#include <stdint.h>

#include "fat12.h"
#include "paracomm.h"

#define kFatAddr ((void*)0x1a00)
#define kRootDirAddr ((void*)0x1c00)
#define kPolmonAddr ((void*)0x1000)
#define kInt80Vector ((uint16_t*)(0x80 * 4))
#define kParallelDataPort 0x3bc
#define kParallelStatusPort 0x3bd
#define kParallelControlPort 0x3be
#define kParaDelay 400

void dosdbt();
void int80h();

uint8_t* parabuf;
uint8_t parasize;

static void paracb(const uint8_t* buf, uint8_t size) {
    if (size > parasize) {
        return paracb(buf, parasize);
    }
    for (int i = 0; i < size; i++) {
        parabuf[i] = buf[i];
    }
    parasize = 0;
}

static void die() {
    while (1) {
    }
}

static void __outb__(uint16_t port, uint8_t data) {
    register uint16_t p asm("dx") = port;
    register uint8_t d asm("al") = data;
    asm volatile("outb %0, %1" ::"r"(d), "r"(p));
}

static uint8_t __inb__(uint16_t port) {
    register uint16_t p asm("dx") = port;
    register uint8_t d asm("al");
    asm volatile("inb %1, %0" : "=r"(d) : "r"(p));
    return d;
}

static void __delay__(int n) {
    for (int i = 0; i < n; i++) {
        asm volatile("");
    }
}

static void paraxfer() {
    uint8_t mosib = paracomm_nextbyte();
    __outb__(kParallelDataPort, mosib);
    __outb__(kParallelControlPort, 1);
    __delay__(kParaDelay);
    __outb__(kParallelControlPort, 0);
    __delay__(kParaDelay);
    uint8_t mison = __inb__(kParallelStatusPort) >> 4;
    paracomm_feed(mison);
}

void pararecv(uint8_t* addr, uint8_t size) {
    parabuf = addr;
    parasize = size;
    for (int i = 0; i < 1 + 2 + size * 2; i++) {
        if (!parasize) {
            break;
        }
        paraxfer();
    }
}

void parasend(uint8_t* addr, uint8_t size) {
    for (int i = 0; i < size; i++) {
        paracomm_send(addr[i]);
    }
    for (int i = 0; i < size + 2; i++) {
        paraxfer();
    }
}

int main() {
    dosdbt();
    paracomm_init(paracb);

    fat12_init(kFatAddr, kRootDirAddr);

    uint16_t* int80v = kInt80Vector;
    int80v[0] = (uint16_t)int80h;
    int80v[1] = 0;

    if (fat12_readfile("POLMON  COM", kPolmonAddr)) {
        die();
    }

    asm volatile("jmp *%0" ::"r"(kPolmonAddr));
}