From bc9f26de6737e762e5e6045fc874d68842e98bca Mon Sep 17 00:00:00 2001
From: "Kartik K. Agaram" <vc@akkartik.com>
Date: Wed, 24 Jan 2018 22:58:30 -0800
Subject: [PATCH] 4196

---
 subx/012indirect_addressing.cc | 46 ++++++++++++++++++++--------------
 subx/014index_addressing.cc    |  2 +-
 2 files changed, 28 insertions(+), 20 deletions(-)

diff --git a/subx/012indirect_addressing.cc b/subx/012indirect_addressing.cc
index ed478632..18ca6b5f 100644
--- a/subx/012indirect_addressing.cc
+++ b/subx/012indirect_addressing.cc
@@ -420,7 +420,7 @@ case 0x8f: {  // pop stack into r/m32
 +run: effective address is 0x60 (disp32)
 +run: storing 0x00000011
 
-:(before "End Mod 0 Special-cases")
+:(before "End Mod 0 Special-cases(addr)")
 case 5:  // exception: mod 0b00 rm 0b101 => incoming disp32
   addr = imm32();
   trace(2, "run") << "effective address is 0x" << std::hex << addr << " (disp32)" << end();
@@ -436,19 +436,22 @@ case 5:  // exception: mod 0b00 rm 0b101 => incoming disp32
   01  58            02                       # add EBX to *(EAX+2)
 # ModR/M in binary: 01 (indirect+disp8 mode) 011 (src EBX) 000 (dest EAX)
 +run: add EBX to r/m32
-+run: effective address is 0x60 (EAX+disp8)
++run: effective address is initially 0x5e (EAX)
++run: effective address is 0x60 (after adding disp8)
 +run: storing 0x00000011
 
 :(before "End Mod Special-cases(addr)")
 case 1:  // indirect + disp8 addressing
   switch (rm) {
-    default: {
-      int8_t disp = next();
-      addr = Reg[rm].u + disp;
-      trace(2, "run") << "effective address is 0x" << std::hex << addr << " (" << rname(rm) << "+disp8)" << end();
-      break;
-    }
-    // End Mod 1 Special-cases(addr)
+  default:
+    addr = Reg[rm].u;
+    trace(2, "run") << "effective address is initially 0x" << std::hex << addr << " (" << rname(rm) << ")" << end();
+    break;
+  // End Mod 1 Special-cases(addr)
+  }
+  if (addr > 0) {
+    addr += static_cast<int8_t>(next());
+    trace(2, "run") << "effective address is 0x" << std::hex << addr << " (after adding disp8)" << end();
   }
   break;
 
@@ -460,7 +463,8 @@ case 1:  // indirect + disp8 addressing
   01  58            ff                       # add EBX to *(EAX-1)
 # ModR/M in binary: 01 (indirect+disp8 mode) 011 (src EBX) 000 (dest EAX)
 +run: add EBX to r/m32
-+run: effective address is 0x60 (EAX+disp8)
++run: effective address is initially 0x61 (EAX)
++run: effective address is 0x60 (after adding disp8)
 +run: storing 0x00000011
 
 //:
@@ -473,19 +477,22 @@ case 1:  // indirect + disp8 addressing
   01  98            02 00 00 00              # add EBX to *(EAX+2)
 # ModR/M in binary: 10 (indirect+disp32 mode) 011 (src EBX) 000 (dest EAX)
 +run: add EBX to r/m32
-+run: effective address is 0x60 (EAX+disp32)
++run: effective address is initially 0x5e (EAX)
++run: effective address is 0x60 (after adding disp32)
 +run: storing 0x00000011
 
 :(before "End Mod Special-cases(addr)")
 case 2:  // indirect + disp32 addressing
   switch (rm) {
-    default: {
-      int32_t disp = imm32();
-      addr = Reg[rm].u + disp;
-      trace(2, "run") << "effective address is 0x" << std::hex << addr << " (" << rname(rm) << "+disp32)" << end();
-      break;
-    }
-    // End Mod 2 Special-cases(addr)
+  default:
+    addr = Reg[rm].u;
+    trace(2, "run") << "effective address is initially 0x" << std::hex << addr << " (" << rname(rm) << ")" << end();
+    break;
+  // End Mod 2 Special-cases(addr)
+  }
+  if (addr > 0) {
+    addr += imm32();
+    trace(2, "run") << "effective address is 0x" << std::hex << addr << " (after adding disp32)" << end();
   }
   break;
 
@@ -497,5 +504,6 @@ case 2:  // indirect + disp32 addressing
   01  98            ff ff ff ff              # add EBX to *(EAX-1)
 # ModR/M in binary: 10 (indirect+disp32 mode) 011 (src EBX) 000 (dest EAX)
 +run: add EBX to r/m32
-+run: effective address is 0x60 (EAX+disp32)
++run: effective address is initially 0x61 (EAX)
++run: effective address is 0x60 (after adding disp32)
 +run: storing 0x00000011
diff --git a/subx/014index_addressing.cc b/subx/014index_addressing.cc
index 37a4b9be..8ab545d3 100644
--- a/subx/014index_addressing.cc
+++ b/subx/014index_addressing.cc
@@ -13,7 +13,7 @@
 +run: effective address is 0x60
 +run: storing 0x00000011
 
-:(before "End Mod 0 Special-cases")
+:(before "End Mod 0 Special-cases(addr)")
 case 4:  // exception: mod 0b00 rm 0b100 => incoming SIB (scale-index-base) byte
   addr = effective_address_from_sib(mod);
   break;