1/* Optimized strcmp implementation for PowerPC32. 2 Copyright (C) 2003-2021 Free Software Foundation, Inc. 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 16 License along with the GNU C Library; if not, see 17 <https://www.gnu.org/licenses/>. */ 18 19#include <sysdep.h> 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 25EALIGN (strncmp, 4, 0) 26 27#define rTMP2 r0 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 */ 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 */ 38#define rTMP r12 39 40 dcbt 0,rSTR1 41 or rTMP, rSTR2, rSTR1 42 lis r7F7F, 0x7f7f 43 dcbt 0,rSTR2 44 clrlwi. rTMP, rTMP, 30 45 cmplwi cr1, rN, 0 46 lis rFEFE, -0x101 47 bne L(unaligned) 48/* We are word aligned so set up for two loops. first a word 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 53 addi r7F7F, r7F7F, 0x7f7f 54 cmplwi cr1, rN, 0 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 62L(g0): 63 lwzu rWORD1, 4(rSTR1) 64 bne- cr1, L(different) 65 lwzu rWORD2, 4(rSTR2) 66L(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) 72 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... */ 76 77#ifdef __LITTLE_ENDIAN__ 78L(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 96L(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 111L(endstring): 112 and rTMP, r7F7F, rWORD1 113 beq cr1, L(equal) 114 add rTMP, rTMP, r7F7F 115 xor. rBITDIF, rWORD1, rWORD2 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 123 bgelr+ cr1 124L(equal): 125 li rRTN, 0 126 blr 127 128L(different): 129 lwz rWORD1, -4(rSTR1) 130 xor. rBITDIF, rWORD1, rWORD2 131 sub rRTN, rWORD1, rWORD2 132 bgelr+ 133L(highbit): 134 ori rRTN, rWORD2, 1 135 blr 136#endif 137 138/* Oh well. In this case, we just do a byte-by-byte comparison. */ 139 .align 4 140L(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, 4 147 cmplwi cr1, rN, 0 148L(unaligned): 149 mtctr rN /* Power4 wants mtctr 1st in dispatch group */ 150 bgt cr1, L(uz) 151L(ux): 152 li rRTN, 0 153 blr 154 .align 4 155L(uz): 156 lbz rWORD1, 0(rSTR1) 157 lbz rWORD2, 0(rSTR2) 158 nop 159 b L(u1) 160L(u0): 161 lbzu rWORD2, 1(rSTR2) 162L(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 177L(u2): lbzu rWORD1, -1(rSTR1) 178L(u3): sub rRTN, rWORD1, rWORD2 179 blr 180END (strncmp) 181libc_hidden_builtin_def (strncmp) 182