/*
 * Copyright (C) 2017 Robin Krahl <robin.krahl@ireas.org>
 * 
 * This program is free software: you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation, either version 3 of the License, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 */

#include <garmos/arch.h>
#include <garmos/gdt.h>
#include <garmos/idt.h>
#include <garmos/kernel.h>
#include <garmos/types.h>

#define IDT_GATE_COUNT 256

struct idt_gate {
	uint16_t handler_lo;
	uint16_t gdt_offset;
	uint8_t reserved;
	uint8_t access;
	uint16_t handler_hi;
} __attribute__((packed));

struct idt_gate idt[IDT_GATE_COUNT];

struct idtp idtp = {
	.limit = IDT_GATE_COUNT * sizeof(*idt) - 1,
	.pointer = idt,
};

static void idt_set(uint8_t no, uint16_t offset, uint32_t handler,
		uint8_t access, uint8_t flags);

void idt_init(void)
{
	uint32_t offset = gdt_get_code_offset();
	uint32_t i;
	uint8_t *no = irqnos;
	uint32_t *addr = irqhdls;

	ker_dbg("Initializing IDT ...");

	for (i = 0; i < IDT_GATE_COUNT; i++)
		idt_set(i, offset, (uint32_t) &irqign, 0, 0xE);

	for (; *no; no++, addr++) {
		if (!*addr)
			continue;
		ker_dbg("Registerung IRQ handler ...");
		idt_set(*no, offset, *addr, 0, 0xE);
	}

	idtset(idtp);
}

void idt_activate(void)
{
	idtact();
}

static void idt_set(uint8_t no, uint16_t offset, uint32_t handler,
		uint8_t access, uint8_t flags)
{
	idt[no].handler_lo = handler & 0xFFFF;
	idt[no].handler_hi = (handler >> 16) & 0xFFFF;
	idt[no].gdt_offset = offset;
	idt[no].reserved = 0;
	idt[no].access = 0x80 | flags | ((access & 0x3) << 5);
}