/* ilo-windows.c (c) 2022, charles childers */

#include <stdio.h>
#include <fcntl.h>

int ip, sp, rp, data[33], address[257], memory[65536];
char *blocks, *rom;

#define T data[sp]
#define N data[sp-1]
#define R address[rp]

int pop() { return data[(--sp) + 1]; }
void push(int value) { data[++sp] = value; }

void prepare_vm() { ip = sp = rp = 0; }

void load_image() {
  int fp;
  fp = open(rom, O_RDONLY, 0666);
  if (!fp) return;
  read(fp, &memory, 65536 * sizeof(int));
  close(fp);
  prepare_vm();
}

void save_image() {
  int fp;
  fp = open(rom, O_WRONLY, 0666);
  write(fp, &memory, 65536 * sizeof(int));
  close(fp);
}

void read_block() {
  int f, block, buffer;
  buffer = pop();
  block = pop();
  f = open(blocks, O_RDONLY, 0666);
  lseek(f, 4096 * block, SEEK_SET);
  read(f, memory + buffer, 1024 * 4);
  close(f);
}

void write_block() {
  int f, block, buffer;
  buffer = pop();
  block = pop();
  f = open(blocks, O_WRONLY, 0666);
  lseek(f, 4096 * block, SEEK_SET);
  write(f, memory + buffer, 4096);
  close(f);
}

void process(int o) {
  int a, b, target, src, dest, len;
  switch (o) {
    case 0: break;
    case 1: ip++; push(memory[ip]); break;
    case 2: push(T); break;
    case 3: data[sp] = 0; sp--; break;
    case 4: a = T; T = N; N = a; break;
    case 5: rp++; R = pop(); break;
    case 6: push(R); rp--; break;
    case 7: ip = pop() - 1; break;
    case 8: rp++; R = ip; ip = pop() - 1; break;
    case 9: target = pop();
            if (pop() != 0) { rp++; R = ip; ip = target - 1; }
            break;
    case 10: target = pop();
             if (pop() != 0) ip = target - 1; break;
    case 11: ip = R; rp--; break;
    case 12: N = (N == T) ? -1 : 0; sp--; break;
    case 13: N = (N != T) ? -1 : 0; sp--; break;
    case 14: N = (N < T) ? -1 : 0; sp--; break;
    case 15: N = (N > T) ? -1 : 0; sp--; break;
    case 16: T = memory[T]; break;
    case 17: memory[T] = N; sp--; sp--; break;
    case 18: N += T; sp--; break;
    case 19: N -= T; sp--; break;
    case 20: N *= T; sp--; break;
    case 21: a = T; b = N; T = b / a; N = b % a; break;
    case 22: N = T & N; sp--; break;
    case 23: N = T | N; sp--; break;
    case 24: N = T ^ N; sp--; break;
    case 25: N = N << T; sp--; break;
    case 26: N = N >> T; sp--; break;
    case 27: len = pop(); dest = pop();
             src = pop(); push(-1);
             while (len) {
               if (memory[dest] != memory[src]) T = 0;
               len -= 1; src += 1; dest += 1;
             }
             break;
    case 28: len = pop(); dest = pop();
             src = pop();
             while (len) {
               memory[dest] = memory[src];
               len -= 1; src += 1; dest += 1;
             }
             break;
    case 29: switch (pop()) {
               case 0: putc(pop(), stdout);  break;
               case 1: push(getc(stdin)); break;
               case 2: read_block(); break;
               case 3: write_block(); break;
               case 4: save_image(); break;
               case 5: load_image(); ip = -1; break;
               case 6: ip = 65536; break;
               case 7: push(sp); push(rp); break;
               default: break;
             }
             break;
    default: break;
  }
}

void process_bundle(int opcode) {
  process(opcode & 0xFF);
  process((opcode >> 8) & 0xFF);
  process((opcode >> 16) & 0xFF);
  process((opcode >> 24) & 0xFF);
}

void execute() {
  while (ip < 65536) {
    process_bundle(memory[ip]);
    ip++;
  }
}

void dump_stack() {
  for (; sp > 0; sp--) printf(" %d", data[sp]); printf("\n");
}

int main(int argc, char **argv) {
  blocks = (argc > 1) ? argv[1] : "ilo.blocks";
  rom = (argc > 2) ? argv[2] : "ilo.rom";
  load_image();
  execute();
  dump_stack();
}