mirror of https://github.com/acidanthera/audk.git
83 lines
2.3 KiB
ArmAsm
83 lines
2.3 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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# LShiftU64.c
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#
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#Abstract:
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#
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# 64-bit left shift function for IA-32
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#
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#--*/
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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(LShiftU64)
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#
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#UINT64
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#LShiftU64 (
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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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#
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# This routine allows a 64 bit value to be left shifted by 32 bits and
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# returns the shifted value.
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# Count is valid up 63. (Only Bits 0-5 is valid for Count)
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#
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#Arguments:
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#
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# Operand - Value to be shifted
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# Count - Number of times to shift left.
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#
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#Returns:
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#
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# Value shifted left identified by the Count.
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#
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#--*/
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ASM_PFX(LShiftU64):
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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 EAX is not touched
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# For CL of 32 - 63, it will be shifted 0 - 31 so we will move eax to edx 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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shld %cl, %eax, %edx
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shlb %cl, %eax
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#
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# Since Count is 32 - 63, eax will have been shifted by 0 - 31
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# If shifted by 32 or more, set lower 32 bits to zero.
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#
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cmpl $32, %ecx
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jc _LShiftU64_Done
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movl %eax, %edx
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xorl %eax, %eax
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_LShiftU64_Done:
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ret
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#LShiftU64 ENDP
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