1 /* Optimized strcmp implementation for PowerPC32.
2 Copyright (C) 2003, 2006 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
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.
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.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, write to the Free
17 Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA
24 /* See strlen.s for comments on how the end-of-string testing works. */
26 /* int [r3] strncmp (const char *s1 [r3], const char *s2 [r4], size_t size [r5]) */
28 EALIGN (BP_SYM(strncmp), 4, 0)
32 #define rSTR1 r3 /* first string arg */
33 #define rSTR2 r4 /* second string arg */
34 #define rN r5 /* max string length */
35 /* Note: The Bounded pointer support in this code is broken. This code
36 was inherited from PPC32 and and that support was never completed.
37 Current PPC gcc does not support -fbounds-check or -fbounded-pointers. */
38 #define rWORD1 r6 /* current word in s1 */
39 #define rWORD2 r7 /* current word in s2 */
42 #define rFEFE r8 /* constant 0xfefefeff (-0x01010101) */
43 #define r7F7F r9 /* constant 0x7f7f7f7f */
44 #define rNEG r10 /* ~(word in s1 | 0x7f7f7f7f) */
45 #define rBITDIF r11 /* bits that differ in s1 & s2 words */
51 clrlwi. rTMP, rTMP, 30
55 /* We are word alligned so set up for two loops. first a word
56 loop, then fall into the byte loop if any residual. */
59 addi rFEFE, rFEFE, -0x101
60 addi r7F7F, r7F7F, 0x7f7f
64 mtctr rTMP /* Power4 wants mtctr 1st in dispatch group. */
71 bne- cr1, L(different)
73 L(g1): add rTMP, rFEFE, rWORD1
74 nor rNEG, r7F7F, rWORD1
77 cmpw cr1, rWORD1, rWORD2
80 /* OK. We've hit the end of the string. We need to be careful that
81 we don't compare two strings as different because of gunk beyond
82 the end of the strings... */
85 and rTMP, r7F7F, rWORD1
88 xor. rBITDIF, rWORD1, rWORD2
92 cntlzw rBITDIF, rBITDIF
95 cmpw cr1, rNEG, rBITDIF
96 sub rRTN, rWORD1, rWORD2
106 lwzu rWORD1, -4(rSTR1)
107 xor. rBITDIF, rWORD1, rWORD2
108 sub rRTN, rWORD1, rWORD2
114 srwi rWORD2, rWORD2, 24
115 srwi rWORD1, rWORD1, 24
116 sub rRTN, rWORD1, rWORD2
120 /* Oh well. In this case, we just do a byte-by-byte comparison. */
123 and. rTMP, rTMP, rNEG
124 cmpw cr1, rWORD1, rWORD2
127 bne- cr1, L(different)
131 mtctr rN /* Power4 wants mtctr 1st in dispatch group */
142 lbzu rWORD3, 1(rSTR1)
143 lbzu rWORD4, 1(rSTR2)
149 lbzu rWORD1, 1(rSTR1)
150 lbzu rWORD2, 1(rSTR2)
156 lbzu rWORD3, 1(rSTR1)
157 lbzu rWORD4, 1(rSTR2)
163 lbzu rWORD1, 1(rSTR1)
164 lbzu rWORD2, 1(rSTR2)
167 L(u3): sub rRTN, rWORD3, rWORD4
169 L(u4): sub rRTN, rWORD1, rWORD2
174 END (BP_SYM (strncmp))
175 libc_hidden_builtin_def (strncmp)