1 /* SPDX-License-Identifier: GPL-2.0-only */ <<
2 /* 1 /*
3 * Based on arch/arm/lib/strchr.S !! 2 * arch/alpha/lib/strchr.S
>> 3 * Contributed by Richard Henderson (rth@tamu.edu)
4 * 4 *
5 * Copyright (C) 1995-2000 Russell King !! 5 * Return the address of a given character within a null-terminated
6 * Copyright (C) 2013 ARM Ltd. !! 6 * string, or null if it is not found.
7 */ 7 */
>> 8 #include <asm/export.h>
>> 9 #include <asm/regdef.h>
8 10
9 #include <linux/linkage.h> !! 11 .set noreorder
10 #include <asm/assembler.h> !! 12 .set noat
11 13
12 /* !! 14 .align 3
13 * Find the first occurrence of a character in !! 15 .globl strchr
14 * !! 16 .ent strchr
15 * Parameters: !! 17 strchr:
16 * x0 - str !! 18 .frame sp, 0, ra
17 * x1 - c !! 19 .prologue 0
18 * Returns: !! 20
19 * x0 - address of first occurrence of 'c !! 21 zapnot a1, 1, a1 # e0 : zero extend the search character
20 */ !! 22 ldq_u t0, 0(a0) # .. e1 : load first quadword
21 SYM_FUNC_START(__pi_strchr) !! 23 sll a1, 8, t5 # e0 : replicate the search character
22 and w1, w1, #0xff !! 24 andnot a0, 7, v0 # .. e1 : align our loop pointer
23 1: ldrb w2, [x0], #1 !! 25 or t5, a1, a1 # e0 :
24 cmp w2, w1 !! 26 lda t4, -1 # .. e1 : build garbage mask
25 ccmp w2, wzr, #4, ne !! 27 sll a1, 16, t5 # e0 :
26 b.ne 1b !! 28 cmpbge zero, t0, t2 # .. e1 : bits set iff byte == zero
27 sub x0, x0, #1 !! 29 mskqh t4, a0, t4 # e0 :
28 cmp w2, w1 !! 30 or t5, a1, a1 # .. e1 :
29 csel x0, x0, xzr, eq !! 31 sll a1, 32, t5 # e0 :
30 ret !! 32 cmpbge zero, t4, t4 # .. e1 : bits set iff byte is garbage
31 SYM_FUNC_END(__pi_strchr) !! 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 :
32 69
33 SYM_FUNC_ALIAS_WEAK(strchr, __pi_strchr) !! 70 .end strchr
34 EXPORT_SYMBOL_NOKASAN(strchr) !! 71 EXPORT_SYMBOL(strchr)
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