From 64d556f60fd6b89acac53e03a2ba41235f8f5998 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Wed, 20 Jan 2021 21:39:13 -0500
Subject: [PATCH] Implements shifts and rotates.

---
 InstructionSets/M50740/Executor.cpp | 30 ++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/InstructionSets/M50740/Executor.cpp b/InstructionSets/M50740/Executor.cpp
index f6cb37b2d..e557067fa 100644
--- a/InstructionSets/M50740/Executor.cpp
+++ b/InstructionSets/M50740/Executor.cpp
@@ -350,7 +350,35 @@ template <Operation operation> void Executor::perform(uint8_t *operand [[maybe_u
 		// TODO:
 		//
 		//	BRK, STP,
-		//	ADC, SBC, BIT, ASL, LSR, ROL, ROR, RRF
+		//	ADC, SBC, BIT
+
+		case Operation::ASL:
+			carry_flag_ = *operand >> 7;
+			*operand <<= 1;
+			set_nz(*operand);
+		break;
+
+		case Operation::LSR:
+			carry_flag_ = *operand & 1;
+			*operand >>= 1;
+			set_nz(*operand);
+		break;
+
+		case Operation::ROL: {
+			const uint8_t temp8 = uint8_t((*operand << 1) | carry_flag_);
+			carry_flag_ = *operand >> 7;
+			set_nz(*operand = temp8);
+		} break;
+
+		case Operation::ROR: {
+			const uint8_t temp8 = uint8_t((*operand >> 1) | (carry_flag_ << 7));
+			carry_flag_ = *operand & 1;
+			set_nz(*operand = temp8);
+		} break;
+
+		case Operation::RRF:
+			*operand = uint8_t((*operand >> 4) | (*operand << 4));
+		break;
 
 	/*
 		Operations affected by the index mode flag: ADC, AND, CMP, EOR, LDA, ORA, and SBC.