Return bit map result code when executing a clock (#20)

kremi151 · Aug 12, 2020 · d8731eb · d8731eb
1 parent 02f35ae
commit d8731eb
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Showing 9 changed files with 58 additions and 23 deletions.
diff --git a/core/CMakeLists.txt b/core/CMakeLists.txt
@@ -82,6 +82,7 @@ set(HEADERS
         source/util/registers.h
         source/util/flags.h
         source/util/gpumode.h
+        source/util/return_codes.h
         )
 
 set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -DFB_DEBUG")

diff --git a/core/source/emulator/cpu.cpp b/core/source/emulator/cpu.cpp
@@ -19,6 +19,7 @@
 #include <utility>
 #include <util/typedefs.h>
 #include <util/registers.h>
+#include <util/return_codes.h>
 #include <emulator/io_registers.h>
 
 using namespace FunkyBoy;
@@ -144,9 +145,9 @@ void CPU::powerUpInit() {
     ioRegisters.updateJoypad();
 }
 
-bool CPU::doMachineCycle() {
+ret_code CPU::doMachineCycle() {
     doJoypad();
-    bool result = doCycle();
+    auto result = doCycle();
 
     // TODO: Handle timer here or earlier?
     doTimers(4);
@@ -167,9 +168,9 @@ bool CPU::doMachineCycle() {
     return result;
 }
 
-bool CPU::doCycle() {
+ret_code CPU::doCycle() {
     if (instrContext.cpuState == CPUState::STOPPED) {
-        return true;
+        return FB_RET_SUCCESS | FB_RET_SKIPPED;
     }
 
     bool shouldDoInterrupts = instrContext.cpuState == CPUState::HALTED;
@@ -207,17 +208,17 @@ bool CPU::doCycle() {
 
     if (isDMA) {
         memory->doDMA();
-        return true;
+        return FB_RET_SUCCESS;
     } else if (!shouldFetch) {
-        return true;
+        return FB_RET_SUCCESS;
     }
 
-    bool result = doFetchAndDecode();
+    auto result = doFetchAndDecode();
     operandIndex = 0;
     return result;
 }
 
-bool CPU::doFetchAndDecode() {
+ret_code CPU::doFetchAndDecode() {
     if (!instrContext.haltBugRequested) {
         instrContext.instr = memory->read8BitsAt(instrContext.progCounter++);
     } else {
@@ -232,9 +233,9 @@ bool CPU::doFetchAndDecode() {
 
     if (!Operands::decodeOpcode(instrContext.instr, operands)) {
         fprintf(stderr, "Illegal instruction 0x%02X at 0x%04X\n", instrContext.instr, instrContext.progCounter - 1);
-        return false;
+        return 0;
     }
-    return true;
+    return FB_RET_SUCCESS;
 }
 
 inline memory_address getInterruptStartAddress(InterruptType type) {

diff --git a/core/source/emulator/cpu.h b/core/source/emulator/cpu.h
@@ -65,8 +65,8 @@ namespace FunkyBoy {
 
         void powerUpInit();
 
-        bool doCycle();
-        bool doFetchAndDecode();
+        ret_code doCycle();
+        ret_code doFetchAndDecode();
 
         void doJoypad();
         bool doInterrupts();
@@ -100,7 +100,7 @@ namespace FunkyBoy {
         void setProgramCounter(u16 offset);
         void requestInterrupt(InterruptType type);
 
-        bool doMachineCycle();
+        ret_code doMachineCycle();
     };
 
     typedef std::shared_ptr<CPU> CPUPtr;

diff --git a/core/source/emulator/emulator.cpp b/core/source/emulator/emulator.cpp
@@ -71,12 +71,13 @@ CartridgeStatus Emulator::loadGame(const fs::path &romPath) {
     return cartridge->getStatus();
 }
 
-bool Emulator::doTick() {
-    if (!cpu->doMachineCycle()) {
-        return false;
+ret_code Emulator::doTick() {
+    auto result = cpu->doMachineCycle();
+    if (!result) {
+        return 0;
     }
-    ppu.doClocks(4);
-    return true;
+    result |= ppu.doClocks(4);
+    return result;
 }
 
 Cartridge & Emulator::getCartridge() {

diff --git a/core/source/emulator/emulator.h b/core/source/emulator/emulator.h
@@ -18,6 +18,7 @@
 #define CORE_EMULATOR_H
 
 #include <util/fs.h>
+#include <util/return_codes.h>
 #include <memory>
 #include <emulator/cpu.h>
 #include <emulator/ppu.h>
@@ -47,7 +48,7 @@ namespace FunkyBoy {
         CartridgeStatus loadGame(const fs::path &romPath);
         Cartridge &getCartridge();
 
-        bool doTick();
+        ret_code doTick();
     };
 
 }

diff --git a/core/source/emulator/ppu.cpp b/core/source/emulator/ppu.cpp
@@ -16,7 +16,7 @@
 
 #include "ppu.h"
 
-#include <util/typedefs.h>
+#include <util/return_codes.h>
 #include <emulator/io_registers.h>
 
 #define FB_TILE_DATA_OBJ 0x8000
@@ -61,17 +61,18 @@ PPU::~PPU() {
 //
 // In total for 155 scanlines => 70224 clocks
 
-void PPU::doClocks(u8 clocks) {
+ret_code PPU::doClocks(u8 clocks) {
     // TODO: Finish implementation
     // See https://gbdev.gg8.se/wiki/articles/Video_Display#VRAM_Tile_Data
     // See http://marc.rawer.de/Gameboy/Docs/GBCPUman.pdf (pages 22-27)
 
     auto lcdc = memory->read8BitsAt(FB_REG_LCDC);
     if (!__fb_lcdc_isOn(lcdc)) {
         ioRegisters.updateLCD(false, gpuMode /* TODO: Correct* */, 0x00);
-        return; // TODO: Correct?
+        return FB_RET_SUCCESS; // TODO: Correct?
     }
 
+    ret_code result = FB_RET_SUCCESS;
     auto ly = memory->read8BitsAt(FB_REG_LY);
 
     modeClocks += clocks;
@@ -83,6 +84,7 @@ void PPU::doClocks(u8 clocks) {
                     gpuMode = GPUMode::GPUMode_1;
                     controllers->getDisplay()->drawScreen();
                     cpu->requestInterrupt(InterruptType::VBLANK);
+                    result |= FB_RET_NEW_FRAME;
                 } else {
                     gpuMode = GPUMode::GPUMode_2;
                 }
@@ -119,6 +121,8 @@ void PPU::doClocks(u8 clocks) {
     // TODO: Compare LY with LYC and trigger interrupt
 
     ioRegisters.updateLCD(true, gpuMode, ly);
+
+    return result;
 }
 
 void PPU::renderScanline(u8 ly) {

diff --git a/core/source/emulator/ppu.h b/core/source/emulator/ppu.h
@@ -22,6 +22,7 @@
 #include <emulator/cpu.h>
 #include <emulator/io_registers.h>
 #include <util/gpumode.h>
+#include <util/typedefs.h>
 
 namespace FunkyBoy {
 
@@ -43,7 +44,7 @@ namespace FunkyBoy {
         PPU(MemoryPtr memory, CPUPtr cpu, Controller::ControllersPtr controllers, const io_registers& ioRegisters);
         ~PPU();
 
-        void doClocks(u8 clocks);
+        ret_code doClocks(u8 clocks);
     };
 
 }

diff --git a/core/source/util/return_codes.h b/core/source/util/return_codes.h
@@ -0,0 +1,24 @@
+/**
+ * Copyright 2020 Michel Kremer (kremi151)
+ *
+ * Licensed under the Apache License, Version 2.0 (the License);
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef FB_CORE_RETURN_CODES_H
+#define FB_CORE_RETURN_CODES_H
+
+#define FB_RET_SUCCESS 1
+#define FB_RET_SKIPPED (1 << 1)
+#define FB_RET_NEW_FRAME (1 << 2)
+
+#endif //FB_CORE_RETURN_CODES_H
diff --git a/core/source/util/typedefs.h b/core/source/util/typedefs.h
@@ -47,6 +47,8 @@ namespace FunkyBoy {
     typedef int32_t i32;
     typedef int64_t i64;
 
+    typedef int ret_code;
+
 }
 
 #endif //FUNKYBOY_CORE_TYPEDEFS_H