busywaitmicroc.nc

tinyos-2.x.rar

/*
 * Copyright (c) 2009 Communication Group and Eislab at
 * Lulea University of Technology
 *
 * Contact: Laurynas Riliskis, LTU
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/**
 * Implementation of the HIL required micro busy wait.
 * For more information see TEP 102.
 *
 * @author Henrik Makitaavola <[e-mail]>
 */
module BusyWaitMicroC
{
  provides interface BusyWait<TMicro, uint16_t>;
}
implementation
{
  // TODO(henrik) This will now only work on 10Mhz speed, easy to
  //              add a signal from the control module of the mcu
  //              to signal the change of speed and the wait function
  //              can adjust to it.
  // The wait function can not be inlined because then the code alignment may
  // go lost thus making the busy wait around 30% slower.
  async command void BusyWait.wait(uint16_t dt ) __attribute__((noinline)) {
    atomic {
      asm("nop"); // Nop needed to align function
      asm volatile (
          "sub.w #1,%[t]\n\t"
          "jeq 2f\n\t"
          "sub.w #1,%[t]\n\t"
          "jeq 2f\n\t"
          "1:\n\t"
          "nop\n\t"
          "add.w #1,%[t]\n\t"
          "sub.w #1,%[t]\n\t"
          "sub.w #1,%[t]\n\t"
          "jgtu 1b\n\t"
          "2:"
          :   
          : [t] "r" (dt)
          );  
    } 
  } 
}