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Diffstat (limited to '')
-rw-r--r-- | src/VBox/Devices/EFI/Firmware/MdePkg/Library/BaseLib/LowBitSet64.c | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/src/VBox/Devices/EFI/Firmware/MdePkg/Library/BaseLib/LowBitSet64.c b/src/VBox/Devices/EFI/Firmware/MdePkg/Library/BaseLib/LowBitSet64.c new file mode 100644 index 00000000..b1e9b4b4 --- /dev/null +++ b/src/VBox/Devices/EFI/Firmware/MdePkg/Library/BaseLib/LowBitSet64.c @@ -0,0 +1,44 @@ +/** @file + Math worker functions. + + Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR> + SPDX-License-Identifier: BSD-2-Clause-Patent + +**/ + + + + +#include "BaseLibInternals.h" + +/** + Returns the bit position of the lowest bit set in a 64-bit value. + + This function computes the bit position of the lowest bit set in the 64-bit + value specified by Operand. If Operand is zero, then -1 is returned. + Otherwise, a value between 0 and 63 is returned. + + @param Operand The 64-bit operand to evaluate. + + @retval 0..63 The lowest bit set in Operand was found. + @retval -1 Operand is zero. + + +**/ +INTN +EFIAPI +LowBitSet64 ( + IN UINT64 Operand + ) +{ + INTN BitIndex; + + if (Operand == 0) { + return -1; + } + + for (BitIndex = 0; + (Operand & 1) == 0; + BitIndex++, Operand = RShiftU64 (Operand, 1)); + return BitIndex; +} |