p18_tmr0.c

/* ########################################################################

   PICsim - PIC simulator

   ########################################################################

   Copyright (c) : 2019-2020  Luis Claudio Gamboa Lopes

   This program 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 2, or (at your option)
   any later version.

   This program 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, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

   For e-mail suggestions :  lcgamboa@yahoo.com
   ######################################################################## */

#include "../../include/periferic18.h"
#include "../../include/picsim.h"
#include <stdio.h>

extern const int fpw2[];

void p18_tmr0_rst(_pic *pic) { pic->cp0 = 0; }

void p18_tmr0(_pic *pic) {
  if (pic->P18map.T0CON) {
    if ((*pic->P18map.T0CON) & 0x80) // TMR0ON
    {
      if ((((*pic->P18map.T0CON) & 0x20) == 0x00) || // TOCS=FOSC/4
          ((((*pic->P18map.T0CON) & 0x30) == 0x20) &&
           ((pic->t0cki_ == 0) &&
            (pic->pins[pic->t0cki - 1].value == 1))) || // T0CS=t0cki  T0SE =0
          ((((*pic->P18map.T0CON) & 0x30) == 0x30) &&
           ((pic->t0cki_ == 1) &&
            (pic->pins[pic->t0cki - 1].value == 0)))) // T0CS=t0cki  T0SE =1
      {
        pic->cp0++;

        if (pic->lram == sfr_addr(pic->P18map.TMR0L))
          pic->cp0 = 0; // RESET prescaler

        if (((*pic->P18map.T0CON) & 0x08) == 0x08) // PSA
        {

          if (((*pic->P18map.T0CON) & 0x40) &&
              (((*pic->P18map.TMR0L) + 1) == 0x100))
            (*pic->P18map.INTCON) |= 0x04; // T0IF

          (*pic->P18map.TMR0L)++;
          if ((!(*pic->P18map.TMR0L)) && (!((*pic->P18map.T0CON) & 0x40))) {
            if (((*pic->P18map.TMR0H) + 1) == 0x100)
              (*pic->P18map.INTCON) |= 0x04; // T0IF
            (*pic->P18map.TMR0H)++;
          }
          pic->cp0 = 0;
        } else {
          if (pic->cp0 >= 2 * (fpw2[(*pic->P18map.T0CON) & 0x07])) {

            if (((*pic->P18map.T0CON) & 0x40) &&
                (((*pic->P18map.TMR0L) + 1) == 0x100))
              (*pic->P18map.INTCON) |= 0x04; // T0IF

            (*pic->P18map.TMR0L)++;
            if ((!(*pic->P18map.TMR0L)) && (!((*pic->P18map.T0CON) & 0x40))) {
              if (((*pic->P18map.TMR0H) + 1) == 0x100)
                (*pic->P18map.INTCON) |= 0x04; // T0IF
              (*pic->P18map.TMR0H)++;
            }
            pic->cp0 = 0;
          }
        }
      }
    }
    pic->t0cki_ = pic->pins[pic->t0cki - 1].value;
  }
}

void p18_tmr0_2(_pic *pic) {
  if (pic->P18map.T0CON0) {
    if ((*pic->P18map.T0CON0) & 0x80) // T0EN
    {
      if ((((*pic->P18map.T0CON1) & 0xE0) == 0x40) || // TOCS=FOSC/4
          ((((*pic->P18map.T0CON1) & 0xE0) == 0x00) &&
           ((pic->t0cki_ == 0) &&
            (pic->pins[pic->t0cki - 1].value == 1))) || // T0CS=t0cki
          ((((*pic->P18map.T0CON1) & 0xE0) == 0x20) &&
           ((pic->t0cki_ == 1) &&
            (pic->pins[pic->t0cki - 1].value == 0)))) // T0CS=t0cki
      {
        pic->cp0++;

        if (pic->lram == sfr_addr(pic->P18map.TMR0L))
          pic->cp0 = 0; // RESET prescaler

        if (pic->cp0 >= 2 * (fpw2[(*pic->P18map.T0CON1) & 0x0F])) {

          (*pic->P18map.TMR0L)++;

          // 8 bit mode
          if (!((*pic->P18map.T0CON0) & 0x10) &&
              ((*pic->P18map.TMR0H) == (*pic->P18map.TMR0L))) {
            (*pic->P18map.PIR0) |= 0x20; // TMR0IF
            (*pic->P18map.TMR0L) = 0;
            // TODO buffer TMR0H writes latch
          }

          // 16 bit mode;
          if ((!(*pic->P18map.TMR0L)) && (((*pic->P18map.T0CON0) & 0x10))) {
            if (((*pic->P18map.TMR0H) + 1) == 0x100)
              (*pic->P18map.PIR0) |= 0x20; // TMR0IF
            (*pic->P18map.TMR0H)++;
          }
          pic->cp0 = 0;
        }
        // TODO implement postscaler
      }
    }
    pic->t0cki_ = pic->pins[pic->t0cki - 1].value;
  }
}