ffsll.S

/* Copyright (c) 2005, 2007 Dmitry Xmelkov

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in
the documentation and/or other materials provided with the
distribution.
* Neither the name of the copyright holders nor the names of
contributors may be used to endorse or promote products derived
from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE. */

/* $Id$ */

#if !defined(__AVR_TINY__)

/** \file */

/** \ingroup avr_string
\fn int ffsll (long long val);

\brief Same as ffs(), for an argument of type long long.    */

#ifndef __DOXYGEN__

#include "macros.inc"

#define val_0   r18
#define val_8   r19
#define val_16  r20
#define val_24  r21
#define val_32  r22
#define val_40  r23
#define val_48  r24
#define val_56  r25

#define wrd_lo  r30
#define wrd_hi  r31
#define cntr    r18

ASSEMBLY_CLIB_SECTION
.global     _U(ffsll)
.type       _U(ffsll), @function
_U(ffsll):

X_movw  wrd_lo, val_0
ldi     cntr, 1
sbiw    wrd_lo, 0
brne    1f
X_movw  wrd_lo, val_16
subi    cntr, -16
sbiw    wrd_lo, 0
brne    1f
X_movw  wrd_lo, val_32
subi    cntr, -16
sbiw    wrd_lo, 0
brne    1f
X_movw  wrd_lo, val_48
subi    cntr, -16
sbiw    wrd_lo, 0
breq    9f

1:      tst     wrd_lo
brne    3f
subi    cntr, -7
mov     wrd_lo, wrd_hi
2:      inc     cntr
3:      ror     wrd_lo
brcc    2b

mov     r24, cntr
clr     r25
9:      ret

.size  _U(ffsll), . - _U(ffsll)
.end

#endif  /* not __DOXYGEN__ */

#endif /* !defined(__AVR_TINY__) */