Modified coding style, removed unnecessary comments and "offset" key words.

[mirror_edk2.git] / MdePkg / Library / BaseLib / Ia32 / Thunk16.asm

diff --git a/MdePkg/Library/BaseLib/Ia32/Thunk16.asm b/MdePkg/Library/BaseLib/Ia32/Thunk16.asm
index 89d4f679b6bd9ede99cd65512d0f9c397503e25c..9fba03ac05072d7540ef95f7188d2726356fc931 100644 (file)
--- a/MdePkg/Library/BaseLib/Ia32/Thunk16.asm
+++ b/MdePkg/Library/BaseLib/Ia32/Thunk16.asm
@@ -29,10 +29,6 @@ EXTERNDEF   C   m16Gdt:WORD
 EXTERNDEF   C   m16GdtrBase:WORD\r
 EXTERNDEF   C   mTransition:WORD\r
 \r
-THUNK_ATTRIBUTE_BIG_REAL_MODE               EQU 1\r
-THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15     EQU 2\r
-THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL   EQU 4\r
-\r
 IA32_REGS   STRUC   4t\r
 _EDI        DD      ?\r
 _ESI        DD      ?\r
@@ -54,19 +50,19 @@ IA32_REGS   ENDS
 \r
     .const\r
 \r
-m16Size         DW      offset InternalAsmThunk16 - offset m16Start\r
-mThunk16Attr    DW      offset _ThunkAttr - offset m16Start\r
-m16Gdt          DW      offset _NullSegDesc - offset m16Start\r
-m16GdtrBase     DW      offset _16GdtrBase - offset m16Start\r
-mTransition     DW      offset _EntryPoint - offset m16Start\r
+m16Size         DW      InternalAsmThunk16 - m16Start\r
+mThunk16Attr    DW      _ThunkAttr - m16Start\r
+m16Gdt          DW      _NullSegDesc - m16Start\r
+m16GdtrBase     DW      _16GdtrBase - m16Start\r
+mTransition     DW      _EntryPoint - m16Start\r
 \r
     .code\r
 \r
 m16Start    LABEL   BYTE\r
 \r
-SavedGdt        LABEL   FWORD\r
-                DW      ?\r
-                DD      ?\r
+SavedGdt    LABEL   FWORD\r
+            DW      ?\r
+            DD      ?\r
 \r
 _BackFromUserCode   PROC\r
     push    ss\r
@@ -106,7 +102,7 @@ _ThunkAttr  DD      ?
 SavedCr4    DD      ?\r
     mov     cr4, eax\r
     DB      66h\r
-    lgdt    fword ptr cs:[edi + (offset SavedGdt - offset @Base)]\r
+    lgdt    fword ptr cs:[edi + (SavedGdt - @Base)]\r
     DB      66h, 0b8h                   ; mov eax, imm32\r
 SavedCr0    DD      ?\r
     mov     cr0, eax\r
@@ -119,12 +115,12 @@ SavedEsp    DD      ?
     retf                                ; return to protected mode\r
 _BackFromUserCode   ENDP\r
 \r
-_EntryPoint     DD      offset _ToUserCode - offset m16Start\r
-                DW      8h\r
-_16Idtr         FWORD   (1 SHL 10) - 1\r
-_16Gdtr         LABEL   FWORD\r
-                DW      offset GdtEnd - offset _NullSegDesc - 1\r
-_16GdtrBase     DD      offset _NullSegDesc\r
+_EntryPoint DD      _ToUserCode - m16Start\r
+            DW      8h\r
+_16Idtr     FWORD   (1 SHL 10) - 1\r
+_16Gdtr     LABEL   FWORD\r
+            DW      GdtEnd - _NullSegDesc - 1\r
+_16GdtrBase DD      _NullSegDesc\r
 \r
 _ToUserCode PROC\r
     mov     edx, ss\r
@@ -140,11 +136,17 @@ _ToUserCode PROC
     DB      66h\r
     call    @Base                       ; push eip\r
 @Base:\r
-    pop     bp                          ; ebp <- offset @Base\r
-    mov     cs:[esi + (offset SavedSs - offset @Base)], edx\r
-    mov     cs:[esi + (offset SavedEsp - offset @Base)], bx\r
+    pop     bp                          ; ebp <- address of @Base\r
+    DB      67h                         ; address size override\r
+    push    [esp + sizeof (IA32_REGS) + 2]\r
+    lea     eax, [esi + (@RealMode - @Base)]\r
+    push    eax\r
+    retf\r
+@RealMode:\r
+    mov     cs:[esi + (SavedSs - @Base)], edx\r
+    mov     cs:[esi + (SavedEsp - @Base)], bx\r
     DB      66h\r
-    lidt    fword ptr cs:[esi + (offset _16Idtr - offset @Base)]\r
+    lidt    fword ptr cs:[esi + (_16Idtr - @Base)]\r
     popaw                               ; popad actually\r
     pop     ds\r
     pop     es\r
@@ -190,25 +192,27 @@ InternalAsmThunk16  PROC    USES    ebp ebx esi edi ds  es  fs  gs
     rep     movsd                       ; copy RegSet\r
     mov     eax, [esp + 40]             ; eax <- address of transition code\r
     mov     esi, edx                    ; esi <- 16-bit stack segment\r
-    lea     edx, [eax + (offset SavedCr0 - offset m16Start)]\r
+    lea     edx, [eax + (SavedCr0 - m16Start)]\r
     mov     ecx, eax\r
     and     ecx, 0fh\r
     shl     eax, 12\r
-    lea     ecx, [ecx + (offset _BackFromUserCode - offset m16Start)]\r
+    lea     ecx, [ecx + (_BackFromUserCode - m16Start)]\r
     mov     ax, cx\r
     stosd                               ; [edi] <- return address of user code\r
-    sgdt    fword ptr [edx + (offset SavedGdt - offset SavedCr0)]\r
+    sgdt    fword ptr [edx + (SavedGdt - SavedCr0)]\r
     sidt    fword ptr [esp + 36]        ; save IDT stack in argument space\r
     mov     eax, cr0\r
     mov     [edx], eax                  ; save CR0 in SavedCr0\r
     and     eax, 7ffffffeh              ; clear PE, PG bits\r
     mov     ebp, cr4\r
-    mov     [edx + (offset SavedCr4 - offset SavedCr0)], ebp\r
+    mov     [edx + (SavedCr4 - SavedCr0)], ebp\r
     and     ebp, 300h                   ; clear all but PCE and OSFXSR bits\r
     push    10h\r
     pop     ecx                         ; ecx <- selector for data segments\r
-    lgdt    fword ptr [edx + (offset _16Gdtr - offset SavedCr0)]\r
-    call    fword ptr [edx + (offset _EntryPoint - offset SavedCr0)]\r
+    lgdt    fword ptr [edx + (_16Gdtr - SavedCr0)]\r
+    pushfd\r
+    call    fword ptr [edx + (_EntryPoint - SavedCr0)]\r
+    popfd\r
     lidt    fword ptr [esp + 36]        ; restore protected mode IDTR\r
     lea     eax, [ebp - sizeof (IA32_REGS)]\r
     ret\r