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[wwwdocs] Add v7 AVR release notes.

Message ID 3f09b368-e948-711f-b44a-200dbadc3a8b@gjlay.de
State New
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Commit Message

Georg-Johann Lay Oct. 7, 2016, 2:06 p.m. UTC 
Mentioning some AVR target specific improvements.

Ok?

Comments

Denis Chertykov Oct. 7, 2016, 6:52 p.m. UTC | #1 
2016-10-07 17:06 GMT+03:00 Georg-Johann Lay <avr@gjlay.de>:
> Mentioning some AVR target specific improvements.
>
> Ok?
>

Ok.
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Patch

Index: changes.html
===================================================================
RCS file: /cvs/gcc/wwwdocs/htdocs/gcc-7/changes.html,v
retrieving revision 1.15
diff -r1.15 changes.html
261c261,299
< <!-- <h3 id="avr">AVR</h3> -->
---
> <h3 id="avr">AVR</h3>
> <ul>
>   <li>On the reduced Tiny cores, the <code>progmem</code>
>     <a href="https://gcc.gnu.org/onlinedocs/gcc/AVR-Variable-Attributes.html">variable
>       attribute</a>
>     is now properly supported.  Respective read-only variables are located
>     in flash memory in section <code>.progmem.data</code>.  No special
>     code is needed to access such variables; the compiler automatically
>     adds an offset of <code>0x4000</code> to all addresses which is needed
>     to access variables in flash memory.  As opposed to ordinary cores
>     where it is sufficient to specify the <code>progmem</code> attribute
>     with definitions, on the reduced Tiny cores the attribute has also to
>     be specified with (external) declarations:
>     <blockquote><pre>
> extern const int array[] __attribute__((__progmem__));
> 
> int get_value2 (void)
> {
>   /* Access via addresses array + 0x4004 and array + 0x4005. */
>   return array[2];
> }
> 
> const int* get_address (unsigned idx)
> {
>   /* Returns array + 0x4000 + 2 * idx. */
>   return &amp;array[idx];
> }</pre></blockquote></li>
>   <li>A new command line option <code>-Wmisspelled-isr</code> has been added.
>     It can be used to turn off &mdash; or turn into errors &mdash;
>     warnings that are reported for interrupt service routines (ISRs)
>     which don't follow AVR-LibC's naming convention of prefixing
>     ISR names with <code>__vector</code>.</li>
>   <li><code>__builtin_avr_nops(n_nops)</code> is a new
>     <a href="https://gcc.gnu.org/onlinedocs/gcc/AVR-Built-in-Functions.html">built-in
>       function</a>
>     that inserts <code>n_nops</code> <code>NOP</code> instructions into
>     the instruction stream. <code>n_nops</code> must be a value known at
>     compile time.</li>
> </ul>