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7df11052 | 1 | /* Optimized strcmp implementation for PowerPC32. |
b168057a | 2 | Copyright (C) 2003-2015 Free Software Foundation, Inc. |
7df11052 UD |
3 | This file is part of the GNU C Library. |
4 | ||
5 | The GNU C Library is free software; you can redistribute it and/or | |
6 | modify it under the terms of the GNU Lesser General Public | |
7 | License as published by the Free Software Foundation; either | |
8 | version 2.1 of the License, or (at your option) any later version. | |
9 | ||
10 | The GNU C Library is distributed in the hope that it will be useful, | |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 | Lesser General Public License for more details. | |
14 | ||
15 | You should have received a copy of the GNU Lesser General Public | |
59ba27a6 PE |
16 | License along with the GNU C Library; if not, see |
17 | <http://www.gnu.org/licenses/>. */ | |
7df11052 UD |
18 | |
19 | #include <sysdep.h> | |
7df11052 UD |
20 | |
21 | /* See strlen.s for comments on how the end-of-string testing works. */ | |
22 | ||
23 | /* int [r3] strncmp (const char *s1 [r3], const char *s2 [r4], size_t size [r5]) */ | |
24 | ||
b5510883 | 25 | EALIGN (strncmp, 4, 0) |
7df11052 | 26 | |
8a7413f9 | 27 | #define rTMP2 r0 |
7df11052 UD |
28 | #define rRTN r3 |
29 | #define rSTR1 r3 /* first string arg */ | |
30 | #define rSTR2 r4 /* second string arg */ | |
31 | #define rN r5 /* max string length */ | |
7df11052 UD |
32 | #define rWORD1 r6 /* current word in s1 */ |
33 | #define rWORD2 r7 /* current word in s2 */ | |
34 | #define rFEFE r8 /* constant 0xfefefeff (-0x01010101) */ | |
35 | #define r7F7F r9 /* constant 0x7f7f7f7f */ | |
36 | #define rNEG r10 /* ~(word in s1 | 0x7f7f7f7f) */ | |
37 | #define rBITDIF r11 /* bits that differ in s1 & s2 words */ | |
8a7413f9 | 38 | #define rTMP r12 |
7df11052 UD |
39 | |
40 | dcbt 0,rSTR1 | |
41 | or rTMP, rSTR2, rSTR1 | |
42 | lis r7F7F, 0x7f7f | |
43 | dcbt 0,rSTR2 | |
44 | clrlwi. rTMP, rTMP, 30 | |
8ce9ea74 | 45 | cmplwi cr1, rN, 0 |
7df11052 UD |
46 | lis rFEFE, -0x101 |
47 | bne L(unaligned) | |
2ccdea26 | 48 | /* We are word aligned so set up for two loops. first a word |
7df11052 UD |
49 | loop, then fall into the byte loop if any residual. */ |
50 | srwi. rTMP, rN, 2 | |
51 | clrlwi rN, rN, 30 | |
52 | addi rFEFE, rFEFE, -0x101 | |
8ce9ea74 | 53 | addi r7F7F, r7F7F, 0x7f7f |
7a41d99a | 54 | cmplwi cr1, rN, 0 |
7df11052 UD |
55 | beq L(unaligned) |
56 | ||
57 | mtctr rTMP /* Power4 wants mtctr 1st in dispatch group. */ | |
58 | lwz rWORD1, 0(rSTR1) | |
59 | lwz rWORD2, 0(rSTR2) | |
60 | b L(g1) | |
61 | ||
7a41d99a | 62 | L(g0): |
7df11052 UD |
63 | lwzu rWORD1, 4(rSTR1) |
64 | bne- cr1, L(different) | |
65 | lwzu rWORD2, 4(rSTR2) | |
66 | L(g1): add rTMP, rFEFE, rWORD1 | |
67 | nor rNEG, r7F7F, rWORD1 | |
68 | bdz L(tail) | |
69 | and. rTMP, rTMP, rNEG | |
70 | cmpw cr1, rWORD1, rWORD2 | |
71 | beq+ L(g0) | |
7a41d99a | 72 | |
7df11052 UD |
73 | /* OK. We've hit the end of the string. We need to be careful that |
74 | we don't compare two strings as different because of gunk beyond | |
75 | the end of the strings... */ | |
7a41d99a | 76 | |
8a7413f9 AM |
77 | #ifdef __LITTLE_ENDIAN__ |
78 | L(endstring): | |
79 | slwi rTMP, rTMP, 1 | |
80 | addi rTMP2, rTMP, -1 | |
81 | andc rTMP2, rTMP2, rTMP | |
82 | and rWORD2, rWORD2, rTMP2 /* Mask off gunk. */ | |
83 | and rWORD1, rWORD1, rTMP2 | |
84 | rlwinm rTMP2, rWORD2, 8, 0xffffffff /* Byte reverse word. */ | |
85 | rlwinm rTMP, rWORD1, 8, 0xffffffff | |
86 | rlwimi rTMP2, rWORD2, 24, 0, 7 | |
87 | rlwimi rTMP, rWORD1, 24, 0, 7 | |
88 | rlwimi rTMP2, rWORD2, 24, 16, 23 | |
89 | rlwimi rTMP, rWORD1, 24, 16, 23 | |
90 | xor. rBITDIF, rTMP, rTMP2 | |
91 | sub rRTN, rTMP, rTMP2 | |
92 | bgelr+ | |
93 | ori rRTN, rTMP2, 1 | |
94 | blr | |
95 | ||
96 | L(different): | |
97 | lwz rWORD1, -4(rSTR1) | |
98 | rlwinm rTMP2, rWORD2, 8, 0xffffffff /* Byte reverse word. */ | |
99 | rlwinm rTMP, rWORD1, 8, 0xffffffff | |
100 | rlwimi rTMP2, rWORD2, 24, 0, 7 | |
101 | rlwimi rTMP, rWORD1, 24, 0, 7 | |
102 | rlwimi rTMP2, rWORD2, 24, 16, 23 | |
103 | rlwimi rTMP, rWORD1, 24, 16, 23 | |
104 | xor. rBITDIF, rTMP, rTMP2 | |
105 | sub rRTN, rTMP, rTMP2 | |
106 | bgelr+ | |
107 | ori rRTN, rTMP2, 1 | |
108 | blr | |
109 | ||
110 | #else | |
7df11052 UD |
111 | L(endstring): |
112 | and rTMP, r7F7F, rWORD1 | |
113 | beq cr1, L(equal) | |
114 | add rTMP, rTMP, r7F7F | |
115 | xor. rBITDIF, rWORD1, rWORD2 | |
7df11052 UD |
116 | andc rNEG, rNEG, rTMP |
117 | blt- L(highbit) | |
118 | cntlzw rBITDIF, rBITDIF | |
119 | cntlzw rNEG, rNEG | |
120 | addi rNEG, rNEG, 7 | |
121 | cmpw cr1, rNEG, rBITDIF | |
122 | sub rRTN, rWORD1, rWORD2 | |
8a7413f9 | 123 | bgelr+ cr1 |
7df11052 UD |
124 | L(equal): |
125 | li rRTN, 0 | |
126 | blr | |
127 | ||
128 | L(different): | |
8a7413f9 | 129 | lwz rWORD1, -4(rSTR1) |
7df11052 UD |
130 | xor. rBITDIF, rWORD1, rWORD2 |
131 | sub rRTN, rWORD1, rWORD2 | |
8a7413f9 | 132 | bgelr+ |
7df11052 | 133 | L(highbit): |
8a7413f9 | 134 | ori rRTN, rWORD2, 1 |
7df11052 | 135 | blr |
8a7413f9 | 136 | #endif |
7df11052 UD |
137 | |
138 | /* Oh well. In this case, we just do a byte-by-byte comparison. */ | |
139 | .align 4 | |
140 | L(tail): | |
141 | and. rTMP, rTMP, rNEG | |
142 | cmpw cr1, rWORD1, rWORD2 | |
143 | bne- L(endstring) | |
144 | addi rSTR1, rSTR1, 4 | |
145 | bne- cr1, L(different) | |
146 | addi rSTR2, rSTR2, 4 | |
8ce9ea74 | 147 | cmplwi cr1, rN, 0 |
7df11052 UD |
148 | L(unaligned): |
149 | mtctr rN /* Power4 wants mtctr 1st in dispatch group */ | |
8ce9ea74 | 150 | bgt cr1, L(uz) |
7df11052 UD |
151 | L(ux): |
152 | li rRTN, 0 | |
153 | blr | |
8ce9ea74 UD |
154 | .align 4 |
155 | L(uz): | |
156 | lbz rWORD1, 0(rSTR1) | |
157 | lbz rWORD2, 0(rSTR2) | |
158 | nop | |
159 | b L(u1) | |
7df11052 UD |
160 | L(u0): |
161 | lbzu rWORD2, 1(rSTR2) | |
162 | L(u1): | |
163 | bdz L(u3) | |
164 | cmpwi cr1, rWORD1, 0 | |
165 | cmpw rWORD1, rWORD2 | |
166 | beq- cr1, L(u3) | |
167 | lbzu rWORD1, 1(rSTR1) | |
168 | bne- L(u2) | |
169 | lbzu rWORD2, 1(rSTR2) | |
170 | bdz L(u3) | |
171 | cmpwi cr1, rWORD1, 0 | |
172 | cmpw rWORD1, rWORD2 | |
173 | bne- L(u3) | |
174 | lbzu rWORD1, 1(rSTR1) | |
175 | bne+ cr1, L(u0) | |
176 | ||
7a41d99a | 177 | L(u2): lbzu rWORD1, -1(rSTR1) |
7df11052 UD |
178 | L(u3): sub rRTN, rWORD1, rWORD2 |
179 | blr | |
b5510883 | 180 | END (strncmp) |
7df11052 | 181 | libc_hidden_builtin_def (strncmp) |