1/* 2 * Copyright (c) 1993,94 Winning Strategies, Inc. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by Winning Strategies, Inc. 16 * 4. The name of the author may not be used to endorse or promote products 17 * derived from this software without specific prior written permission 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 */ 30 31#include <machine/asm.h> 32/* 33 * strncmp(s1, s2, n) 34 * return an integer greater than, equal to, or less than 0, 35 * according as the first n characters of string s1 is greater 36 * than, equal to, or less than the string s2. 37 * 38 * %eax - pointer to s1 39 * %ecx - pointer to s2 40 * %edx - length 41 * 42 * Written by: 43 * J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc. 44 */ 45 46/* 47 * I've unrolled the loop eight times: large enough to make a 48 * significant difference, and small enough not to totally trash the 49 * cache. 50 * 51 * TODO: change all the jz's back to je for consistency. 52 */ 53 54ENTRY(strncmp) 55 pushl %ebx 56 movl 8(%esp),%eax 57 movl 12(%esp),%ecx 58 movl 16(%esp),%edx 59 testl %edx,%edx 60 jmp L2 /* Jump into the loop! */ 61 62 .align 2,0x90 63L1: incl %eax 64 incl %ecx 65 decl %edx 66L2: jz L4 /* strings are equal */ 67 movb (%eax),%bl 68 testb %bl,%bl 69 jz L3 70 cmpb %bl,(%ecx) 71 jne L3 72 73/* 74 * XXX it might be best to move the next 4 instructions to the end of the 75 * unrolled part of the loop. The unrolled part would then be 76 * movb n(%eax),%bl; testb %bl, %bl; je L3; cmpb n(%ecx); jne L3 77 * or maybe better 78 * movb n(%eax),%bl; cmpb n(%ecx); jne L3; testb %bl,%bl; je return_0 79 * for n = 0, 1, ..., 8. The end of the loop would be 80 * L1: addl $8,%eax; addl $8,%ecx; subl $8,%edx; cmpl $8,%edx; jae Lx 81 * where residual counts of 0 to 7 are handled at Lx. However, this would 82 * be slower for short strings. Cache effects are probably not so 83 * important because we are only handling a byte at a time. 84 */ 85 incl %eax 86 incl %ecx 87 decl %edx 88 jz L4 89 movb (%eax),%bl 90 testb %bl,%bl 91 jz L3 92 cmpb %bl,(%ecx) 93 jne L3 94 95 incl %eax 96 incl %ecx 97 decl %edx 98 jz L4 99 movb (%eax),%bl 100 testb %bl,%bl 101 jz L3 102 cmpb %bl,(%ecx) 103 jne L3 104 105 incl %eax 106 incl %ecx 107 decl %edx 108 jz L4 109 movb (%eax),%bl 110 testb %bl,%bl 111 jz L3 112 cmpb %bl,(%ecx) 113 jne L3 114 115 incl %eax 116 incl %ecx 117 decl %edx 118 jz L4 119 movb (%eax),%bl 120 testb %bl,%bl 121 jz L3 122 cmpb %bl,(%ecx) 123 jne L3 124 125 incl %eax 126 incl %ecx 127 decl %edx 128 jz L4 129 movb (%eax),%bl 130 testb %bl,%bl 131 jz L3 132 cmpb %bl,(%ecx) 133 jne L3 134 135 incl %eax 136 incl %ecx 137 decl %edx 138 jz L4 139 movb (%eax),%bl 140 testb %bl,%bl 141 jz L3 142 cmpb %bl,(%ecx) 143 jne L3 144 145 incl %eax 146 incl %ecx 147 decl %edx 148 jz L4 149 movb (%eax),%bl 150 testb %bl,%bl 151 jz L3 152 cmpb %bl,(%ecx) 153 je L1 154 155 .align 2,0x90 156L3: movzbl (%eax),%eax /* unsigned comparison */ 157 movzbl (%ecx),%ecx 158 subl %ecx,%eax 159 popl %ebx 160 ret 161 .align 2,0x90 162L4: xorl %eax,%eax 163 popl %ebx 164 ret 165END(strncmp) 166 167 .section .note.GNU-stack,"",%progbits 168