feat: enhance timer

kernel/include/apic/timer.h

@@ -1,15 +1,57 @@
 #pragma once
 
 #include "acpi/madt.h"
-#include "util/optional.h"
 
 namespace apic {
 
-struct lapic_timer_calibration_t {
-    uint64_t tsc_frequency_hz;
+struct duration_t {
+    uint64_t timer_count;
 };
 
-optional<lapic_timer_calibration_t> calibrateTimer(const acpi::Madt& madt);
+struct timestamp_t {
+    uint64_t timer_count;
+};
+
+constexpr duration_t operator+(duration_t left, duration_t right) {
+    return duration_t{left.timer_count + right.timer_count};
+}
+
+constexpr duration_t operator-(duration_t left, duration_t right) {
+    return duration_t{left.timer_count - right.timer_count};
+}
+
+constexpr duration_t operator*(duration_t duration, uint64_t scalar) {
+    return duration_t{duration.timer_count * scalar};
+}
+
+constexpr duration_t operator*(uint64_t scalar, duration_t duration) {
+    return duration_t{duration.timer_count * scalar};
+}
+
+constexpr timestamp_t operator+(timestamp_t timestamp, duration_t duration) {
+    return timestamp_t{timestamp.timer_count + duration.timer_count};
+}
+
+constexpr timestamp_t operator+(duration_t duration, timestamp_t timestamp) {
+    return timestamp_t{timestamp.timer_count + duration.timer_count};
+}
+
+constexpr timestamp_t operator-(timestamp_t timestamp, duration_t duration) {
+    return timestamp_t{timestamp.timer_count - duration.timer_count};
+}
+
+constexpr duration_t operator-(timestamp_t left, timestamp_t right) {
+    return duration_t{left.timer_count - right.timer_count};
+}
+
+bool calibrateTimer(const acpi::Madt& madt);
+
+duration_t seconds(uint64_t count);
+duration_t milliseconds(uint64_t count);
+duration_t microseconds(uint64_t count);
+duration_t nanoseconds(uint64_t count);
+
+timestamp_t now();
 
 // TODO: when dynamic allocation and lists are available
 // struct Timer {};