// **********ExtMem.c************

// Extended memory access for DPAGE PPAGE

// MC68HC812A4

// Last modified 1/15/02 by Jonathan W. Valvano

 

// Copyright 2002 by Jonathan W. Valvano, valvano@uts.cc.utexas.edu 

//    You may use, edit, run or distribute this file 

//    as long as the above copyright notice remains 



#include "HC12.h"



struct ExtAddr{

  unsigned char msb;  // DPage A19-A12  PPage A21-A14

  unsigned int lsw;   // DPage A11-A0   PPage A13-A0

};

typedef struct ExtAddr ExtAddrtype;

ExtAddrtype MyPt;

char ReadRamByte(ExtAddrtype addr){ char *pt;

  DPAGE = addr.msb;  // set DPage A19-A12

  pt = (char*)(0x7000 + addr.lsw);

  return *pt;

}

void WriteRamByte(ExtAddrtype addr, char data){ char *pt;

  DPAGE = addr.msb;   // set DPage A19-A12

  pt = (char*)(0x7000 + addr.lsw);

  *pt = data;

}

int ReadRamWord(ExtAddrtype addr){ int *pt;

  DPAGE = addr.msb;  // set DPage A19-A12

  pt = (int*)(0x7000 + addr.lsw);

  return *pt;

}

void WriteRamWord(ExtAddrtype addr, int data){ int *pt;

  DPAGE = addr.msb;  // set DPage A19-A12

  pt = (int*)(0x7000 + addr.lsw);

  *pt = data;

}

	

void main(void){ char data; int wdata;

  MyPt.msb = 0;

  MyPt.lsw = 0;

  WriteRamByte(MyPt,5);

  data = ReadRamByte(MyPt);

  WriteRamWord(MyPt,5000);

  wdata = ReadRamWord(MyPt);

}







extern void _start();	

#pragma abs_address:0xfffe

void (*reset_vector[])() = { _start };

#pragma end_abs_address