Re: [avr-libc-dev] Re: [avr-libc-commit] [2158] Submitted by Jan Waclawek:

[Jan Waclawek]

#$%^... sorry. Mea culpa.

Joerg, would you please fix it? Thanks.

Jan


On Thu, 10 Jun 2010 22:25:12 +0200
Wouter van Gulik <address@hidden> wrote:

> Joerg Wunsch schreef:
> >
> > +
> > +\code
> > +#define cli() __asm volatile( "cli" ::: "memory" )
> > +#define sei() __asm volatile( "sei" ::: "memory" )
> > +
> > +unsigned int ivar;
> > +
> > +void test2( unsigned int val )
> > +{
> > +  val = 65535U / val;
> > +
> > +  cli();
> > +
> > +  ivar = val;
> > +
> > +  sei();
> > +}
> > +\endcode
> > +
> > +compiles with optimisations switched on (-Os) to
> > +
> > +\verbatim
> > +00000112 <test2>:
> > + 112:      bc 01           movw    r22, r24
> > + 114:      f8 94           cli
> > + 116:      8f ef           ldi     r24, 0xFF       ; 255
> > + 118:      9f ef           ldi     r25, 0xFF       ; 255
> > + 11a:      0e 94 96 00     call    0x12c   ; 0x12c <__udivmodhi4>
> > + 11e:      70 93 01 02     sts     0x0201, r23
> > + 122:      60 93 00 02     sts     0x0200, r22
> > + 126:      78 94           sei
> > + 128:      08 95           ret
> > +\endverbatim
> > +
> > +where the potentially slow multiplication is moved across cli(),
> > +resulting in interrupts to be disabled longer than intended.
> There is "typo", the texts talks about multiplication instead of divide.
> 
> HTH,
> 
> Wouter
>