SRL::Timer Class Reference

Detailed Description

High-precision hardware timer with DVU-accelerated conversions.

The Timer class provides Sega Saturn game developers with precise, hardware-accelerated timing capabilities. It combines the SH-2's FRT (Free Running Timer) for counting and DVU (Division Unit) for fast fixed-point conversions.

Key Features:

• 48-bit timer range: Up to ~673 days of continuous timing
• Hardware acceleration: DVU provides single-cycle division
• Fixed-point output: Native Fxp 16.16 compatibility (no float conversion needed)
• Frame-rate independent: Delta time calculations for smooth animation
• Regional support: Automatic NTSC/PAL frequency handling

Architecture:

The timer uses a two-tier counting system:

1. FRT (16-bit): Hardware counter running at ~222 kHz (PHI_128)
2. Timer32 (32-bit): Software overflow counter incremented via interrupt
3. Combined: 48-bit range with ~4.47μs precision (PHI_128)

Precision (PHI_128 mode, SGL default):

Tick Rate	Precision	Hardware Max
~222 kHz	~4.47 μs	~673 days

Basic Usage:

// Use delta time for animation (called automatically by Core::Synchronize)
Fxp delta = Timer::DeltaSeconds();
position = position + velocity * delta;

Manual Timing:

Tickstamp start = Timer::Capture();
// ... operation to measure ...
Tickstamp end = Timer::Capture();
Tickstamp elapsed = end - start;
Fxp seconds = elapsed.ToSeconds();

Warning

The hardware can track up to ~673 days, but the Fxp 16.16 format limits conversions: ToMilliseconds() to ~32.8s, ToSeconds() to ~9.1h, ToMinutes() to ~22.7 days. For GUI display use ToClock() which returns a ClockTime struct with no Fxp limitation (up to ~546 hours).

See also

Tickstamp

#include <srl_timer.hpp>

Static Public Member Functions
Timing State
Pre-calculated timing values for frame-rate independent operations.
static const Tickstamp &	DeltaTicks () noexcept
	Frame delta ticks (raw elapsed ticks between frames).
static const Tickstamp &	CurrentTickstamp () noexcept
	Current frame timestamp (const reference).
static const Math::Types::Fxp &	DeltaSeconds () noexcept
	Frame delta time in seconds (fixed-point 16.16).
static const Math::Types::Fxp &	DeltaMilliseconds () noexcept
	Frame delta time in milliseconds (fixed-point 16.16).
static const Math::Types::Fxp &	DeltaMinutes () noexcept
	Frame delta time in minutes (fixed-point 16.16).
Core Operations
Fundamental timer operations for frame updates and timestamp capture.
static Tickstamp	Capture () noexcept
	Captures current hardware state into a Tickstamp.