1 /* SPDX-License-Identifier: GPL-2.0-only */ !! 1 /* SPDX-License-Identifier: GPL-2.0 */
2 /* 2 /*
3 * Based on arch/arm/lib/strchr.S !! 3 * arch/alpha/lib/strchr.S
>> 4 * Contributed by Richard Henderson (rth@tamu.edu)
4 * 5 *
5 * Copyright (C) 1995-2000 Russell King !! 6 * Return the address of a given character within a null-terminated
6 * Copyright (C) 2013 ARM Ltd. !! 7 * string, or null if it is not found.
7 */ 8 */
>> 9 #include <linux/export.h>
>> 10 #include <asm/regdef.h>
8 11
9 #include <linux/linkage.h> !! 12 .set noreorder
10 #include <asm/assembler.h> !! 13 .set noat
11 14
12 /* !! 15 .align 3
13 * Find the first occurrence of a character in !! 16 .globl strchr
14 * !! 17 .ent strchr
15 * Parameters: !! 18 strchr:
16 * x0 - str !! 19 .frame sp, 0, ra
17 * x1 - c !! 20 .prologue 0
18 * Returns: !! 21
19 * x0 - address of first occurrence of 'c !! 22 zapnot a1, 1, a1 # e0 : zero extend the search character
20 */ !! 23 ldq_u t0, 0(a0) # .. e1 : load first quadword
21 SYM_FUNC_START(__pi_strchr) !! 24 sll a1, 8, t5 # e0 : replicate the search character
22 and w1, w1, #0xff !! 25 andnot a0, 7, v0 # .. e1 : align our loop pointer
23 1: ldrb w2, [x0], #1 !! 26 or t5, a1, a1 # e0 :
24 cmp w2, w1 !! 27 lda t4, -1 # .. e1 : build garbage mask
25 ccmp w2, wzr, #4, ne !! 28 sll a1, 16, t5 # e0 :
26 b.ne 1b !! 29 cmpbge zero, t0, t2 # .. e1 : bits set iff byte == zero
27 sub x0, x0, #1 !! 30 mskqh t4, a0, t4 # e0 :
28 cmp w2, w1 !! 31 or t5, a1, a1 # .. e1 :
29 csel x0, x0, xzr, eq !! 32 sll a1, 32, t5 # e0 :
30 ret !! 33 cmpbge zero, t4, t4 # .. e1 : bits set iff byte is garbage
31 SYM_FUNC_END(__pi_strchr) !! 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 :
32 70
33 SYM_FUNC_ALIAS_WEAK(strchr, __pi_strchr) !! 71 .end strchr
34 EXPORT_SYMBOL_NOKASAN(strchr) !! 72 EXPORT_SYMBOL(strchr)
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