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1/*
2 * arch/alpha/lib/strrchr.S
3 * Contributed by Richard Henderson (rth@tamu.edu)
4 *
5 * Return the address of the last occurrence of a given character
6 * within a null-terminated string, or null if it is not found.
7 */
8#include <asm/export.h>
9#include <asm/regdef.h>
10
11 .set noreorder
12 .set noat
13
14 .align 3
15 .ent strrchr
16 .globl strrchr
17strrchr:
18 .frame sp, 0, ra
19 .prologue 0
20
21 zapnot a1, 1, a1 # e0 : zero extend our test character
22 mov zero, t6 # .. e1 : t6 is last match aligned addr
23 sll a1, 8, t5 # e0 : replicate our test character
24 mov zero, t8 # .. e1 : t8 is last match byte compare mask
25 or t5, a1, a1 # e0 :
26 ldq_u t0, 0(a0) # .. e1 : load first quadword
27 sll a1, 16, t5 # e0 :
28 andnot a0, 7, v0 # .. e1 : align source addr
29 or t5, a1, a1 # e0 :
30 lda t4, -1 # .. e1 : build garbage mask
31 sll a1, 32, t5 # e0 :
32 cmpbge zero, t0, t1 # .. e1 : bits set iff byte == zero
33 mskqh t4, a0, t4 # e0 :
34 or t5, a1, a1 # .. e1 : character replication complete
35 xor t0, a1, t2 # e0 : make bytes == c zero
36 cmpbge zero, t4, t4 # .. e1 : bits set iff byte is garbage
37 cmpbge zero, t2, t3 # e0 : bits set iff byte == c
38 andnot t1, t4, t1 # .. e1 : clear garbage from null test
39 andnot t3, t4, t3 # e0 : clear garbage from char test
40 bne t1, $eos # .. e1 : did we already hit the terminator?
41
42 /* Character search main loop */
43$loop:
44 ldq t0, 8(v0) # e0 : load next quadword
45 cmovne t3, v0, t6 # .. e1 : save previous comparisons match
46 cmovne t3, t3, t8 # e0 :
47 addq v0, 8, v0 # .. e1 :
48 xor t0, a1, t2 # e0 :
49 cmpbge zero, t0, t1 # .. e1 : bits set iff byte == zero
50 cmpbge zero, t2, t3 # e0 : bits set iff byte == c
51 beq t1, $loop # .. e1 : if we havnt seen a null, loop
52
53 /* Mask out character matches after terminator */
54$eos:
55 negq t1, t4 # e0 : isolate first null byte match
56 and t1, t4, t4 # e1 :
57 subq t4, 1, t5 # e0 : build a mask of the bytes up to...
58 or t4, t5, t4 # e1 : ... and including the null
59
60 and t3, t4, t3 # e0 : mask out char matches after null
61 cmovne t3, t3, t8 # .. e1 : save it, if match found
62 cmovne t3, v0, t6 # e0 :
63
64 /* Locate the address of the last matched character */
65
66 /* Retain the early exit for the ev4 -- the ev5 mispredict penalty
67 is 5 cycles -- the same as just falling through. */
68 beq t8, $retnull # .. e1 :
69
70 and t8, 0xf0, t2 # e0 : binary search for the high bit set
71 cmovne t2, t2, t8 # .. e1 (zdb)
72 cmovne t2, 4, t2 # e0 :
73 and t8, 0xcc, t1 # .. e1 :
74 cmovne t1, t1, t8 # e0 :
75 cmovne t1, 2, t1 # .. e1 :
76 and t8, 0xaa, t0 # e0 :
77 cmovne t0, 1, t0 # .. e1 (zdb)
78 addq t2, t1, t1 # e0 :
79 addq t6, t0, v0 # .. e1 : add our aligned base ptr to the mix
80 addq v0, t1, v0 # e0 :
81 ret # .. e1 :
82
83$retnull:
84 mov zero, v0 # e0 :
85 ret # .. e1 :
86
87 .end strrchr
88 EXPORT_SYMBOL(strrchr)
1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * arch/alpha/lib/strrchr.S
4 * Contributed by Richard Henderson (rth@tamu.edu)
5 *
6 * Return the address of the last occurrence of a given character
7 * within a null-terminated string, or null if it is not found.
8 */
9#include <asm/export.h>
10#include <asm/regdef.h>
11
12 .set noreorder
13 .set noat
14
15 .align 3
16 .ent strrchr
17 .globl strrchr
18strrchr:
19 .frame sp, 0, ra
20 .prologue 0
21
22 zapnot a1, 1, a1 # e0 : zero extend our test character
23 mov zero, t6 # .. e1 : t6 is last match aligned addr
24 sll a1, 8, t5 # e0 : replicate our test character
25 mov zero, t8 # .. e1 : t8 is last match byte compare mask
26 or t5, a1, a1 # e0 :
27 ldq_u t0, 0(a0) # .. e1 : load first quadword
28 sll a1, 16, t5 # e0 :
29 andnot a0, 7, v0 # .. e1 : align source addr
30 or t5, a1, a1 # e0 :
31 lda t4, -1 # .. e1 : build garbage mask
32 sll a1, 32, t5 # e0 :
33 cmpbge zero, t0, t1 # .. e1 : bits set iff byte == zero
34 mskqh t4, a0, t4 # e0 :
35 or t5, a1, a1 # .. e1 : character replication complete
36 xor t0, a1, t2 # e0 : make bytes == c zero
37 cmpbge zero, t4, t4 # .. e1 : bits set iff byte is garbage
38 cmpbge zero, t2, t3 # e0 : bits set iff byte == c
39 andnot t1, t4, t1 # .. e1 : clear garbage from null test
40 andnot t3, t4, t3 # e0 : clear garbage from char test
41 bne t1, $eos # .. e1 : did we already hit the terminator?
42
43 /* Character search main loop */
44$loop:
45 ldq t0, 8(v0) # e0 : load next quadword
46 cmovne t3, v0, t6 # .. e1 : save previous comparisons match
47 cmovne t3, t3, t8 # e0 :
48 addq v0, 8, v0 # .. e1 :
49 xor t0, a1, t2 # e0 :
50 cmpbge zero, t0, t1 # .. e1 : bits set iff byte == zero
51 cmpbge zero, t2, t3 # e0 : bits set iff byte == c
52 beq t1, $loop # .. e1 : if we havnt seen a null, loop
53
54 /* Mask out character matches after terminator */
55$eos:
56 negq t1, t4 # e0 : isolate first null byte match
57 and t1, t4, t4 # e1 :
58 subq t4, 1, t5 # e0 : build a mask of the bytes up to...
59 or t4, t5, t4 # e1 : ... and including the null
60
61 and t3, t4, t3 # e0 : mask out char matches after null
62 cmovne t3, t3, t8 # .. e1 : save it, if match found
63 cmovne t3, v0, t6 # e0 :
64
65 /* Locate the address of the last matched character */
66
67 /* Retain the early exit for the ev4 -- the ev5 mispredict penalty
68 is 5 cycles -- the same as just falling through. */
69 beq t8, $retnull # .. e1 :
70
71 and t8, 0xf0, t2 # e0 : binary search for the high bit set
72 cmovne t2, t2, t8 # .. e1 (zdb)
73 cmovne t2, 4, t2 # e0 :
74 and t8, 0xcc, t1 # .. e1 :
75 cmovne t1, t1, t8 # e0 :
76 cmovne t1, 2, t1 # .. e1 :
77 and t8, 0xaa, t0 # e0 :
78 cmovne t0, 1, t0 # .. e1 (zdb)
79 addq t2, t1, t1 # e0 :
80 addq t6, t0, v0 # .. e1 : add our aligned base ptr to the mix
81 addq v0, t1, v0 # e0 :
82 ret # .. e1 :
83
84$retnull:
85 mov zero, v0 # e0 :
86 ret # .. e1 :
87
88 .end strrchr
89 EXPORT_SYMBOL(strrchr)