UserspaceEmulator+LibX86: Implement the LEA instruction

This piggybacks nicely on Instruction's ModR/M resolution code. :^)

DevTools/UserspaceEmulator/SoftCPU.cpp

@@ -625,8 +625,17 @@ void SoftCPU::LDS_reg16_mem16(const X86::Instruction&) { TODO(); }
 void SoftCPU::LDS_reg32_mem32(const X86::Instruction&) { TODO(); }
 void SoftCPU::LEAVE16(const X86::Instruction&) { TODO(); }
 void SoftCPU::LEAVE32(const X86::Instruction&) { TODO(); }
-void SoftCPU::LEA_reg16_mem16(const X86::Instruction&) { TODO(); }
-void SoftCPU::LEA_reg32_mem32(const X86::Instruction&) { TODO(); }
+
+void SoftCPU::LEA_reg16_mem16(const X86::Instruction& insn)
+{
+    gpr16(insn.reg16()) = insn.modrm().resolve(*this, insn.segment_prefix()).offset();
+}
+
+void SoftCPU::LEA_reg32_mem32(const X86::Instruction& insn)
+{
+    gpr32(insn.reg32()) = insn.modrm().resolve(*this, insn.segment_prefix()).offset();
+}
+
 void SoftCPU::LES_reg16_mem16(const X86::Instruction&) { TODO(); }
 void SoftCPU::LES_reg32_mem32(const X86::Instruction&) { TODO(); }
 void SoftCPU::LFS_reg16_mem16(const X86::Instruction&) { TODO(); }

Libraries/LibX86/Instruction.h

@@ -218,6 +218,14 @@ public:
     template<typename CPU>
     u32 read32(CPU&, const Instruction&);
 
+    template<typename CPU>
+    LogicalAddress resolve(const CPU& cpu, Optional<SegmentRegister> segment_prefix)
+    {
+        if (m_a32)
+            return resolve32(cpu, segment_prefix);
+        return resolve16(cpu, segment_prefix);
+    }
+
 private:
     MemoryOrRegisterReference() { }
 
@@ -234,14 +242,6 @@ private:
     template<typename CPU>
     LogicalAddress resolve32(const CPU&, Optional<SegmentRegister>);
 
-    template<typename CPU>
-    LogicalAddress resolve(const CPU& cpu, Optional<SegmentRegister> segment_prefix)
-    {
-        if (m_a32)
-            return resolve32(cpu, segment_prefix);
-        return resolve16(cpu, segment_prefix);
-    }
-
     template<typename CPU>
     u32 evaluate_sib(const CPU&, SegmentRegister& default_segment) const;