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static uint8_t memory_read(struct nes_state *restrict state, uint32_t offset) {
state->cycle++;
ppu_tick(state); ppu_tick(state); ppu_tick(state);
if(offset > 0xffff) {
printf("%x\n", offset);
}
// state->ram[0x301] = 0x1;
if(offset < 0x2000) {
return state->ram[offset & 0x07ff];
} else if(offset < 0x4000) {
switch(offset & 7) {
case 2: return ppu_read_2002(state);
case 4: return ppu_read_2004(state);
case 7: return ppu_read_2007(state);
default: return 0;
}
} else if(offset < 0x4020) {
// TODO: APU and I/O reads
return 0;
} else if(offset >= 0x6000) {
return state->mapper.read(state, offset);
} else {
return 0;
}
}
static void memory_write(struct nes_state *restrict state, uint32_t offset, uint8_t value) {
state->cycle++;
ppu_tick(state); ppu_tick(state); ppu_tick(state);
if(offset > 0xffff) {
printf("%x\n", offset);
}
// if(offset == 0x0300) {
// printf("WRITE $0300 = %02x @ PC=%04x\n", value, state->cpu.pc);
// }
if(offset < 0x2000) {
state->ram[offset & 0x07ff] = value;
} else if(offset < 0x4000) {
switch(offset & 7) {
case 0: ppu_write_2000(state, value); break;
case 1: ppu_write_2001(state, value); break;
case 3: ppu_write_2003(state, value); break;
case 4: ppu_write_2004(state, value); break;
case 5: ppu_write_2005(state, value); break;
case 6: ppu_write_2006(state, value); break;
case 7: ppu_write_2007(state, value); break;
default: break;
}
} else if(offset == 0x4014) {
ppu_dma_4014(state, value);
} else if(offset < 0x4020) {
// TODO: APU and I/O writes
} else if(offset >= 0x6000) {
state->mapper.write(state, offset, value);
}
}
static uint8_t memory_read_dma(struct nes_state *restrict state, uint32_t offset) {
// Do not tick CPU/PPU/APU — caller handles timing
if(offset < 0x2000) {
return state->ram[offset & 0x07ff];
} else if(offset < 0x4000) {
// PPU register reads are ignored during DMA
return 0;
} else if(offset < 0x4020) {
// APU and I/O — usually ignored or blocked during DMA
return 0;
} else if(offset >= 0x6000) {
return state->mapper.read(state, offset);
} else {
return 0;
}
}
static uint8_t memory_read_dummy(struct nes_state *restrict state, uint32_t offset) {
state->cycle++;
ppu_tick(state); ppu_tick(state); ppu_tick(state);
if(offset < 0x2000) {
return 0;
} else if(offset < 0x4000) {
switch(offset & 7) {
case 2: return ppu_read_2002(state);
case 7: return ppu_read_2007(state);
default: return 0;
}
} else if(offset < 0x4020) {
return 0;
} else if(offset >= 0x6000) {
return state->mapper.read(state, offset);
} else {
return 0;
}
}
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