mirror of https://github.com/bsnes-emu/bsnes.git
51 lines
1.6 KiB
C++
51 lines
1.6 KiB
C++
//PPUcounter emulates the H/V latch counters of the S-PPU2.
|
|
//
|
|
//real hardware has the S-CPU maintain its own copy of these counters that are
|
|
//updated based on the state of the S-PPU Vblank and Hblank pins. emulating this
|
|
//would require full lock-step synchronization for every clock tick.
|
|
//to bypass this and allow the two to run out-of-order, both the CPU and PPU
|
|
//classes inherit PPUcounter and keep their own counters.
|
|
//the timers are kept in sync, as the only differences occur on V=240 and V=261,
|
|
//based on interlace. thus, we need only synchronize and fetch interlace at any
|
|
//point before this in the frame, which is handled internally by this class at
|
|
//V=128.
|
|
|
|
struct PPUcounter {
|
|
alwaysinline auto tick() -> void;
|
|
alwaysinline auto tick(uint clocks) -> void;
|
|
|
|
alwaysinline auto interlace() const -> bool;
|
|
alwaysinline auto field() const -> bool;
|
|
alwaysinline auto vcounter() const -> uint;
|
|
alwaysinline auto hcounter() const -> uint;
|
|
alwaysinline auto hdot() const -> uint;
|
|
alwaysinline auto lineclocks() const -> uint;
|
|
|
|
alwaysinline auto field(uint offset) const -> bool;
|
|
alwaysinline auto vcounter(uint offset) const -> uint;
|
|
alwaysinline auto hcounter(uint offset) const -> uint;
|
|
|
|
inline auto reset() -> void;
|
|
auto serialize(serializer&) -> void;
|
|
|
|
function<void ()> scanline;
|
|
|
|
private:
|
|
alwaysinline auto vcounterTick() -> void;
|
|
|
|
struct {
|
|
bool interlace = 0;
|
|
bool field = 0;
|
|
uint vcounter = 0;
|
|
uint hcounter = 0;
|
|
uint lineclocks = 1364;
|
|
} status;
|
|
|
|
struct {
|
|
uint index = 0;
|
|
bool field[2048] = {};
|
|
uint vcounter[2048] = {};
|
|
uint hcounter[2048] = {};
|
|
} history;
|
|
};
|