IncBC IncB DecB instructions

juiceboy/include/juiceboy/instructions.hpp

@@ -25,6 +25,9 @@ std::uint8_t NotImplemented(Processor &processor);
 std::uint8_t Nop(Processor &processor);
 std::uint8_t LdBcD16(Processor &processor);
 std::uint8_t LdBcA(Processor &processor);
+std::uint8_t IncBc(Processor &processor);
+std::uint8_t IncB(Processor &processor);
+std::uint8_t DecB(Processor &processor);
 } // namespace instructions
 
 } // namespace juiceboy

juiceboy/include/juiceboy/registers.hpp

@@ -6,7 +6,12 @@ namespace juiceboy {
 class Registers {
 public:
   /// @brief Flags in the flags (af) register.
-  enum class Flags { Zero, Subtract, HalfCarry, Carry };
+  enum class Flags : std::uint8_t {
+    Zero = 0x80,
+    Subtract = 0x40,
+    HalfCarry = 0x20,
+    Carry = 0x10
+  };
 
   /// @brief Get the current program counter.
   /// @return The current value of the program counter.
@@ -25,16 +30,22 @@ public:
   [[nodiscard]] std::uint16_t GetStackPointer() const;
 
   [[nodiscard]] std::uint8_t GetA() const;
+  [[nodiscard]] std::uint8_t GetF() const;
+  [[nodiscard]] std::uint8_t GetB() const;
 
   [[nodiscard]] std::uint16_t GetBC() const;
 
   void SetA(std::uint8_t value);
+  void SetF(std::uint8_t value);
+  void SetB(std::uint8_t value);
 
   void SetBC(std::uint16_t value);
 
   /// @brief Get the current value of the given flag.
   /// @return True if the given flag bit is set, false otherwise.
-  // [[nodiscard]] bool GetFlag(Flags flag) const;
+  [[nodiscard]] bool GetFlag(Flags flag) const;
+
+  void SetFlag(Flags flag, bool value);
 
 private:
   std::uint8_t m_regA{};

juiceboy/src/instructions.cpp

@@ -11,9 +11,12 @@ Instructions::Instructions() {
   // For now, all not implemented instructions should throw.
   m_instructions.fill(&instructions::NotImplemented);
 
-  std::get<0>(m_instructions) = &instructions::Nop;
+  std::get<0x0>(m_instructions) = &instructions::Nop;
-  std::get<1>(m_instructions) = &instructions::LdBcD16;
+  std::get<0x1>(m_instructions) = &instructions::LdBcD16;
-  std::get<2>(m_instructions) = &instructions::LdBcA;
+  std::get<0x2>(m_instructions) = &instructions::LdBcA;
+  std::get<0x3>(m_instructions) = &instructions::IncBc;
+  std::get<0x4>(m_instructions) = &instructions::IncB;
+  std::get<0x5>(m_instructions) = &instructions::DecB;
 }
 
 std::uint8_t Instructions::ExecuteInstruction(const std::uint8_t opcode,
@@ -41,6 +44,39 @@ std::uint8_t LdBcA(Processor &processor) {
   return 8;
 }
 
+std::uint8_t IncBc(Processor &processor) {
+  processor.GetRegisters().SetBC(processor.GetRegisters().GetBC() + 1);
+  return 8;
+}
+
+std::uint8_t IncB(Processor &processor) {
+  const auto value = processor.GetRegisters().GetB();
+  const std::uint8_t result = value + 1;
+
+  processor.GetRegisters().SetB(result);
+
+  processor.GetRegisters().SetFlag(Registers::Flags::Zero, result == 0);
+  processor.GetRegisters().SetFlag(Registers::Flags::Subtract, false);
+  processor.GetRegisters().SetFlag(Registers::Flags::HalfCarry,
+                                   (value & 0x0F) == 0x0F);
+
+  return 4;
+}
+
+std::uint8_t DecB(Processor &processor) {
+  const auto value = processor.GetRegisters().GetB();
+  const std::uint8_t result = value - 1;
+
+  processor.GetRegisters().SetB(result);
+
+  processor.GetRegisters().SetFlag(Registers::Flags::Zero, result == 0);
+  processor.GetRegisters().SetFlag(Registers::Flags::Subtract, true);
+  processor.GetRegisters().SetFlag(Registers::Flags::HalfCarry,
+                                   (value & 0x0F) == 0x0);
+
+  return 4;
+}
+
 } // namespace instructions
 
 } // namespace juiceboy

juiceboy/src/processor.cpp

@@ -28,6 +28,6 @@ std::uint8_t Processor::FetchByte() {
 std::uint16_t Processor::FetchWord() {
   const auto low = static_cast<std::uint16_t>(FetchByte());
   const auto high = static_cast<std::uint16_t>(FetchByte()) << 8;
-  return low | high;
+  return static_cast<std::uint16_t>(low | high);
 }
 } // namespace juiceboy

juiceboy/src/registers.cpp

@@ -7,8 +7,8 @@ namespace juiceboy {
 
 namespace {
 std::uint16_t BytesToWord(const std::uint8_t low, const std::uint8_t high) {
-  return static_cast<std::uint16_t>(low) | static_cast<std::uint16_t>(high)
+  return static_cast<std::uint16_t>(low) |
-                                               << 8;
+         static_cast<std::uint16_t>(high << 8);
 }
 
 std::pair<std::uint8_t, std::uint8_t> WordToBytes(const std::uint16_t word) {
@@ -28,12 +28,30 @@ void Registers::IncrementProgramCounter(const std::uint16_t value) {
 std::uint16_t Registers::GetStackPointer() const { return m_sp; }
 
 std::uint8_t Registers::GetA() const { return m_regA; }
+std::uint8_t Registers::GetF() const { return m_regF; }
+std::uint8_t Registers::GetB() const { return m_regB; }
 
 std::uint16_t Registers::GetBC() const { return BytesToWord(m_regB, m_regC); }
 
 void Registers::SetA(const std::uint8_t value) { m_regA = value; }
+void Registers::SetF(const std::uint8_t value) { m_regF = value; }
+void Registers::SetB(const std::uint8_t value) { m_regB = value; }
 
 void Registers::SetBC(const std::uint16_t value) {
   std::tie(m_regB, m_regC) = WordToBytes(value);
 }
+
+bool Registers::GetFlag(Flags flag) const {
+  return (m_regF & static_cast<std::uint8_t>(flag)) != 0;
+}
+
+void Registers::SetFlag(Flags flag, bool value) {
+  const auto mask = static_cast<std::uint8_t>(flag);
+
+  if (value) {
+    m_regF |= mask;
+  } else {
+    m_regF &= static_cast<std::uint8_t>(~mask);
+  }
+}
 } // namespace juiceboy

juiceboy/test/instructions_test.cpp

@@ -1,7 +1,9 @@
 #include "juiceboy/instructions.hpp"
 
 #include "juiceboy/cartridge.hpp"
+#include "juiceboy/memory.hpp"
 #include "juiceboy/processor.hpp"
+#include "juiceboy/registers.hpp"
 
 #include <gtest/gtest.h>
 #include <memory>
@@ -16,42 +18,132 @@ public:
 };
 
 class InstructionsTest : public testing::Test {
-public:
+protected:
   Processor &GetProcessor() { return processor; }
+  Memory &GetMemory() { return processor.GetMemory(); }
+  Registers &GetRegisters() { return processor.GetRegisters(); }
 
 private:
   Processor processor{Memory{std::make_shared<TestCartridge>()}};
 };
 } // namespace
 
-TEST_F(InstructionsTest, Noop) {
+TEST_F(InstructionsTest, Nop) {
   const auto cycles = instructions::Nop(GetProcessor());
 
   EXPECT_EQ(cycles, 4);
-  EXPECT_EQ(GetProcessor().GetRegisters().GetProgramCounter(), 0);
+  EXPECT_EQ(GetRegisters().GetProgramCounter(), 0);
 }
 
 TEST_F(InstructionsTest, LdBcD16) {
-  GetProcessor().GetMemory().WriteByte(0x8000, 0x34);
+  GetMemory().WriteByte(0x8000, 0x34);
-  GetProcessor().GetMemory().WriteByte(0x8001, 0x12);
+  GetMemory().WriteByte(0x8001, 0x12);
-  GetProcessor().GetRegisters().SetProgramCounter(0x8000);
+  GetRegisters().SetProgramCounter(0x8000);
 
   const auto cycles = instructions::LdBcD16(GetProcessor());
 
   EXPECT_EQ(cycles, 12);
-  EXPECT_EQ(GetProcessor().GetRegisters().GetBC(), 0x1234);
+  EXPECT_EQ(GetRegisters().GetBC(), 0x1234);
-  EXPECT_EQ(GetProcessor().GetRegisters().GetProgramCounter(), 0x8002);
+  EXPECT_EQ(GetRegisters().GetProgramCounter(), 0x8002);
 }
 
 TEST_F(InstructionsTest, LdBcA) {
-  GetProcessor().GetRegisters().SetBC(0x8000);
+  GetRegisters().SetBC(0x8000);
-  GetProcessor().GetRegisters().SetA(0x12);
+  GetRegisters().SetA(0x12);
 
   const auto cycles = instructions::LdBcA(GetProcessor());
 
   EXPECT_EQ(cycles, 8);
-  EXPECT_EQ(GetProcessor().GetMemory().ReadByte(0x8000), 0x12);
+  EXPECT_EQ(GetMemory().ReadByte(0x8000), 0x12);
-  EXPECT_EQ(GetProcessor().GetRegisters().GetProgramCounter(), 0);
+  EXPECT_EQ(GetRegisters().GetProgramCounter(), 0);
+}
+
+TEST_F(InstructionsTest, IncBC) {
+  GetRegisters().SetBC(0x1);
+
+  const auto cycles = instructions::IncBc(GetProcessor());
+
+  EXPECT_EQ(cycles, 8);
+  EXPECT_EQ(GetRegisters().GetBC(), 0x2);
+  EXPECT_EQ(GetRegisters().GetProgramCounter(), 0);
+}
+
+TEST_F(InstructionsTest, IncB) {
+  GetRegisters().SetB(0x1);
+
+  const auto cycles = instructions::IncB(GetProcessor());
+
+  EXPECT_EQ(cycles, 4);
+  EXPECT_EQ(GetRegisters().GetB(), 0x2);
+  EXPECT_EQ(GetRegisters().GetProgramCounter(), 0);
+  EXPECT_FALSE(GetRegisters().GetFlag(Registers::Flags::Zero));
+  EXPECT_FALSE(GetRegisters().GetFlag(Registers::Flags::Subtract));
+  EXPECT_FALSE(GetRegisters().GetFlag(Registers::Flags::HalfCarry));
+}
+
+TEST_F(InstructionsTest, IncBSetsZeroFlag) {
+  GetRegisters().SetB(0xFF);
+
+  (void)instructions::IncB(GetProcessor());
+
+  EXPECT_EQ(GetRegisters().GetB(), 0x00);
+  EXPECT_TRUE(GetRegisters().GetFlag(Registers::Flags::Zero));
+}
+
+TEST_F(InstructionsTest, IncBSetsHalfCarryFlag) {
+  GetRegisters().SetB(0x0F);
+
+  (void)instructions::IncB(GetProcessor());
+
+  EXPECT_EQ(GetRegisters().GetB(), 0x10);
+  EXPECT_TRUE(GetRegisters().GetFlag(Registers::Flags::HalfCarry));
+}
+
+TEST_F(InstructionsTest, IncBPreservesCarry) {
+  GetRegisters().SetFlag(Registers::Flags::Carry, true);
+
+  (void)instructions::IncB(GetProcessor());
+
+  EXPECT_TRUE(GetRegisters().GetFlag(Registers::Flags::Carry));
+}
+
+TEST_F(InstructionsTest, DecB) {
+  GetRegisters().SetB(0x2);
+
+  const auto cycles = instructions::DecB(GetProcessor());
+
+  EXPECT_EQ(cycles, 4);
+  EXPECT_EQ(GetRegisters().GetB(), 0x1);
+  EXPECT_EQ(GetRegisters().GetProgramCounter(), 0);
+  EXPECT_FALSE(GetRegisters().GetFlag(Registers::Flags::Zero));
+  EXPECT_TRUE(GetRegisters().GetFlag(Registers::Flags::Subtract));
+  EXPECT_FALSE(GetRegisters().GetFlag(Registers::Flags::HalfCarry));
+}
+
+TEST_F(InstructionsTest, DecBSetsZeroFlag) {
+  GetRegisters().SetB(0x1);
+
+  (void)instructions::DecB(GetProcessor());
+
+  EXPECT_EQ(GetRegisters().GetB(), 0x00);
+  EXPECT_TRUE(GetRegisters().GetFlag(Registers::Flags::Zero));
+}
+
+TEST_F(InstructionsTest, DecBSetsHalfCarryFlag) {
+  GetRegisters().SetB(0x10);
+
+  (void)instructions::DecB(GetProcessor());
+
+  EXPECT_EQ(GetRegisters().GetB(), 0x0F);
+  EXPECT_TRUE(GetRegisters().GetFlag(Registers::Flags::HalfCarry));
+}
+
+TEST_F(InstructionsTest, DecBPreservesCarry) {
+  GetRegisters().SetFlag(Registers::Flags::Carry, true);
+
+  (void)instructions::IncB(GetProcessor());
+
+  EXPECT_TRUE(GetRegisters().GetFlag(Registers::Flags::Carry));
 }
 
 } // namespace juiceboy::test