Adds a presently-unreachable step for SIB consumption.

InstructionSets/x86/Decoder.cpp

@@ -637,6 +637,14 @@ std::pair<int, InstructionSet::x86::Instruction> Decoder::decode(const uint8_t *
 		phase_ = (displacement_size_ + operand_size_) ? Phase::DisplacementOrOperand : Phase::ReadyToPost;
 	}
 
+	// MARK: - ScaleIndexBase
+
+	if(phase_ == Phase::ScaleIndexBase && source != end) {
+		sib_ = *source;
+		++source;
+		++consumed_;
+	}
+
 	// MARK: - Displacement and operand.
 
 	if(phase_ == Phase::DisplacementOrOperand && source != end) {

InstructionSets/x86/Decoder.hpp

@@ -53,6 +53,8 @@ class Decoder {
 			/// Receives a ModRegRM byte and either populates the source_ and dest_ fields appropriately
 			/// or completes decoding of the instruction, as per the instruction format.
 			ModRegRM,
+			/// Awaits n 80386+-style scale-index-base byte ('SIB'), indicating the form of indirect addressing.
+			ScaleIndexBase,
 			/// Waits for sufficiently many bytes to pass for the required displacement and operand to be captured.
 			/// Cf. displacement_size_ and operand_size_.
 			DisplacementOrOperand,
@@ -143,6 +145,9 @@ class Decoder {
 		uint16_t operand_ = 0;
 		uint64_t inward_data_ = 0;
 
+		// Indirection style.
+		uint8_t sib_;
+
 		// Facts about the instruction.
 		int displacement_size_ = 0;		// i.e. size of in-stream displacement, if any.
 		int operand_size_ = 0;			// i.e. size of in-stream operand, if any.

InstructionSets/x86/Instruction.hpp

@@ -319,7 +319,7 @@ enum class Size: uint8_t {
 
 enum class Source: uint8_t {
 	// These are in SIB order; this matters for packing later on.
-	// Whether each refers to e.g. EAX or AX depends on the
+	// Whether each refers to e.g. EAX, AX or AL depends on the
 	// instruction's data size.
 	eAX, eCX, eDX, eBX, eSP, eBP, eSI, eDI,