[thirdparty/glibc.git] / sysdeps / arm / armv6t2 / strlen.S

/* Copyright (C) 2010-2015 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library.  If not, see
   <http://www.gnu.org/licenses/>.  */

/*
   Assumes:
   ARMv6T2, AArch32

 */

#include <arm-features.h>               /* This might #define NO_THUMB.  */
#include <sysdep.h>

#ifdef __ARMEB__
#define S2LO		lsl
#define S2HI		lsr
#else
#define S2LO		lsr
#define S2HI		lsl
#endif

#ifndef NO_THUMB
/* This code is best on Thumb.  */
	.thumb
#else
/* Using bne.w explicitly is desirable in Thumb mode because it helps
   align the following label without a nop.  In ARM mode there is no
   such difference.  */
.macro bne.w label
	bne \label
.endm

/* This clobbers the condition codes, which the real Thumb cbnz instruction
   does not do.  But it doesn't matter for any of the uses here.  */
.macro cbnz reg, label
	cmp \reg, #0
	bne \label
.endm
#endif

/* Parameters and result.  */
#define srcin		r0
#define result		r0

/* Internal variables.  */
#define src		r1
#define data1a		r2
#define data1b		r3
#define const_m1	r12
#define const_0		r4
#define tmp1		r4		/* Overlaps const_0  */
#define tmp2		r5

	.text
	.p2align 6
ENTRY(strlen)
	sfi_pld	srcin, #0
	strd	r4, r5, [sp, #-8]!
	cfi_adjust_cfa_offset (8)
	cfi_rel_offset (r4, 0)
	cfi_rel_offset (r5, 4)
	cfi_remember_state
	bic	src, srcin, #7
	mvn	const_m1, #0
	ands	tmp1, srcin, #7		/* (8 - bytes) to alignment.  */
	sfi_pld	src, #32
	bne.w	.Lmisaligned8
	mov	const_0, #0
	mov	result, #-8
.Lloop_aligned:
	/* Bytes 0-7.  */
	sfi_breg src, \
	ldrd	data1a, data1b, [\B]
	sfi_pld	src, #64
	add	result, result, #8
.Lstart_realigned:
	uadd8	data1a, data1a, const_m1	/* Saturating GE<0:3> set.  */
	sel	data1a, const_0, const_m1	/* Select based on GE<0:3>.  */
	uadd8	data1b, data1b, const_m1
	sel	data1b, data1a, const_m1	/* Only used if d1a == 0.  */
	cbnz	data1b, .Lnull_found

	/* Bytes 8-15.  */
	sfi_breg src, \
	ldrd	data1a, data1b, [\B, #8]
	uadd8	data1a, data1a, const_m1	/* Saturating GE<0:3> set.  */
	add	result, result, #8
	sel	data1a, const_0, const_m1	/* Select based on GE<0:3>.  */
	uadd8	data1b, data1b, const_m1
	sel	data1b, data1a, const_m1	/* Only used if d1a == 0.  */
	cbnz	data1b, .Lnull_found

	/* Bytes 16-23.  */
	sfi_breg src, \
	ldrd	data1a, data1b, [\B, #16]
	uadd8	data1a, data1a, const_m1	/* Saturating GE<0:3> set.  */
	add	result, result, #8
	sel	data1a, const_0, const_m1	/* Select based on GE<0:3>.  */
	uadd8	data1b, data1b, const_m1
	sel	data1b, data1a, const_m1	/* Only used if d1a == 0.  */
	cbnz	data1b, .Lnull_found

	/* Bytes 24-31.  */
	sfi_breg src, \
	ldrd	data1a, data1b, [\B, #24]
	add	src, src, #32
	uadd8	data1a, data1a, const_m1	/* Saturating GE<0:3> set.  */
	add	result, result, #8
	sel	data1a, const_0, const_m1	/* Select based on GE<0:3>.  */
	uadd8	data1b, data1b, const_m1
	sel	data1b, data1a, const_m1	/* Only used if d1a == 0.  */
	cmp	data1b, #0
	beq	.Lloop_aligned

.Lnull_found:
	cmp	data1a, #0
	itt	eq
	addeq	result, result, #4
	moveq	data1a, data1b
#ifndef __ARMEB__
	rev	data1a, data1a
#endif
	clz	data1a, data1a
	ldrd	r4, r5, [sp], #8
	cfi_adjust_cfa_offset (-8)
	cfi_restore (r4)
	cfi_restore (r5)
	add	result, result, data1a, lsr #3	/* Bits -> Bytes.  */
	DO_RET(lr)

.Lmisaligned8:
	cfi_restore_state
	sfi_breg src, \
	ldrd	data1a, data1b, [\B]
	and	tmp2, tmp1, #3
	rsb	result, tmp1, #0
	lsl	tmp2, tmp2, #3			/* Bytes -> bits.  */
	tst	tmp1, #4
	sfi_pld	src, #64
	S2HI	tmp2, const_m1, tmp2
#ifdef NO_THUMB
	mvn	tmp1, tmp2
	orr	data1a, data1a, tmp1
	itt	ne
	orrne	data1b, data1b, tmp1
#else
	orn	data1a, data1a, tmp2
	itt	ne
	ornne	data1b, data1b, tmp2
#endif
	movne	data1a, const_m1
	mov	const_0, #0
	b	.Lstart_realigned

END(strlen)
libc_hidden_builtin_def (strlen)
Commit	Line	Data
b168057a	1	/* Copyright (C) 2010-2015 Free Software Foundation, Inc.
2601bc18 WN	2	This file is part of the GNU C Library.
	3
	4	The GNU C Library is free software; you can redistribute it and/or
	5	modify it under the terms of the GNU Lesser General Public
	6	License as published by the Free Software Foundation; either
	7	version 2.1 of the License, or (at your option) any later version.
	8
	9	The GNU C Library is distributed in the hope that it will be useful,
	10	but WITHOUT ANY WARRANTY; without even the implied warranty of
	11	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	12	Lesser General Public License for more details.
	13
	14	You should have received a copy of the GNU Lesser General Public
	15	License along with the GNU C Library. If not, see
	16	<http://www.gnu.org/licenses/>. */
	17
	18	/*
	19	Assumes:
	20	ARMv6T2, AArch32
	21
	22	*/
	23
21bfcecf	24	#include <arm-features.h> /* This might #define NO_THUMB. */
2601bc18 WN	25	#include <sysdep.h>
	26
	27	#ifdef __ARMEB__
	28	#define S2LO lsl
	29	#define S2HI lsr
	30	#else
	31	#define S2LO lsr
	32	#define S2HI lsl
	33	#endif
	34
21bfcecf RM	35	#ifndef NO_THUMB
21bfcecf RM	36	/* This code is best on Thumb. */
2601bc18	37	.thumb
21bfcecf RM	38	#else
	39	/* Using bne.w explicitly is desirable in Thumb mode because it helps
	40	align the following label without a nop. In ARM mode there is no
	41	such difference. */
	42	.macro bne.w label
	43	bne \label
	44	.endm
	45
	46	/* This clobbers the condition codes, which the real Thumb cbnz instruction
	47	does not do. But it doesn't matter for any of the uses here. */
	48	.macro cbnz reg, label
	49	cmp \reg, #0
	50	bne \label
	51	.endm
	52	#endif
2601bc18 WN	53
	54	/* Parameters and result. */
	55	#define srcin r0
	56	#define result r0
	57
	58	/* Internal variables. */
	59	#define src r1
	60	#define data1a r2
	61	#define data1b r3
	62	#define const_m1 r12
	63	#define const_0 r4
	64	#define tmp1 r4 /* Overlaps const_0 */
	65	#define tmp2 r5
	66
	67	.text
	68	.p2align 6
	69	ENTRY(strlen)
b0350db9	70	sfi_pld srcin, #0
2601bc18 WN	71	strd r4, r5, [sp, #-8]!
	72	cfi_adjust_cfa_offset (8)
	73	cfi_rel_offset (r4, 0)
	74	cfi_rel_offset (r5, 4)
	75	cfi_remember_state
	76	bic src, srcin, #7
	77	mvn const_m1, #0
	78	ands tmp1, srcin, #7 /* (8 - bytes) to alignment. */
b0350db9	79	sfi_pld src, #32
2601bc18 WN	80	bne.w .Lmisaligned8
	81	mov const_0, #0
	82	mov result, #-8
	83	.Lloop_aligned:
	84	/* Bytes 0-7. */
b0350db9 RM	85	sfi_breg src, \
	86	ldrd data1a, data1b, [\B]
	87	sfi_pld src, #64
2601bc18 WN	88	add result, result, #8
	89	.Lstart_realigned:
	90	uadd8 data1a, data1a, const_m1 /* Saturating GE<0:3> set. */
	91	sel data1a, const_0, const_m1 /* Select based on GE<0:3>. */
	92	uadd8 data1b, data1b, const_m1
	93	sel data1b, data1a, const_m1 /* Only used if d1a == 0. */
	94	cbnz data1b, .Lnull_found
	95
	96	/* Bytes 8-15. */
b0350db9 RM	97	sfi_breg src, \
b0350db9 RM	98	ldrd data1a, data1b, [\B, #8]
2601bc18 WN	99	uadd8 data1a, data1a, const_m1 /* Saturating GE<0:3> set. */
	100	add result, result, #8
	101	sel data1a, const_0, const_m1 /* Select based on GE<0:3>. */
	102	uadd8 data1b, data1b, const_m1
	103	sel data1b, data1a, const_m1 /* Only used if d1a == 0. */
	104	cbnz data1b, .Lnull_found
	105
	106	/* Bytes 16-23. */
b0350db9 RM	107	sfi_breg src, \
b0350db9 RM	108	ldrd data1a, data1b, [\B, #16]
2601bc18 WN	109	uadd8 data1a, data1a, const_m1 /* Saturating GE<0:3> set. */
	110	add result, result, #8
	111	sel data1a, const_0, const_m1 /* Select based on GE<0:3>. */
	112	uadd8 data1b, data1b, const_m1
	113	sel data1b, data1a, const_m1 /* Only used if d1a == 0. */
	114	cbnz data1b, .Lnull_found
	115
	116	/* Bytes 24-31. */
b0350db9 RM	117	sfi_breg src, \
b0350db9 RM	118	ldrd data1a, data1b, [\B, #24]
2601bc18 WN	119	add src, src, #32
	120	uadd8 data1a, data1a, const_m1 /* Saturating GE<0:3> set. */
	121	add result, result, #8
	122	sel data1a, const_0, const_m1 /* Select based on GE<0:3>. */
	123	uadd8 data1b, data1b, const_m1
	124	sel data1b, data1a, const_m1 /* Only used if d1a == 0. */
	125	cmp data1b, #0
	126	beq .Lloop_aligned
	127
	128	.Lnull_found:
	129	cmp data1a, #0
	130	itt eq
	131	addeq result, result, #4
	132	moveq data1a, data1b
	133	#ifndef __ARMEB__
	134	rev data1a, data1a
	135	#endif
	136	clz data1a, data1a
	137	ldrd r4, r5, [sp], #8
	138	cfi_adjust_cfa_offset (-8)
	139	cfi_restore (r4)
	140	cfi_restore (r5)
	141	add result, result, data1a, lsr #3 /* Bits -> Bytes. */
	142	DO_RET(lr)
	143
	144	.Lmisaligned8:
	145	cfi_restore_state
b0350db9 RM	146	sfi_breg src, \
b0350db9 RM	147	ldrd data1a, data1b, [\B]
2601bc18 WN	148	and tmp2, tmp1, #3
	149	rsb result, tmp1, #0
	150	lsl tmp2, tmp2, #3 /* Bytes -> bits. */
	151	tst tmp1, #4
b0350db9	152	sfi_pld src, #64
2601bc18	153	S2HI tmp2, const_m1, tmp2
21bfcecf RM	154	#ifdef NO_THUMB
	155	mvn tmp1, tmp2
	156	orr data1a, data1a, tmp1
	157	itt ne
	158	orrne data1b, data1b, tmp1
	159	#else
2601bc18 WN	160	orn data1a, data1a, tmp2
	161	itt ne
	162	ornne data1b, data1b, tmp2
21bfcecf	163	#endif
2601bc18 WN	164	movne data1a, const_m1
	165	mov const_0, #0
	166	b .Lstart_realigned
	167
	168	END(strlen)
	169	libc_hidden_builtin_def (strlen)