Add initial IDT and GDT setup.

WIP interrupt handling. Interrupts do not yet return.

src/modules/main/device_manager.cpp

@@ -0,0 +1,68 @@
+#include <stddef.h>
+#include <stdint.h>
+
+#include "device_manager.h"
+#include "console.h"
+#include "util.h"
+
+static const char expected_signature[] = "RSD PTR ";
+
+struct Acpi10RSDPDescriptor
+{
+	char signature[8];
+	uint8_t checksum;
+	char oem_id[6];
+	uint8_t revision;
+	uint32_t rsdt_address;
+} __attribute__ ((packed));
+
+struct Acpi20RSDPDescriptor
+{
+	char signature[8];
+	uint8_t checksum10;
+	char oem_id[6];
+	uint8_t revision;
+	uint32_t rsdt_address;
+
+	uint32_t length;
+	uint64_t xsdt_address;
+	uint8_t checksum20;
+	uint8_t reserved[3];
+} __attribute__ ((packed));
+
+
+template <typename T>
+uint8_t acpi_checksum(const T *p, size_t off = 0)
+{
+	uint8_t sum = 0;
+	const uint8_t *c = reinterpret_cast<const uint8_t *>(p);
+	for (int i = off; i < sizeof(T); ++i) sum += c[i];
+	return sum;
+}
+
+device_manager::device_manager(const void *root_table)
+{
+	console *cons = console::get();
+
+	kassert(root_table != 0, "ACPI root table pointer is null.");
+
+	const Acpi10RSDPDescriptor *acpi1 =
+		reinterpret_cast<const Acpi10RSDPDescriptor *>(root_table);
+
+	for (int i = 0; i < sizeof(acpi1->signature); ++i)
+		kassert(acpi1->signature[i] == expected_signature[i],
+				"ACPI RSDP table signature mismatch");
+
+	uint8_t sum = acpi_checksum(acpi1, 0);
+	kassert(sum == 0, "ACPI 1.0 RSDP checksum mismatch.");
+
+	kassert(acpi1->revision > 1, "ACPI 1.0 not supported.");
+
+	const Acpi20RSDPDescriptor *acpi2 =
+		reinterpret_cast<const Acpi20RSDPDescriptor *>(acpi1);
+
+	sum = acpi_checksum(acpi2, sizeof(Acpi10RSDPDescriptor));
+	kassert(sum == 0, "ACPI 2.0 RSDP checksum mismatch.");
+
+	cons->puts("ACPI 2.0 tables loading...\n");
+}