/* Complicated Moore FSM   filename  fsm.c
   Simulator program of a Moore Finite State Machine

   This example accompanies the book
     "Embedded Microcomputer Systems: Real Time Interfacing", Brooks-Cole, copyright (c) 2000,
      Jonathan W. Valvano 7/6/99

   Interface between the TExaS simulator running a MC68HC11 EVB
      with ICC11 freeware compiler 
   TExaS Copyright 1999 by Jonathan W. Valvano 
   for more information about ICC11 
      see http://www.imagecraft.com
   You may use this file without restrictions
*/

/* PortC bits 7-0 are inputs, Port B bits 7-0 are outputs */

#include "HC11.h"
/* Each state can have up to 4 next state arrows
   The input to cause a state change is a sequence of 8 1,0,X
   E.g., 1X0XX1XX means Bit7=1, Bit5=0 and Bit2=1
   This pattern is encoded with AndMask=0xA4 and
                                EquMask=0x84 */

struct State{
   unsigned char Out;     /* Output to Port B */
   unsigned int Wait;     /* Time (E cycles) to wait in this state */
   unsigned char AndMask[4];
   unsigned char EquMask[4];
   struct State *Next[4];};  /* Next state if input=matches */
typedef struct State StateType;
typedef StateType * StatePtr;

#define SA &fsm[0]
#define SB &fsm[1]
#define SC &fsm[2]
StateType fsm[3]={
{0x34, 200,   /* 100us */
  	{0xFF,   0xF0,   0x27,   0x00},
	{0x51,   0xA0,   0x07,   0x00},
	{SB,SA,SB,SC}},
{0xB3,80,   /* 40 us */
	{0x80,   0xF0,   0x00,   0x00},
	{0x00,   0x90,   0x00,   0x00},
	{SC,SA,SB,SB}},
{0x76,100,   /* 50us */
	{0xFF,   0x0F,   0x01,   0x00},
	{0x12,   0x05,   0x00,   0x00},
	{SA,SA,SB,SA}}
}; 
StatePtr Pt;          /* pointer to current state */
unsigned char Input;  /* input from machine */

void Wait(unsigned int delay){ int Endt;
    Endt=TCNT+delay;        /* Time (500ns cycles) to wait */
    while((Endt-(int)TCNT)>0);   /* wait */
};

void main(void){ unsigned int i;
  Pt=SA;           /* Initial State */
  DDRC=0x00;       /* PortC are inputs, PortB is output */
  while(1){
    PORTB=Pt->Out;
    Wait(Pt->Wait);  /* Time to wait in this state */
    Input=PORTC;     /* Input=0 to 255 */
    for(i=0;i<4;i++)
      if((Input&(Pt->AndMask[i]))==(Pt->EquMask[i])){
          Pt=Pt->Next[i];
          i=4; }
}};
void resetVectors(void){
/* not really a function, 
   but this must be last */
  asm(" org $FFFE");
  asm(" FDB __start");
  asm(" org $FFd5"); /* puts rts in a harmless place */
}