To turn on bit 6 of x:
  x = x | 0x00000080 ;
or, with fewer characters
  x |= 0x00000080 ;
or, without having to figure out where the 6'th bit isor, 
  x = x | (1<<6) ;

To turn off bit 6 of x:
  x = x & 0xFFFFFF7F ;
or, To turn off bit 6 without evening knowing the word size
  x = x & ~0x0080 ;
or, with fewer character
  x &= & ~0x0080 ;
or, without even knowing the word size!
  x = x & ~(1<<6) ;

Turning on bits 6 to 11
  x = x | 0x00000FC0 ;
  x |= 0x00000FC0 ;
  x = x | (0x3F<<6) ;

Turning off bits 6 to 11
  x = x & 0xFFFFF03F ;
  x = x & ~0x0FC0 ;
  x &= ~0x0FC0 ;
  x = x & ~(0x3F<<6) ;

Turning on bits BS to BF
  x = x |  ( ((1 << (BF - BS)) - 1) << BS) ;
Turning off bits BS to BF
  x = x & ~( ((1 << (BF - BS)) - 1) << BS) ;