1 | /* Copyright (C) 1996-2022 Free Software Foundation, Inc. |
2 | This file is part of the GNU C Library. |
3 | |
4 | The GNU C Library is free software; you can redistribute it and/or |
5 | modify it under the terms of the GNU Lesser General Public |
6 | License as published by the Free Software Foundation; either |
7 | version 2.1 of the License, or (at your option) any later version. |
8 | |
9 | The GNU C Library is distributed in the hope that it will be useful, |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
12 | Lesser General Public License for more details. |
13 | |
14 | You should have received a copy of the GNU Lesser General Public |
15 | License along with the GNU C Library. If not, see |
16 | <https://www.gnu.org/licenses/>. */ |
17 | |
18 | /* Return the address of the last occurrence of a given character |
19 | within a null-terminated string, or null if it is not found. |
20 | |
21 | This is generally scheduled for the EV5 (got to look out for my own |
22 | interests :-), but with EV4 needs in mind. There are, in fact, fewer |
23 | stalls on the EV4 than there are on the EV5. |
24 | */ |
25 | |
26 | #include <sysdep.h> |
27 | |
28 | .set noreorder |
29 | .set noat |
30 | |
31 | ENTRY(strrchr) |
32 | #ifdef PROF |
33 | ldgp gp, 0(pv) |
34 | lda AT, _mcount |
35 | jsr AT, (AT), _mcount |
36 | .prologue 1 |
37 | #else |
38 | .prologue 0 |
39 | #endif |
40 | |
41 | and a1, 0xff, a1 # e0 : zero extend our test character |
42 | mov zero, t6 # .. e1 : t6 is last match aligned addr |
43 | sll a1, 8, t5 # e0 : replicate our test character |
44 | mov zero, t7 # .. e1 : t7 is last match byte compare mask |
45 | or t5, a1, a1 # e0 : |
46 | ldq_u t0, 0(a0) # .. e1 : load first quadword |
47 | sll a1, 16, t5 # e0 : |
48 | andnot a0, 7, v0 # .. e1 : align source addr |
49 | or t5, a1, a1 # e0 : |
50 | lda t4, -1 # .. e1 : build garbage mask |
51 | sll a1, 32, t5 # e0 : |
52 | cmpbge zero, t0, t1 # .. e1 : bits set iff byte == zero |
53 | mskqh t4, a0, t4 # e0 : |
54 | or t5, a1, a1 # .. e1 : character replication complete |
55 | xor t0, a1, t2 # e0 : make bytes == c zero |
56 | cmpbge zero, t4, t4 # .. e1 : bits set iff byte is garbage |
57 | cmpbge zero, t2, t3 # e0 : bits set iff byte == c |
58 | andnot t1, t4, t1 # .. e1 : clear garbage from null test |
59 | andnot t3, t4, t3 # e0 : clear garbage from char test |
60 | bne t1, $eos # .. e1 : did we already hit the terminator? |
61 | |
62 | /* Character search main loop */ |
63 | $loop: |
64 | ldq t0, 8(v0) # e0 : load next quadword |
65 | cmovne t3, v0, t6 # .. e1 : save previous comparisons match |
66 | cmovne t3, t3, t7 # e0 : |
67 | addq v0, 8, v0 # .. e1 : |
68 | xor t0, a1, t2 # e0 : |
69 | cmpbge zero, t0, t1 # .. e1 : bits set iff byte == zero |
70 | cmpbge zero, t2, t3 # e0 : bits set iff byte == c |
71 | beq t1, $loop # .. e1 : if we havnt seen a null, loop |
72 | |
73 | /* Mask out character matches after terminator */ |
74 | $eos: |
75 | negq t1, t4 # e0 : isolate first null byte match |
76 | and t1, t4, t4 # e1 : |
77 | subq t4, 1, t5 # e0 : build a mask of the bytes upto... |
78 | or t4, t5, t4 # e1 : ... and including the null |
79 | |
80 | and t3, t4, t3 # e0 : mask out char matches after null |
81 | cmovne t3, t3, t7 # .. e1 : save it, if match found |
82 | cmovne t3, v0, t6 # e0 : |
83 | |
84 | /* Locate the address of the last matched character */ |
85 | |
86 | /* Retain the early exit for the ev4 -- the ev5 mispredict penalty |
87 | is 5 cycles -- the same as just falling through. */ |
88 | beq t7, $retnull # .. e1 : |
89 | |
90 | and t7, 0xf0, t2 # e0 : binary search for the high bit set |
91 | cmovne t2, t2, t7 # .. e1 (zdb) |
92 | cmovne t2, 4, t2 # e0 : |
93 | and t7, 0xcc, t1 # .. e1 : |
94 | cmovne t1, t1, t7 # e0 : |
95 | cmovne t1, 2, t1 # .. e1 : |
96 | and t7, 0xaa, t0 # e0 : |
97 | cmovne t0, 1, t0 # .. e1 (zdb) |
98 | addq t2, t1, t1 # e0 : |
99 | addq t6, t0, v0 # .. e1 : add our aligned base ptr to the mix |
100 | addq v0, t1, v0 # e0 : |
101 | ret # .. e1 : |
102 | |
103 | $retnull: |
104 | mov zero, v0 # e0 : |
105 | ret # .. e1 : |
106 | |
107 | END(strrchr) |
108 | |
109 | weak_alias (strrchr, rindex) |
110 | libc_hidden_builtin_def (strrchr) |
111 | |