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

/* Copyright (C) 2010-2019 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
   <https://www.gnu.org/licenses/>.  */

/*
   Assumes:
   ARMv6T2, AArch32

 */

#include <arm-features.h>
#include <sysdep.h>

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

/* This code is best on Thumb.  */
	.thumb

/* 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)
	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.  */
	pld	[src, #32]
	bne.w	.Lmisaligned8
	mov	const_0, #0
	mov	result, #-8
.Lloop_aligned:
	/* Bytes 0-7.  */
	ldrd	data1a, data1b, [src]
	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.  */
	ldrd	data1a, data1b, [src, #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.  */
	ldrd	data1a, data1b, [src, #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.  */
	ldrd	data1a, data1b, [src, #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
	ldrd	data1a, data1b, [src]
	and	tmp2, tmp1, #3
	rsb	result, tmp1, #0
	lsl	tmp2, tmp2, #3			/* Bytes -> bits.  */
	tst	tmp1, #4
	pld	[src, #64]
	S2HI	tmp2, const_m1, tmp2
	orn	data1a, data1a, tmp2
	itt	ne
	ornne	data1b, data1b, tmp2
	movne	data1a, const_m1
	mov	const_0, #0
	b	.Lstart_realigned

END(strlen)
libc_hidden_builtin_def (strlen)
Commit	Line	Data
04277e02	1	/* Copyright (C) 2010-2019 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
5a82c748	16	<https://www.gnu.org/licenses/>. */
2601bc18 WN	17
	18	/*
	19	Assumes:
	20	ARMv6T2, AArch32
	21
	22	*/
	23
743b9c2a	24	#include <arm-features.h>
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	35	/* This code is best on Thumb. */
2601bc18	36	.thumb
2601bc18 WN	37
	38	/* Parameters and result. */
	39	#define srcin r0
	40	#define result r0
	41
	42	/* Internal variables. */
	43	#define src r1
	44	#define data1a r2
	45	#define data1b r3
	46	#define const_m1 r12
	47	#define const_0 r4
	48	#define tmp1 r4 /* Overlaps const_0 */
	49	#define tmp2 r5
	50
	51	.text
	52	.p2align 6
	53	ENTRY(strlen)
81cb7a0b	54	pld [srcin, #0]
2601bc18 WN	55	strd r4, r5, [sp, #-8]!
	56	cfi_adjust_cfa_offset (8)
	57	cfi_rel_offset (r4, 0)
	58	cfi_rel_offset (r5, 4)
	59	cfi_remember_state
	60	bic src, srcin, #7
	61	mvn const_m1, #0
	62	ands tmp1, srcin, #7 /* (8 - bytes) to alignment. */
81cb7a0b	63	pld [src, #32]
2601bc18 WN	64	bne.w .Lmisaligned8
	65	mov const_0, #0
	66	mov result, #-8
	67	.Lloop_aligned:
	68	/* Bytes 0-7. */
81cb7a0b ZW	69	ldrd data1a, data1b, [src]
81cb7a0b ZW	70	pld [src, #64]
2601bc18 WN	71	add result, result, #8
	72	.Lstart_realigned:
	73	uadd8 data1a, data1a, const_m1 /* Saturating GE<0:3> set. */
	74	sel data1a, const_0, const_m1 /* Select based on GE<0:3>. */
	75	uadd8 data1b, data1b, const_m1
	76	sel data1b, data1a, const_m1 /* Only used if d1a == 0. */
	77	cbnz data1b, .Lnull_found
	78
	79	/* Bytes 8-15. */
81cb7a0b	80	ldrd data1a, data1b, [src, #8]
2601bc18 WN	81	uadd8 data1a, data1a, const_m1 /* Saturating GE<0:3> set. */
	82	add result, result, #8
	83	sel data1a, const_0, const_m1 /* Select based on GE<0:3>. */
	84	uadd8 data1b, data1b, const_m1
	85	sel data1b, data1a, const_m1 /* Only used if d1a == 0. */
	86	cbnz data1b, .Lnull_found
	87
	88	/* Bytes 16-23. */
81cb7a0b	89	ldrd data1a, data1b, [src, #16]
2601bc18 WN	90	uadd8 data1a, data1a, const_m1 /* Saturating GE<0:3> set. */
	91	add result, result, #8
	92	sel data1a, const_0, const_m1 /* Select based on GE<0:3>. */
	93	uadd8 data1b, data1b, const_m1
	94	sel data1b, data1a, const_m1 /* Only used if d1a == 0. */
	95	cbnz data1b, .Lnull_found
	96
	97	/* Bytes 24-31. */
81cb7a0b	98	ldrd data1a, data1b, [src, #24]
2601bc18 WN	99	add src, src, #32
	100	uadd8 data1a, data1a, const_m1 /* Saturating GE<0:3> set. */
	101	add result, result, #8
	102	sel data1a, const_0, const_m1 /* Select based on GE<0:3>. */
	103	uadd8 data1b, data1b, const_m1
	104	sel data1b, data1a, const_m1 /* Only used if d1a == 0. */
	105	cmp data1b, #0
	106	beq .Lloop_aligned
	107
	108	.Lnull_found:
	109	cmp data1a, #0
	110	itt eq
	111	addeq result, result, #4
	112	moveq data1a, data1b
	113	#ifndef __ARMEB__
	114	rev data1a, data1a
	115	#endif
	116	clz data1a, data1a
	117	ldrd r4, r5, [sp], #8
	118	cfi_adjust_cfa_offset (-8)
	119	cfi_restore (r4)
	120	cfi_restore (r5)
	121	add result, result, data1a, lsr #3 /* Bits -> Bytes. */
	122	DO_RET(lr)
	123
	124	.Lmisaligned8:
	125	cfi_restore_state
81cb7a0b	126	ldrd data1a, data1b, [src]
2601bc18 WN	127	and tmp2, tmp1, #3
	128	rsb result, tmp1, #0
	129	lsl tmp2, tmp2, #3 /* Bytes -> bits. */
	130	tst tmp1, #4
81cb7a0b	131	pld [src, #64]
2601bc18 WN	132	S2HI tmp2, const_m1, tmp2
	133	orn data1a, data1a, tmp2
	134	itt ne
	135	ornne data1b, data1b, tmp2
	136	movne data1a, const_m1
	137	mov const_0, #0
	138	b .Lstart_realigned
	139
	140	END(strlen)
	141	libc_hidden_builtin_def (strlen)