glibc/sysdeps/alpha/rawmemchr.S

/* Copyright (C) 2000-2022 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/>.  */

/* Return pointer to first occurrence of CH in STR.  */

#include <sysdep.h>

	.set noreorder
	.set noat

ENTRY(__rawmemchr)
#ifdef PROF
	ldgp	gp, 0(pv)
	lda	AT, _mcount
	jsr	AT, (AT), _mcount
	.prologue 1
#else
	.prologue 0
#endif

	zapnot	a1, 1, a1	# e0    : zero extend the search character
	ldq_u   t0, 0(a0)	# .. e1 : load first quadword
	sll	a1, 8, t5	# e0    : replicate the search character
	andnot  a0, 7, v0	# .. e1 : align our loop pointer

	or	t5, a1, a1	# e0    :
	lda	t4, -1		# .. e1 : build garbage mask
	sll	a1, 16, t5	# e0    :
	unop			#	:

	mskqh	t4, a0, t4	# e0    :
	or	t5, a1, a1	# .. e1 :
	sll	a1, 32, t5	# e0    :
	cmpbge	zero, t4, t4	# .. e1 : bits set iff byte is garbage

	or	t5, a1, a1	# e0    :
	xor	t0, a1, t1	# .. e1 : make bytes == c zero
	cmpbge  zero, t1, t3	# e0    : bits set iff byte == c
	unop			#	:

	andnot	t3, t4, t0	# e0    : clear garbage bits
	fnop			# .. fa :
	unop			#	:
	bne	t0, $found	# .. e1 (zdb)

	.align 4
$loop:
	ldq	t0, 8(v0)	# e0    :
	addq	v0, 8, v0	# .. e1 :
	nop			# e0    :
	xor	t0, a1, t1	# .. e1 (ev5 data stall)

	cmpbge	zero, t1, t0	# e0	: bits set iff byte == c
	beq	t0, $loop	# .. e1 (zdb)

$found:
	negq    t0, t1		# e0    : clear all but least set bit
	and     t0, t1, t0	# e1 (stall)
	and     t0, 0xf0, t2	# e0    : binary search for that set bit
	and	t0, 0xcc, t3	# .. e1 :

	and	t0, 0xaa, t4	# e0    :
	cmovne	t2, 4, t2	# .. e1 :
	cmovne	t3, 2, t3	# e0    :
	cmovne	t4, 1, t4	# .. e1 :

	addq	t2, t3, t2	# e0    :
	addq	v0, t4, v0	# .. e1 :
	addq	v0, t2, v0	# e0    :
	ret			# .. e1 :

	END(__rawmemchr)

libc_hidden_def (__rawmemchr)
weak_alias (__rawmemchr, rawmemchr)