cosmopolitan/libc/intrin/aarch64/memset.S

/*-*- mode:unix-assembly; indent-tabs-mode:t; tab-width:8; coding:utf-8     -*-│
│ vi: set noet ft=asm ts=8 sw=8 fenc=utf-8                                 :vi │
╚──────────────────────────────────────────────────────────────────────────────╝
│                                                                              │
│  Optimized Routines                                                          │
│  Copyright (c) 2018-2024, Arm Limited.                                       │
│                                                                              │
│  Permission is hereby granted, free of charge, to any person obtaining       │
│  a copy of this software and associated documentation files (the             │
│  "Software"), to deal in the Software without restriction, including         │
│  without limitation the rights to use, copy, modify, merge, publish,         │
│  distribute, sublicense, and/or sell copies of the Software, and to          │
│  permit persons to whom the Software is furnished to do so, subject to       │
│  the following conditions:                                                   │
│                                                                              │
│  The above copyright notice and this permission notice shall be              │
│  included in all copies or substantial portions of the Software.             │
│                                                                              │
│  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,             │
│  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF          │
│  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.      │
│  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY        │
│  CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,        │
│  TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE           │
│  SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                      │
│                                                                              │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/intrin/aarch64/asmdefs.h"
.yoink arm_optimized_routines_notice

#define __memset_aarch64 memset

/* Assumptions:
 *
 * ARMv8-a, AArch64, Advanced SIMD, unaligned accesses.
 *
 */

#define dstin	x0
#define val	x1
#define valw	w1
#define count	x2
#define dst	x3
#define dstend	x4
#define zva_val	x5

ENTRY (__memset_aarch64)
	PTR_ARG (0)
	SIZE_ARG (2)

	dup	v0.16B, valw
	add	dstend, dstin, count

	cmp	count, 96
	b.hi	L(set_long)
	cmp	count, 16
	b.hs	L(set_medium)
	mov	val, v0.D[0]

	/* Set 0..15 bytes.  */
	tbz	count, 3, 1f
	str	val, [dstin]
	str	val, [dstend, -8]
	ret
	.p2align 4
1:	tbz	count, 2, 2f
	str	valw, [dstin]
	str	valw, [dstend, -4]
	ret
2:	cbz	count, 3f
	strb	valw, [dstin]
	tbz	count, 1, 3f
	strh	valw, [dstend, -2]
3:	ret

	/* Set 17..96 bytes.  */
L(set_medium):
	str	q0, [dstin]
	tbnz	count, 6, L(set96)
	str	q0, [dstend, -16]
	tbz	count, 5, 1f
	str	q0, [dstin, 16]
	str	q0, [dstend, -32]
1:	ret

	.p2align 4
	/* Set 64..96 bytes.  Write 64 bytes from the start and
	   32 bytes from the end.  */
L(set96):
	str	q0, [dstin, 16]
	stp	q0, q0, [dstin, 32]
	stp	q0, q0, [dstend, -32]
	ret

	.p2align 4
L(set_long):
	and	valw, valw, 255
	bic	dst, dstin, 15
	str	q0, [dstin]
	cmp	count, 160
	ccmp	valw, 0, 0, hs
	b.ne	L(no_zva)

#ifndef SKIP_ZVA_CHECK
	mrs	zva_val, dczid_el0
	and	zva_val, zva_val, 31
	cmp	zva_val, 4		/* ZVA size is 64 bytes.  */
	b.ne	L(no_zva)
#endif
	str	q0, [dst, 16]
	stp	q0, q0, [dst, 32]
	bic	dst, dst, 63
	sub	count, dstend, dst	/* Count is now 64 too large.  */
	sub	count, count, 128	/* Adjust count and bias for loop.  */

	.p2align 4
L(zva_loop):
	add	dst, dst, 64
	dc	zva, dst
	subs	count, count, 64
	b.hi	L(zva_loop)
	stp	q0, q0, [dstend, -64]
	stp	q0, q0, [dstend, -32]
	ret

L(no_zva):
	sub	count, dstend, dst	/* Count is 16 too large.  */
	sub	dst, dst, 16		/* Dst is biased by -32.  */
	sub	count, count, 64 + 16	/* Adjust count and bias for loop.  */
L(no_zva_loop):
	stp	q0, q0, [dst, 32]
	stp	q0, q0, [dst, 64]!
	subs	count, count, 64
	b.hi	L(no_zva_loop)
	stp	q0, q0, [dstend, -64]
	stp	q0, q0, [dstend, -32]
	ret

END (__memset_aarch64)