[avr-libc-commit] [2349] Edit documentation of 'system-tick().

[Mike Rice]

Revision: 2349
          http://svn.sv.gnu.org/viewvc/?view=rev&root=avr-libc&revision=2349
Author:   swfltek
Date:     2013-04-17 21:27:25 +0000 (Wed, 17 Apr 2013)
Log Message:
-----------
Edit documentation of 'system-tick(). The previous description has been 
construed by some to assert that it is unsafe to be called from anywhere except 
a 'naked' ISR.

Modified Paths:
--------------
    trunk/avr-libc/include/time.h

Modified: trunk/avr-libc/include/time.h
===================================================================
--- trunk/avr-libc/include/time.h       2013-04-16 23:42:05 UTC (rev 2348)
+++ trunk/avr-libc/include/time.h       2013-04-17 21:27:25 UTC (rev 2349)
@@ -232,9 +232,15 @@
     void            set_system_time(struct tm * tmptr);
 
     /**
-        This function increments the system clock, and must be called at a 
rate of one Hertz
-        to maintain the system time. This function is safe to be called from a 
'naked' ISR...
+        Maintain the system time by calling this function at a rate of 1 Hertz.
 
+        It is anticipated that this function will typically be called from 
within an
+        Interrupt Service Routine, (though that is not required). It therefore 
includes all necessary
+        prologue and epilogue, allowing it to be called from within a 'naked' 
ISR,  which will prevent
+        an unnecessary cpu register 'spill'
+
+        Such an ISR may resemble the following example...
+
             ISR(TIMER2_COMPA_vect, ISR_NAKED)
             {
                 system_tick_i();