1 /* Optimized strcmp implementation for POWER7/PowerPC32.
2 Copyright (C) 2010, 2011 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, see
17 <http://www.gnu.org/licenses/>. */
23 /* See strlen.s for comments on how the end-of-string testing works. */
25 /* int [r3] strncmp (const char *s1 [r3],
29 EALIGN (BP_SYM(strncmp),5,0)
33 #define rSTR1 r3 /* first string arg */
34 #define rSTR2 r4 /* second string arg */
35 #define rN r5 /* max string length */
36 /* Note: The Bounded pointer support in this code is broken. This code
37 was inherited from PPC32 and that support was never completed.
38 Current PPC gcc does not support -fbounds-check or -fbounded-pointers. */
39 #define rWORD1 r6 /* current word in s1 */
40 #define rWORD2 r7 /* current word in s2 */
43 #define rFEFE r8 /* constant 0xfefefeff (-0x01010101) */
44 #define r7F7F r9 /* constant 0x7f7f7f7f */
45 #define rNEG r10 /* ~(word in s1 | 0x7f7f7f7f) */
46 #define rBITDIF r11 /* bits that differ in s1 & s2 words */
58 /* We are word alligned so set up for two loops. first a word
59 loop, then fall into the byte loop if any residual. */
62 addi rFEFE,rFEFE,-0x101
63 addi r7F7F,r7F7F,0x7f7f
76 L(g1): add rTMP,rFEFE,rWORD1
80 cmpw cr1,rWORD1,rWORD2
83 /* OK. We've hit the end of the string. We need to be careful that
84 we don't compare two strings as different because of gunk beyond
85 the end of the strings... */
91 xor. rBITDIF,rWORD1,rWORD2
95 cntlzw rBITDIF,rBITDIF
99 sub rRTN,rWORD1,rWORD2
109 lwzu rWORD1,-4(rSTR1)
110 xor. rBITDIF,rWORD1,rWORD2
111 sub rRTN,rWORD1,rWORD2
117 srwi rWORD2,rWORD2,24
118 srwi rWORD1,rWORD1,24
119 sub rRTN,rWORD1,rWORD2
123 /* Oh well. In this case, we just do a byte-by-byte comparison. */
127 cmpw cr1,rWORD1,rWORD2
171 L(u3): sub rRTN,rWORD3,rWORD4
173 L(u4): sub rRTN,rWORD1,rWORD2
178 END (BP_SYM (strncmp))
179 libc_hidden_builtin_def (strncmp)