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author | raywu <raywu0301@gmail.com> | 2018-06-15 00:00:50 +0800 |
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committer | raywu <raywu0301@gmail.com> | 2018-06-15 00:00:50 +0800 |
commit | b7c51c9cf4864df6aabb99a1ae843becd577237c (patch) | |
tree | eebe9b0d0ca03062955223097e57da84dd618b9a /EDK/Foundation/Library/EfiCommonLib/Ia32/GetPowerOfTwo.asm | |
download | zprj-b7c51c9cf4864df6aabb99a1ae843becd577237c.tar.xz |
Diffstat (limited to 'EDK/Foundation/Library/EfiCommonLib/Ia32/GetPowerOfTwo.asm')
-rw-r--r-- | EDK/Foundation/Library/EfiCommonLib/Ia32/GetPowerOfTwo.asm | 67 |
1 files changed, 67 insertions, 0 deletions
diff --git a/EDK/Foundation/Library/EfiCommonLib/Ia32/GetPowerOfTwo.asm b/EDK/Foundation/Library/EfiCommonLib/Ia32/GetPowerOfTwo.asm new file mode 100644 index 0000000..9f0d962 --- /dev/null +++ b/EDK/Foundation/Library/EfiCommonLib/Ia32/GetPowerOfTwo.asm @@ -0,0 +1,67 @@ + TITLE GetPowerOfTwo.asm: Calculates the power of two value just below input + +;------------------------------------------------------------------------------ +; +; Copyright (c) 2005 Intel Corporation +; All rights reserved. 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. +; +; Module Name: +; +; GetPowerOfTwo.asm +; +; Abstract: +; +; Calculates the largest integer that is both +; a power of two and less than Input +; +;------------------------------------------------------------------------------ + + .686P + .XMM + .MODEL SMALL + .CODE + +_GetPowerOfTwo PROC +;------------------------------------------------------------------------------ +; UINT32 +; _GetPowerOfTwo ( +; IN UINT32 Input +; ) +; +; Routine Description: +; +; Calculates the largest integer that is both +; a power of two and less than Input +; +; Arguments: +; +; Input - value to calculate power of two +; +; Returns: +; +; the largest integer that is both a power of +; two and less than Input +;------------------------------------------------------------------------------ + xor eax, eax + mov edx, eax + mov ecx, [esp + 8] + jecxz @F + bsr ecx, ecx + bts edx, ecx + jmp @Exit +@@: + mov ecx, [esp + 4] + jecxz @Exit + bsr ecx, ecx + bts eax, ecx +@Exit: + ret +_GetPowerOfTwo ENDP + +END |