mirror of https://github.com/acidanthera/audk.git
81 lines
2.2 KiB
ArmAsm
81 lines
2.2 KiB
ArmAsm
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#/*++
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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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# RShiftU64.c
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#
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#Abstract:
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#
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# 64-bit right shift function for IA-32
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#
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#--*/
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#
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##include "Tiano.h"
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#
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#include "EfiBind.h"
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#---------------------------------------------------------------------------
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.686:
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#.MODEL flat,C
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.code:
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#---------------------------------------------------------------------------
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.globl ASM_PFX(RShiftU64)
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#UINT64
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#RShiftU64 (
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# IN UINT64 Operand,
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# IN UINTN Count
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# )
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#/*++
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#
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#Routine Description:
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# This routine allows a 64 bit value to be right shifted by 32 bits and returns the
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# shifted value.
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# Count is valid up 63. (Only Bits 0-5 is valid for Count)
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#Arguments:
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# Operand - Value to be shifted
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# Count - Number of times to shift right.
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#
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#Returns:
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#
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# Value shifted right identified by the Count.
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#
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#--*/
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ASM_PFX(RShiftU64):
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movl 4(%esp), %eax # dword ptr Operand[0]
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movl 8(%esp), %edx # dword ptr Operand[4]
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#
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# CL is valid from 0 - 31. shld will move EDX:EAX by CL times but EDX is not touched
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# For CL of 32 - 63, it will be shifted 0 - 31 so we will move edx to eax later.
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#
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movl 0xC(%esp), %ecx # Count
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andl $63, %ecx
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shrd %cl, %edx, %eax
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shrb %cl, %edx
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cmpl $32, %ecx
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jc _RShiftU64_Done
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#
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# Since Count is 32 - 63, edx will have been shifted by 0 - 31
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# If shifted by 32 or more, set upper 32 bits to zero.
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#
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movl %edx, %eax
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xorl %edx, %edx
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_RShiftU64_Done:
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ret
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#RShiftU64 ENDP
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