; -// case 2: -// return r + 1; -// case 1: -// case 3: -// return r; -// } - return r + ((2 - (x >> 1)) & -((x & 1) == 0)); -} +/** @file
+ Compiler intrinsic to return the number of trailing zeros, ported from LLVM code.
+
+ Copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
+ This program and the accompanying materials
+ are licensed and made available under the terms and conditions of the BSD License
+ which accompanies this distribution. The full text of the license may be found at
+ http://opensource.org/licenses/bsd-license.php
+
+ THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+
+**/
+/**
+ University of Illinois/NCSA
+ Open Source License
+
+ Copyright (c) 2003-2008 University of Illinois at Urbana-Champaign.
+ 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.
+**/
+
+
+#include "Llvm_int_lib.h"
+
+// Returns: the number of trailing 0-bits
+
+// Precondition: a != 0
+
+INT32
+__ctzsi2(INT32 a)
+{
+ UINT32 x = (UINT32)a;
+ INT32 t = ((x & 0x0000FFFF) == 0) << 4; // if (x has no small bits) t = 16 else 0
+ x >>= t; // x = [0 - 0xFFFF] + higher garbage bits
+ UINT32 r = t; // r = [0, 16]
+ // return r + ctz(x)
+ t = ((x & 0x00FF) == 0) << 3;
+ x >>= t; // x = [0 - 0xFF] + higher garbage bits
+ r += t; // r = [0, 8, 16, 24]
+ // return r + ctz(x)
+ t = ((x & 0x0F) == 0) << 2;
+ x >>= t; // x = [0 - 0xF] + higher garbage bits
+ r += t; // r = [0, 4, 8, 12, 16, 20, 24, 28]
+ // return r + ctz(x)
+ t = ((x & 0x3) == 0) << 1;
+ x >>= t;
+ x &= 3; // x = [0 - 3]
+ r += t; // r = [0 - 30] and is even
+ // return r + ctz(x)
+// The branch-less return statement below is equivalent
+// to the following switch statement:
+// switch (x)
+// {
+// case 0:
+// return r + 2;
+// case 2:
+// return r + 1;
+// case 1:
+// case 3:
+// return r;
+// }
+ return r + ((2 - (x >> 1)) & -((x & 1) == 0));
+}
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