feat: implement core initialization and local APIC setup

kernel/include/apic/core.h

@@ -2,6 +2,28 @@
 
 #include "memory/pointer.h"
 
+#include "acpi/discovery.h"
+#include "memory/pagetable.h"
+
 namespace apic {
-void startupCore(paddr_t code, paddr_t stack);
-}
+
+struct stack_t {
+    paddr_t ptr;
+    size_t size;
+};
+
+using core_id = uint8_t;
+
+struct Core {
+    core_id id;
+    stack_t stack;
+    PageTable kernelPageTable;
+};
+
+optional<Core> initCore(acpi::Madt madt, core_id id);
+
+void initCores(acpi::discovery_result_t);
+
+void transitionStartupCore();
+
+} // namespace apic

kernel/include/apic/lapic.h

@@ -0,0 +1,24 @@
+#pragma once
+
+#include "acpi/discovery.h"
+#include "util/number.h"
+
+namespace apic {
+
+using lapic_id_t = uint32_t;
+
+void initLocalApic(const acpi::discovery_result_t& discovery);
+
+lapic_id_t localApicId();
+
+void sendInit(lapic_id_t destination);
+
+// startup_page: physical address of the real-mode entry point divided by 4096;
+// must point below 1 MiB, so only values < 0x100 are meaningful.
+void sendStartup(lapic_id_t destination, uint8_t startup_page);
+
+void sendInterrupt(lapic_id_t destination, uint8_t vector);
+
+void signalEndOfInterrupt();
+
+} // namespace apic

kernel/include/apic/timer.h

@@ -33,6 +33,26 @@ constexpr duration_t operator*(uint64_t scalar, duration_t duration) {
     return duration_t{duration.timer_count * scalar};
 }
 
+constexpr bool operator==(duration_t left, duration_t right) {
+    return left.timer_count == right.timer_count;
+}
+
+constexpr bool operator<(duration_t left, duration_t right) {
+    return left.timer_count < right.timer_count;
+}
+
+constexpr bool operator<=(duration_t left, duration_t right) {
+    return left.timer_count <= right.timer_count;
+}
+
+constexpr bool operator>(duration_t left, duration_t right) {
+    return left.timer_count > right.timer_count;
+}
+
+constexpr bool operator>=(duration_t left, duration_t right) {
+    return left.timer_count >= right.timer_count;
+}
+
 constexpr timestamp_t operator+(timestamp_t timestamp, duration_t duration) {
     return timestamp_t{timestamp.timer_count + duration.timer_count};
 }
@@ -62,9 +82,4 @@ void busyWait(duration_t duration);
 
 timestamp_t now();
 
-// TODO: when dynamic allocation and lists are available
-// struct Timer {};
-//
-// Timer getCoreTimerInstance();
-
 } // namespace apic