Merge pull request #83 from matheusgomes28/add-bit-tests

Fix for BIT and unit tests

README.md

@@ -384,8 +384,8 @@ total number of interrupt instructions: `2`.
 
 | **Opcode** | **Addressing Mode** | **Opcode (Hex)** | **Bytes** | **Cycles** | **Supported**      |
 |------------|---------------------|------------------|-----------|------------|--------------------|
-| BIT        | Zeropage            | 0x24             | 2         | 3          | :ok:               |
-| BIT        | Absolute            | 0x2c             | 3         | 4          | :ok:               |
+| BIT        | Zeropage            | 0x24             | 2         | 3          | :white_check_mark: |
+| BIT        | Absolute            | 0x2c             | 3         | 4          | :white_check_mark: |
 | NOP        | Implied             | 0xEA             | 1         | 2          | :white_check_mark: |
 
 total number of random instructions: `2`.

emulator/emulator.cpp

@@ -236,9 +236,9 @@ std::optional<InstructionConfig> nop(emulator::Cpu& cpu, std::span<const std::ui
 
 void bit_operation(emulator::Cpu& cpu, std::uint8_t value)
 {
-    cpu.flags.n = static_cast<bool>(value | 0b1000'0000);
-    cpu.flags.z = static_cast<bool>(value | 0b0100'0000);
-    cpu.flags.c = cpu.reg.a & value;
+    cpu.flags.n = static_cast<bool>(value & 0b1000'0000);
+    cpu.flags.v = static_cast<bool>(value & 0b0100'0000);
+    cpu.flags.z = !static_cast<bool>(cpu.reg.a & value);
 }
 
 std::optional<InstructionConfig> bit_zp(emulator::Cpu& cpu, std::span<const std::uint8_t> program)

tests/CMakeLists.txt

@@ -25,6 +25,7 @@ create_tests(and_indirect_indexed_tests)
 create_tests(and_zeropage_indexed_tests)
 create_tests(and_zeropage_tests)
 create_tests(asl_tests)
+create_tests(bit_tests)
 create_tests(branch_tests)
 create_tests(cmp_tests)
 create_tests(cpx_tests)

tests/bit_tests.cpp

@@ -0,0 +1,114 @@
+import emulator;
+
+#include "common.h"
+
+#include <gtest/gtest.h>
+
+#include <array>
+#include <cstdint>
+
+// NOLINTNEXTLINE
+TEST(BITTests, ZeropageNegativeFlag)
+{
+    constexpr std::array<std::uint8_t, 2> program{0x24, 0xff};
+
+    emulator::Cpu cpu;
+    cpu.reg.a     = 0b1111'1111;
+    cpu.mem[0xff] = 0b1000'0000;
+
+    EXPECT_EQ(emulator::execute(cpu, program), 3);
+    EXPECT_EQ(cpu.reg.a, 0b1111'1111);
+    EXPECT_EQ(cpu.reg.x, 0x00);
+    EXPECT_EQ(cpu.reg.y, 0x00);
+    EXPECT_EQ(cpu.reg.sp, 0xff);
+    EXPECT_EQ(cpu.reg.pc, 0x02);
+    EXPECT_EQ(cpu.flags, make_flags(0b1000'0000));
+}
+
+// NOLINTNEXTLINE
+TEST(BITTests, ZeropageOverflowFlag)
+{
+    constexpr std::array<std::uint8_t, 2> program{0x24, 0xff};
+
+    emulator::Cpu cpu;
+    cpu.reg.a     = 0b1111'1111;
+    cpu.mem[0xff] = 0b0100'0000;
+
+    EXPECT_EQ(emulator::execute(cpu, program), 3);
+    EXPECT_EQ(cpu.reg.a, 0b1111'1111);
+    EXPECT_EQ(cpu.reg.x, 0x00);
+    EXPECT_EQ(cpu.reg.y, 0x00);
+    EXPECT_EQ(cpu.reg.sp, 0xff);
+    EXPECT_EQ(cpu.reg.pc, 0x02);
+    EXPECT_EQ(cpu.flags, make_flags(0b0100'0000));
+}
+
+// NOLINTNEXTLINE
+TEST(BITTests, ZeropageZeroFlag)
+{
+    constexpr std::array<std::uint8_t, 2> program{0x24, 0xff};
+
+    emulator::Cpu cpu;
+    cpu.mem[0xff] = 0b0011'1111;
+
+    EXPECT_EQ(emulator::execute(cpu, program), 3);
+    EXPECT_EQ(cpu.reg.a, 0x00);
+    EXPECT_EQ(cpu.reg.x, 0x00);
+    EXPECT_EQ(cpu.reg.y, 0x00);
+    EXPECT_EQ(cpu.reg.sp, 0xff);
+    EXPECT_EQ(cpu.reg.pc, 0x02);
+    EXPECT_EQ(cpu.flags, make_flags(0b0000'0010));
+}
+
+// NOLINTNEXTLINE
+TEST(BITTests, AbsoluteNegativeFlag)
+{
+    constexpr std::array<std::uint8_t, 3> program{0x2c, 0xfe, 0xff};
+
+    emulator::Cpu cpu;
+    cpu.reg.a       = 0b1111'1111;
+    cpu.mem[0xfffe] = 0b1000'0000;
+
+    EXPECT_EQ(emulator::execute(cpu, program), 4);
+    EXPECT_EQ(cpu.reg.a, 0b1111'1111);
+    EXPECT_EQ(cpu.reg.x, 0x00);
+    EXPECT_EQ(cpu.reg.y, 0x00);
+    EXPECT_EQ(cpu.reg.sp, 0xff);
+    EXPECT_EQ(cpu.reg.pc, 0x03);
+    EXPECT_EQ(cpu.flags, make_flags(0b1000'0000));
+}
+
+// NOLINTNEXTLINE
+TEST(BITTests, AbsoluteOverflowFlag)
+{
+    constexpr std::array<std::uint8_t, 3> program{0x2c, 0xfe, 0xff};
+
+    emulator::Cpu cpu;
+    cpu.reg.a       = 0b1111'1111;
+    cpu.mem[0xfffe] = 0b0100'0000;
+
+    EXPECT_EQ(emulator::execute(cpu, program), 4);
+    EXPECT_EQ(cpu.reg.a, 0b1111'1111);
+    EXPECT_EQ(cpu.reg.x, 0x00);
+    EXPECT_EQ(cpu.reg.y, 0x00);
+    EXPECT_EQ(cpu.reg.sp, 0xff);
+    EXPECT_EQ(cpu.reg.pc, 0x03);
+    EXPECT_EQ(cpu.flags, make_flags(0b0100'0000));
+}
+
+// NOLINTNEXTLINE
+TEST(BITTests, AbsoluteZeroFlag)
+{
+    constexpr std::array<std::uint8_t, 3> program{0x2c, 0xfe, 0xff};
+
+    emulator::Cpu cpu;
+    cpu.mem[0xfffe] = 0b0011'1111;
+
+    EXPECT_EQ(emulator::execute(cpu, program), 4);
+    EXPECT_EQ(cpu.reg.a, 0x00);
+    EXPECT_EQ(cpu.reg.x, 0x00);
+    EXPECT_EQ(cpu.reg.y, 0x00);
+    EXPECT_EQ(cpu.reg.sp, 0xff);
+    EXPECT_EQ(cpu.reg.pc, 0x03);
+    EXPECT_EQ(cpu.flags, make_flags(0b0000'0010));
+}