#include "std.h"

#include <bootboot.h>

#define COM1_BASE_PORT 0x3F8

static inline uint8_t
inb(uint16_t port)
{
	uint8_t data;
	__asm__ ("inb %%dx, %%al" : "=a"(data) : "d"(port));
	return data;
}

static inline void
outb(uint16_t port, uint8_t data)
{
	__asm__ ("outb %%al, %%dx" :: "a"(data), "d"(port));
}

extern void bios_write(const char *msg);
extern void *bios_getmap(void *buffer);

extern BOOTBOOT bootboot;

#define E820_TYPE_FREE        0x1
#define E820_TYPE_RESERVED    0x2
#define E820_TYPE_RECLAIMABLE 0x3
#define E820_TYPE_NONVOLATILE 0x4
#define E820_TYPE_BADMEM      0x5

struct e820_entry {
	uint64_t base;
	uint64_t length;
	uint32_t type;
	uint32_t xattr;
};

struct e820_entry memmap[128];

struct vesa_info {
	char signature[4];
	uint16_t version;
	uint16_t oem_name[2];
	uint8_t capab[4];
	uint16_t video_mode_offset;
	uint16_t video_mode_segment;
	uint16_t num_64k_blocks;
	uint8_t reserved[492];
};

extern uint16_t bios_func(uint8_t inum, uint16_t reg[]);

#define PG_PRESENT 0x001
#define PG_WRITE   0x002
#define PG_USER    0x004
#define PG_SIZE    0x080
#define PG_GLOBAL  0x100

__attribute__((aligned(4096))) uint64_t pml4[512];
__attribute__((aligned(4096))) uint64_t pdp[512];
__attribute__((aligned(4096))) uint64_t pd[512];

uint64_t
pg_setup()
{
	pml4[0] = (uint64_t)(uint32_t)pdp | PG_WRITE | PG_PRESENT;
	pdp[0] = (uint64_t)(uint32_t)pd | PG_WRITE | PG_PRESENT;
	for (unsigned i = 0; i < 512; i++) {
		pd[i] = (i * (uint64_t)0x200000) | PG_WRITE | PG_PRESENT | PG_SIZE;
	}
	uint64_t cr3 = (uint64_t)(uint32_t)pml4;
	return cr3;
}

void
main()
{
	bios_write("Netboot via fernlader v2 ...\r\n");

	memcpy(bootboot.magic, BOOTBOOT_MAGIC, sizeof bootboot.magic);
	bootboot.size = 128;
	bootboot.protocol = PROTOCOL_MINIMAL | LOADER_BIOS;
	bootboot.numcores = 1;

	bios_write("init\r\n");
	struct e820_entry *end = bios_getmap(memmap);
	bios_write("karlos\r\n");
	for (int i = 0; ; i++) {
		if (&memmap[i] >= end) break;
		char buf[2];
		buf[0] = memmap[i].type < 10 ? memmap[i].type + '0' : '?';
		buf[1] = 0;
		bios_write(buf);
	}

	pg_setup();

#if 0
	char foo[24];

	bios_write("bios_func():\r\n");
	uint32_t reg[6];
	reg[0] = 0xE820;
	reg[1] = 24;
	reg[2] = 0x534D4150;
	reg[3] = 0;
	reg[4] = (uint32_t)&foo;
	reg[5] = 0;
	uint16_t flags = bios_func(0x15, reg);

	const char *hex_digits = "0123456789ABCDEF";
	char buf[100];
	buf[0] = hex_digits[(flags >> 12) & 0xF];
	buf[1] = hex_digits[(flags >>  8) & 0xF];
	buf[2] = hex_digits[(flags >>  4) & 0xF];
	buf[3] = hex_digits[(flags >>  0) & 0xF];
	buf[4] = ' ';
	buf[5] = hex_digits[(foo[16] >> 0) & 0xF];
	buf[6] = ' ';
	buf[7] = 0;

	bios_write(buf);
#endif

	uint16_t reg[7];
	reg[0] = (0x0E << 8) + 'J';
	reg[1] = 0;
	reg[2] = 0;
	reg[3] = 0;
	reg[4] = 0;
	reg[5] = 0;
	reg[6] = 0;
	bios_func(0x10, reg);

	bios_write("what?\r\n");

	for (;;) {
		__asm__ ("hlt");
	}
}