/************************************************************************/
/*                                                                      */
/*              Bit Pointer Implementation                              */
/*                                                                      */
/*              SFR bits can not be accessed !                          */
/*                                                                      */
/************************************************************************/
#pragma cd
#include <types.h>


#define BIT_START       0x20


static uint getibit( uchar bitptr )
{
  uchar code bitmask[] = { 1, 2, 4, 8, 0x10, 0x20, 0x40, 0x80 };
  return (uint)bitmask[bitptr & 7] << 8 |       // high byte = bit mask
         (uchar)(bitptr / 8 + BIT_START);       // low  byte = byte address
}


void setibit( uchar bitptr )                    // *bitptr = 1;
{
  uint mask_addr = getibit( bitptr );
  *(uchar idata *)(mask_addr |= mask_addr >> 8;
}


void clribit( uchar bitptr )                    // *bitptr = 0;
{
  uint mask_addr = getibit( bitptr );
  *(uchar idata *)mask_addr &= ~(mask_addr >> 8);
}


void cplibit( uchar bitptr )                    // *bitptr ^= 1;
{
  uint mask_addr = getibit( bitptr );
  *(uchar idata *)mask_addr ^= ~(mask_addr >> 8);
}


void movibit( uchar bitptr, bit inbit )         // *bitptr = inbit;
{
  inbit ? setibit( bitptr ) : clribit( bitptr );
}


bit tstibit( uchar bitptr )                     // return *bitptr;
{
  uint mask_addr = getibit( bitptr );
  return *(uchar idata *)mask_addr & mask_addr >> 8;
}