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 rWORD3 r10 35#define rWORD4 r11 36#define rFEFE r8 /* constant 0xfefefeff (-0x01010101) */ 37#define r7F7F r9 /* constant 0x7f7f7f7f */ 38#define rNEG r10 /* ~(word in s1 | 0x7f7f7f7f) */ 39#define rBITDIF r11 /* bits that differ in s1 & s2 words */ 40#define rTMP r12 41 42 dcbt 0,rSTR1 43 or rTMP, rSTR2, rSTR1 44 lis r7F7F, 0x7f7f 45 dcbt 0,rSTR2 46 clrlwi. rTMP, rTMP, 30 47 cmplwi cr1, rN, 0 48 lis rFEFE, -0x101 49 bne L(unaligned) 50/* We are word aligned so set up for two loops. first a word 51 loop, then fall into the byte loop if any residual. */ 52 srwi. rTMP, rN, 2 53 clrlwi rN, rN, 30 54 addi rFEFE, rFEFE, -0x101 55 addi r7F7F, r7F7F, 0x7f7f 56 cmplwi cr1, rN, 0 57 beq L(unaligned) 58 59 mtctr rTMP /* Power4 wants mtctr 1st in dispatch group. */ 60 lwz rWORD1, 0(rSTR1) 61 lwz rWORD2, 0(rSTR2) 62 b L(g1) 63 64L(g0): 65 lwzu rWORD1, 4(rSTR1) 66 bne- cr1, L(different) 67 lwzu rWORD2, 4(rSTR2) 68L(g1): add rTMP, rFEFE, rWORD1 69 nor rNEG, r7F7F, rWORD1 70 bdz L(tail) 71 and. rTMP, rTMP, rNEG 72 cmpw cr1, rWORD1, rWORD2 73 beq+ L(g0) 74 75/* OK. We've hit the end of the string. We need to be careful that 76 we don't compare two strings as different because of gunk beyond 77 the end of the strings... */ 78 79#ifdef __LITTLE_ENDIAN__ 80L(endstring): 81 slwi rTMP, rTMP, 1 82 addi rTMP2, rTMP, -1 83 andc rTMP2, rTMP2, rTMP 84 and rWORD2, rWORD2, rTMP2 /* Mask off gunk. */ 85 and rWORD1, rWORD1, rTMP2 86 rlwinm rTMP2, rWORD2, 8, 0xffffffff /* Byte reverse word. */ 87 rlwinm rTMP, rWORD1, 8, 0xffffffff 88 rldimi rTMP2, rWORD2, 24, 32 89 rldimi rTMP, rWORD1, 24, 32 90 rlwimi rTMP2, rWORD2, 24, 16, 23 91 rlwimi rTMP, rWORD1, 24, 16, 23 92 xor. rBITDIF, rTMP, rTMP2 93 sub rRTN, rTMP, rTMP2 94 bgelr+ 95 ori rRTN, rTMP2, 1 96 blr 97 98L(different): 99 lwz rWORD1, -4(rSTR1) 100 rlwinm rTMP2, rWORD2, 8, 0xffffffff /* Byte reverse word. */ 101 rlwinm rTMP, rWORD1, 8, 0xffffffff 102 rldimi rTMP2, rWORD2, 24, 32 103 rldimi rTMP, rWORD1, 24, 32 104 rlwimi rTMP2, rWORD2, 24, 16, 23 105 rlwimi rTMP, rWORD1, 24, 16, 23 106 xor. rBITDIF, rTMP, rTMP2 107 sub rRTN, rTMP, rTMP2 108 bgelr+ 109 ori rRTN, rTMP2, 1 110 blr 111 112#else 113L(endstring): 114 and rTMP, r7F7F, rWORD1 115 beq cr1, L(equal) 116 add rTMP, rTMP, r7F7F 117 xor. rBITDIF, rWORD1, rWORD2 118 andc rNEG, rNEG, rTMP 119 blt- L(highbit) 120 cntlzw rBITDIF, rBITDIF 121 cntlzw rNEG, rNEG 122 addi rNEG, rNEG, 7 123 cmpw cr1, rNEG, rBITDIF 124 sub rRTN, rWORD1, rWORD2 125 bgelr+ cr1 126L(equal): 127 li rRTN, 0 128 blr 129 130L(different): 131 lwz rWORD1, -4(rSTR1) 132 xor. rBITDIF, rWORD1, rWORD2 133 sub rRTN, rWORD1, rWORD2 134 bgelr+ 135L(highbit): 136 ori rRTN, rWORD2, 1 137 blr 138#endif 139 140/* Oh well. In this case, we just do a byte-by-byte comparison. */ 141 .align 4 142L(tail): 143 and. rTMP, rTMP, rNEG 144 cmpw cr1, rWORD1, rWORD2 145 bne- L(endstring) 146 addi rSTR1, rSTR1, 4 147 bne- cr1, L(different) 148 addi rSTR2, rSTR2, 4 149 cmplwi cr1, rN, 0 150L(unaligned): 151 mtctr rN /* Power4 wants mtctr 1st in dispatch group */ 152 ble cr1, L(ux) 153L(uz): 154 lbz rWORD1, 0(rSTR1) 155 lbz rWORD2, 0(rSTR2) 156 .align 4 157L(u1): 158 cmpwi cr1, rWORD1, 0 159 bdz L(u4) 160 cmpw rWORD1, rWORD2 161 beq- cr1, L(u4) 162 bne- L(u4) 163 lbzu rWORD3, 1(rSTR1) 164 lbzu rWORD4, 1(rSTR2) 165 cmpwi cr1, rWORD3, 0 166 bdz L(u3) 167 cmpw rWORD3, rWORD4 168 beq- cr1, L(u3) 169 bne- L(u3) 170 lbzu rWORD1, 1(rSTR1) 171 lbzu rWORD2, 1(rSTR2) 172 cmpwi cr1, rWORD1, 0 173 bdz L(u4) 174 cmpw rWORD1, rWORD2 175 beq- cr1, L(u4) 176 bne- L(u4) 177 lbzu rWORD3, 1(rSTR1) 178 lbzu rWORD4, 1(rSTR2) 179 cmpwi cr1, rWORD3, 0 180 bdz L(u3) 181 cmpw rWORD3, rWORD4 182 beq- cr1, L(u3) 183 bne- L(u3) 184 lbzu rWORD1, 1(rSTR1) 185 lbzu rWORD2, 1(rSTR2) 186 b L(u1) 187 188L(u3): sub rRTN, rWORD3, rWORD4 189 blr 190L(u4): sub rRTN, rWORD1, rWORD2 191 blr 192L(ux): 193 li rRTN, 0 194 blr 195END (strncmp) 196libc_hidden_builtin_def (strncmp) 197