[avr-libc-commit] [2105] Add forgotten ChaneLog entry about the builtins probing and header

[Joerg Wunsch]

Revision: 2105
          http://svn.sv.gnu.org/viewvc/?view=rev&root=avr-libc&revision=2105
Author:   joerg_wunsch
Date:     2010-03-19 22:35:01 +0000 (Fri, 19 Mar 2010)
Log Message:
-----------
Add forgotten ChaneLog entry about the builtins probing and header
file generation.

Modified Paths:
--------------
    trunk/avr-libc/ChangeLog

Modified: trunk/avr-libc/ChangeLog
===================================================================
--- trunk/avr-libc/ChangeLog    2010-03-19 22:23:20 UTC (rev 2104)
+++ trunk/avr-libc/ChangeLog    2010-03-19 22:35:01 UTC (rev 2105)
@@ -13,6 +13,28 @@
        * include/avr/iousb646.h: Same.
        * NEWS: Add to fixed bug list.
 
+2010-02-17  Joerg Wunsch <address@hidden>
+
+       Probe the compiler for the availability of the
+       __builtin_avr_delay_cycles() function, and modify the header files
+       <util/delay.h> and <avr/builtins.h> appropriately.  Note that the
+       modification is done by setting __HAS_DELAY_CYCLES on top of those
+       files, which has been left overridable from the compiler
+       environment (i.e., commandline -D option) on purpose.  Note also
+       that _delay_us() and _delay_ms() can only use
+       __builtin_avr_delay_cycles() if optimization is enabled as they'd
+       otherwise try to pass a floating-point argument to it which is not
+       allowed.  (The compiler does not seem to be able to convert it
+       into an unsigned long internally, not even with a type cast.)
+       However, not enabling optimization for them yields garbage timing
+       anyway, due to moving the compile-time constant floating-point
+       calculations from the compiler into the AVR.
+       * configure.ac: Add detection of __builtin_avr_delay_cycles
+       * include/util/delay.h.in: repocopied from delay.h
+       * include/util/Makefile.am: added delay.h.in
+       * include/avr/builtins.h.in: New file.
+       * include/avr/Makefile.am: added builtins.h.in
+
 2010-03-11  Eric B. Weddington  <address@hidden>
 
        Fix bug #28812.