The until statement

SPC also defines an until macro for compatibility with NQC.

This construct provides a convenient alternative to the while loop. The actual definition of until is shown below.

#define until(c)        while(!(c))

In other words, until will continue looping until the condition becomes true. It is most often used in conjunction with an empty body statement or a body which simply yields to other tasks:

until(EVENT_OCCURS);    // wait for some event to occur