1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * arch/alpha/lib/strchr.S
4  * Contributed by Richard Henderson (rth@tamu.edu)
5  *
6  * Return the address of a given character within a null-terminated
7  * string, or null if it is not found.
8  */
9 #include <linux/export.h>
10 #include <asm/regdef.h>
11 
12 	.set noreorder
13 	.set noat
14 
15 	.align 3
16 	.globl strchr
17 	.ent strchr
18 strchr:
19 	.frame sp, 0, ra
20 	.prologue 0
21 
22 	zapnot	a1, 1, a1	# e0    : zero extend the search character
23 	ldq_u   t0, 0(a0)	# .. e1 : load first quadword
24 	sll	a1, 8, t5	# e0    : replicate the search character
25 	andnot  a0, 7, v0	# .. e1 : align our loop pointer
26 	or	t5, a1, a1	# e0    :
27 	lda	t4, -1		# .. e1 : build garbage mask
28 	sll	a1, 16, t5	# e0    :
29 	cmpbge  zero, t0, t2	# .. e1 : bits set iff byte == zero
30 	mskqh	t4, a0, t4	# e0    :
31 	or	t5, a1, a1	# .. e1 :
32 	sll	a1, 32, t5	# e0    :
33 	cmpbge	zero, t4, t4	# .. e1 : bits set iff byte is garbage
34 	or	t5, a1, a1	# e0    :
35 	xor	t0, a1, t1	# .. e1 : make bytes == c zero
36 	cmpbge  zero, t1, t3	# e0    : bits set iff byte == c
37 	or	t2, t3, t0	# e1    : bits set iff char match or zero match
38 	andnot	t0, t4, t0	# e0    : clear garbage bits
39 	bne	t0, $found	# .. e1 (zdb)
40 
41 $loop:	ldq	t0, 8(v0)	# e0    :
42 	addq	v0, 8, v0	# .. e1 :
43 	nop			# e0    :
44 	xor	t0, a1, t1	# .. e1 (ev5 data stall)
45 	cmpbge	zero, t0, t2	# e0    : bits set iff byte == 0
46 	cmpbge	zero, t1, t3	# .. e1 : bits set iff byte == c
47 	or	t2, t3, t0	# e0    :
48 	beq	t0, $loop	# .. e1 (zdb)
49 
50 $found:	negq    t0, t1		# e0    : clear all but least set bit
51 	and     t0, t1, t0	# e1 (stall)
52 
53 	and	t0, t3, t1	# e0    : bit set iff byte was the char
54 	beq	t1, $retnull	# .. e1 (zdb)
55 
56 	and     t0, 0xf0, t2	# e0    : binary search for that set bit
57 	and	t0, 0xcc, t3	# .. e1 :
58 	and	t0, 0xaa, t4	# e0    :
59 	cmovne	t2, 4, t2	# .. e1 :
60 	cmovne	t3, 2, t3	# e0    :
61 	cmovne	t4, 1, t4	# .. e1 :
62 	addq	t2, t3, t2	# e0    :
63 	addq	v0, t4, v0	# .. e1 :
64 	addq	v0, t2, v0	# e0    :
65 	ret			# .. e1 :
66 
67 $retnull:
68 	mov	zero, v0	# e0    :
69 	ret			# .. e1 :
70 
71 	.end strchr
72 	EXPORT_SYMBOL(strchr)
73