Initial import.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@3 6f19259b-4bc3-4df7-8a09-765794883524
2006-04-21 22:54:32 +00:00
commit 878ddf1fc3
2651 changed files with 624620 additions and 0 deletions
--- a/MdePkg/Library/BaseLib/x86Thunk.c
+++ b/MdePkg/Library/BaseLib/x86Thunk.c
@@ -0,0 +1,127 @@
+/** @file
+  Real Mode Thunk Functions for IA32 and X64.
+
+  Copyright (c) 2006, Intel Corporation<BR>
+  All rights reserved. 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.
+
+  Module Name:  x86Thunk.c
+
+**/
+
+/**
+  Invokes 16-bit code in big real mode and returns the updated register set.
+
+  This function transfers control to the 16-bit code specified by CS:EIP using
+  the stack specified by SS:ESP in RegisterSet. The updated registers are saved
+  on the real mode stack and the starting address of the save area is returned.
+
+  @param  RegisterSet Values of registers before invocation of 16-bit code.
+  @param  Patch       Pointer to the area following the 16-bit code.
+
+  @return The pointer to a IA32_REGISTER_SET structure containing the updated
+          register values.
+
+**/
+IA32_REGISTER_SET *
+InternalAsmThunk16 (
+  IN      IA32_REGISTER_SET         *RegisterSet,
+  IN OUT  VOID                      *Patch
+  );
+
+/**
+  Prepares all structures a code required to use AsmThunk16().
+
+  Prepares all structures and code required to use AsmThunk16().
+
+  If ThunkContext is NULL, then ASSERT().
+
+  @param  ThunkContext  A pointer to the context structure that describes the
+                        16-bit real mode code to call.
+
+**/
+VOID
+EFIAPI
+AsmPrepareThunk16 (
+  OUT     THUNK_CONTEXT             *ThunkContext
+  )
+{
+  ASSERT (ThunkContext != NULL);
+}
+
+/**
+  Transfers control to a 16-bit real mode entry point and returns the results.
+
+  Transfers control to a 16-bit real mode entry point and returns the results.
+  AsmPrepareThunk16() must be called with ThunkContext before this function is
+  used. This function must be called with interrupts disabled.
+
+  If ThunkContext is NULL, then ASSERT().
+  If AsmPrepareThunk16() was not previously called with ThunkContext, then ASSERT().
+
+  @param  ThunkContext  A pointer to the context structure that describes the
+                        16-bit real mode code to call.
+
+**/
+VOID
+EFIAPI
+AsmThunk16 (
+  IN OUT  THUNK_CONTEXT             *ThunkContext
+  )
+{
+  UINT16                            *Patch;
+
+  ASSERT (ThunkContext != NULL);
+
+  Patch = (UINT16*)(
+            (UINTN)ThunkContext->RealModeCode +
+            ThunkContext->RealModeCodeSize
+            );
+
+  //
+  // 0x9a66 is the OpCode of far call with an operand size override.
+  //
+  *Patch = 0x9a66;
+
+  //
+  // CopyMem() here copies the updated register values back to RealModeState
+  //
+  CopyMem (
+    &ThunkContext->RealModeState,
+    InternalAsmThunk16 (&ThunkContext->RealModeState, Patch + 1),
+    sizeof (ThunkContext->RealModeState)
+    );
+}
+
+/**
+  Prepares all structures and code for a 16-bit real mode thunk, transfers
+  control to a 16-bit real mode entry point, and returns the results.
+
+  Prepares all structures and code for a 16-bit real mode thunk, transfers
+  control to a 16-bit real mode entry point, and returns the results. If the
+  caller only need to perform a single 16-bit real mode thunk, then this
+  service should be used. If the caller intends to make more than one 16-bit
+  real mode thunk, then it is more efficient if AsmPrepareThunk16() is called
+  once and AsmThunk16() can be called for each 16-bit real mode thunk. This
+  function must be called with interrupts disabled.
+
+  If ThunkContext is NULL, then ASSERT().
+
+  @param  ThunkContext  A pointer to the context structure that describes the
+                        16-bit real mode code to call.
+
+**/
+VOID
+EFIAPI
+AsmPrepareAndThunk16 (
+  IN OUT  THUNK_CONTEXT             *ThunkContext
+  )
+{
+  AsmPrepareThunk16 (ThunkContext);
+  AsmThunk16 (ThunkContext);
+}