mirror of https://github.com/bsnes-emu/bsnes.git
72 lines
1.2 KiB
C++
72 lines
1.2 KiB
C++
auto Z80::yield() -> void {
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//freeze Z80, allow external access until relinquished
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if(bus->requested()) {
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bus->grant(true);
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while(bus->requested()) step(1);
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bus->grant(false);
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}
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}
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auto Z80::wait(uint clocks) -> void {
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yield();
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step(clocks);
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}
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auto Z80::opcode() -> uint8 {
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yield();
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step(4);
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return bus->read(r.pc++);
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}
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auto Z80::operand() -> uint8 {
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yield();
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step(3);
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return bus->read(r.pc++);
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}
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auto Z80::operands() -> uint16 {
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uint16 data = operand() << 0;
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return data | operand() << 8;
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}
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auto Z80::push(uint16 x) -> void {
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write(--SP, x >> 8);
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write(--SP, x >> 0);
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}
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auto Z80::pop() -> uint16 {
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uint16 data = read(SP++) << 0;
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return data | read(SP++) << 8;
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}
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auto Z80::displace(uint16& x) -> uint16 {
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if(&x != &r.ix.word && &x != &r.iy.word) return x;
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auto d = operand();
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wait(5);
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return x + (int8)d;
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}
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auto Z80::read(uint16 addr) -> uint8 {
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yield();
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step(3);
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return bus->read(addr);
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}
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auto Z80::write(uint16 addr, uint8 data) -> void {
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yield();
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step(3);
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return bus->write(addr, data);
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}
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auto Z80::in(uint8 addr) -> uint8 {
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yield();
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step(4);
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return bus->in(addr);
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}
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auto Z80::out(uint8 addr, uint8 data) -> void {
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yield();
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step(4);
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return bus->out(addr, data);
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}
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