__attribute__((hot)) static inline uint8_t memory_read(struct nes_state *state, uint32_t offset) { state->cpu.cycles++; ppu_tick(state); apu_tick(state); if(offset <= 0x1fff) { return state->ram[offset & 0x07ff]; } if(offset >= 0x8000) { return state->mapper_function.prg_rom_read(state, offset); } if(offset >= 0x2000 && offset <= 0x3fff) { return ppu_read(state, offset); } if(offset == 0x4015) { return apu_read4015(state); } if(offset == 0x4016 || offset == 0x4017) { uint32_t index = offset & 1; uint8_t value = (state->ppu.input_latch[index] >> state->ppu.input_bit[index]) & 1; state->ppu.input_bit[index]++; return value | 0x40; // Bit 6 open bus high, bit 7 low } if(offset >= 0x6000 && offset <= 0x7fff) { return state->mapper_function.prg_ram_read(state, offset); } return 0; } __attribute__((hot)) static inline uint8_t memory_read_dummy(struct nes_state *state, uint32_t offset) { state->cpu.cycles++; ppu_tick(state); apu_tick(state); if(offset >= 0x2000 && offset < 0x4000) { return ppu_read(state, offset); } return 0; } __attribute__((hot, optimize("no-jump-tables"))) static inline void memory_write(struct nes_state *state, uint32_t offset, uint8_t value) { state->cpu.cycles++; ppu_tick(state); apu_tick(state); if(offset <= 0x1fff) { state->ram[offset & 0x07ff] = value; } if(offset >= 0x2000 && offset <= 0x3fff) { ppu_write(state, offset, value); } if(offset >= 0x4000 && offset <= 0x4017) { if(offset == 0x4014) { ppu_dma_4014(state, value); } if(offset == 0x4016) { uint8_t s = value & 1; uint8_t prev = state->ppu.input_strobe; state->ppu.input_strobe = s; if(prev == 1 && s == 0) { state->ppu.input_latch[0] = state->ppu.input[0]; state->ppu.input_latch[1] = state->ppu.input[1]; state->ppu.input_bit[0] = 0; state->ppu.input_bit[1] = 0; } } if(offset != 0x4014 && offset != 0x4016) { apu_write(state, offset, value); } } if(offset >= 0x6000 && offset <= 0x7fff) { state->mapper_function.prg_ram_write(state, offset, value); } if(offset >= 0x8000) { state->mapper_function.prg_rom_write(state, offset, value); } } __attribute__((hot, flatten)) static inline uint8_t memory_read_dma(struct nes_state *state, uint32_t offset) { // NOTE(peter): DO NOT tick CPU/PPU/APU — caller handles timing return state->ram[offset & 0x07ff]; }