4057

1 files changed, 21 insertions, 0 deletions

diff --git a/subx/011direct_addressing.cc b/subx/011direct_addressing.cc
index bbd482d4..3286cbea 100644
--- a/subx/011direct_addressing.cc
+++ b/subx/011direct_addressing.cc
@@ -104,3 +104,24 @@ case 0x09: {  // or r32 with r/m32
   BINARY_BITWISE_OP(|, *arg1, Reg[arg2].u);
   break;
 }
+
+//:: xor
+
+:(scenario xor_r32_with_r32)
+% Reg[0].i = 0x0a0b0c0d;
+% Reg[3].i = 0xaabbc0d0;
+# op  ModR/M  SIB   displacement  immediate
+  31  d8                                      # xor EBX (reg 3) with destination EAX (reg 0)
++run: xor reg 3 with effective address
++run: effective address is reg 0
++run: storing 0xa0b0ccdd
+
+:(before "End Single-Byte Opcodes")
+case 0x31: {  // xor r32 with r/m32
+  uint8_t modrm = next();
+  uint8_t arg2 = (modrm>>3)&0x7;
+  trace(2, "run") << "xor reg " << NUM(arg2) << " with effective address" << end();
+  int32_t* arg1 = effective_address(modrm);
+  BINARY_BITWISE_OP(^, *arg1, Reg[arg2].u);
+  break;
+}