From 5dc185866ec06cf1249aedef4c24b6a94e465d30 Mon Sep 17 00:00:00 2001
From: Adrian Conlon <Adrian.conlon@gmail.com>
Date: Sun, 7 Oct 2018 09:14:30 +0100
Subject: [PATCH] Add a test for ADCA immediate.  Half carry and overflow flags
 incorrect!

Signed-off-by: Adrian Conlon <Adrian.conlon@gmail.com>
---
 MC6809/inc/mc6809.h              | 10 ++++++++--
 MC6809/unittest/mc6809_tests.cpp | 26 +++++++++++++++++++++++++-
 2 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/MC6809/inc/mc6809.h b/MC6809/inc/mc6809.h
index bd722e8..41de2a4 100644
--- a/MC6809/inc/mc6809.h
+++ b/MC6809/inc/mc6809.h
@@ -206,21 +206,27 @@ namespace EightBit {
 		void adjustBorrow(register16_t datum) { adjustBorrow(datum.word); }
 
 		void adjustOverflow(uint8_t before, uint8_t data, uint8_t after) {
-			setFlag(CC(), VF, (before ^ data) & (before ^ after) & Bit7);
+			setFlag(CC(), VF, !!((before ^ data ^ after ^ (after >> 1)) & Bit7));
 		}
 
 		void adjustOverflow(uint16_t before, uint16_t data, uint16_t after) {
-			setFlag(CC(), VF, (before ^ data) & (before ^ after) & Bit15);
+			setFlag(CC(), VF, !!((before ^ data ^ after ^ (after >> 1)) & Bit15));
 		}
+
 		void adjustOverflow(register16_t before, register16_t data, register16_t after) {
 			adjustOverflow(before.word, data.word, after.word);
 		}
 
+		void adjustHalfCarry(uint8_t before, uint8_t data, uint8_t after) {
+			setFlag(CC(), HF, !!((before ^ data ^ after) & Bit4));
+		}
+
 		void adjustAddition(uint8_t before, uint8_t data, register16_t after) {
 			const auto result = after.low;
 			adjustNZ(result);
 			adjustCarry(after);
 			adjustOverflow(before, data, result);
+			adjustHalfCarry(before, data, result);
 		}
 
 		void adjustAddition(uint16_t before, uint16_t data, uint32_t after) {
diff --git a/MC6809/unittest/mc6809_tests.cpp b/MC6809/unittest/mc6809_tests.cpp
index 10a23f5..6d2a16d 100644
--- a/MC6809/unittest/mc6809_tests.cpp
+++ b/MC6809/unittest/mc6809_tests.cpp
@@ -4,7 +4,7 @@
 // Using examples from 6809 Assembly Language Programming, by Lance A. Leventhal
 // Just test the basics...
 
-TEST_CASE("Add Accumulator B to Index Register X Unsigned ", "[ABX]") {
+TEST_CASE("Add Accumulator B to Index Register X Unsigned", "[ABX]") {
 
 	Board board;
 	board.initialise();
@@ -17,5 +17,29 @@ TEST_CASE("Add Accumulator B to Index Register X Unsigned ", "[ABX]") {
 		cpu.X() = 0x1097;
 		cpu.step();
 		REQUIRE(cpu.X() == 0x111b);
+		REQUIRE(cpu.cycles() == 3);
+    }
+}
+
+TEST_CASE("Add Memory Plus Carry to Accumulator A", "[ADC][ADCA]") {
+
+	Board board;
+	board.initialise();
+	auto& cpu = board.CPU();
+	cpu.step();	// Step over the reset
+
+    SECTION("Immediate (byte)") {
+		board.poke(0, 0x89);
+		board.poke(1, 0x7c);
+		EightBit::Chip::setFlag(cpu.CC(), EightBit::mc6809::CF);
+		cpu.A() = 0x3a;
+		cpu.step();
+		REQUIRE(cpu.A() == 0xb7);
+		REQUIRE((cpu.CC() & EightBit::mc6809::ZF) == 0);
+		REQUIRE((cpu.CC() & EightBit::mc6809::HF) != 0);
+		REQUIRE((cpu.CC() & EightBit::mc6809::VF) != 0);
+		REQUIRE((cpu.CC() & EightBit::mc6809::NF) != 0);
+		REQUIRE((cpu.CC() & EightBit::mc6809::CF) == 0);
+		REQUIRE(cpu.cycles() == 2);
     }
 }