From: Aleksandar Andrejevic <aandrejevic@reactos.org>
Date: Sat, 25 Jan 2014 00:53:10 +0000 (+0000)
Subject: [NTVDM]
X-Git-Tag: backups/0.3.17@66124~1365^2~122
X-Git-Url: https://git.reactos.org/?p=reactos.git;a=commitdiff_plain;h=a3a28181c22b72d2b7f403b7a2077c358c475a9f

[NTVDM]
Add two general-purpose variables to the interrupt handler stub stack.
Fix INT 29h so that it works correctly when the INT 10h, AH = 0Eh call is hooked.


svn path=/branches/ntvdm/; revision=61797
---

diff --git a/subsystems/ntvdm/dos/dos.c b/subsystems/ntvdm/dos/dos.c
index 1136807b63e..53223c91a26 100644
--- a/subsystems/ntvdm/dos/dos.c
+++ b/subsystems/ntvdm/dos/dos.c
@@ -2675,15 +2675,31 @@ VOID WINAPI DosFastConOut(LPWORD Stack)
      * See Ralf Brown: http://www.ctyme.com/intr/rb-4124.htm
      * for more information.
      */
-    UNREFERENCED_PARAMETER(Stack);
 
-    /*
-     * The default handler under DOS 2.x and 3.x simply calls INT 10/AH=0Eh.
-     * Do better and call directly VidBiosPrintCharacter: it's what INT 10/AH=0Eh
-     * does. Otherwise we would have to set BL to DOS_CHAR_ATTRIBUTE and
-     * BH to Bda->VideoPage.
-     */
-    VidBiosPrintCharacter(getAL(), DOS_CHAR_ATTRIBUTE, Bda->VideoPage);
+    if (Stack[STACK_COUNTER] == 0)
+    {
+        Stack[STACK_COUNTER]++;
+
+        /* Save AX and BX */
+        Stack[STACK_VAR_A] = getAX();
+        Stack[STACK_VAR_B] = getBX();
+
+        /* Rewind the BOP manually, we can't use CF because the interrupt could modify it */
+        EmulatorExecute(getCS(), getIP() - 4);
+
+        /* Call INT 0x10, AH = 0x0E */
+        setAH(0x0E);
+        setBL(DOS_CHAR_ATTRIBUTE);
+        setBH(Bda->VideoPage);
+
+        EmulatorInterrupt(0x10);
+    }
+    else
+    {
+        /* Restore AX and BX */
+        setAX(Stack[STACK_VAR_A]);
+        setBX(Stack[STACK_VAR_B]);
+    }
 }
 
 VOID WINAPI DosInt2Fh(LPWORD Stack)
diff --git a/subsystems/ntvdm/emulator.h b/subsystems/ntvdm/emulator.h
index 3e25b5f39d2..24749688fee 100644
--- a/subsystems/ntvdm/emulator.h
+++ b/subsystems/ntvdm/emulator.h
@@ -34,11 +34,13 @@
 #define EMULATOR_FLAG_VIP (1 << 20)
 #define EMULATOR_FLAG_ID (1 << 21)
 
-#define STACK_COUNTER   0
-#define STACK_INT_NUM   1
-#define STACK_IP        2
-#define STACK_CS        3
-#define STACK_FLAGS     4
+#define STACK_VAR_B     0
+#define STACK_VAR_A     1
+#define STACK_COUNTER   2
+#define STACK_INT_NUM   3
+#define STACK_IP        4
+#define STACK_CS        5
+#define STACK_FLAGS     6
 
 
 /* Basic Memory Management */
diff --git a/subsystems/ntvdm/int32.c b/subsystems/ntvdm/int32.c
index d61625148a8..b89eb137e03 100644
--- a/subsystems/ntvdm/int32.c
+++ b/subsystems/ntvdm/int32.c
@@ -74,9 +74,15 @@ VOID InitializeInt32(WORD BiosSegment)
         BiosCode[Offset++] = 0x6A; // push i
         BiosCode[Offset++] = (UCHAR)i;
 
+        /* The counter variable (initialized to 0) */
         BiosCode[Offset++] = 0x6A; // push 0
         BiosCode[Offset++] = 0x00;
 
+        /* Stack variables */
+        BiosCode[Offset++] = 0x83; // sub sp, 4
+        BiosCode[Offset++] = 0xEC;
+        BiosCode[Offset++] = 0x04;
+
         BopSeqOffset = COMMON_STUB_OFFSET - (Offset + 3);
 
         BiosCode[Offset++] = 0xE9; // jmp near BOP_SEQ
@@ -107,9 +113,9 @@ VOID InitializeInt32(WORD BiosSegment)
     BiosCode[Offset++] = 0xF5;
 
 // EXIT:
-    BiosCode[Offset++] = 0x83; // add sp, 4
+    BiosCode[Offset++] = 0x83; // add sp, 8
     BiosCode[Offset++] = 0xC4;
-    BiosCode[Offset++] = 0x04;
+    BiosCode[Offset++] = 0x08;
 
     BiosCode[Offset++] = 0xCF; // iret