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uint8 CPU::op_read(uint16 addr) {
if(status.oam_dma_pending) {
status.oam_dma_pending = false;
op_read(addr);
oam_dma();
}
while(status.rdy_line == 0) {
regs.mdr = bus.read(status.rdy_addr_valid ? status.rdy_addr_value : addr);
add_clocks(12);
}
regs.mdr = bus.read(addr);
add_clocks(12);
return regs.mdr;
}
void CPU::op_write(uint16 addr, uint8 data) {
bus.write(addr, regs.mdr = data);
add_clocks(12);
}
void CPU::last_cycle() {
status.interrupt_pending = ((status.irq_line | status.irq_apu_line) & ~regs.p.i) | status.nmi_pending;
}
void CPU::nmi(uint16 &vector) {
if(status.nmi_pending) {
status.nmi_pending = false;
vector = 0xfffa;
}
}
void CPU::oam_dma() {
for(unsigned n = 0; n < 256; n++) {
uint8 data = op_read((status.oam_dma_page << 8) + n);
op_write(0x2004, data);
}
}
void CPU::set_nmi_line(bool line) {
//edge-sensitive (0->1)
if(!status.nmi_line && line) status.nmi_pending = true;
status.nmi_line = line;
}
void CPU::set_irq_line(bool line) {
//level-sensitive
status.irq_line = line;
}
void CPU::set_irq_apu_line(bool line) {
//level-sensitive
status.irq_apu_line = line;
}
void CPU::set_rdy_line(bool line) {
status.rdy_line = line;
}
void CPU::set_rdy_addr(bool valid, uint16 value) {
status.rdy_addr_valid = valid;
status.rdy_addr_value = value;
}
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