diff options
Diffstat (limited to 'lib/nes/util/cycle-count.hh')
| -rw-r--r-- | lib/nes/util/cycle-count.hh | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/lib/nes/util/cycle-count.hh b/lib/nes/util/cycle-count.hh new file mode 100644 index 0000000..f1a4a7e --- /dev/null +++ b/lib/nes/util/cycle-count.hh @@ -0,0 +1,87 @@ +#pragma once + +#include <chrono> + +namespace nes +{ + /// A cycle count that can be used for multiple components. + /// + /// Each component can have a different clock frequency and this structure offers conversions between different + /// cycle counts. + class cycle_count + { + friend constexpr auto operator+(cycle_count, cycle_count) -> cycle_count; + friend constexpr auto operator-(cycle_count, cycle_count) -> cycle_count; + friend constexpr auto operator*(std::uint64_t, cycle_count) -> cycle_count; + friend constexpr auto operator*(cycle_count, std::uint64_t) -> cycle_count; + friend constexpr auto operator/(cycle_count, cycle_count) -> std::uint64_t; + + std::uint64_t units_{ 0 }; // The most fine-granular cycle count (here: PPU cycles). + + static constexpr auto ppu_cycle() -> cycle_count { return cycle_count{ 1 }; } + static constexpr auto cpu_cycle() -> cycle_count { return cycle_count{ 3 }; } + static constexpr auto second() -> cycle_count { return 1789773 * cpu_cycle(); } + + public: + constexpr explicit cycle_count() = default; + + constexpr auto operator+=(cycle_count const other) -> cycle_count& { return *this = *this + other; } + constexpr auto operator*=(std::uint64_t const other) -> cycle_count& { return *this = *this * other; } + + static constexpr auto from_units(std::uint64_t const units) -> cycle_count + { + return cycle_count{ units }; + } + + static constexpr auto from_duration(std::chrono::microseconds const duration) -> cycle_count + { + return from_units(static_cast<std::uint64_t>(duration.count()) * second().get_units() / (1000 * 1000)); + } + + static constexpr auto from_cpu(std::uint64_t const cpu_cycles) -> cycle_count + { + return cpu_cycles * cpu_cycle(); + } + + static constexpr auto from_ppu(std::uint64_t const ppu_cycles) -> cycle_count + { + return ppu_cycles * ppu_cycle(); + } + + /// Value in implementation-defined units. + constexpr auto get_units() const -> std::uint64_t { return units_; } + + constexpr auto to_duration() const -> std::chrono::microseconds + { + return std::chrono::microseconds{ get_units() * 1000 * 1000 / second().get_units() }; + } + + constexpr auto to_cpu() const -> std::uint64_t + { + return *this / cpu_cycle(); + } + + constexpr auto to_ppu() const -> std::uint64_t + { + return *this / ppu_cycle(); + } + + private: + constexpr explicit cycle_count(std::uint64_t const units) + : units_{ units } + { + } + }; + + constexpr auto operator==(cycle_count const a, cycle_count const b) -> bool { return a.get_units() == b.get_units(); } + constexpr auto operator!=(cycle_count const a, cycle_count const b) -> bool { return a.get_units() != b.get_units(); } + constexpr auto operator<(cycle_count const a, cycle_count const b) -> bool { return a.get_units() < b.get_units(); } + constexpr auto operator>(cycle_count const a, cycle_count const b) -> bool { return a.get_units() > b.get_units(); } + constexpr auto operator<=(cycle_count const a, cycle_count const b) -> bool { return a.get_units() <= b.get_units(); } + constexpr auto operator>=(cycle_count const a, cycle_count const b) -> bool { return a.get_units() >= b.get_units(); } + constexpr auto operator+(cycle_count const a, cycle_count const b) -> cycle_count { return cycle_count{ a.get_units() + b.get_units() }; } + constexpr auto operator-(cycle_count const a, cycle_count const b) -> cycle_count { return cycle_count{ a.get_units() - b.get_units() }; } + constexpr auto operator*(std::uint64_t const a, cycle_count const b) -> cycle_count { return cycle_count{ a * b.get_units() }; } + constexpr auto operator*(cycle_count const a, std::uint64_t const b) -> cycle_count { return cycle_count{ a.get_units() * b }; } + constexpr auto operator/(cycle_count const a, cycle_count const b) -> std::uint64_t { return a.get_units() / b.get_units(); } +} // namespace nes
\ No newline at end of file |