Atomic instructions

core/CMakeLists.txt

@@ -26,18 +26,16 @@ set(SOURCES
         source/cartridge/mbc2.cpp
         source/cartridge/mbc_none.cpp
         source/memory/ppu_memory.cpp
-        source/operands/instruction_context.cpp
-        source/operands/alu.cpp
-        source/operands/loads.cpp
-        source/operands/misc.cpp
-        source/operands/prefix.cpp
-        source/operands/reads.cpp
-        source/operands/writes.cpp
-        source/operands/jumps.cpp
-        source/operands/rot_shifts.cpp
-        source/operands/conditions.cpp
-        source/operands/debug.cpp
-        source/operands/decoder.cpp
+        source/instructions/debug.cpp
+        source/instructions/instructions.cpp
+        source/instructions/context.cpp
+        source/instructions/loads.cpp
+        source/instructions/alu.cpp
+        source/instructions/jumps.cpp
+        source/instructions/rot_shifts.cpp
+        source/instructions/stack.cpp
+        source/instructions/misc.cpp
+        source/instructions/prefix.cpp
         source/util/registers.cpp
         source/util/flags.cpp
         source/exception/state_exception.cpp
@@ -49,6 +47,7 @@ set(HEADERS
         source/emulator/io_registers.h
         source/emulator/cpu.h
         source/emulator/ppu.h
+        source/emulator/state_types.h
         source/controllers/controllers.h
         source/controllers/serial.h
         source/controllers/serial_null.h
@@ -70,19 +69,16 @@ set(HEADERS
         source/cartridge/mbc2.h
         source/cartridge/mbc_none.h
         source/memory/ppu_memory.h
-        source/operands/instruction_context.h
-        source/operands/alu.h
-        source/operands/loads.h
-        source/operands/instructions.h
-        source/operands/misc.h
-        source/operands/prefix.h
-        source/operands/reads.h
-        source/operands/writes.h
-        source/operands/jumps.h
-        source/operands/rot_shifts.h
-        source/operands/conditions.h
-        source/operands/debug.h
-        source/operands/decoder.h
+        source/instructions/debug.h
+        source/instructions/instructions.h
+        source/instructions/context.h
+        source/instructions/loads.h
+        source/instructions/alu.h
+        source/instructions/jumps.h
+        source/instructions/rot_shifts.h
+        source/instructions/stack.h
+        source/instructions/misc.h
+        source/instructions/prefix.h
         source/util/endianness.h
         source/util/registers.h
         source/util/flags.h

core/source/emulator/cpu.cpp

@@ -21,6 +21,7 @@
 #include <util/registers.h>
 #include <util/return_codes.h>
 #include <emulator/io_registers.h>
+#include <instructions/instructions.h>
 
 using namespace FunkyBoy;
 
@@ -31,7 +32,7 @@ CPU::CPU(GameBoyType gbType, MemoryPtr memory, const io_registers& ioRegisters)
     , instrContext(gbType)
     , timerOverflowingCycles(-1)
     , delayedTIMAIncrease(false)
-    , operandIndex(0)
+    , currentOpcode(0)
     , joypadWasNotPressed(true)
 #ifdef FB_DEBUG_WRITE_EXECUTION_LOG
     , file("exec_opcodes_fb_v2.txt")
@@ -61,7 +62,6 @@ CPU::CPU(GameBoyType gbType, MemoryPtr memory, const io_registers& ioRegisters)
     instrContext.regA = regA;
     instrContext.progCounter = 0;
     instrContext.stackPointer = 0xFFFE;
-    instrContext.operands = operands;
     instrContext.interruptMasterEnable = IMEState::DISABLED;
     instrContext.haltBugRequested = false;
     instrContext.cpuState = CPUState::RUNNING;
@@ -70,11 +70,6 @@ CPU::CPU(GameBoyType gbType, MemoryPtr memory, const io_registers& ioRegisters)
     instrContext.executionLog = &file;
 #endif
 
-    // Fetch/Execute overlapping -> initial fetch is performed without executing any other instruction
-    // To simulate this, we set a NOP as the first instruction, which does nothing
-    operands[0] = Operands::nop;
-    operands[1] = nullptr;
-
     // Initialize registers
     powerUpInit();
 }
@@ -182,16 +177,15 @@ ret_code CPU::doCycle() {
     if (instrContext.cpuState == CPUState::RUNNING) {
         memory->doDMA(); // TODO: Implement delay of 2 clocks
 
-        auto op = operands[operandIndex++];
-
-        if (operands[operandIndex] == nullptr) {
-            shouldFetch = true;
-            result |= FB_RET_INSTRUCTION_DONE;
+        int clocks = Instructions::execute(currentOpcode, instrContext, *memory);
+        if (clocks <= 0) {
+            fprintf(stderr, "Illegal instruction 0x%02X at 0x%04X\n", currentOpcode, instrContext.progCounter - 1);
+            return 0;
         }
 
-        if (!op(instrContext, *memory)) {
-            shouldFetch = true;
-        }
+        shouldFetch = true;
+        result |= FB_RET_INSTRUCTION_DONE;
+
         shouldDoInterrupts = shouldFetch;
     }
 
@@ -208,32 +202,21 @@ ret_code CPU::doCycle() {
     }
 
     if (interruptServiced || (shouldFetch && instrContext.cpuState == CPUState::RUNNING)) { // TODO: Can this be simplified to just instrContext.cpuState == CPUState::RUNNING ?
-        result |= doFetchAndDecode();
-        operandIndex = 0;
-        return result;
-    }
-
-    return result;
-}
-
-ret_code CPU::doFetchAndDecode() {
-    if (!instrContext.haltBugRequested) {
-        instrContext.instr = memory->read8BitsAt(instrContext.progCounter++);
-    } else {
-        instrContext.instr = memory->read8BitsAt(instrContext.progCounter);
-        instrContext.haltBugRequested = false;
-    }
-
+        // Fetch next opcode
+        if (!instrContext.haltBugRequested) {
+            currentOpcode = memory->read8BitsAt(instrContext.progCounter++);
+        } else {
+            currentOpcode = memory->read8BitsAt(instrContext.progCounter);
+            instrContext.haltBugRequested = false;
+        }
 #ifdef FB_DEBUG_WRITE_EXECUTION_LOG
-    FunkyBoy::Debug::writeExecutionToLog('I', file, instrContext);
-    instr++;
+        FunkyBoy::Debug::writeExecutionToLog('I', file, instrContext);
+        instr++;
 #endif
-
-    if (!Operands::decodeOpcode(instrContext.instr, operands)) {
-        fprintf(stderr, "Illegal instruction 0x%02X at 0x%04X\n", instrContext.instr, instrContext.progCounter - 1);
-        return 0;
+        return result | FB_RET_SUCCESS;
     }
-    return FB_RET_SUCCESS;
+
+    return result;
 }
 
 inline memory_address getInterruptStartAddress(InterruptType type) {

core/source/emulator/cpu.h

@@ -23,8 +23,8 @@
 #include <memory>
 #include <util/testing.h>
 #include <util/debug.h>
-#include <operands/decoder.h>
-#include <operands/debug.h>
+#include <instructions/instructions.h>
+#include <instructions/debug.h>
 #include <emulator/gb_type.h>
 #include <emulator/io_registers.h>
 
@@ -53,10 +53,7 @@ namespace FunkyBoy {
         std::ofstream file;
 #endif
 
-        u8 registers[8]{};
-
-        u8 operandIndex;
-        Operand operands[25]{};
+        register_t registers[8]{};
 
         i8 timerOverflowingCycles;
         bool delayedTIMAIncrease;
@@ -66,15 +63,15 @@ namespace FunkyBoy {
         void powerUpInit();
 
         ret_code doCycle();
-        ret_code doFetchAndDecode();
 
         void doJoypad();
         bool doInterrupts();
         void doTimers(u8 clocks);
 
     test_public:
 
-        InstrContext instrContext;
+        Instructions::context instrContext;
+        opcode_t currentOpcode;
 
         u16 readAF();
         void writeAF(u16 val);
@@ -85,14 +82,14 @@ namespace FunkyBoy {
 
         // Do not free these pointers, they are proxies to specific locations in the registers array
 
-        u8 *regB;
-        u8 *regC;
-        u8 *regD;
-        u8 *regE;
-        u8 *regH;
-        u8 *regL;
-        u8 *regF_do_not_use_directly;
-        u8 *regA;
+        register_t *regB;
+        register_t *regC;
+        register_t *regD;
+        register_t *regE;
+        register_t *regH;
+        register_t *regL;
+        register_t *regF_do_not_use_directly;
+        register_t *regA;
 
     public:
         CPU(GameBoyType gbType, MemoryPtr memory, const io_registers& ioRegisters);

core/source/operands/instructions.h → core/source/emulator/state_types.h

@@ -14,18 +14,24 @@
  * limitations under the License.
  */
 
-#ifndef FB_CORE_OPERANDS_H
-#define FB_CORE_OPERANDS_H
+#ifndef FB_CORE_EMULATOR_STATE_TYPES_H
+#define FB_CORE_EMULATOR_STATE_TYPES_H
 
-#include <operands/instruction_context.h>
-#include <operands/misc.h>
-#include <operands/prefix.h>
-#include <operands/alu.h>
-#include <operands/loads.h>
-#include <operands/reads.h>
-#include <operands/writes.h>
-#include <operands/jumps.h>
-#include <operands/rot_shifts.h>
-#include <operands/conditions.h>
+namespace FunkyBoy {
 
-#endif //FB_CORE_OPERANDS_H
+    enum IMEState {
+        DISABLED = 0,
+        REQUEST_ENABLE = 1,
+        ENABLING = 2,
+        ENABLED = 3
+    };
+
+    enum CPUState {
+        RUNNING = 0,
+        HALTED = 1,
+        STOPPED = 2
+    };
+
+}
+
+#endif //FB_CORE_EMULATOR_STATE_TYPES_H