Update timer subsystem with multi-backend dispatch table

xtoskrnl/hl/data.cc

@@ -9,59 +9,104 @@
 #include <xtos.hh>
 
 
-/* ACPI tables cache count */
+/* Tracks the total number of currently cached ACPI tables */
 ULONG HL::Acpi::CacheCount = 0;
 
-/* ACPI tables cache entries */
+/* Array holding the cached ACPI tables */
 ACPI_CACHE_LIST HL::Acpi::CacheEntries[ACPI_MAX_CACHED_TABLES];
 
-/* ACPI tables cache list */
+/* Head of the linked list tracking dynamically mapped ACPI tables */
 LIST_ENTRY HL::Acpi::CacheList;
 
-/* ACPI Root System Description Pointer (RSDP) */
+/* Pointer to the ACPI Root System Description Pointer (RSDP) */
 PACPI_RSDP HL::Acpi::RsdpStructure;
 
-/* System information */
+/* Global architectural system states and hardware feature flags parsed from the ACPI tables */
 ACPI_SYSTEM_INFO HL::Acpi::SystemInfo;
 
-/* ACPI timer information */
+/* Hardware configuration details and port addresses for the ACPI Power Management Timer */
 ACPI_TIMER_INFO HL::Acpi::TimerInfo;
 
-/* Active processors count */
+/* Represents the number of active processors */
 KAFFINITY HL::Cpu::ActiveProcessors;
 
-/* FrameBuffer information */
+/* Metadata detailing the linear frame buffer geometry */
 HL_FRAMEBUFFER_DATA HL::FrameBuffer::FrameBufferData;
 
 /* Pointer to the RAM shadow buffer used for double-buffered rendering */
 PVOID HL::FrameBuffer::ScreenShadowBuffer;
 
-/* Scroll region information */
+/* Tracks the bounding box, dimensions, and cursor position for the kernel video console */
 HL_SCROLL_REGION_DATA HL::FrameBuffer::ScrollRegionData;
 
-/* APIC mode */
+/* Indicates the active hardware interrupt controller mode */
 APIC_MODE HL::Pic::ApicMode;
 
-/* Number of I/O APIC controllers */
+/* Total number of I/O APIC chips discovered and initialized */
 ULONG HL::Pic::ControllerCount;
 
-/* I/O APIC controllers information */
+/* Array containing MMIO bases, IDs, and line counts for all I/O APICs */
 IOAPIC_DATA HL::Pic::Controllers[IOAPIC_MAX_CONTROLLERS];
 
-/* Number of I/O APIC overrides */
+/* Total number of legacy ISA interrupt routing overrides */
 ULONG HL::Pic::IrqOverrideCount;
 
-/* I/O APIC overrides information */
+/* Hardware routing definitions mapping legacy ISA interrupts to Global System Interrupts (GSI) */
 ACPI_MADT_INTERRUPT_OVERRIDE HL::Pic::IrqOverrides[IOAPIC_MAX_OVERRIDES];
 
-/* Mapped interrupt vectors */
+/* Lookup table mapping allocated hardware APIC vectors to their assigned Run Levels */
 UCHAR HL::Pic::MappedVectors[256];
 
-/* Kernel profiling interval */
-ULONG HL::Timer::ProfilingInterval;
+/* Accumulated tick value of the ACPI Power Management Timer */
+ULONG HL::Timer::AcpiPmPerformanceCounter = 0;
+
+/* Primary hardware timer driving the periodic system clock interrupt */
+TIMER_TYPE HL::Timer::ClockType;
+
+/* Fractional remainder used to maintain long-term system clock accuracy */
+ULONG HL::Timer::FractionalIncrement = 0;
+
+/* Virtual address mapped to the HPET hardware MMIO registers */
+PVOID HL::Timer::HpetAddress = NULLPTR;
+
+/* Operating frequency of the High Precision Event Timer in ticks per second */
+ULONGLONG HL::Timer::HpetFrequency = 0;
+
+/* Spinlock protecting concurrent multiprocessor access to the global performance counters */
+KSPIN_LOCK HL::Timer::PerformanceCounterLock;
+
+/* The performance counter frequency in ticks per second */
+ULONGLONG HL::Timer::PerformanceFrequency = 0;
+
+/* Absolute monotonic tick count driven by the legacy Programmable Interval Timer */
+ULONGLONG HL::Timer::PitPerformanceCounter;
+
+/* Programmed hardware divider interval used to increment the PIT performance counter */
+ULONG HL::Timer::PitRollover;
+
+/* Flag indicating whether statistical system execution profiling is currently active */
+BOOLEAN HL::Timer::ProfilingEnabled = FALSE;
+
+/* Tick interval required to trigger a profile interrupt */
+ULONG HL::Timer::ProfilingTicks;
+
+/* Global accumulator for fractional time drift and precision compensation */
+ULONG HL::Timer::RunningFraction = 0;
+
+/* System counter driven by the highest precision available hardware */
+ULONGLONG HL::Timer::SystemPerformanceCounter;
+
+/* Current base clock increment in standard 100-nanosecond intervals */
+ULONG HL::Timer::TimeIncrement = 0;
 
 /* Timer capabilities */
 TIMER_CAPABILITIES HL::Timer::TimerCapabilities = {0};
 
 /* APIC timer frequency */
 ULONG HL::Timer::TimerFrequency;
+
+/* Function dispatch table for the active hardware timer backend */
+TIMER_ROUTINES HL::Timer::TimerRoutines = {0};
+
+/* Identifies the hardware timer backing */
+TIMER_TYPE HL::Timer::TimerType;