1/* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License, Version 1.0 only 6 * (the "License"). You may not use this file except in compliance 7 * with the License. 8 * 9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10 * or http://www.opensolaris.org/os/licensing. 11 * See the License for the specific language governing permissions 12 * and limitations under the License. 13 * 14 * When distributing Covered Code, include this CDDL HEADER in each 15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16 * If applicable, add the following below this CDDL HEADER, with the 17 * fields enclosed by brackets "[]" replaced with your own identifying 18 * information: Portions Copyright [yyyy] [name of copyright owner] 19 * 20 * CDDL HEADER END 21 */ 22/* 23 * Copyright 2003 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 28.ident "%Z%%M% %I% %E% SMI" 29 30 .file "%M%" 31 32/* strcmp(s1, s2) 33 * 34 * Compare strings: s1>s2: >0 s1==s2: 0 s1<s2: <0 35 * 36 * Fast assembler language version of the following C-program for strcmp 37 * which represents the `standard' for the C-library. 38 * 39 * int 40 * strcmp(s1, s2) 41 * register const char *s1; 42 * register const char *s2; 43 * { 44 * 45 * if(s1 == s2) 46 * return(0); 47 * while(*s1 == *s2++) 48 * if(*s1++ == '\0') 49 * return(0); 50 * return(*s1 - s2[-1]); 51 * } 52 */ 53 54#include <sys/asm_linkage.h> 55#include "synonyms.h" 56 57 ! This strcmp implementation first determines whether s1 is aligned. 58 ! If it is not, it attempts to align it and then checks the 59 ! alignment of the destination string. If it is possible to 60 ! align s2, this also happens and then the compare begins. Otherwise, 61 ! a different compare for non-aligned strings is used. 62 63 ENTRY(strcmp) 64 65 .align 32 66 67 subcc %o0, %o1, %o2 ! s1 == s2 ? 68 bz,pn %xcc, .stringsequal ! yup, same string, done 69 sethi %hi(0x01010101), %o5 ! magic2<31:13> 70 andcc %o0, 7, %o3 ! s1 sword-aligned ? 71 or %o5, %lo(0x01010101),%o5! magic2<31:0> 72 bz,pn %xcc, .s1aligned ! yup 73 sllx %o5, 32, %o4 ! magic2<63:32> 74 sub %o3, 8, %o3 ! number of bytes till s1 aligned 75 76.aligns1: 77 ldub [%o1 + %o2], %o0 ! s1[] 78 ldub [%o1], %g1 ! s2[] 79 subcc %o0, %g1, %o0 ! s1[] != s2[] ? 80 bne,pn %xcc, .done ! yup, done 81 addcc %o0, %g1, %g0 ! s1[] == 0 ? 82 bz,pn %xcc, .done ! yup, done 83 inccc %o3 ! s1 aligned yet? 84 bnz,pt %xcc, .aligns1 ! nope, compare another pair of bytes 85 inc %o1 ! s1++, s2++ 86 87.s1aligned: 88 andcc %o1, 7, %o3 ! s2 dword aligned ? 89 or %o5, %o4, %o5 ! magic2<63:0> 90 bz,pn %xcc, .s2aligned ! yup 91 sllx %o5, 7, %o4 ! magic1 92 sllx %o3, 3, %g5 ! leftshift = 8*ofs 93 orn %g0, %g0, %g1 ! all ones 94 and %o1, -8, %o1 ! round s1 down to next aligned dword 95 srlx %g1, %g5, %g1 ! mask for fixing up bytes 96 ldx [%o1], %o0 ! new lower dword in s2 97 orn %o0, %g1, %o0 ! force start bytes to non-zero 98 sub %g0, %g5, %g4 ! rightshift = -(8*ofs) mod 64 99 sllx %o0, %g5, %g1 ! partial unaligned word from s2 100 add %o2, %o3, %o2 ! adjust pointers 101 nop ! align loop to 16-byte boundary 102 nop ! align loop to 16-byte boundary 103 104.cmp: 105 andn %o4, %o0, %o3 ! ~word & 0x80808080 106 sub %o0, %o5, %o0 ! word - 0x01010101 107 andcc %o0, %o3, %g0 ! (word - 0x01010101) & ~word & 0x80808080 108 bz,a,pt %xcc, .doload ! no null byte in previous word from s2 109 ldx [%o1+8], %o0 ! next aligned word in s2 110.doload: 111 srlx %o0, %g4, %o3 ! bytes from aligned word from s2 112 or %g1, %o3, %g1 ! merge to get unaligned word from s2 113 ldx [%o1 + %o2], %o3 ! word from s1 114 cmp %o3, %g1 ! *s1 != *s2 ? 115 bne,pn %xcc, .wordsdiffer ! yup, find the byte that is different 116 add %o1, 8, %o1 ! s1+=8, s2+=8 117 andn %o4, %o3, %g1 ! ~word & 0x80808080 118 sub %o3, %o5, %o3 ! word - 0x01010101 119 andcc %o3, %g1, %g0 ! (word - 0x01010101) & ~word & 0x80808080 120 bz,pt %xcc, .cmp ! no null-byte in s1 yet 121 sllx %o0, %g5, %g1 ! partial unaligned word from s2 122 123 ! words are equal but the end of s1 has been reached 124 ! this means the strings must be equal 125.strequal: 126 retl ! return from leaf function 127 mov %g0, %o0 ! return 0, i.e. strings are equal 128 nop 129 130.s2aligned: 131 ldx [%o1 + %o2], %o3 ! load word from s1 132 133.cmpaligned: 134 ldx [%o1], %g1 ! load word from s2 135 cmp %o3, %g1 ! *scr1 == *src2 ? 136 bne,pn %xcc, .wordsdiffer ! nope, find mismatching character 137 add %o1, 8, %o1 ! src1 += 8, src2 += 8 138 andn %o4, %o3, %o0 ! ~word & 0x80808080 139 sub %o3, %o5, %o3 ! word - 0x01010101 140 andcc %o3, %o0, %g0 ! (word - 0x01010101) & ~word & 0x80808080 141 bz,a,pt %xcc, .cmpaligned ! no null-byte in s1 yet 142 ldx [%o1 + %o2], %o3 ! load word from s1 143 144 ! words are equal but the end of s1 has been reached 145 ! this means the strings must be equal 146 147.stringsequal: 148 retl ! return from leaf function 149 mov %g0, %o0 ! return 0, i.e. strings are equal 150 nop ! align loop on 16-byte boundary 151 nop ! align loop on 16-byte boundary 152 nop ! align loop on 16-byte boundary 153 154.wordsdiffer: 155 mov 56, %o4 ! initial shift count 156 srlx %g1, %o4, %o2 ! first byte of mismatching word in s2 157.cmpbytes: 158 srlx %o3, %o4, %o1 ! first byte of mismatching word in s1 159 subcc %o1, %o2, %o0 ! *s1-*s2 160 bnz,pn %xcc, .done ! bytes differ, return difference 161 nop 162 andcc %o1, 0xff, %o0 ! *s1 == 0 ? 163 bz,pn %xcc, .done ! yup, strings match 164 subcc %o4, 8, %o4 ! shift_count -= 8 165 bpos,pt %xcc, .cmpbytes ! until all bytes processed 166 srlx %g1, %o4, %o2 ! first byte of mismatching word in s2 167 168.done: 169 retl ! return from leaf routine 170 nop ! padding 171 172 SET_SIZE(strcmp) 173