SpookyDervish/MyLittleCPU
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change how flags works

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SpookyDervish
2026-07-16 17:57:14 +10:00
parent bb0709f6ce
commit 82f9644e15
2 changed files with 20 additions and 7 deletions
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15
src/emu.c
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@@ -5,13 +5,14 @@ static inline Instruction fetchInst(Emulator* emu) {
} }
static inline void updateFlagsRegister(Emulator* emu, int32_t value) { static inline void updateFlagsRegister(Emulator* emu, int32_t value) {
if (value == 0) {
emu->regs[REG_F] = FLAG_ZERO; FlagsRegister flags = (FlagsRegister)emu->regs[REG_F];
} else if (value < 0) {
emu->regs[REG_F] = FLAG_NEGATIVE; flags.fields.zero = value == 0;
} else if (value > UINT16_MAX) { flags.fields.negative = value < 0;
emu->regs[REG_F] = FLAG_OVERFLOW; flags.fields.overflow = value > UINT16_MAX;
}
emu->regs[REG_F] = flags.raw;
} }
static inline void updateDevices(Emulator* emu) { static inline void updateDevices(Emulator* emu) {

12
src/emu.h
View File

@@ -24,9 +24,21 @@ typedef struct {
uint32_t ihp; uint32_t ihp;
uint32_t sp; uint32_t sp;
bool irq;
bool halted; bool halted;
} Emulator; } Emulator;
typedef union {
struct {
uint16_t zero : 1;
uint16_t overflow : 1;
uint16_t negative : 1;
uint16_t interrupts : 1;
} fields;
uint16_t raw;
} FlagsRegister;
// -- FUNCTIONS -- // // -- FUNCTIONS -- //
Emulator* initEmulator(uint32_t memorySize); Emulator* initEmulator(uint32_t memorySize);
void freeEmulator(Emulator* emu); void freeEmulator(Emulator* emu);