mirror of https://github.com/acidanthera/audk.git
154 lines
4.5 KiB
NASM
154 lines
4.5 KiB
NASM
;/** @file
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;
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; This code provides low level routines that support the Virtual Machine
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; for option ROMs.
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;
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; Copyright (c) 2006 - 2008, Intel Corporation. <BR>
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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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;**/
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page ,132
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title VM ASSEMBLY LANGUAGE ROUTINES
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;---------------------------------------------------------------------------
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; Equate files needed.
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;---------------------------------------------------------------------------
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.XLIST
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.LIST
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;---------------------------------------------------------------------------
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; Assembler options
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;---------------------------------------------------------------------------
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.686p
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.model flat
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.code
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;---------------------------------------------------------------------------
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;;GenericPostSegment SEGMENT USE16
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;---------------------------------------------------------------------------
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CopyMem PROTO C Destination:PTR DWORD, Source:PTR DWORD, Count:DWORD
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;****************************************************************************
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; EbcLLCALLEXNative
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;
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; This function is called to execute an EBC CALLEX instruction
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; to native code.
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; This instruction requires that we thunk out to external native
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; code. For IA32, we simply switch stacks and jump to the
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; specified function. On return, we restore the stack pointer
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; to its original location.
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;
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; Destroys no working registers.
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;****************************************************************************
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; VOID EbcLLCALLEXNative(UINTN FuncAddr, UINTN NewStackPointer, VOID *FramePtr)
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_EbcLLCALLEXNative PROC NEAR PUBLIC
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push ebp
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push ebx
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mov ebp, esp ; standard function prolog
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; Get function address in a register
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; mov ecx, FuncAddr => mov ecx, dword ptr [FuncAddr]
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mov ecx, dword ptr [esp]+0Ch
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; Set stack pointer to new value
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; mov eax, NewStackPointer => mov eax, dword ptr [NewSp]
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mov eax, dword ptr [esp] + 14h
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mov edx, dword ptr [esp] + 10h
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sub eax, edx
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sub esp, eax
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mov ebx, esp
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push ecx
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push eax
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push edx
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push ebx
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call CopyMem
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pop eax
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pop eax
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pop eax
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pop ecx
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; Now call the external routine
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call ecx
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; ebp is preserved by the callee. In this function it
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; equals the original esp, so set them equal
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mov esp, ebp
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; Standard function epilog
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mov esp, ebp
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pop ebx
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pop ebp
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ret
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_EbcLLCALLEXNative ENDP
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; UINTN EbcLLGetEbcEntryPoint(VOID);
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; Routine Description:
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; The VM thunk code stuffs an EBC entry point into a processor
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; register. Since we can't use inline assembly to get it from
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; the interpreter C code, stuff it into the return value
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; register and return.
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;
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; Arguments:
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; None.
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;
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; Returns:
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; The contents of the register in which the entry point is passed.
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;
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_EbcLLGetEbcEntryPoint PROC NEAR PUBLIC
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ret
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_EbcLLGetEbcEntryPoint ENDP
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;/*++
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;
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;Routine Description:
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;
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; Return the caller's value of the stack pointer.
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;
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;Arguments:
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;
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; None.
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;
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;Returns:
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;
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; The current value of the stack pointer for the caller. We
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; adjust it by 4 here because when they called us, the return address
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; is put on the stack, thereby lowering it by 4 bytes.
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;
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;--*/
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; UINTN EbcLLGetStackPointer()
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_EbcLLGetStackPointer PROC NEAR PUBLIC
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mov eax, esp ; get current stack pointer
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add eax, 4 ; stack adjusted by this much when we were called
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ret
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_EbcLLGetStackPointer ENDP
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; UINT64 EbcLLGetReturnValue(VOID);
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; Routine Description:
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; When EBC calls native, on return the VM has to stuff the return
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; value into a VM register. It's assumed here that the value is still
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; in the register, so simply return and the caller should get the
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; return result properly.
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;
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; Arguments:
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; None.
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;
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; Returns:
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; The unmodified value returned by the native code.
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;
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_EbcLLGetReturnValue PROC NEAR PUBLIC
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ret
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_EbcLLGetReturnValue ENDP
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END
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