mirror of https://github.com/acidanthera/audk.git
79 lines
1.9 KiB
ArmAsm
79 lines
1.9 KiB
ArmAsm
#/*++
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#
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#Copyright (c) 2006, Intel Corporation
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#All rights reserved. This program and the accompanying materials
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#are licensed and made available under the terms and conditions of the BSD License
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#which accompanies this distribution. The full text of the license may be found at
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#http://opensource.org/licenses/bsd-license.php
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#
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#THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
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#WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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#
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#Module Name:
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#
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# Log2.c
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#
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#Abstract:
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#
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# 64-bit integer logarithm function for IA-32
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#
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#--*/
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#
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#---------------------------------------------------------------------------
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#include "EfiBind.h" //For ASM_PFX
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#---------------------------------------------------------------------------
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.globl ASM_PFX(Log2)
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#UINT8
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#Log2 (
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# IN UINT64 Operand
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# )
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#/*++
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#
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#Routine Description:
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#
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# Calculates and floors logarithms based on 2
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#
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#Arguments:
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#
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# Operand - value to calculate logarithm
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#
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#Returns:
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#
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# The largest integer that is less than or equal
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# to the logarithm of Operand based on 2
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#
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#--*/
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ASM_PFX(Log2):
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movl $64, %ecx
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cmpl $0, 4(%esp) # (UINT32 *(&Operand))
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jne _Log2_Wend
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cmpl $0, 8(%esp) # (UINT32 *(&Operand)) + 1
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jne _Log2_Wend
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movb $0xFF, %cl
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jmp _Log2_Done
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_Log2_Wend:
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decl %ecx
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cmpl $32, %ecx
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jae _Log2_Higher
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btl %ecx, 4(%esp) # (UINT32 *(&Operand))
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jmp _Log2_Bit
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_Log2_Higher:
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movl %ecx, %eax
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subl $32, %eax
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btl %eax, 8(%esp) # (UINT32 *(&Operand)) + 1
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_Log2_Bit:
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jc _Log2_Done
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jmp _Log2_Wend
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_Log2_Done:
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movb %cl, %al
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ret
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