// This file uses the 8080 emulator to run the test suite (roms in cpu_tests
// directory). It uses a simple array as memory.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include "8080/i8080.h"

// memory callbacks
#define MEMORY_SIZE 0x10000
static uint8_t* memory = NULL;
static bool test_finished = 0;

static uint8_t rb(void* userdata, const uint16_t addr) {
    return memory[addr];
}

static void wb(void* userdata, const uint16_t addr, const uint8_t val) {
    memory[addr] = val;
}

uint16_t dma_addr;
uint8_t cur_disk = 'Z'-'A';
char filename[16];

void filename_from_fcb(void* userdata, uint16_t addr) {
  i8080* const c = (i8080*) userdata;
  memset(&filename, 0, sizeof(filename));
  char* ptr = filename;
  while(rb(c, addr) != '.' && rb(c, addr) > ' ') {
    *ptr++ = rb(c, addr++);
  }
  if (rb(c, addr) == '.') {
    addr++;
    while(rb(c, addr) > ' ') {
      *ptr++ = rb(c, addr++);
    }
  }
}

void filename_to_fcb(void* userdata, uint16_t addr) {

}

static uint8_t port_in(void* userdata, uint8_t port) {
  i8080* const c = (i8080*) userdata;
  uint16_t de = (c->d << 8) | c->e;

  switch(c->c) {
  case 2:
    printf("%c", c->e);
    break;
  case 9:
    do {
      printf("%c", rb(c, de++));
    } while(rb(c, de) != '$');
    break;
  case 15:
    filename_from_fcb(userdata, de);
    printf("filename: %s\n", filename);
    exit(1);
    break;
  case 25:
    c->a = cur_disk;
    break;
  case 26:
    dma_addr = (c->d << 8) | c->e;
    break;
  default:
    i8080_debug_output(c);
    fprintf(stderr, "fatal: unknown syscall C=%02Xh (%d)\n", c->c, c->c);
    exit(255);
  }

  return c->a;
}

static int load_file(const char* filename, uint16_t addr) {
    FILE* f = fopen(filename, "rb");
    if (f == NULL) {
        fprintf(stderr, "error: can't open file '%s'.\n", filename);
        return 1;
    }

    // file size check:
    fseek(f, 0, SEEK_END);
    size_t file_size = ftell(f);
    rewind(f);

    if (file_size + addr >= MEMORY_SIZE) {
        fprintf(stderr, "error: file %s can't fit in memory.\n", filename);
        return 1;
    }

    // copying the bytes in memory:
    size_t result = fread(&memory[addr], sizeof(uint8_t), file_size, f);
    if (result != file_size) {
        fprintf(stderr, "error: while reading file '%s'\n", filename);
        return 1;
    }

    fclose(f);
    return 0;
}

int main(int argc, char** argv) {
    memory = malloc(MEMORY_SIZE);
    if (memory == NULL) {
        return 255;
    }

    argc--;
    if (!argc) {
      fprintf(stderr, "No filename given\n");
      return 255;
    }
    argv++;

    i8080 cpu;
    i8080_init(&cpu);
    cpu.userdata = &cpu;
    cpu.read_byte = rb;
    cpu.write_byte = wb;
    cpu.port_in = port_in;
    memset(memory, 0, MEMORY_SIZE);

    if (load_file(argv[0], 0x100) != 0) {
        return 255;
    }

    cpu.pc = 0x100;
    // inject "hlt" at 0x0000
    memory[0x0000] = 0x76;

    // inject "in a,0" at 0x0005 (cpm syscall)
    memory[0x0005] = 0xDB;
    memory[0x0006] = 0x00;
    memory[0x0007] = 0xC9;

    while (!cpu.halted) {
//        i8080_debug_output(&cpu);
        i8080_step(&cpu);
    }

    free(memory);

    return cpu.a;
}