feat(cpu): install IDT with exception and syscall gate handling

src/idt.c

@@ -0,0 +1,48 @@
+#include "idt.h"
+#include "types.h"
+
+typedef struct IdtEntry {
+    uint16 offsetLow;
+    uint16 selector;
+    uint8 ist;
+    uint8 typeAttr;
+    uint16 offsetMid;
+    uint32 offsetHigh;
+    uint32 reserved;
+} __attribute__((packed)) IdtEntry;
+
+typedef struct IdtPointer {
+    uint16 limit;
+    uint64 base;
+} __attribute__((packed)) IdtPointer;
+
+static IdtEntry idtEntries[256];
+static IdtPointer idtPointer;
+
+extern void* isrStubTable[];
+extern void isrStub128(void);
+
+static void setGate(int vector, void* handler, uint8 typeAttr)
+{
+    uint64 address = (uint64)handler;
+    idtEntries[vector].offsetLow = (uint16)(address & 0xFFFF);
+    idtEntries[vector].selector = 0x08;
+    idtEntries[vector].ist = 0;
+    idtEntries[vector].typeAttr = typeAttr;
+    idtEntries[vector].offsetMid = (uint16)((address >> 16) & 0xFFFF);
+    idtEntries[vector].offsetHigh = (uint32)((address >> 32) & 0xFFFFFFFF);
+    idtEntries[vector].reserved = 0;
+}
+
+void idtInit(void)
+{
+    for (int vector = 0; vector < 48; vector++)
+        setGate(vector, isrStubTable[vector], 0x8E);
+
+    setGate(0x80, (void*)isrStub128, 0xEE);
+
+    idtPointer.limit = (uint16)(sizeof(idtEntries) - 1);
+    idtPointer.base = (uint64)&idtEntries;
+
+    __asm__ volatile("lidt %0" : : "m"(idtPointer));
+}