/*
  MSP430 Emulator
  Copyright (C) 2020 Rudolf Geosits (rgeosits@live.esu.edu)

  "MSP430 Emulator" is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  "MSP430 Emulator" is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program. If not, see <https://www.gnu.org/licenses/>.
*/

#ifndef _REGISTERS_H_
#define _REGISTERS_H_

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

#include "../../emulator.h"

#define CLK_PER_INSTR 4.883;  // Approximation

enum {
  P1_0_ON_PACKET  = 0x00,
  P1_0_OFF_PACKET = 0x01,
  P1_0_PULLU_PACKET = 0x30,
  P1_0_PULLD_PACKET = 0x31,
  P1_0_HIGHZ_PACKET = 0x32,

  P1_1_ON_PACKET  = 0x02,
  P1_1_OFF_PACKET = 0x03,
  P1_1_PULLU_PACKET = 0x33,
  P1_1_PULLD_PACKET = 0x34,
  P1_1_HIGHZ_PACKET = 0x35,

  P1_2_ON_PACKET  = 0x04,
  P1_2_OFF_PACKET = 0x05,
  P1_2_PULLU_PACKET = 0x36,
  P1_2_PULLD_PACKET = 0x37,
  P1_2_HIGHZ_PACKET = 0x38,

  P1_3_ON_PACKET  = 0x06,
  P1_3_OFF_PACKET = 0x07,
  P1_3_PULLU_PACKET = 0x39,
  P1_3_PULLD_PACKET = 0x3A,
  P1_3_HIGHZ_PACKET = 0x3B,

  P1_4_ON_PACKET  = 0x08,
  P1_4_OFF_PACKET = 0x09,
  P1_4_PULLU_PACKET = 0x3C,
  P1_4_PULLD_PACKET = 0x3D,
  P1_4_HIGHZ_PACKET = 0x3E,

  P1_5_ON_PACKET  = 0x0A,
  P1_5_OFF_PACKET = 0x0B,
  P1_5_PULLU_PACKET = 0x3F,
  P1_5_PULLD_PACKET = 0x40,
  P1_5_HIGHZ_PACKET = 0x41,

  P1_6_ON_PACKET  = 0x0C,
  P1_6_OFF_PACKET = 0x0D,
  P1_6_PULLU_PACKET = 0x42,
  P1_6_PULLD_PACKET = 0x43,
  P1_6_HIGHZ_PACKET = 0x44,

  P1_7_ON_PACKET  = 0x0E,
  P1_7_OFF_PACKET = 0x0F,
  P1_7_PULLU_PACKET = 0x45,
  P1_7_PULLD_PACKET = 0x46,
  P1_7_HIGHZ_PACKET = 0x47,

  UPDATE_REG_R0_PACKET = 0x10,
  UPDATE_REG_R1_PACKET = 0x11,
  UPDATE_REG_R2_PACKET = 0x12,
  UPDATE_REG_R3_PACKET = 0x13,
  UPDATE_REG_R4_PACKET = 0x14,
  UPDATE_REG_R5_PACKET = 0x15,
  UPDATE_REG_R6_PACKET = 0x16,
  UPDATE_REG_R7_PACKET = 0x17,
  UPDATE_REG_R8_PACKET = 0x18,
  UPDATE_REG_R9_PACKET = 0x19,
  UPDATE_REG_R10_PACKET = 0x1A,
  UPDATE_REG_R11_PACKET = 0x1B,
  UPDATE_REG_R12_PACKET = 0x1C,
  UPDATE_REG_R13_PACKET = 0x1D,
  UPDATE_REG_R14_PACKET = 0x1E,
  UPDATE_REG_R15_PACKET = 0x1F,
  UPDATE_ALL_REGS_PACKET = 0x20,

  SERVO_MOTOR = 0x21,
};

/* r2 or SR, the status register */
typedef struct Status_reg {
  uint8_t reserved : 7;   // Reserved bits    
  uint8_t overflow : 1;   // Overflow flag
  uint8_t SCG1 : 1;  // System Clock Generator SMCLK; ON = 0; OFF = 1;
  uint8_t SCG0 : 1;  // System Clock Generator DCOCLK DCO ON = 0; DCO OFF = 1;
  uint8_t OSCOFF : 1;    // Oscillator Off. LFXT1CLK ON = 0; LFXT1CLK OFF = 1; 
  uint8_t CPUOFF : 1;     // CPU off; CPU OFF = 1; CPU ON = 0;                
  uint8_t GIE : 1;    // General Inter enabl; Enbl maskable ints = 1; 0 = dont 
  uint8_t negative : 1;   // Negative flag                                  
  uint8_t zero : 1;       // Zero flag                                     
  uint8_t carry : 1;      // Carry flag; Set when result produces a carry   
} Status_reg;

// Main CPU structure //
typedef struct Cpu {
  bool running;      /* CPU running or not */

  uint16_t pc, sp;   /* R0 and R1 respectively */
  Status_reg sr;     /* Status register fields */
  int16_t cg2;       /* R3 or Constant Generator #2 */
  
  int16_t r4, r5, r6, r7;   /* R4-R15 General Purpose Registers */
  int16_t r8, r9, r10, r11;
  int16_t r12, r13, r14, r15;

  Port_1 *p1;
  //Port_2 *p2;
  Usci *usci;
  Bcm *bcm;
  Timer_a *timer_a;
  uint16_t interrupt;
  uint64_t nsecs;  // nanoseconds since emulator started;
} Cpu;

uint16_t sr_to_value (Emulator *emu);
void set_sr_value (Emulator *emu, uint16_t value);
void initialize_msp_registers (Emulator *emu);
void update_register_display (Emulator *emu);

void cpu_step (Emulator *emu);
void cpu_reset (Emulator *emu);

#endif