From 50f36e7cb3ec453ec9fe3c93cc5c8de747958036 Mon Sep 17 00:00:00 2001
From: Aleksandar Andrejevic <aandrejevic@reactos.org>
Date: Fri, 5 Jun 2015 22:22:04 +0000
Subject: [PATCH] [NTVDM] - Implement the DOS idle interrupt. - Link to the
 parent's environment block by default in DosCreatePsp. - Fix INT 21h/36h (Get
 Free Space) to report 0xFFFF if the number of clusters is too high to fit in
 a word.

svn path=/trunk/; revision=68028
---
 .../subsystems/mvdm/ntvdm/dos/dos32krnl/dos.c    | 16 ++++++++++++++--
 .../mvdm/ntvdm/dos/dos32krnl/process.c           |  7 +++++--
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/dos.c b/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/dos.c
index 1405962b960..75a04fe7ea8 100644
--- a/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/dos.c
+++ b/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/dos.c
@@ -825,8 +825,8 @@ VOID WINAPI DosInt21h(LPWORD Stack)
             {
                 setAX(LOWORD(SectorsPerCluster));
                 setCX(LOWORD(BytesPerSector));
-                setBX(LOWORD(NumberOfFreeClusters));
-                setDX(LOWORD(TotalNumberOfClusters));
+                setBX(min(NumberOfFreeClusters, 0xFFFF));
+                setDX(min(TotalNumberOfClusters, 0xFFFF));
             }
             else
             {
@@ -1873,6 +1873,15 @@ VOID WINAPI DosInt27h(LPWORD Stack)
     DosTerminateProcess(getCS(), 0, (getDX() + 0x0F) >> 4);
 }
 
+VOID WINAPI DosIdle(LPWORD Stack)
+{
+    /*
+     * This will set the carry flag on the first call (to repeat the BOP),
+     * and clear it in the next, so that exactly one HLT occurs.
+     */
+    setCF(!getCF());
+}
+
 VOID WINAPI DosFastConOut(LPWORD Stack)
 {
     /*
@@ -2070,10 +2079,13 @@ BOOLEAN DosKRNLInitialize(VOID)
     RegisterDosInt32(0x23, DosBreakInterrupt); // Ctrl-C / Ctrl-Break
 //  RegisterDosInt32(0x24, DosInt24h        ); // Critical Error
     RegisterDosInt32(0x27, DosInt27h        ); // Terminate and Stay Resident
+    RegisterDosInt32(0x28, DosIdle          ); // DOS Idle Interrupt
     RegisterDosInt32(0x29, DosFastConOut    ); // DOS 2+ Fast Console Output
     RegisterDosInt32(0x2F, DosInt2Fh        );
 
     /* Unimplemented DOS interrupts */
+    RegisterDosInt32(0x25, NULL); // Absolute Disk Read
+    RegisterDosInt32(0x26, NULL); // Absolute Disk Write
     RegisterDosInt32(0x2A, NULL); // Network - Installation Check
 
     /* Load the CON driver */
diff --git a/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/process.c b/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/process.c
index a5140777f4d..d1e22b1891e 100644
--- a/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/process.c
+++ b/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/process.c
@@ -212,8 +212,11 @@ VOID DosCreatePsp(WORD Segment, WORD ProgramSize)
     /* Set the parent PSP */
     PspBlock->ParentPsp = Sda->CurrentPsp;
 
-    /* No environment block yet */
-    PspBlock->EnvBlock = 0;
+    if (Sda->CurrentPsp != SYSTEM_PSP)
+    {
+        /* Link to the parent's environment block */
+        PspBlock->EnvBlock = SEGMENT_TO_PSP(Sda->CurrentPsp)->EnvBlock;
+    }
 
     /* Copy the parent handle table */
     DosCopyHandleTable(PspBlock->HandleTable);