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