__builtin_propeller_waitcnt()

JonnyMac

What is the purpose of param1 in __builtin_propeller_waitcnt(target, param1)?

macca

It is the equivalent of waitcnt target, param1 in pasm.
To get the same functionality, you need to use the return value of __builtin_propeller_waitcnt which is target+param1, since In C parameters are passed by value so any modification is local to the function.

See also the waitcnt and waitcnt2 helper functions.

ersmith

JonnyMac wrote: »

What is the purpose of param1 in __builtin_propeller_waitcnt(target, param1)?

It's used to update the target time for the next waitcnt:

  targetCnt = CNT + freq; // set up initial interval
  do {
      // do something useful that takes less than "freq" cycles
      ...
      // now sleep until interval is finished
      targetCnt = __builtin_propeller_waitcnt(targetCnt, freq);
      // targetCnt has been updated to the next CNT to wait for
   } while (condition);

JonnyMac

SMH. I should have known that. Thanks!