1/* Optimized strchrnul implementation for PowerPC64/POWER7 using cmpb insn. 2 Copyright (C) 2010-2022 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#ifndef STRCHRNUL 22# define STRCHRNUL __strchrnul 23#endif 24/* int [r3] strchrnul (char *s [r3], int c [r4]) */ 25 .machine power7 26ENTRY_TOCLESS (STRCHRNUL) 27 CALL_MCOUNT 2 28 dcbt 0,r3 29 clrrdi r8,r3,3 /* Align the address to doubleword boundary. */ 30 31 /* Replicate byte to doubleword. */ 32 insrdi r4,r4,8,48 33 insrdi r4,r4,16,32 34 insrdi r4,r4,32,0 35 36 rlwinm r6,r3,3,26,28 /* Calculate padding. */ 37 ld r12,0(r8) /* Load doubleword from memory. */ 38 li r0,0 /* Doubleword with null chars to use 39 with cmpb. */ 40 41 /* Now r4 has a doubleword of c bytes and r0 has 42 a doubleword of null bytes. */ 43 44 cmpb r10,r12,r0 /* Compare each byte against c byte. */ 45 cmpb r9,r12,r4 /* Compare each byte against null byte. */ 46 47 /* Move the doublewords left and right to discard the bits that are 48 not part of the string and to bring them back as zeros. */ 49#ifdef __LITTLE_ENDIAN__ 50 srd r10,r10,r6 51 srd r9,r9,r6 52 sld r10,r10,r6 53 sld r9,r9,r6 54#else 55 sld r10,r10,r6 56 sld r9,r9,r6 57 srd r10,r10,r6 58 srd r9,r9,r6 59#endif 60 or r5,r9,r10 /* OR the results to speed things up. */ 61 cmpdi cr7,r5,0 /* If r5 == 0, no c or null bytes 62 have been found. */ 63 bne cr7,L(done) 64 65 mtcrf 0x01,r8 66 67 /* Are we now aligned to a quadword boundary? If so, skip to 68 the main loop. Otherwise, go through the alignment code. */ 69 70 bt 28,L(loop) 71 72 /* Handle DWORD2 of pair. */ 73 ldu r12,8(r8) 74 cmpb r10,r12,r0 75 cmpb r9,r12,r4 76 or r5,r9,r10 77 cmpdi cr7,r5,0 78 bne cr7,L(done) 79 b L(loop) /* We branch here (rather than falling through) 80 to skip the nops due to heavy alignment 81 of the loop below. */ 82 83 .p2align 5 84L(loop): 85 /* Load two doublewords, compare and merge in a 86 single register for speed. This is an attempt 87 to speed up the null-checking process for bigger strings. */ 88 ld r12,8(r8) 89 ldu r11,16(r8) 90 cmpb r10,r12,r0 91 cmpb r9,r12,r4 92 cmpb r6,r11,r0 93 cmpb r7,r11,r4 94 or r5,r9,r10 95 or r10,r6,r7 96 or r11,r5,r10 97 cmpdi cr7,r11,0 98 beq cr7,L(loop) 99 100 /* OK, one (or both) of the doublewords contains a c/null byte. Check 101 the first doubleword and decrement the address in case the first 102 doubleword really contains a c/null byte. */ 103 104 cmpdi cr6,r5,0 105 addi r8,r8,-8 106 bne cr6,L(done) 107 108 /* The c/null byte must be in the second doubleword. Adjust the 109 address again and move the result of cmpb to r5 so we can calculate 110 the pointer. */ 111 mr r5,r10 112 addi r8,r8,8 113 114 /* r5 has the output of the cmpb instruction, that is, it contains 115 0xff in the same position as the c/null byte in the original 116 doubleword from the string. Use that to calculate the pointer. */ 117L(done): 118#ifdef __LITTLE_ENDIAN__ 119 addi r0,r5,-1 120 andc r0,r0,r5 121 popcntd r0,r0 122#else 123 cntlzd r0,r5 /* Count leading zeros before the match. */ 124#endif 125 srdi r0,r0,3 /* Convert leading zeros to bytes. */ 126 add r3,r8,r0 /* Return address of matching c/null byte. */ 127 blr 128END (STRCHRNUL) 129weak_alias (STRCHRNUL, strchrnul) 130libc_hidden_builtin_def (STRCHRNUL) 131