/******************************************************************************
 * ATOMIC OPERATIONS for ATMEGA328 ONLY
 * Since the ATMega328 is an 8 bit processor it is possible that you will end
 * up trying to read a multi-byte quantity that is modified in an interrupt while
 * you are doing the read or write. The result is a corrupt value. 32 bit processors
 * are unlikely to suffer from this since quantities are read in a single operation.
 *
 * The AVR compiler provides a method for you to disable interrupts for the
 * duration of a block of code and then restore the state at the end of the block.
 *
 * It is not enough to simply turn off interrupts and then turn them back on because
 * you need to remember the state of the interrupt enable flag at the start of the
 * block.
 *
 * These macros do this for you and should be either modified for different processors
 * or bypassed if needed.
 *
 * Use like this:
 * ATOMIC {
 * // code to protect
 * }
 *
 */