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 (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22 /* 23 * Copyright 2008 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 .file "strchr.s" 28 29 /* 30 * The strchr() function returns a pointer to the first occurrence of c 31 * (converted to a char) in string s, or a null pointer if c does not occur 32 * in the string. 33 */ 34 35 #include <sys/asm_linkage.h> 36 37 ! Here, we start by checking to see if we're searching the dest 38 ! string for a null byte. We have fast code for this, so it's 39 ! an important special case. Otherwise, if the string is not 40 ! word aligned, we check a for the search char a byte at a time 41 ! until we've reached a word boundary. Once this has happened 42 ! some zero-byte finding values are initialized and the string 43 ! is checked a word at a time 44 45 ENTRY(strchr) 46 47 .align 32 48 49 andcc %o1, 0xff, %o1 ! search only for this one byte 50 bz,pn %ncc, .searchnullbyte ! faster code for searching null 51 andcc %o0, 3, %o4 ! str word aligned ? 52 bz,a,pn %ncc, .prepword2 ! yup, prepare for word-wise search 53 sll %o1, 8, %g1 ! start spreading findchar across word 54 55 ldub [%o0], %o2 ! str[0] 56 cmp %o2, %o1 ! str[0] == findchar ? 57 be,pn %ncc, .done ! yup, done 58 tst %o2 ! str[0] == 0 ? 59 bz,pn %ncc, .notfound ! yup, return null pointer 60 cmp %o4, 3 ! only one byte needed to align? 61 bz,pn %ncc, .prepword ! yup, prepare for word-wise search 62 inc %o0 ! str++ 63 ldub [%o0], %o2 ! str[1] 64 cmp %o2, %o1 ! str[1] == findchar ? 65 be,pn %ncc, .done ! yup, done 66 tst %o2 ! str[1] == 0 ? 67 bz,pn %ncc, .notfound ! yup, return null pointer 68 cmp %o4, 2 ! only two bytes needed to align? 69 bz,pn %ncc, .prepword ! yup, prepare for word-wise search 70 inc %o0 ! str++ 71 ldub [%o0], %o2 ! str[2] 72 cmp %o2, %o1 ! str[2] == findchar ? 73 be,pn %ncc, .done ! yup, done 74 tst %o2 ! str[2] == 0 ? 75 bz,pn %ncc, .notfound ! yup, return null pointer 76 inc %o0 ! str++ 77 78 .prepword: 79 sll %o1, 8, %g1 ! spread findchar ------+ 80 .prepword2: ! 81 sethi %hi(0x01010101), %o4 ! Alan Mycroft's magic1 ! 82 or %o1, %g1, %o1 ! across all <---------+ 83 sethi %hi(0x80808080), %o5 ! Alan Mycroft's magic2 ! 84 sll %o1, 16, %g1 ! four bytes <--------+ 85 or %o4, %lo(0x01010101), %o4 ! 86 or %o1, %g1, %o1 ! of a word <--------+ 87 or %o5, %lo(0x80808080), %o5 88 89 .searchchar: 90 lduw [%o0], %o2 ! src word 91 andn %o5, %o2, %o3 ! ~word & 0x80808080 92 sub %o2, %o4, %g1 ! word = (word - 0x01010101) 93 andcc %o3, %g1, %g0 ! ((word - 0x01010101) & ~word & 0x80808080) 94 bnz,pn %ncc, .haszerobyte ! zero byte if magic expression != 0 95 xor %o2, %o1, %g1 ! tword = word ^ findchar 96 andn %o5, %g1, %o3 ! ~tword & 0x80808080 97 sub %g1, %o4, %o2 ! (tword - 0x01010101) 98 andcc %o3, %o2, %g0 ! ((tword - 0x01010101) & ~tword & 0x80808080) 99 bz,a,pt %ncc, .searchchar ! no findchar if magic expression == 0 100 add %o0, 4, %o0 ! str += 4 101 102 ! here we know "word" contains the searched character, but no null 103 ! byte. if there was a null byte, we would have gone to .haszerobyte 104 ! "tword" has null bytes where "word" had findchar. Examine "tword" 105 106 .foundchar: 107 set 0xff000000, %o4 ! mask for 1st byte 108 andcc %g1, %o4, %g0 ! first byte zero (= found search char) ? 109 bz,pn %ncc, .done ! yup, done 110 set 0x00ff0000, %o5 ! mask for 2nd byte 111 inc %o0 ! str++ 112 andcc %g1, %o5, %g0 ! second byte zero (= found search char) ? 113 bz,pn %ncc, .done ! yup, done 114 srl %o4, 16, %o4 ! 0x0000ff00 = mask for 3rd byte 115 inc %o0 ! str++ 116 andcc %g1, %o4, %g0 ! third byte zero (= found search char) ? 117 bnz,a %ncc, .done ! nope, increment in delay slot 118 inc %o0 ! str++ 119 120 .done: 121 retl ! done with leaf function 122 nop ! padding 123 124 ! Here we know that "word" contains a null byte indicating the 125 ! end of the string. However, "word" might also contain findchar 126 ! "tword" (in %g1) has null bytes where "word" had findchar. So 127 ! check both "tword" and "word" 128 129 .haszerobyte: 130 set 0xff000000, %o4 ! mask for 1st byte 131 andcc %g1, %o4, %g0 ! first byte == findchar ? 132 bz,pn %ncc, .done ! yup, done 133 andcc %o2, %o4, %g0 ! first byte == 0 ? 134 bz,pn %ncc, .notfound ! yup, return null pointer 135 set 0x00ff0000, %o4 ! mask for 2nd byte 136 inc %o0 ! str++ 137 andcc %g1, %o4, %g0 ! second byte == findchar ? 138 bz,pn %ncc, .done ! yup, done 139 andcc %o2, %o4, %g0 ! second byte == 0 ? 140 bz,pn %ncc, .notfound ! yup, return null pointer 141 srl %o4, 8, %o4 ! mask for 3rd byte = 0x0000ff00 142 inc %o0 ! str++ 143 andcc %g1, %o4, %g0 ! third byte == findchar ? 144 bz,pn %ncc, .done ! yup, done 145 andcc %o2, %o4, %g0 ! third byte == 0 ? 146 bz,pn %ncc, .notfound ! yup, return null pointer 147 andcc %g1, 0xff, %g0 ! fourth byte == findchar ? 148 bz,pn %ncc, .done ! yup, done 149 inc %o0 ! str++ 150 151 .notfound: 152 retl ! done with leaf function 153 xor %o0, %o0, %o0 ! return null pointer 154 155 ! since findchar == 0, we only have to do one test per item 156 ! instead of two. This makes the search much faster. 157 158 .searchnullbyte: 159 bz,pn %ncc, .straligned ! str is word aligned 160 nop ! padding 161 162 cmp %o4, 2 ! str halfword aligned ? 163 be,pn %ncc, .s2aligned ! yup 164 ldub [%o0], %o1 ! str[0] 165 tst %o1 ! byte zero? 166 bz,pn %ncc, .done ! yup, done 167 cmp %o4, 3 ! only one byte needed to align? 168 bz,pn %ncc, .straligned ! yup 169 inc %o0 ! str++ 170 171 ! check to see if we're half word aligned, which it better than 172 ! not being aligned at all. Search the first half of the word 173 ! if we are, and then search by whole word. 174 175 .s2aligned: 176 lduh [%o0], %o1 ! str[] 177 srl %o1, 8, %o4 ! %o4<7:0> = first byte 178 tst %o4 ! first byte zero ? 179 bz,pn %ncc, .done2 ! yup, done 180 andcc %o1, 0xff, %g0 ! second byte zero ? 181 bz,a,pn %ncc, .done2 ! yup, done 182 inc %o0 ! str++ 183 add %o0, 2, %o0 ! str+=2 184 185 .straligned: 186 sethi %hi(0x01010101), %o4 ! Alan Mycroft's magic1 187 sethi %hi(0x80808080), %o5 ! Alan Mycroft's magic2 188 or %o4, %lo(0x01010101), %o4 189 or %o5, %lo(0x80808080), %o5 190 191 .searchword: 192 lduw [%o0], %o1 ! src word 193 andn %o5, %o1, %o3 ! ~word & 0x80808080 194 sub %o1, %o4, %g1 ! word = (word - 0x01010101) 195 andcc %o3, %g1, %g0 ! ((word - 0x01010101) & ~word & 0x80808080) 196 bz,a,pt %ncc, .searchword ! no zero byte if magic expression == 0 197 add %o0, 4, %o0 ! str += 4 198 199 .zerobyte: 200 set 0xff000000, %o4 ! mask for 1st byte 201 andcc %o1, %o4, %g0 ! first byte zero? 202 bz,pn %ncc, .done2 ! yup, done 203 set 0x00ff0000, %o5 ! mask for 2nd byte 204 inc %o0 ! str++ 205 andcc %o1, %o5, %g0 ! second byte zero? 206 bz,pn %ncc, .done2 ! yup, done 207 srl %o4, 16, %o4 ! 0x0000ff00 = mask for 3rd byte 208 inc %o0 ! str++ 209 andcc %o1, %o4, %g0 ! third byte zero? 210 bnz,a %ncc, .done2 ! nope, increment in delay slot 211 inc %o0 ! str++ 212 .done2: 213 retl ! return from leaf function 214 nop ! padding 215 216 SET_SIZE(strchr) 217
Indexes created Sat Nov 28 02:26:42 UTC 2009
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