From Fri, 21 Aug 2009 21:35:39 +0200 (MET DST) j...@uriah.heep.sax.de (Joerg Wunsch) wrote:
> Francisco Silva <fran...@gmail.com> wrote:
> > Try the following spell:
> Using a typecast looks a little better, I think.
Looks better, but does not work. But Francisco recipe works, wonders.
Another solution which works is your hint about inline functions, e.g:
static inline uint8_t dummy (uint8_t x) { return x; }
if (dummy (flags & (FLAG_A | FLAG_B))) ...
what's interesting as well is that I have two of such if's in code, and
"fixing" the first one automagically fixes the second if without making
any actual modifications to it.
> Andrew, maybe you can post some compilable code snippet to check.
Sure, I've attached a bare-bone sample which I can't force to use eight
bits without the temporary variable or inline function hack.
The command line I use is:
avr-gcc -mmcu=atmega168 -S -Os code.c
in the resulting .S file (I hope) you will see this:
movw r24,r28
andi r24,lo8(7)
andi r25,hi8(7)
or r24,r25
breq .L2
call something
.L2:
...
ditto for second if.
--
Andrew
#include <stdint.h>
#define TTY_F_DISPLAY ((uint8_t)0x01)
#define TTY_F_CURSOR ((uint8_t)0x02)
#define TTY_F_BLINKCURSOR ((uint8_t)0x04)
#define TTY_F_SCROLL ((uint8_t)0x08)
#define TTY_F_L2R ((uint8_t)0x10)
uint8_t tty_flags;
extern void something (void);
extern void somethingelse (void);
static inline uint8_t blah (uint8_t x)
{ return x; }
void tty_setup (uint8_t flags, uint8_t mask)
{
uint8_t new_flags = (tty_flags & ~mask) | (flags & mask);
uint8_t flags_changed = new_flags ^ tty_flags;
tty_flags = new_flags;
if (flags_changed & (TTY_F_DISPLAY | TTY_F_CURSOR | TTY_F_BLINKCURSOR))
something ();
if (flags_changed & (TTY_F_SCROLL | TTY_F_L2R))
somethingelse ();
}
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