1 /* Optimized strcmp implementation for POWER7/PowerPC32.
2 Copyright (C) 2010 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],
30 EALIGN (BP_SYM(strncmp),4,0)
34 #define rSTR1 r3 /* first string arg */
35 #define rSTR2 r4 /* second string arg */
36 #define rN r5 /* max string length */
37 /* Note: The Bounded pointer support in this code is broken. This code
38 was inherited from PPC32 and and that support was never completed.
39 Current PPC gcc does not support -fbounds-check or -fbounded-pointers. */
40 #define rWORD1 r6 /* current word in s1 */
41 #define rWORD2 r7 /* current word in s2 */
44 #define rFEFE r8 /* constant 0xfefefeff (-0x01010101) */
45 #define r7F7F r9 /* constant 0x7f7f7f7f */
46 #define rNEG r10 /* ~(word in s1 | 0x7f7f7f7f) */
47 #define rBITDIF r11 /* bits that differ in s1 & s2 words */
57 /* We are word alligned so set up for two loops. first a word
58 loop, then fall into the byte loop if any residual. */
61 addi rFEFE,rFEFE,-0x101
62 addi r7F7F,r7F7F,0x7f7f
75 L(g1): add rTMP,rFEFE,rWORD1
79 cmpw cr1,rWORD1,rWORD2
82 /* OK. We've hit the end of the string. We need to be careful that
83 we don't compare two strings as different because of gunk beyond
84 the end of the strings... */
90 xor. rBITDIF,rWORD1,rWORD2
94 cntlzw rBITDIF,rBITDIF
98 sub rRTN,rWORD1,rWORD2
108 lwzu rWORD1,-4(rSTR1)
109 xor. rBITDIF,rWORD1,rWORD2
110 sub rRTN,rWORD1,rWORD2
116 srwi rWORD2,rWORD2,24
117 srwi rWORD1,rWORD1,24
118 sub rRTN,rWORD1,rWORD2
122 /* Oh well. In this case, we just do a byte-by-byte comparison. */
126 cmpw cr1,rWORD1,rWORD2
169 L(u3): sub rRTN,rWORD3,rWORD4
171 L(u4): sub rRTN,rWORD1,rWORD2
176 END (BP_SYM (strncmp))
177 libc_hidden_builtin_def (strncmp)