#include <stdint.h>
#include <stdlib.h>

#include "fat12.h"

#define kPolmonAddress ((void*)0x0600)
#define kFatAddress ((void*)0x1000)
#define kRootDirAddress ((void*)0x1200)


static int putchar(int c) {
    register uint8_t khar asm ("al") = c;
    register uint8_t func asm ("ah") = 0x0e;
    register uint8_t page asm ("bh") = 0;

    asm volatile ("int $0x10"
            :: "r" (khar), "r" (func), "r" (page)
            : "bp");

    return c;
}

static int puts(const char* msg) {
    while (*msg) {
        putchar(*msg++);
    }
    return 0;
}

__attribute__((noreturn))
static void die(const char* msg) {
    puts(msg);
    while (1) {
    }
    __builtin_unreachable();
}

__attribute__((noreturn))
static void jump(void* addr) {
    asm volatile ("ljmp $0,%0" :: "i"(addr));
    __builtin_unreachable();
}

__attribute__((noreturn))
static void loadpolmon() {
    if (fat12_init(kFatAddress, kRootDirAddress)) {
        die("fi");
    }

    while (fat12_readfile("POLIO   COM", kPolmonAddress)) {
        asm volatile (
                "mov $00, %%ah      \n\t"
                "int $0x16          \n\t"
                ::: "ax"
                );
    }

    jump(kPolmonAddress);
}

int main() {
    loadpolmon();
}