#include "vm.h"
#include "debug.h"
#include "vmas.h"
#include <string.h>

/*
DBG UTILS
*/

uint8_t *VM::reg_name(uint8_t regvalue) {
  uint8_t *buf = new uint8_t[2];
#ifdef DBG
  switch (regvalue) {
  case R0:
    memcpy(buf, "R0", 2);
    break;
  case R1:
    memcpy(buf, "R1", 2);
    break;
  case R2:
    memcpy(buf, "R2", 2);
    break;
  case R3:
    memcpy(buf, "R3", 2);
    break;
  case S0:
    memcpy(buf, "S0", 2);
    break;
  case S1:
    memcpy(buf, "S1", 2);
    break;
  case S2:
    memcpy(buf, "S2", 2);
    break;
  case S3:
    memcpy(buf, "S3", 2);
    break;
  case IP:
    memcpy(buf, "IP", 2);
    break;
  case BP:
    memcpy(buf, "BP", 2);
    break;
  case SP:
    memcpy(buf, "SP", 2);
    break;
  default:
    memcpy(buf, "??", 2);
    break;
  }
#endif
  return buf;
}

void VM::status(void) {
#ifdef DBG
  uint8_t i;
  DBG_SUCC(("VM Status:\n"));
  DBG_SUCC(("~~~~~~~~~~\n"));
  for (i = R0; i <= SP; i++) {
    switch (i) {
    case R0:
      DBG_INFO(("R0:\t0x%x\n", this->regs[i]));
      break;
    case R1:
      DBG_INFO(("R1:\t0x%x\n", this->regs[i]));
      break;
    case R2:
      DBG_INFO(("R2:\t0x%x\n", this->regs[i]));
      break;
    case R3:
      DBG_INFO(("R3:\t0x%x\n", this->regs[i]));
      break;
    case S0:
      DBG_INFO(("S0:\t0x%x\n", this->regs[i]));
      break;
    case S1:
      DBG_INFO(("S1:\t0x%x\n", this->regs[i]));
      break;
    case S2:
      DBG_INFO(("S2:\t0x%x\n", this->regs[i]));
      break;
    case S3:
      DBG_INFO(("S3:\t0x%x\n", this->regs[i]));
      break;
    case IP:
      DBG_INFO(("IP:\t0x%x\n", this->regs[i]));
      break;
    case BP:
      DBG_INFO(("BP:\t0x%x\n", this->regs[i]));
      break;
    case SP:
      DBG_INFO(("SP:\t0x%x\n", this->regs[i]));
      break;
    }
  }
  DBG_SUCC(("~~~~~~~~~~\n"));
#endif
  return;
}
/*
CONSTRUCTORS
*/
VM::VM() {
  DBG_SUCC(("Creating VM without code.\n"));
  as.allocate();
  init_regs();
}

VM::VM(uint8_t *code, uint32_t codesize) {
  DBG_SUCC(("Creating VM with code.\n"));
  if (as.allocate()) {
    as.insCode(code, codesize);
  }
  init_regs();
}

void VM::init_regs(void) {
  uint8_t i;

  for (i = R0; i <= SP; i++) {
    this->regs[i] = 0;
  }
  return;
}

/*
INSTRUCTIONS IMPLEMENTATIONS
*/

bool VM::exec_movi(void) {
  /*
  MOVI R0, 0x2400 | R0 = 0x2400
  */
  uint8_t dst;
  uint16_t imm;
  dst = as.code[regs[IP] + 1];
  imm = *((uint16_t *)&as.code[regs[IP] + 2]);
  DBG_INFO(("MOVI %s, 0x%x\n", reg_name(dst), imm));
  if (dst == IP) {
    DBG_ERROR(("Can't MOVI to IP!\n"));
    return false;
  }
  regs[dst] = imm;
  return true;
}

bool VM::exec_movr(void) {
  /*
  MOVR R1, R0 | R1 = R0
  ---------------------
  R1, R0 = 0x10 <- DST / SRC are nibbles!
  */
  uint8_t dst, src;
  dst = as.code[regs[IP] + 1] >> 4;
  src = as.code[regs[IP] + 1] & 0b00001111;
  DBG_INFO(("MOVR %s, %s\n", reg_name(dst), reg_name(src)));
  if (dst == IP || src == IP) {
    DBG_ERROR(("Can't MOVR IP!\n"));
    return false;
  }
  regs[dst] = regs[src];
  return true;
}

bool VM::exec_getm(void) {
  /*
  GETM R0, 0x1000 | R0 = data[0x1000]
  */
  uint8_t dst;
  uint16_t src;
  dst = as.code[regs[IP] + 1];
  src = *((uint16_t *)&as.code[regs[IP] + 2]);
  DBG_INFO(("GETM %s, 0x%x\n", reg_name(dst), src));
  regs[dst] = *((uint16_t *)&as.data[src]);
  return true;
}

bool VM::exec_putm(void) {
  /*
  PUTM 0x1000, R0 | data[0x1000] = R0
  */
  uint16_t dst;
  uint8_t src;
  dst = *((uint16_t *)&as.code[regs[IP] + 1]);
  src = as.code[regs[IP] + 3];
  DBG_INFO(("PUTM 0x%x, %s\n", dst, reg_name(src)));
  *((uint16_t *)&as.data[dst]) = regs[src];
  return true;
}

bool VM::exec_addi(void) {
  /*
  ADDI R0, 0x2 | R0 += 2
  */
  uint8_t dst;
  uint16_t src;

  dst = as.code[regs[IP] + 1];
  src = *((uint16_t *)&as.code[regs[IP] + 2]);
  DBG_INFO(("ADDI %s, 0x%x\n", reg_name(dst), src));
  regs[dst] += src;
  return true;
}

void VM::run(void) {
  uint8_t opcode;
  bool finished = false;
  while (!finished) {
    opcode = (uint8_t)as.code[regs[IP]];
    switch (opcode) {
    case MOVI:
      exec_movi();
      regs[IP] += MOVI_SIZE;
      break;
    case MOVR:
      exec_movr();
      regs[IP] += MOVR_SIZE;
      break;
    case GETM:
      exec_getm();
      regs[IP] += GETM_SIZE;
      break;
    case PUTM:
      exec_putm();
      regs[IP] += PUTM_SIZE;
      break;
    case ADDI:
      exec_addi();
      regs[IP] += ADDI_SIZE;
      break;
    case HALT:
      DBG_INFO(("HALT\n"));
      finished = true;
      break;
    default:
      DBG_INFO(("WAT: 0x%x\n", opcode));
      finished = true;
      break;
    }
  }
  return;
}