From 3ad78aac17eb7ded071727d3f1e806acc078904b Mon Sep 17 00:00:00 2001
From: Aleksandar Andrejevic <aandrejevic@reactos.org>
Date: Sun, 25 Aug 2013 14:53:58 +0000
Subject: [PATCH] [SOFT386] Implement the following opcodes: NOP XCHG (E)AX,
 reg16/reg32

svn path=/branches/ntvdm/; revision=59819
---
 lib/soft386/opcodes.c | 78 ++++++++++++++++++++++++++++++++++++++-----
 lib/soft386/opcodes.h | 16 +++++++++
 2 files changed, 86 insertions(+), 8 deletions(-)

diff --git a/lib/soft386/opcodes.c b/lib/soft386/opcodes.c
index 268463143d1..6a9331a6670 100644
--- a/lib/soft386/opcodes.c
+++ b/lib/soft386/opcodes.c
@@ -168,14 +168,14 @@ Soft386OpcodeHandlers[SOFT386_NUM_OPCODE_HANDLERS] =
     NULL, // TODO: OPCODE 0x8D NOT SUPPORTED
     NULL, // TODO: OPCODE 0x8E NOT SUPPORTED
     NULL, // TODO: OPCODE 0x8F NOT SUPPORTED
-    NULL, // TODO: OPCODE 0x90 NOT SUPPORTED
-    NULL, // TODO: OPCODE 0x91 NOT SUPPORTED
-    NULL, // TODO: OPCODE 0x92 NOT SUPPORTED
-    NULL, // TODO: OPCODE 0x93 NOT SUPPORTED
-    NULL, // TODO: OPCODE 0x94 NOT SUPPORTED
-    NULL, // TODO: OPCODE 0x95 NOT SUPPORTED
-    NULL, // TODO: OPCODE 0x96 NOT SUPPORTED
-    NULL, // TODO: OPCODE 0x97 NOT SUPPORTED
+    Soft386OpcodeNop,
+    Soft386OpcodeExchangeEax,
+    Soft386OpcodeExchangeEax,
+    Soft386OpcodeExchangeEax,
+    Soft386OpcodeExchangeEax,
+    Soft386OpcodeExchangeEax,
+    Soft386OpcodeExchangeEax,
+    Soft386OpcodeExchangeEax,
     NULL, // TODO: OPCODE 0x98 NOT SUPPORTED
     NULL, // TODO: OPCODE 0x99 NOT SUPPORTED
     NULL, // TODO: OPCODE 0x9A NOT SUPPORTED
@@ -586,3 +586,65 @@ Soft386OpcodePopReg(PSOFT386_STATE State, UCHAR Opcode)
     /* Return success */
     return TRUE;
 }
+
+BOOLEAN
+FASTCALL
+Soft386OpcodeNop(PSOFT386_STATE State, UCHAR Opcode)
+{
+    if (State->PrefixFlags & ~(SOFT386_PREFIX_OPSIZE | SOFT386_PREFIX_REP))
+    {
+        /* Allowed prefixes are REP and OPSIZE */
+        Soft386Exception(State, SOFT386_EXCEPTION_UD);
+        return FALSE;
+    }
+
+    if (State->PrefixFlags & SOFT386_PREFIX_REP)
+    {
+        // TODO: Handle PAUSE instruction.
+    }
+
+    return TRUE;
+}
+
+BOOLEAN
+FASTCALL
+Soft386OpcodeExchangeEax(PSOFT386_STATE State, UCHAR Opcode)
+{
+    INT Reg = Opcode & 0x07;
+    BOOLEAN Size = State->SegmentRegs[SOFT386_REG_CS].Size;
+
+    if (State->PrefixFlags == SOFT386_PREFIX_OPSIZE)
+    {
+        /* The OPSIZE prefix toggles the size */
+        Size = !Size;
+    }
+    else if (State->PrefixFlags != 0)
+    {
+        /* Invalid prefix */
+        Soft386Exception(State, SOFT386_EXCEPTION_UD);
+        return FALSE;
+    }
+
+    /* Make sure this is the right instruction */
+    ASSERT((Opcode & 0xF8) == 0x90);
+
+    /* Exchange the values */
+    if (Size)
+    {
+        ULONG Value;
+
+        Value = State->GeneralRegs[Reg].Long;
+        State->GeneralRegs[Reg].Long = State->GeneralRegs[SOFT386_REG_EAX].Long;
+        State->GeneralRegs[SOFT386_REG_EAX].Long = Value;
+    }
+    else
+    {
+        USHORT Value;
+
+        Value = State->GeneralRegs[Reg].LowWord;
+        State->GeneralRegs[Reg].LowWord = State->GeneralRegs[SOFT386_REG_EAX].LowWord;
+        State->GeneralRegs[SOFT386_REG_EAX].LowWord = Value;
+    }
+
+    return TRUE;
+}
diff --git a/lib/soft386/opcodes.h b/lib/soft386/opcodes.h
index 59a7e540fe7..17688735f08 100644
--- a/lib/soft386/opcodes.h
+++ b/lib/soft386/opcodes.h
@@ -63,4 +63,20 @@ Soft386OpcodePopReg
     UCHAR Opcode
 );
 
+BOOLEAN
+FASTCALL
+Soft386OpcodeNop
+(
+    PSOFT386_STATE State,
+    UCHAR Opcode
+);
+
+BOOLEAN
+FASTCALL
+Soft386OpcodeExchangeEax
+(
+    PSOFT386_STATE State,
+    UCHAR Opcode
+);
+
 #endif // _OPCODES_H_