;/** @file

;

; This code provides low level routines that support the Virtual Machine

; for option ROMs.

;

; Copyright (c) 2006 - 2011, Intel Corporation. All rights reserved.<BR>

; 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.

;

;**/

page ,132

title VM ASSEMBLY LANGUAGE ROUTINES

;---------------------------------------------------------------------------

; Equate files needed.

;---------------------------------------------------------------------------

.XLIST

.LIST

;---------------------------------------------------------------------------

; Assembler options

;---------------------------------------------------------------------------

.686p

.model flat, C

.code

CopyMem PROTO Destination:PTR DWORD, Source:PTR DWORD, Count:DWORD

EbcInterpret PROTO

ExecuteEbcImageEntryPoint PROTO

;****************************************************************************

; EbcLLCALLEXNative

;

; This function is called to execute an EBC CALLEX instruction

; to native code.

; This instruction requires that we thunk out to external native

; code. For IA32, we simply switch stacks and jump to the

; specified function. On return, we restore the stack pointer

; to its original location.

;

; Destroys no working registers.

;****************************************************************************

; INT64 EbcLLCALLEXNative(UINTN FuncAddr, UINTN NewStackPointer, VOID *FramePtr)

EbcLLCALLEXNative PROC PUBLIC

push ebp

push ebx

mov ebp, esp ; standard function prolog

; Get function address in a register

; mov ecx, FuncAddr => mov ecx, dword ptr [FuncAddr]

mov ecx, dword ptr [esp]+0Ch

; Set stack pointer to new value

; mov eax, NewStackPointer => mov eax, dword ptr [NewSp]

mov eax, dword ptr [esp] + 14h

mov edx, dword ptr [esp] + 10h

sub eax, edx

sub esp, eax

mov ebx, esp

push ecx

push eax

push edx

push ebx

call CopyMem

pop eax

pop eax

pop eax

pop ecx

; Now call the external routine

call ecx

; ebp is preserved by the callee. In this function it

; equals the original esp, so set them equal

mov esp, ebp

; Standard function epilog

mov esp, ebp

pop ebx

pop ebp

ret

EbcLLCALLEXNative ENDP

;****************************************************************************

; EbcLLEbcInterpret

;

; Begin executing an EBC image.

;****************************************************************************

; UINT64 EbcLLEbcInterpret(VOID)

EbcLLEbcInterpret PROC PUBLIC

;

;; mov eax, 0xca112ebc

;; mov eax, EbcEntryPoint

;; mov ecx, EbcLLEbcInterpret

;; jmp ecx

;

; Caller uses above instruction to jump here

; The stack is below:

; +-----------+

; | RetAddr |

; +-----------+

; |EntryPoint | (EAX)

; +-----------+

; | Arg1 | <- EDI

; +-----------+

; | Arg2 |

; +-----------+

; | ... |

; +-----------+

; | Arg16 |

; +-----------+

; | EDI |

; +-----------+

; | ESI |

; +-----------+

; | EBP | <- EBP

; +-----------+

; | RetAddr | <- ESP is here

; +-----------+

; | Arg1 | <- ESI

; +-----------+

; | Arg2 |

; +-----------+

; | ... |

; +-----------+

; | Arg16 |

; +-----------+

;

; Construct new stack

push ebp

mov ebp, esp

push esi

push edi

sub esp, 40h

push eax

mov esi, ebp

add esi, 8

mov edi, esp

add edi, 4

mov ecx, 16

rep movsd

; call C-code

call EbcInterpret

add esp, 44h

pop edi

pop esi

pop ebp

ret

EbcLLEbcInterpret ENDP

;****************************************************************************

; EbcLLExecuteEbcImageEntryPoint

;

; Begin executing an EBC image.

;****************************************************************************

; UINT64 EbcLLExecuteEbcImageEntryPoint(VOID)

EbcLLExecuteEbcImageEntryPoint PROC PUBLIC

;

;; mov eax, 0xca112ebc

;; mov eax, EbcEntryPoint

;; mov ecx, EbcLLExecuteEbcImageEntryPoint

;; jmp ecx

;

; Caller uses above instruction to jump here

; The stack is below:

; +-----------+

; | RetAddr |

; +-----------+

; |EntryPoint | (EAX)

; +-----------+

; |ImageHandle|

; +-----------+

; |SystemTable|

; +-----------+

; | RetAddr | <- ESP is here

; +-----------+

; |ImageHandle|

; +-----------+

; |SystemTable|

; +-----------+

;

; Construct new stack

mov [esp - 0Ch], eax

mov eax, [esp + 04h]

mov [esp - 08h], eax

mov eax, [esp + 08h]

mov [esp - 04h], eax

; call C-code

sub esp, 0Ch

call ExecuteEbcImageEntryPoint

add esp, 0Ch

ret

EbcLLExecuteEbcImageEntryPoint ENDP

END