minix/lib/nbsd_libc/arch/hppa/string/ffs.S
Gianluca Guida b6cbf7203b Import unmodified NetBSD libc in trunk
This patch imports the unmodified current version of NetBSD libc.
The NetBSD includes are in /nbsd_include, while the libc code itself is 
split between lib/nbsd_libc and common/lib/libc.
2011-02-14 19:36:03 +00:00

63 lines
2.2 KiB
ArmAsm

/* $NetBSD: ffs.S,v 1.3 2004/07/18 20:30:04 chs Exp $ */
/* $OpenBSD: ffs.S,v 1.3 2001/06/04 23:14:02 mickey Exp $ */
/*
* Copyright (c) 1990, 1991, 1992, 1994, The University of Utah and
* the Computer Systems Laboratory at the University of Utah (CSL).
* All rights reserved.
*
* Permission to use, copy, modify and distribute this software and its
* documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
* IS" CONDITION. THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
* ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* CSL requests users of this software to return to csl-dist@cs.utah.edu any
* improvements that they make and grant CSL redistribution rights.
*
*/
#include <machine/asm.h>
#ifdef SYSLIBC_SCCS
.text
.asciz "$OpenBSD: ffs.S,v 1.3 2001/06/04 23:14:02 mickey Exp $"
.align 4
#endif
/*
* ffs(bitmask)
*
* Return the position of the "most significant" bit in `bitmask'.
* Since this is similar to the VAX ffs instruction, bits in a word
* are numbered as "32, 31, ... 1", 0 is returned if no bits are set.
*/
LEAF_ENTRY(ffs)
comb,= %arg0,%r0,ffsdone ; If arg0 is 0
or %r0,%r0,%ret0 ; return 0
ldi 32,%ret0 ; Set return to high bit
extru,= %arg0,31,16,%r0 ; If low 16 bits are non-zero
addi,tr -16,%ret0,%ret0 ; subtract 16 from bitpos
shd %r0,%arg0,16,%arg0 ; else shift right 16 bits
extru,= %arg0,31,8,%r0 ; If low 8 bits are non-zero
addi,tr -8,%ret0,%ret0 ; subtract 8 from bitpos
shd %r0,%arg0,8,%arg0 ; else shift right 8 bits
extru,= %arg0,31,4,%r0 ; If low 4 bits are non-zero
addi,tr -4,%ret0,%ret0 ; subtract 4 from bitpos
shd %r0,%arg0,4,%arg0 ; else shift right 4 bits
extru,= %arg0,31,2,%r0 ; If low 2 bits are non-zero
addi,tr -2,%ret0,%ret0 ; subtract 2 from bitpos
shd %r0,%arg0,2,%arg0 ; else shift right 2 bits
extru,= %arg0,31,1,%r0 ; If low bit is non-zero
addi -1,%ret0,%ret0 ; subtract 1 from bitpos
ffsdone:
bv,n %r0(%rp)
EXIT(ffs)
.end