From ba3db9e7f6f8d2be5a5170dbac3f12c789306970 Mon Sep 17 00:00:00 2001
From: notaz <notasas@gmail.com>
Date: Mon, 6 Oct 2014 01:51:00 +0300
Subject: [PATCH] don't pass trash in MSB bits to write8 and write16 handlers

otherwise it effectively breaks the C ABI
---
 Ea.cpp     | 30 ++++++++++++++++++++++++++----
 OpMove.cpp | 23 ++++++++++++++++++-----
 2 files changed, 44 insertions(+), 9 deletions(-)

diff --git a/Ea.cpp b/Ea.cpp
index effd4c2..fc4dff9 100644
--- a/Ea.cpp
+++ b/Ea.cpp
@@ -338,7 +338,7 @@ int EaRead(int a,int v,int ea,int size,int mask,EaRWType type,int set_nz)
 
     if      (lsl>0) ot("  ldr%s r%d,[r7,r%d,lsl #%i]\n",Narm[nsarm],v,a,lsl);
     else if (lsl<0) ot("  ldr%s r%d,[r7,r%d,lsr #%i]\n",Narm[nsarm],v,a,-lsl);
-    else            ot("  ldr%s r%d,[r7,r%d]\n",Sarm[nsarm],v,a);
+    else            ot("  ldr%s r%d,[r7,r%d]\n",type==earwt_sign_extend?Sarm[nsarm]:Narm[nsarm],v,a);
 
     if (type == earwt_shifted_up && shift)
       ot("  mov%s r%d,r%d,asl #%d\n",s,v,v,shift);
@@ -472,7 +472,7 @@ int EaWrite(int a,int v,int ea,int size,int mask,EaRWType type)
     }
 
     ot(";@ EaWrite: r%d into register[r%d]:\n",v,a);
-    if (shift)  ot("  mov r%d,r%d,asr #%d\n",v,v,shift);
+    if (shift)  ot("  mov r%d,r%d,lsr #%d\n",v,v,shift);
 
     if      (lsl>0) ot("  str%s r%d,[r7,r%d,lsl #%i]\n",Narm[size&3],v,a,lsl);
     else if (lsl<0) ot("  str%s r%d,[r7,r%d,lsr #%i]\n",Narm[size&3],v,a,-lsl);
@@ -485,8 +485,30 @@ int EaWrite(int a,int v,int ea,int size,int mask,EaRWType type)
 
   if (ea==0x3c) { ot("Error! Write EA=0x%x\n\n",ea); return 1; }
 
-  if (shift)     ot("  mov r1,r%d,asr #%d\n",v,shift);
-  else if (v!=1) ot("  mov r1,r%d\n",v);
+  if (shift)
+  {
+    ot("  mov r1,r%d,lsr #%d\n",v,shift);
+  }
+  else if (v != 1 || (size < 2 && type != earwt_zero_extend))
+  {
+    switch (size) {
+    case 0:
+      ot("  and r1,r%d,#0xff\n",v);
+      break;
+    case 1:
+      if (type != earwt_zero_extend)
+      {
+        ot("  mov r1,r%d,lsl #16\n",v);
+        ot("  mov r1,r1,lsr #16\n");
+        break;
+      }
+      // fallthrough
+    case 2:
+    default:
+      ot("  mov r1,r%d\n",v);
+      break;
+    }
+  }
 
   MemHandler(1,size,a,eawrite_check_addrerr); // Call write handler
 
diff --git a/OpMove.cpp b/OpMove.cpp
index 3d893de..44842ee 100644
--- a/OpMove.cpp
+++ b/OpMove.cpp
@@ -96,6 +96,7 @@ void SuperChange(int op,int srh_reg)
 // Emit a Move opcode, 00xxdddd ddssssss
 int OpMove(int op)
 {
+  EaRWType eatype;
   int sea=0,tea=0;
   int size=0,use=0;
   int movea=0;
@@ -133,13 +134,25 @@ int OpMove(int op)
 
   if (movea==0)
   {
-    EaCalcRead(-1,1,sea,size,0x003f,earwt_sign_extend,1);
-    OpGetFlagsNZ(1);
+    if (sea < 0x10 && size < 2)
+    {
+      eatype = earwt_zero_extend;
+      EaCalcRead(-1,1,sea,size,0x003f,eatype);
+      ot("  movs r2,r1,lsl #%d\n",size?16:24);
+      OpGetFlagsNZ(2);
+    }
+    else
+    {
+      eatype = earwt_shifted_up;
+      EaCalcRead(-1,1,sea,size,0x003f,eatype,1);
+      OpGetFlagsNZ(1);
+    }
     ot("\n");
   }
   else
   {
-    EaCalcRead(-1,1,sea,size,0x003f,earwt_sign_extend);
+    eatype = earwt_sign_extend;
+    EaCalcRead(-1,1,sea,size,0x003f,eatype);
     size=2; // movea always expands to 32-bits
   }
 
@@ -155,8 +168,8 @@ int OpMove(int op)
   else
 #endif
   {
-    EaCalc (0,0x0e00,tea,size,earwt_msb_dont_care);
-    EaWrite(0,     1,tea,size,0x0e00,earwt_msb_dont_care);
+    EaCalc (0,0x0e00,tea,size,eatype);
+    EaWrite(0,     1,tea,size,0x0e00,eatype);
   }
 
 #if CYCLONE_FOR_GENESIS && !MEMHANDLERS_CHANGE_CYCLES
-- 
2.39.5