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1 | /** @file\r |
2 | Math worker functions.\r |
3 | \r |
4 | Copyright (c) 2006, Intel Corporation<BR>\r |
5 | All rights reserved. This program and the accompanying materials\r |
6 | are licensed and made available under the terms and conditions of the BSD License\r |
7 | which accompanies this distribution. The full text of the license may be found at\r |
8 | http://opensource.org/licenses/bsd-license.php\r |
9 | \r |
10 | THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r |
11 | WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r |
12 | \r |
13 | **/\r |
14 | \r |
15 | #include "BaseLibInternals.h"\r |
16 | \r |
17 | /**\r |
18 | Returns the bit position of the highest bit set in a 64-bit value. Equivalent\r |
19 | to log2(x).\r |
20 | \r |
21 | This function computes the bit position of the highest bit set in the 64-bit\r |
22 | value specified by Operand. If Operand is zero, then -1 is returned.\r |
23 | Otherwise, a value between 0 and 63 is returned.\r |
24 | \r |
25 | @param Operand The 64-bit operand to evaluate.\r |
26 | \r |
27 | @return Position of the highest bit set in Operand if found.\r |
28 | @retval -1 Operand is zero.\r |
29 | \r |
30 | **/\r |
31 | INTN\r |
32 | EFIAPI\r |
33 | HighBitSet64 (\r |
34 | IN UINT64 Operand\r |
35 | )\r |
36 | {\r |
37 | INTN BitIndex;\r |
38 | \r |
39 | for (BitIndex = -1;\r |
40 | Operand != 0;\r |
41 | BitIndex++, Operand = RShiftU64 (Operand, 1));\r |
42 | return BitIndex;\r |
43 | }\r |