minix/sys/lib/libkern/arch/arm/clzsi2.S
2012-02-09 18:48:13 +01:00

89 lines
2.5 KiB
ArmAsm

/*-
* Copyright (c) 2008 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Matt Thomas <matt@3am-software.com>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
#include <machine/asm.h>
.text
ENTRY(__clzdi2)
movs r3, r0
movne r0, #31
bne .L_clz
movs r3, r1
movne r0, #63
bne .L_clz
mov r0, #64
RET
END(__clzdi2)
ENTRY(__clzsi2)
movs r3, r0
moveq r0, #32
RETc(eq)
mov r0, #31
.L_clz:
mvn r1, #0
#ifndef __OPTIMIZE_SIZE__
eor r1, r1, r1, lsr #16 /* 0xFFFFFFFF -> 0xFFFF0000 */
ands r2, r3, r1
eorne r0, r0, #16
movne r3, r2
eor r1, r1, r1, lsr #8 /* 0xFFFF0000 -> 0xFF00FF00 */
ands r2, r3, r1
eorne r0, r0, #8
movne r3, r2
eor r1, r1, r1, lsr #4 /* 0xFF00FF00 -> 0xF0F0F0F0 */
ands r2, r3, r1
eorne r0, r0, #4
movne r3, r2
eor r1, r1, r1, lsr #2 /* 0xF0F0F0F0 -> 0xCCCCCCCC */
ands r2, r3, r1
eorne r0, r0, #2
movne r3, r2
eor r1, r1, r1, lsr #1 /* 0xCCCCCCCC -> 0xAAAAAAAA */
ands r2, r3, r1
eorne r0, r0, #1
#if 0
teqeq r3, #0
addeq r0, r0, #1
#endif
#else
mov r2, #16
1: eor r1, r1, r1, lsr r2
ands ip, r3, r1
movne r3, ip
eorne r0, r0, r2
movs r2, r2, lsr #1
bne 1b
#if 0
teq r3, #0
addeq r0, r0, #1
#endif
#endif /* __OPTIMIZE_SIZE__ */
RET
END(__clzsi2)